Idiopathic Intracranial Hypertension

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Practice Essentials

Idiopathic intracranial hypertension (IIH) is a disorder of unknown etiology that predominantly affects obese women of childbearing age.[1] The primary problem is chronically elevated intracranial pressure (ICP), and the most important neurologic manifestation is papilledema, which may lead to progressive optic atrophy and blindness. Although IIH, pseudotumor cerebri, and benign intracranial hypertension (BIH) are synonymous, IIH is the preferred term.

Essential update: Acetazolamide improves visual function in patients with idiopathic intracranial hypertension

In a new study of 165 patients with IIH and mild vision loss, researchers found that acetazolamide treatment for six months in conjunction with a low-sodium weight-reduction diet modestly improved vision, reduced intracranial pressure, improved quality of life, and reduced papilledema. Average improvement in perimetric mean deviation (PMD) was 1.43 dB with acetazolamide and 0.71 dB with placebo. Data show that the effect of the drug was independent of weight loss.[2, 3]

Signs and symptoms

Patients with IIH usually present with symptoms related to increased ICP and papilledema. Symptoms of increased ICP may include the following:

Rarely, patients presenting with increased ICP with related optic nerve edema may be asymptomatic.

Symptoms of papilledema may include the following:

Nonspecific symptoms of IIH may include dizziness, nausea, vomiting, photopsias, and retrobulbar pain.[4]

The most significant physical finding is bilateral disc edema secondary to the increased ICP. In more pronounced cases, macular involvement with subsequent edema and diminished central vision may be present.

High-grade and atrophic papilledema in addition to subretinal hemorrhages are poor visual prognostic signs. Uncontrolled papilledema results in progressive peripheral visual field constriction or nerve fiber bundle defects.

Sudden loss of central vision may result from an associated anterior ischemic optic neuropathy, a vascular occlusion, or an associated subretinal neovascular membrane

Visual function tests are the most important parts of the neurologic examination for diagnosing and monitoring patients with IIH. Such tests include the following:

See Clinical Presentation for more detail.

Diagnosis

Recommended blood tests include the following:

Cerebrospinal fluid studies include the following:

Imaging studies that may be helpful include the following:

Once an intracranial mass lesion is ruled out, lumbar puncture is indicated.

See Workup for more detail.

Management

The goal is to preserve optic nerve function while managing increased ICP. Pharmacologic therapy may include the following:

If visual function deteriorates, surgical or other invasive interventions may be considered. Such interventions include the following general approaches:

Treatment of IIH with repeated lumbar punctures is considered to be of historic interest only.

A meta-analysis comparing visual outcomes after these interventions reported the following findings[5] :

Weight loss is a cornerstone of long-term management of these patients. No activity restriction is required; in fact, exercise programs are strongly recommended in conjunction with the weight-reduction diet.

See Treatment and Medication for more detail.

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Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped ....

Background

Idiopathic intracranial hypertension (IIH) is a disorder of unknown etiology that predominantly affects obese women of childbearing age.[1] The primary problem is chronically elevated intracranial pressure (ICP), and the most important neurologic manifestation is papilledema, which may lead to progressive optic atrophy and blindness.

The presentation of a patient with symptoms of increased ICP and papilledema should be considered a clinical emergency until neuroimaging study results confirm the presence or absence of an intracranial mass. A significant number of patients presenting in this manner whose neuroimaging study results do not reveal a mass lesion are diagnosed with IIH. Although IIH, pseudotumor cerebri, and benign intracranial hypertension (BIH) are synonymous and refer to the same diagnosis, IIH is the preferred term.

The diagnostic criteria for IIH, including those of the modified Dandy criteria as described by Dandy in 1937 and later modified by Smith in 1985, are as follows:

Subsequent additions to these criteria include the following[6, 7, 8] :

Pathophysiology

The pathophysiology of IIH is unclear. A dominant early theory held that cerebral edema played a role in the pathogenesis of elevated ICP in these patients. Against this view was the observation that no altered levels of alertness, cognitive impairments, or focal neurologic findings were associated with the elevated ICP. In addition, no pathologic signs of cerebral edema were documented in these patients. Early reports describing edema were later considered to represent fixation artifact (ie, from tissue preparation) rather than in vivo edema.

Current hypotheses include the link between relatively obstructive segments in the distal transverse sinus and IIH and the presence of increased arterial inflow with an accompanying low-grade stenosis of the transverse sinus.[9, 4]

In a series reported by Farb et al, 29 patients with IIH showed demonstrable narrowing of the transverse dural venous sinus on magnetic resonance (MR) venography, whereas none of the 59 control subjects had this finding.[10] The authors suggested that the narrowing is a consequence of elevated ICP and that when the narrowing develops, it exacerbates the pressure elevation by increasing venous pressure in the superior sagittal sinus. Their findings underscored the following points:

Bateman showed that some IIH patients with normal dural venous drainage have increased arterial inflow, which suggests that collateral venous drainage occurs in addition to the drainage provided by the superior sagittal sinus and transverse sinuses.[11]

Bateman also used MR venography and MR flow quantification in cerebral arteries and veins in 40 IIH patients, 21 of whom had venous stenosis; arterial inflow was 21% higher than normal, and superior sagittal sinus outflow was normal, resulting in a reduced percentage of venous outflow as compared with inflow.[12] The remainder of arterial inflow volume was presumed to have drained via collateral venous channels. With clinical remission of symptoms, arterial inflow volumes returned to normal.

Subsequently, Bateman et al proposed a mathematical model to address the role of collapsible dural venous sinuses in the pathogenesis of IIH; the model included arterial inflow volume, venous outflow resistance, and CSF pressure.[9] The investigators used combined flow rates in the 2 carotid arteries and the basilar artery (as measured by MRI in individual patients) as the measure of inflow blood volume and used measured values from the literature for the pressure gradient from superior sagittal sinus to jugular bulb and venous outflow resistance.

The model predicts 2 CSF pressure equilibrium points for the collapsible dural sinus cases with greater than 40% stenosis (usually of the transverse sinus), one in the normal range and the other in the range encountered in IIH patients.[9] This accounts for the prolonged remission of symptoms that follows removal of CSF through lumbar puncture, presumably because this step relieves the venous sinus stenosis.

Without dural sinus collapse and stenosis, as is encountered in some patients with IIH, the model required increased arterial inflow volume to account for the elevated ICP; however, it did not require increased resistance to outflow of CSF across the arachnoid villi.[9]

IIH commonly occurs in women who are overweight; however, the role obesity plays in this disorder is unclear. In some instances, obesity and IIH may be familial.[13] It has been proposed that obesity increases intra-abdominal pressure and thereby raises cardiac filling pressures. These rises in pressure lead to impeded venous return from the brain (due to the valveless venous system that exists from the brain to the heart) with a subsequent elevation in intracranial venous pressure.

If this process is not treated appropriately, chronic interruption of the axoplasmic flow of the optic nerves with ensuing papilledema as a consequence of this pressure may lead to irreversible optic neuropathy.[14]

Etiology

Most cases of IIH occur in young women who are obese; a considerably smaller percentage occur in men who are otherwise healthy. Patients with higher body mass indexes (BMIs) and recent weight gain are at increased risk.[4, 14] If IIH presents in an individual who is not overweight, it is necessary to rule out associated risk factors, such as the following[8, 4] :

In 1994, Radhakrishnan et al reviewed the literature on IIH associated with other diseases and with drugs. They argued that for these diseases and drugs to be included in the list of causally related associations, the following criteria should be met[15] :

Exogenous substances

The list of exogenous substances associated with IIH is extensive. Although the association between these substances and this disorder is generally considered well established, the exact causal relation has not been fully clarified in the literature.

Exogenous substances associated with IIH include amiodarone, antibiotics (eg, nalidixic acid, penicillin, and tetracycline), carbidopa, levodopa, chlordecone, corticosteroids (topical and systemic), cyclosporine, danazol, growth hormone, indomethacin, ketoprofen, lead, leuprolide acetate, levonorgestrel implants, lithium, oral contraceptives, oxytocin, perhexiline, phenytoin, and vitamin A (> 100,000 U/day)/retinoic acid.[8, 4]

According to the 1994 review by Radhakrishnan et al and numerous subsequent reports,[16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32] medication risk factors that meet minimal criteria but have not been confirmed in case-controlled studies include the following:

In some instances, although a patient may present with IIH after exposure to a certain medication, the disorder can continue despite discontinuance of the presumed offending agent.

Withdrawal from corticosteroids may result in IIH.[8] If corticosteroids are used for the treatment of IIH, their withdrawal may lead to a rebound increase in ICP.[6]

Systemic diseases

A myriad of illnesses are associated with IIH. Some of these disorders are known to result in increased viscosity of the CSF. In most of them, however, the causal link with Increased ICP is not clear. The following diseases have all been associated with IIH[8] :

Disorders of cerebral venous drainage

Compression of cerebral veins by extravascular tumors, secondary thrombosis due to coagulopathy, or relative stenosis due to a venous flow anomaly can result in impaired absorption of CSF and, thus, IIH.[9, 35] Restriction of venous drainage from the head may be impaired with radical neck dissection, even if it is completed only on the right (drainage from the head takes place mainly via the right jugular vein). Spontaneous recanalization usually occurs, but if it is delayed, chronic papilledema may result.

The diagnosis of cerebral sinus thrombosis may be missed if only computed tomography (CT) is performed. Therefore, in patients who present atypically or in cases where management dilemmas arise, it is worthwhile to perform MRI or MR venography to rule out cerebral venous thrombosis.

Endocrine disturbances

Pregnancy is occasionally associated with IIH.[6] The disorder can present at any stage of pregnancy. In view of the limitations of neuroimaging studies and the restrictions on medical treatment in pregnant patients, it is advisable that both diagnostic and therapeutic strategies be formulated on a case-by-case basis. Any neuroimaging studies or therapeutic interventions should be performed in conjunction with the patient’s obstetrician.

According to reports by Radhakrishnan and others,[16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32] endocrine risk factors that have been confirmed in epidemiologic studies include the following:

Endocrine risk factors that meet minimal criteria but have not been confirmed in case-controlled studies include the following:

Other risk factors

Increased venous red blood cell (RBC) aggregation and relatively elevated fibrinogen concentrations have been demonstrated in patients with IIH as compared with matched control subjects.[36]

The ratio of retinol to retinol-binding protein is elevated in the CSF of patients with IIH as compared with non-IIH neurologic control subjects and with normal control subjects.[37]

Because IIH is concentrated in women between puberty and menopause, Fraser et al emphasized the potential role of sex hormones in the pathogenesis of IIH; they also pointed out that obstructive sleep apnea (OSA) has been proposed as a risk factor.[38] Because women taking exogenous estrogen and pregnant women are not at particular risk for IIH, the investigators suggested that low levels of testosterone might be the important hormonal link in women with IIH.

Fraser et al administered 2 standardized questionnaires embedded in a telephone interview of 24 men with IIH and 48 control subjects matched for gender, age, race, and World Health Organization (WHO) BMI category.[38] They found that the men with IIH were significantly more likely to have symptoms of testosterone deficiency and OSA than the control subjects were.

Epidemiology

United States statistics

Studies of American-based populations have estimated that the incidence of IIH ranges from 0.9 to 1.0 per 100,000 in the general population, increasing to 1.6-3.5 per 100,000 in women and to 7.9-20 per 100,000 in women who are overweight.[6, 8, 4]

For example, annual figures for IIH in Iowa and Louisiana in the late 1980s were as follows[39] :

Annual incidence figures for the Mayo Clinic (Rochester, MN) between 1976 and 1990 were as follows[40] :

International statistics

The incidence of IIH varies from country to country. Because of the disease’s relation to body habitus, its occurrence varies according to the incidence of obesity in the respective region.

In a study conducted between 1982 and 1989 that comprised 81 patients (76 females and 5 males) aged 8-55 years, the annual incidence of IIH in Benghazi, Libya, was as follows[41] :

Age-, sex-, and race-related demographics

Although IIH may affect individuals of any age, most patients with this disease present in the third decade of life.[4] IIH can occur in the pediatric population[42] ; these younger patients are often not obese.

IIH has a strong predilection for women. More than 90% of patients with IIH are women of childbearing age.[4] However, men with IIH are twice as likely as women to lose visual function as a result of papilledema. Thus, the visual function of men with IIH must be followed more closely to avoid irreversible damage.[43]

No evidence exists to suggest that IIH has a predilection for any particular racial or ethnic group over and above any variations in the prevalence of obesity that may be noted in the different groups.

Prognosis

IIH is not known to be associated with any specific mortality risk. The increased mortality associated with morbid obesity has a selective expression in this group because of the strong predilection of the disease to affect obese females.

The morbidity of IIH is mainly related to the effects of papilledema on visual function.[44] If left untreated, long-standing disc edema results in an irreversible optic neuropathy with accompanying constriction of the visual field and loss of color vision.[45, 46, 47] In end-stage papilledema, central visual acuity is also involved. With timely and appropriate treatment of IIH, the visual prognosis can be encouraging.

Unfortunately, the incidence of visual loss has been reported to be significant in some studies of this disease.

Since the increase in ICP tends to be chronic, all patients with IIH must be monitored for years after presentation. If necessary, medical treatment should be continued on a long-term basis.

Vision loss

The frequency and degree to which vision loss occurs in IIH is difficult to establish from the existing literature. Depending on the referral population and the rigor with which visual function is tested, the prognosis for vision loss in IIH has varied considerably in different series. Authors writing in the 1960s and 1970s indicated that fewer than 25% of these patients had functionally significant blindness; however, this figure has since been revised upward.

As outlined by Radhakrishnan et al in 1994,[15] the reported incidence of vision impairment is much higher in series from referral centers (as many as 96% of cases with some degree of visual field loss) than in population-based series (eg, 22% in Iowa[39] ). Two equally valid explanations for this discrepancy have been proposed:

In a major prospective study of visual function in IIH, Wall and George found that 96% of the 50 patients in a series had some degree of visual field loss on Goldmann-type perimetry, whereas 92% had abnormal findings on automated perimetry[48] ; 50% had abnormal contrast sensitivity, and 22% had abnormal Snellen visual acuity. During follow-up (2-39 months; average, 12.4 months), visual fields improved in 60% of patients and deteriorated in 10%.

The University of Iowa observed 20 IIH patients for more than 10 years and found that whereas 11 of the 20 had followed a stable course without visual-field changes or papilledema, 9 had experienced deterioration after initially following a stable course for a time.[49] In 6 of the 9, the deterioration occurred late (28-135 months after initial presentation), and in 3 of the 9, recurrences after resolution of papilledema developed 12-78 months after the initial resolution of IIH.

Patient Education

Informing patients who are overweight that weight control is a long-term factor in the management of IIH is important. Asking patients about their weight loss at the beginning of each visit reinforces this concept. In addition, it may be worthwhile to mention that the loss of as little as 6% of body weight may lead to the termination of this disorder and also may significantly diminish the risk of its recurrence. An ongoing study is trying to determine if systematic weight loss alone is sufficient to resolve this disease in patients without visual loss (Idiopathic Intracranial Hypertension Treatment Trial at NORDIC Clinical Trials).

In particular, it is essential to educate patients regarding the potential for disabling blindness. The importance of weight loss as the only effective means of reducing the papilledema—and with it the threat of progressive blindness—cannot be overemphasized.[50, 51]

Patients should be urged to enroll in an aggressive weight-loss program, ideally one using a multidisciplinary approach that includes diet and exercise along with psychological and lifestyle counseling. Even when such a program is followed, many patients cannot sustain significant weight reduction and may require drastic steps such as gastric stapling or resection. These measures can be effective for patients who experience vision loss despite aggressive medical and surgical management.[52, 53]

Although IIH may appear to be self-limiting, it is considered to be a chronic disorder; therefore, once the medications given to treat it are tapered off, patients should be instructed to return to an ophthalmologist if symptoms of increased ICP recur. If a particular agent, such as tetracycline, is associated with the rise in ICP, the patient should be educated to avoid this agent.

History

Patients with idiopathic intracranial hypertension (IIH) usually present with symptoms related to increased intracranial pressure (ICP) and papilledema, including headache, transient visual obscurations, and diplopia due to unilateral or bilateral abducens nerve (cranial nerve [CN] VI) palsy. Rarely, patients presenting with increased ICP with related optic nerve edema may be asymptomatic. Nonspecific symptoms may include dizziness, nausea, vomiting, photopsias, retrobulbar pain, and pulse-synchronous tinnitus.[4]

Symptoms of elevated intracranial pressure (ICP)

Headaches are recorded in almost all IIH patients.[54] They are typically nonspecific and vary in type, location, and frequency. The pain is generally described as being diffuse, worsening in the morning and being exacerbated by the Valsalva maneuver.

Patients who present with double vision most frequently complain of horizontal displacement of the images. Horizontal diplopia is a symptom of a false-localizing CN VI palsy. Vertical diplopia is rare, but it has been reported.

Pulsatile tinnitus may be reported. This is a rhythmic sound, heard in one or both ears, with a pulsing synchronous rhythm that may be exacerbated by the supine or bending position.

Radicular pain (usually in the arms) is an uncommon symptom.

Symptoms of papilledema

Transient visual obscurationsoccur in most patients. The disturbance can last up to 30 seconds and is described as a dimming or blackout of vision in one or both of the eyes. These obscurations may be predominantly or uniformly orthostatic (ie, developing with standing up or bending over).

Progressive loss of peripheral vision in one or both of the eyes may be noted. Typically, the vision loss starts in the nasal inferior quadrant and is followed by loss of the central visual field (possibly affecting visual acuity) and, finally, loss of color vision.

Blurring and distortion (ie, metamorphopsia) of central vision is caused by macular wrinkling and subretinal fluid spreading from the swollen optic disc.

Sudden visual loss is due to intraocular hemorrhage secondary to peripapillary subretinal neovascularization related to chronic papilledema.

Physical Examination

The most significant physical finding in patients with IIH is bilateral disc edema secondary to the increased ICP.

This papilledema varies from patient to patient and is indistinguishable from optic nerve swelling caused by intracranial space-occupying lesions. In more pronounced cases of disc swelling, macular involvement with subsequent edema and diminished central vision may be present. High-grade and atrophic papilledema in addition to subretinal hemorrhages are poor visual prognostic signs. In some instances, the disc swelling is asymmetric; in rare instances, the appearance of the optic nerve is relatively normal.

If left untreated, chronic disc swelling eventually leads to clinically significant visual loss. Although all patients present with enlarged blind spots during their initial perimetry, uncontrolled papilledema results in progressive peripheral visual field constriction or nerve fiber bundle defects (eg, nasal depression, nasal steps, and arcuate scotomas).

The central visual field is affected in end-stage chronic papilledema. Sudden loss of central vision may result from an associated anterior ischemic optic neuropathy, a vascular occlusion, or an associated subretinal neovascular membrane.

The diplopia noted in patients with idiopathic intracranial hypertension is invariably due to unilateral or bilateral CN VI palsy. These CN palsies diminish with the lowering of the ICP. Occasionally, patients with diplopia present with oculomotor or trochlear nerve palsy. In rare instances, vertical diplopia is due to a skew deviation.

Visual function testing

Visual function tests—in particular, ophthalmoscopy (funduscopy), visual field assessment, and ocular motility examination—are the most important parts of the neurologic examination for diagnosing and monitoring patients with IIH.

Ophthalmoscopy

Peripapillary flame hemorrhages, venous engorgement, and hard exudates are features consistent with acute papilledema. Telangiectatic vessels on the disc surface, optociliary shunt veins (which exit the disc at its margin), and optic disc pallor are associated with chronic papilledema (see the images below).


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Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped ....


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Right optic disc with postpapilledema optic atrophy in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc....

Visual field assessment

The first sign of incipient postpapilledema optic atrophy is constriction of the inferior nasal quadrant of the visual field with a border reflecting the nasal horizontal midline (nasal step). This starts in the most peripheral points in the visual field (ie, 50° from fixation) and progresses inward (see the image below).


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Most common early visual field defect in papilledema as optic nerve develops optic atrophy is inferior nasal defect, as shown in left eye field chart ....

Goldmann-type dynamic perimetry is the best test, in that it provides reliable information concerning the most peripheral parts of the visual field. Computerized automated Humphrey-type static perimetry is generally unreliable beyond 30° of eccentricity and may not be as sensitive as dynamic perimetry for this problem.

Visual acuity is usually normal until significant peripheral visual field loss with progressive postpapilledema optic atrophy has occurred.

Color vision is usually tested in the office with color-confusion type plates, most commonly the Ishihara or Hardy-Rand-Rittler (HRR) plates. Unlike visual acuity testing, it is not sensitive in picking up early postpapilledema optic atrophy, because color perception is concentrated in the central visual field.

Ocular motility examination

Occasionally, limited abduction of one or both of the eyes results from increased ICP. This is termed false-localizing CN VI palsy. It can usually be observed as the patient follows the examiner’s hand to the right and the left with both eyes.

Typically, the involved eye does not move fully outward, leaving some white sclera showing lateral to the cornea on the involved side in comparison with the other side. The speed of the abducting movement also is usually less in the paretic eye than in the normal eye. Some patients with full abduction still show some sclera; therefore, when using this sign demonstrating asymmetry between the eyes in abduction is important.

Diplopia testing is another way to detect even a low-grade CN VI paresis. The patient is told to look at a focal light source (eg, a penlight or Finnoff head), preferably placed more than 3 m away. Either a red glass or a Maddox rod is placed in front of the patient’s right eye. The Maddox rod creates an image of a vertical red line when the patient views a focal light source through it.

In a positive test for limited abduction, the red image (the focal light or line) is displaced to the right of the light in the patient’s view (ie, homonymous or uncrossed diplopia). This indicates that the visual axes are convergent with respect to one another (esotropia, relative weakness of the lateral rectus muscle or muscles, or CN VI palsy).

Alternate cover testing also may reveal a slight corrective saccade when the other eye is covered in patients with CN VI palsies.

Complications

The only severe and permanent complication of IIH is progressive blindness from postpapilledema optic atrophy. As optic nerve axons die, the apparent degree of papilledema may diminish, giving a false sense of improvement. For this reason (and others), the patients must be monitored with frequent visual field examinations.

The earliest visual loss is in the peripheral fields (outside 30°), and thus, Goldmann-type dynamic perimetry is preferred to computerized automated static perimetry. For reasons that are not clear, the earliest field loss tends to be in the inferior nasal quadrant. Visual acuity and color vision are not affected until late in the disease, when the peripheral visual field isopters are quite contracted.

Occasionally, a patient may develop an acute loss of vision due to ischemic optic neuropathy or a retinal vascular occlusion associated with the papilledema.

Laboratory Studies

Blood tests

Blood tests are useful for ruling out systemic lupus erythematosus or other collagen-vascular diseases, which have been reported as underlying conditions in some patients who present with idiopathic intracranial hypertension (IIH).[55]

An increased incidence of anticardiolipin antibodies has been reported in patients with IIH. Accordingly, some authors advocate anticardiolipin antibody assessment in all IIH patients, regardless of prior history of thrombosis.[56] Some authors advocate screening for anticardiolipin antibodies and other procoagulant states in all patients with IIH who are either male or nonobese.[57]

Cases of IIH associated with Lyme disease have been reported.[58]

Most patients with typical history, gender, and body habitus need only routine blood work, if any. Recommended blood tests include the following:

Lyme screening test (enzyme-linked immunosorbent assay [ELISA]) in patients who have a history of exposure to Lyme in areas of endemic disease

CSF tests

CSF studies include the following:

Most patients with typical history, gender, and body habitus need only routine CSF tests. However, extra fluid should be frozen in case the preliminary workup reveals unexpected abnormalities such as pleocytosis or elevated gamma globulin, which would indicate that more complete investigation for autoimmune, infectious, or neoplastic conditions is warranted.

MRI and CT

A patient with bilateral disc swelling should undergo urgent neuroimaging studies to rule out an intracranial mass or a dural sinus thrombosis. In the setting of IIH, the findings on neuroimaging studies include normal or small slitlike ventricles, enlarged optic nerve sheaths, and, occasionally, an empty sella.

MRI of the brain with gadolinium enhancement is probably the study of choice for all patients with IIH, in that it provides sensitive screening for hydrocephalus, intracerebral masses, meningeal infiltrative or inflammatory disease, and dural venous sinus thrombosis. In a retrospective study of imaging features that have been suggested as typical for patients with IIH, only flattening of the posterior globe was found to be a reliable indicator of IIH, with a specificity of 100% and a sensitivity of 43.5%.[59]

MR venography can be useful for patients who are at greater risk for dural venous sinus thrombosis, such as those with suspected thrombosis on MRI, nonobese or male individuals, or those with a documented procoagulant state. Sagittal T1-weighted images often provide excellent views of the superior sagittal sinus, and these typically are included in routine MRI. Extraluminal narrowing of the transverse sinuses may be a typical feature of IIH, as reported by Farb et al.[10]

Computed tomography (CT) of the brain is less expensive than MRI and is adequate to rule out an intracranial lesion in most instances; however, MRI and magnetic resonance (MR) venography are more effective in ruling out a mass lesion and a dural sinus thrombosis, respectively. Although MR venography was once considered an elective imaging study for atypical patients, it is now increasingly accepted as a routine study for all patients with IIH.[60]

Ultrasonography

Bedside ultrasonography has been used to identify intracranial hypertension by precisely measuring the diameter of the optic nerve sheath.[61] If this diameter increases in primary gaze and diminishes by 25% in eccentric gaze (30° test), then increased subarachnoid fluid surrounding the optic nerve is presumably present. This finding is consistent with papilledema if it is bilateral.

The drawback of this noninvasive technique is that it requires a highly skilled clinician to obtain reproducible results.

Lumbar Puncture

Once an intracranial mass lesion is ruled out, lumbar puncture is indicated. The opening pressure should be measured with the patient relaxed in the decubitus position to prevent a falsely elevated pressure reading. If any specific difficulty was encountered that may have caused such as false elevation, the clinician performing the procedure must communicate this to the ophthalmologist. Unfortunately, some patients demonstrate a transiently normal pressure despite harboring IIH; confirming the disease in these patients is difficult.

Besides the value of the opening pressure, the clarity and the color of the cerebrospinal fluid should be noted. In addition, the cerebrospinal fluid (CSF) should be forwarded for cell count, cytology, culture, and measurement of glucose, protein, and electrolyte concentrations. All of these findings are normal in patients with IIH.

In obese patients, finding landmarks may be difficult; consequently, the tap is often performed with the patient seated. It should be kept in mind that the normal CSF pressure at the foramen magnum in the seated position is nearly 500 mm water from the lumbar entry point in persons of average height. Thus, an opening pressure of 500 mm water is extremely high for the lateral decubitus position but normal for the sitting position. If possible, the patient should be moved to the lateral decubitus position before the pressure is measured.

Another approach to lumbar puncture in obese patients utilizes fluoroscopic guidance in the radiology department. The prone positioning on the x-ray table and the increased abdominal pressure in this position may elevate the CSF pressure falsely. If the pressure is normal with the patient in the prone position, then the measurement is probably accurate. However, if it is high, the patient must be rolled into the lateral decubitus position and allowed to relax before a reliable pressure reading can be completed.

Obviously, such maneuvers carry a risk of displacing the needle from the thecal space. However, no alternative method exists for obtaining an accurate pressure reading.

Approach Considerations

The treatment goal for patients with idiopathic intracranial hypertension (IIH) is to preserve optic nerve function while managing increased intracranial pressure (ICP). Medical management is multifaceted. Optic nerve function should be carefully monitored with an assessment of visual acuity, color vision, optic nerve head appearance, and perimetry. Weight control is recommended for obese patients.[62] Exogenous agents related to increased ICP should be discontinued.

Patients without visual loss most often are treated with a carbonic anhydrase inhibitor (eg, acetazolamide) to lower the ICP. Some authors believe that digoxin has the same effect and is associated with fewer adverse effects. In patients with severe symptoms, early visual field loss, or poor response to standard medical therapy, some clinicians utilize a short course of high-dose corticosteroids (eg, prednisone).

When new visual field loss is documented, medical management should be coupled with plans for emergency surgical intervention if the visual function continues to deteriorate or does not improve immediately with corticosteroid treatment.

Visual loss in one or both of the eyes can evolve rapidly despite the best efforts to arrest the process. In this author’s experience, IIH has been the most frequent cause of litigation encountered. Almost uniformly, cases center on the delay of maximum medical and surgical management beyond what is considered ideal and standard practice in the United States for patients who present with rapidly declining vision.

The exact time window within which vision loss can be reversed after symptomatic decline is not known. Opinions among experts in the field vary as to how rapidly and aggressively any given patient should have been treated. As a rule, it is better to err on the side of rapid intervention (ie, within hours to days) in such patients. This is a dramatic opportunity to save vision that can be easily lost. A major medicolegal pitfall is created when poor outcome is coupled with the perception of delayed treatment.

One of the standard teachings regarding this condition has been that pregnancy exacerbates or triggers the onset of symptomatic IIH. At present, however, there is little statistical evidence of a causal association between pregnancy and IIH, beyond the fact that pregnancy is common in the age group and gender that is predominantly affected by IIH.[63, 64]

Pharmacologic Therapy

Acetazolamide and furosemide

Acetazolamide appears to be the most effective agent for lowering ICP. Most patients experience adequate relief of symptoms (typically, headache) with this first-line agent. The brand-name formulation Diamox appears to be better tolerated than generic acetazolamide is.

The initial dosage should be 0.5-1 g/day. Although many physicians start patients on 250 mg twice daily, others consider this dosage too low. A 500-mg oral dose of Diamox Sequels twice daily is preferred; however, some insurers only cover an oral dose of 250 mg 4 times per day. Most patients respond to a dosage of 1-2 g/day. This can be increased to 3-4 g/day, but most patients cannot tolerate the adverse effects (eg, extremity paresthesias, fatigue, metallic taste from carbonated beverages, and decreased libido) that occur at this high dosage.[4, 6]

In the event of intolerance to acetazolamide, furosemide may be used as a replacement diuretic in this group. Unfortunately, it does not appear to be as effective as acetazolamide.

Headache prophylaxis

For patients with stable visual function but inadequate headache relief with first-line pressure-lowering drugs, primary headache prophylaxis should be considered. Patients with IIH may experience headaches that have many of the features of migraine. These headaches can often be controlled with amitriptyline, propranolol, or other commonly prescribed migraine prophylaxis agents. Topiramate is also an excellent choice, in that one of its side effects is weight loss (a common association in IIH), which can help put the disease in remission.

Corticosteroids

Corticosteroids are effective in lowering ICP in patients whose IIH has an inflammatory etiology. In addition, they may be used as a supplement to acetazolamide to hasten recovery in patients who present with severe papilledema. Because of their significant adverse effects, corticosteroids should not be considered as a long-term solution for IIH patients. In addition, a rebound in the ICP may occur during the tapering of the corticosteroid dosage.[6]

Patients experiencing a progressive loss of visual field in one or both of the eyes should immediately be placed on high-dose (60-100 mg/day) oral prednisone (or an equivalent corticosteroid regimen). Digoxin and furosemide have been advocated by some investigators, but these are on the same level of effectiveness as acetazolamide and are not appropriate as sole therapy for patients who are losing vision.

If a moderately severe new visual field loss is detected on a routine office visit, and the patient is not experiencing progressive symptoms, outpatient management can continue. However, visual fields should be measured every few days or at 1- to 2-week intervals, depending on the magnitude and progression of the defect. If the visual field continues to worsen on corticosteroid treatment, the patient should be admitted for immediate surgical management.

If the patient presents with symptomatic deterioration of vision, and the examination documents worsening of visual field despite adequate standard medical therapy, the patient should be started immediately on corticosteroids, as previously outlined. The patient also should be admitted to the hospital for consideration of emergency surgical decompression. Visual field examination should be performed daily, and surgical decompression should be carried out if no improvement or further worsening is noted in the subsequent 24-48 hours.

Optic Nerve Sheath Fenestration, CSF Diversion, and Venous Sinus Stenting

Patients with IIH should be closely monitored while on medical treatment. The frequency of visits is determined by the initial state of the patient’s visual function and the response to medical treatment. Despite close follow-up care and maximum medical treatment, some patients experience deterioration of their visual function. In this situation, surgical intervention may be considered. Such intervention most often takes 1 of the following 2 general approaches:

However, intracranial venous sinus stenting has also been investigated (see below). Treatment of IIH with repeated lumbar punctures is considered to be of historic interest only.

Optic nerve sheath fenestration

The ophthalmic surgical approach to managing patients with progressive vision loss and papilledema involves cutting slits or rectangular patches in the dura surrounding the optic nerve immediately behind the globe.[65] This allows direct egress of CSF into the orbital fat, where it is absorbed into the venous circulation.

Optic nerve sheath fenestration has been demonstrated to reverse optic nerve edema and to bring about some recovery of optic nerve function. In addition, it may decrease headache in many patients. The approach to the optic nerve may be from either the medial or the lateral aspect of the orbit; each approach has its benefits and drawbacks.[66]

Although ICP typically remains elevated in these patients postoperatively, the local filtering effect of the fenestration acts as a safety valve and keeps the pressure from being transmitted to the optic nerve. Despite the general lack of an ICP-lowering effect, unilateral surgery occasionally has a bilateral curative effect on the papilledema. However, if this is not the case, the opposite nerve must undergo the same procedure.

Complications related to optic nerve sheath fenestration include the following:

Diplopia

Optic nerve injury

Unfortunately, the procedure may not have lasting benefits. In most cases, visual function stabilizes or improves after optic nerve sheath decompression in the short run,[67] but in at least one third of cases, secondary visual decline may occur within 3-5 years and may necessitate repeat surgery or an alternative treatment; Spoor and McHenry found the long-term success rate of this operation to be only 16%.[68]

A study of optic nerve sheath fenestration performed in 41 eyes from 21 patients with vision loss from either IIH or intracranial hypertension from cerebral venous thrombosis found best-corrected visual acuity and visual field to be stabilized or improved in 32 of 34 eyes (94%) over a 3-month follow-up interval.[69] Transient benign complications were apparent in 4 eyes. Only marginal improvement was shown in 4 eyes with no light perception vision; these were not analyzed with the remainder of the group.

CSF diversion procedures

CSF diversion procedures are highly effective in lowering ICP.[70] In some facilities, they remain the procedures of choice for treating IIH patients who do not respond to maximum medical treatment.[6, 8, 66] Shunts are also indicated for patients with intractable headaches, patients in regions where there is no access to a surgeon comfortable with optic nerve sheath fenestration, and patients in whom optic nerve sheath fenestration has failed.

Lumboperitoneal shunting is the traditional method for providing prompt reduction of ICP in patients with IIH.[71] However, this procedure has a high 1-year failure rate. Some neurosurgeons currently prefer ventriculoperitoneal or ventriculoatrial shunting to lumboperitoneal shunting.

The main reason why these neurosurgeons prefer ventricular shunts is that such shunts can be monitored for function by using an extracranial subcutaneous compressible bulb and a 1-way valve (permitting intracranial-to-abdominal flow) in series with the intracranial and abdominal ends of the shunt. The bulb will resist digital compression if the distal (abdominal or atrial) end is obstructed. It will collapse under digital pressure but will fail to reinflate if the intracranial end is obstructed.

Many neurosurgeons have been reluctant to place ventricular shunts in patients with IIH because the ventricles are small and difficult to cannulate without radiographic guidance. In addition, there is a significant risk of complications (eg, infection, stroke, seizures, and shunt failure). However, Woodworth et al reported that with a frameless stereotactic approach, they were able to place ventricular shunts in a single pass in all patients, even into slit ventricles, with good long-term viability.[72]

Sinclair et al found that although CSF diversion minimizes visual decline and improves visual acuity, 68% of patients continued to have headaches and 28% had low-pressure headaches that complicated surgery. Shunt revision was required for 51% of patients, with most requiring multiple revisions. For those with otherwise untreatable rapidly declining vision, CSF diversion shunting should be conducted as a last resort. Other treatments, such as weight reduction, may be more effective and may have less associated morbidity.[73]

Intracranial venous sinus stenting

Following up on the work of Farb et al, Bussière et al studied 13 patients with IIH that was refractory to medical management who were found to have stenosis of one or both of the transverse dural sinuses on time-of-flight magnetic resonance (MR) venography. Of these, 10 also had increased pressure gradient across the stenotic dural venous sinus (>10 mm Hg), and these underwent stent placement without significant complications.[74]

All 10 of the patients experienced complete resolution or significant improvement of their headaches, and 8 experienced complete or near-complete resolution of papilledema.[74] The authors suggested only that a randomized, controlled study of transverse dural venous sinus stenting in the management of IIH was needed to establish the safety and efficacy of the procedure in this setting.

Arac et al reported 1 case of endovascular stenting for IIH and reviewed the same published series that Bussière et al did, arriving at essentially the same conclusions.[75] They also discussed Bateman’s proposed mathematical model of the relations among intracranial arterial inflow, CSF pressure, and venous outflow (see Pathophysiology).

Comparison of visual outcomes

In a meta-analysis of the existing literature comparing visual outcomes after optic nerve sheath decompression, ventriculoperitoneal and lumboperitoneal shunting, and intracranial venous sinus stenting, Feldon reported the following findings[5] :

Visual worsening was rare for all procedures. The author concluded that visual outcome was best documented for optic nerve sheath fenestration, which appeared to be the best surgical procedure for vision loss in IIH.

Bariatric Surgery

In a review of the literature on bariatric surgery for obese patients with IIH, Fridley et al found a total of 62 patients, of whom 52 (92%) experienced resolution of the presenting symptoms.[76] Of 35 patients who underwent postoperative funduscopy, 34 had resolution of papilledema. Of 12 patients who underwent pre- and postoperative visual field examinations, 11 showed resolution of visual field defects.

Among 13 patients in whom CSF pressures were measured pre- and postoperatively, there was an average postoperative decrease of 254 mm water.[76] The authors called for prospective controlled studies to confirm the effectiveness of this surgical approach for IIH patients in long-term follow-up.

Admission Criteria

Admission for pain management

Even for initial diagnosis, most patients do not require inpatient care, because lumbar puncture is usually performed in the ambulatory care setting. An occasional patient may develop an intractable low-tension headache after lumbar puncture and may require a short hospital stay for intravenous (IV) hydration and analgesic management. A blood patch (by an anesthesiologist) is sometimes indicated if the post–lumbar puncture headache does not subside spontaneously within a few days.

Admission for surgical management of increased ICP

Patients who complain of progressive visual loss (typically, constriction of peripheral vision or dimming of vision in one or both of the eyes) and have documented new visual field loss may respond to high-dose corticosteroid therapy; they should be admitted to the hospital and should undergo daily monitoring of visual function.

If the visual field worsens or does not recover promptly (ie, within 24-48 hours) with corticosteroid therapy, then emergency CSF shunting (lumboperitoneal, ventriculoperitoneal, or ventriculoatrial) or optic nerve sheath fenestration should be carried out.

If any delay in implementing surgical decompression of the failing optic nerve is anticipated, the patient should be moved to the intensive care unit (ICU) or a stepdown unit for lumbar CSF drainage until the definitive procedure can be performed. Another short-term treatment option is IV mannitol, but definitive pressure-lowering surgery must still be done within 2-3 days.

A very small number of patients with normal visual fields may require surgical relief of CSF pressure because of intractable headache. Optic nerve sheath fenestration does not provide reliable CSF pressure normalization or headache relief; thus, these patients will require a shunting procedure. Because patients with IIH frequently have other types of headaches, the decision to choose ventriculoperitoneal shunting over optic nerve sheath fenestration should not be made on the basis of headache alone.

Diet and Activity

Most patients with this disorder are females who are overweight. Weight loss is a cornerstone in the long-term management of these patients. As little as a 5-10% weight loss has been demonstrated to yield a reduction in ICP with accompanying resolution of papilledema.[51, 50, 4] Unfortunately, weight reduction generally proves to be a difficult task for these patients.[77] To formalize the process of weight reduction, referral to a dietitian is appropriate.

On initial diagnosis, a weight-reduction diet should be strongly recommended to all patients with IIH. Often, a formal weight-loss program is required. No activity restriction is required in managing IIH. In fact, exercise programs are strongly recommended in conjunction with the weight-reduction diet.

Consultations

Diagnosis and long-term management of patients with IIH requires the performance of lumbar puncture, which is typically performed by neurologists or internists, and careful monitoring of visual status (in particular, peripheral visual field and fundus photography). Vision examination and fundus photography are the domain of ophthalmologists, and neuro-ophthalmologists are especially expert in examining visual fields. A team approach is therefore needed for most, if not all, patients.

Neurosurgical consultation is required for ventriculoperitoneal shunting when patients are losing visual field and medical management does not arrest or reverse the process promptly (ie, within hours to days). Consultation with an orbital plastic surgeon is required for optic nerve sheath fenestration for the same clinical indications.

Long-Term Monitoring

The frequency of the follow-up visits is determined by a number of factors, to include the following:

Once the initial diagnosis has been established, investigations have been performed, and therapy has been initiated, the patient can be observed every 3-4 weeks.

If, however, the patient presents with a significant visual function deficit or marked papilledema, daily monitoring for 1 week is appropriate until some improvement and subsequent stability in visual function can be demonstrated. The clinician should be prepared to titrate the patient’s treatment to the status of visual function and should not hesitate to refer the patient for surgical treatment (optic nerve sheath fenestration or CSF diversion) visual function does not stabilize.

During follow-up visits, the best-corrected visual acuity for distant and near vision, color vision (with pseudoisochromatic plates), static perimetry, and optic nerve appearance (including the status of spontaneous venous pulsations) should be recorded. Patients who do not perform well on static perimetry testing may be better followed with kinetic perimetry testing.

Spontaneous pulsation of large retinal veins generally indicates a normal ICP. If the patient continues to remark on the persistence of a significant headache despite the presence of spontaneous venous pulsations, a source other than IIH for the headache should be considered.

When a patient appears to have stabilized with respect to visual function and treatment, the frequency of follow-up visits can be extended to once every 2-4 months.

Medication Summary

Specific therapy for idiopathic intracranial hypertension (IIH) is aimed at lowering intracranial pressure (ICP) pharmacologically. Carbonic anhydrase inhibitors (eg, acetazolamide) and loop diuretics (eg, furosemide) are thought to exert their effect on ICP by reducing cerebrospinal fluid (CSF) production at the choroid plexus. Cardiac glycosides have a similar effect.

Corticosteroids are indicated on a short-term basis in patients who present with severe papilledema and compromise of their visual function. They are effective in reducing ICP, but the mechanism of action is unknown. Corticosteroids are often used as maximum medical management when rapid lowering of ICP is required.

Patients with IIH may experience headaches that have many of the features of migraine. These headaches can often be controlled with amitriptyline, propranolol, or other commonly prescribed migraine prophylaxis agents. Topiramate is also an excellent choice, in that one of its side effects is weight loss (a common association in IIH), which can help put the disease in remission.

Acetazolamide (Diamox Sequels)

Clinical Context:  Acetazolamide is a nonbacteriostatic sulfonamide and a potent CA inhibitor that is effective in diminishing fluid secretion. It lowers ICP by decreasing production of CSF. Inhibition of CA results in a drop in sodium ion transport across the choroidal epithelium. Reduction of CSF production occurs within hours.

Acetazolamide commonly achieves long-lasting control of transient visual obscurations, headache, and diplopia, all of which are manifestations of intracranial hypertension, even though papilledema does not resolve completely. The effect on ICP is not sustained, and many patients develop adverse effects severe enough to hinder compliance.

Few patients tolerate dosages higher than 2 g/day, but 4 g/day may be required to produce a measurable pressure-lowering effect. Treatment is usually initiated at 1 g/day and increased to 2 g/day if symptoms are not controlled and adverse effects are not severe. Treatment with acetazolamide alone is not appropriate for patients who are experiencing progressive visual field loss.

Class Summary

Carbonic anhydrase (CA) is an enzyme found in many tissues. It catalyzes a reversible reaction whereby carbon dioxide becomes hydrated and carbonic acid becomes dehydrated. These changes may result in a decrease in CSF production by the choroid plexus.

Furosemide (Lasix)

Clinical Context:  Furosemide inhibits CSF production, but the precise mechanism by which it does so is unclear. A combination of CA inhibition and an effect on sodium absorption across the choroid plexus may result in the decreased CSF production.

Class Summary

Loop diuretics inhibit reabsorption of sodium in the ascending limb of the loop of Henle and have a weak inhibitory action on CA.

Digoxin (Lanoxin)

Clinical Context:  Digoxin is present in high concentrations in the choroid plexuses of patients taking standard cardiac doses. It has been shown to reduce CSF production by as much as 78% in humans, probably by inhibiting the Na-K-ATPase pump. There has been only 1 report in which a patient with IIH was treated with digoxin, but the patient was asymptomatic, and thus, it is not known whether symptoms would have been controlled.

Class Summary

Cardiac glycosides reduce CSF production at choroid plexus and reduce ICP.

Prednisone

Clinical Context:  The mechanism of action by which corticosteroids lower CSF pressure has not been established. Some believe that they may facilitate outflow at arachnoid granulations.

Prednisolone (Pediapred, Millipred, Orapred)

Clinical Context:  The mechanism of action by which corticosteroids lower CSF pressure has not been established. Some believe that they may facilitate outflow at arachnoid granulations.

Class Summary

Glucocorticoids reduce ICP through an unknown mechanism.

Propranolol (Inderal LA)

Clinical Context:  Propranolol is FDA approved for migraine prophylaxis.

Class Summary

Beta-blockers may prevent migraines by blocking vasodilators, decreasing platelet adhesiveness and aggregation, stabilizing the membrane, and increasing the release of oxygen to tissues. Significant to their activity as migraine prophylactic agents is the lack of partial agonistic activity. Latency from initial treatment to therapeutic results may be as long as 2 months.

Amitriptyline

Clinical Context:  Amitriptyline has efficacy for migraine prophylaxis that is independent of its antidepressant effect. Its mechanism of action is unknown, but it inhibits activity of such diverse agents as histamine, 5-HT, and acetylcholine.

Class Summary

Amitriptyline, nortriptyline, doxepin, and protriptyline have been used for migraine prophylaxis, but only amitriptyline has proven efficacy and appears to exert its antimigraine effect independent of its effect on depression.

Topiramate (Topamax)

Clinical Context:  Topiramate is indicated for migraine headache prophylaxis. Its precise mechanism of action is unknown, but the following properties may contribute to its efficacy: (1) blockage of voltage-dependent sodium channels, (2) augmentation of activity of the neurotransmitter GABA at some GABA-A receptor subtypes, (3) antagonization of the AMPA/kainate subtype of the glutamate receptor, and (4) inhibition of the carbonic anhydrase enzyme, particularly isozymes II and IV. Topiramate is also an excellent choice, in that one of its side effects is weight loss (a common association in IIH), which can help put the disease in remission.

Divalproex sodium/valproate (Depakote, Stavzor, Depacon, Depakene)

Clinical Context:  Divalproex is now considered first-line preventive medication for migraine. This agent is believed to enhance GABA neurotransmission, which may suppress events related to migraine that occur in cortex, perivascular sympathetics, or trigeminal nucleus caudalis. Divalproex has been shown to reduce migraine frequency by 50%.

Gabapentin (Neurontin)

Clinical Context:  Gabapentin is used for migraine headache prophylaxis. It has shown efficacy in migraine and transformed migraine.

Class Summary

These drugs are effective in prophylaxis of migraine headache.

Author

Mark S Gans, MD, Associate Professor, Director of Neuro-Ophthalmology, Interim Chair, Department of Ophthalmology, McGill University Faculty of Medicine; Clinical Director, Department of Ophthalmology, Adult Sites, McGill University Hospital Center, Canada

Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Disclosure: Nothing to disclose.

Additional Contributors

Robert A Egan, MD Director of Neuro-Ophthalmology, St Helena Hospital

Robert A Egan, MD is a member of the following medical societies: American Academy of Neurology, American Heart Association, North American Neuro-Ophthalmology Society, and Oregon Medical Association

Disclosure: Nothing to disclose.

Eric R Eggenberger, DO, MS, FAAN Professor, Vice-Chairman, Department of Neurology and Ophthalmology, Colleges of Osteopathic Medicine and Human Medicine, Michigan State University; Director of Michigan State University Ocular Motility Laboratory; Director of National Multiple Sclerosis Society Clinic, Michigan State University

Eric R Eggenberger, DO, MS, FAAN is a member of the following medical societies: American Academy of Neurology, American Academy of Ophthalmology, American Osteopathic Association, and North American Neuro-Ophthalmology Society

Disclosure: Nothing to disclose.

James Goodwin, MD Associate Professor, Departments of Neurology and Ophthalmology, University of Illinois College of Medicine; Director, Neuro-Ophthalmology Service, University of Illinois Eye and Ear Infirmary

James Goodwin, MD is a member of the following medical societies: American Academy of Neurology, Illinois State Medical Society, North American Neuro-Ophthalmology Society, and Royal Society of Medicine

Disclosure: Nothing to disclose.

Edsel Ing, MD, FRCSC Associate Professor, Department of Ophthalmology and Vision Sciences, University of Toronto Faculty of Medicine; Consulting Staff, Toronto East General Hospital, Canada

Edsel Ing, MD, FRCSC is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, American Society of Ophthalmic Plastic and Reconstructive Surgery, Canadian Ophthalmological Society, North American Neuro-Ophthalmology Society, and Royal College of Physicians and Surgeons of Canada

Disclosure: Nothing to disclose.

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Medscape Salary Employment

Brian R Younge, MD Professor of Ophthalmology, Mayo Clinic School of Medicine

Brian R Younge, MD is a member of the following medical societies: American Medical Association, American Ophthalmological Society, and North American Neuro-Ophthalmology Society

Disclosure: Nothing to disclose.

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Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with disc margin) are seen along temporal side of inferior pole of disc.

Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with disc margin) are seen along temporal side of inferior pole of disc.

Right optic disc with postpapilledema optic atrophy in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc and absence of small arterial vessels on surface are noted, with very little disc elevation. Disc margin at upper and lower poles and nasally is obscured by some residual edema in nerve fiber layer and gliosis that often persists even after all edema has resolved.

Most common early visual field defect in papilledema as optic nerve develops optic atrophy is inferior nasal defect, as shown in left eye field chart (left side of figure). Shaded area indicates defective portion of field. Note sharp line of demarcation between defective lower nasal quadrant and normal upper nasal quadrant along horizontal midline. This is characteristic of early papilledema optic atrophy and is referred to as nasal step or inferonasal step.

Left optic disc with moderate chronic papilledema in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Paton lines (arc-shaped retinal wrinkles concentric with disc margin) are seen along temporal side of inferior pole of disc.

Right optic disc with postpapilledema optic atrophy in patient with idiopathic intracranial hypertension (pseudotumor cerebri). Diffuse pallor of disc and absence of small arterial vessels on surface are noted, with very little disc elevation. Disc margin at upper and lower poles and nasally is obscured by some residual edema in nerve fiber layer and gliosis that often persists even after all edema has resolved.

Most common early visual field defect in papilledema as optic nerve develops optic atrophy is inferior nasal defect, as shown in left eye field chart (left side of figure). Shaded area indicates defective portion of field. Note sharp line of demarcation between defective lower nasal quadrant and normal upper nasal quadrant along horizontal midline. This is characteristic of early papilledema optic atrophy and is referred to as nasal step or inferonasal step.