Shuddering Attacks

Background

Shuddering attacks are benign paroxysmal spells of childhood that can mimic epileptic seizures. They may superficially resemble several seizure types, including tonic, absence (typical and atypical), and myoclonic seizures.

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Pathophysiology

The pathophysiology is unknown, although a relationship with essential tremor has been postulated.^[1] The origin is unclear, but shuddering attacks are not epileptic in nature.

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Epidemiology

Frequency

International

Incidence is unknown, but shuddering attacks are relatively uncommon.

Mortality/Morbidity

These episodes are usually benign and nondisabling. They are not associated with increased morbidity or mortality and tend to remit spontaneously.

Sex

No sex predilection is reported.

Age

The condition is seen in older infants and young children.

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History

• Parents describe the paroxysmal episodes of shuddering attacks as a sudden flexion of the neck and trunk and adduction of the arms.
• A shiverlike movement of the trunk ("like a chill") occurs, and the body may stiffen.
• Consciousness does not seem to be altered, but this can be difficult to confirm.
• The episode usually lasts 5-15 seconds.
• Unlike epileptic seizures, shuddering attacks do not occur during sleep.

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Physical

General and neurologic examination findings are normal.

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Causes

The cause is unknown. A relationship with essential tremor has been postulated because there may be an increased frequency of essential tremor in the families of these children.

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Laboratory Studies

No laboratory studies are helpful for the diagnosis of shuddering attacks.

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Imaging Studies

Brain CT scan or MRI may be performed because epileptic seizures are in the differential diagnosis. However, the results of these studies are normal.

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Procedures

• Reviewing the appearance of a typical episode as captured on video camera by the parents is helpful in suggesting the diagnosis; however, prolonged electroencephalography (EEG) video monitoring to record a typical episode definitively differentiates shuddering attacks from epileptic seizures.^[2]
• Recordings of the spells confirm that typical characteristics of an episode are 5-10 seconds of shiver-like movements of the trunk and limbs with no impairment of consciousness and no EEG discharge during the episode. A normal EEG result helps to rule out an epileptic origin.
• Ambulatory EEG^[3] without video recording is useful for diagnosis but does not record the clinical event.
• Routine EEG results are typically normal.

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Medical Care

In most cases, no treatment is necessary for shuddering attacks.

• Occasionally, if the episodes are unusually frequent or disabling, treatment may be attempted. However, there is no consistently effective treatment.
• Do not use antiepileptic drugs. They are ineffective.
• Propranolol can be helpful in isolated cases. However, it is used very rarely in the treatment of this condition.

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Consultations

Infants and children with shuddering attacks are typically referred to a neurologist to check for possible seizures.

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Medication Summary

Medications are rarely used for shuddering attacks. However, propranolol may have some efficacy.

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Class Summary

These agents compete with beta-adrenergic agonists for available beta-receptor sites.

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Propranolol (Inderal)

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Clinical Context:  Has membrane-stabilizing activity and decreases automaticity of contractions.

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Prognosis

Shuddering attack episodes tend to remit. A relationship to essential tremor occurring later in life has not been established.

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