Alternating hemiplegia

Alternating hemiplegia (also known as alternating hemiplegia of childhood, AHC) is a rare neurodevelopmental disorder characterized by recurrent episodes of temporary paralysis (hemiplegia) affecting one or both sides of the body. These episodes typically begin before 18 months of age and can last from minutes to days. The condition primarily affects the nervous system, with episodes of hemiplegia resolving during sleep but potentially recurring upon awakening. The disorder is most commonly caused by mutations in the ATP1A3 gene, which encodes a subunit of the sodium-potassium ATPase pump critical for neuronal function. In addition to the hallmark hemiplegic episodes, affected individuals frequently experience dystonic spells, abnormal eye movements (episodic nystagmus or monocular deviation), autonomic disturbances (such as changes in skin color and temperature), and epileptic seizures. Over time, most patients develop progressive cognitive impairment, developmental delay, ataxia, and choreoathetosis. The severity of the condition varies considerably among individuals, but most experience some degree of permanent neurological disability. There is currently no cure for alternating hemiplegia. Treatment is primarily symptomatic and supportive. Flunarizine, a calcium channel blocker, is the most widely used medication and may reduce the frequency and severity of hemiplegic episodes in some patients, though its effectiveness varies. Avoidance of known triggers—such as emotional stress, temperature extremes, bathing, and physical exertion—is an important part of management. Benzodiazepines may be used during acute episodes, and antiepileptic drugs are prescribed for seizure management. Multidisciplinary care including physical therapy, occupational therapy, and speech therapy is essential to optimize developmental outcomes.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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