Benign nocturnal alternating hemiplegia of childhood

Benign nocturnal alternating hemiplegia of childhood (BNAHC) is a rare neurological condition characterized by episodes of hemiplegia (paralysis affecting one side of the body) that occur exclusively during sleep, typically during the night. Unlike the more severe alternating hemiplegia of childhood (AHC), BNAHC follows a benign course and does not lead to progressive neurological deterioration or cognitive impairment. The episodes alternate between the left and right sides of the body and resolve spontaneously upon awakening or shortly thereafter. The condition primarily affects the motor nervous system. During sleep, affected children experience episodes of unilateral weakness or paralysis that may be noticed by parents when the child is found unable to move one side of the body upon waking. These hemiplegic episodes are transient, typically lasting minutes to hours, and resolve completely without residual deficits. Importantly, children with BNAHC have normal neurological development, normal brain imaging, and no associated epileptic activity, which helps distinguish it from other causes of childhood hemiplegia. The prognosis for BNAHC is favorable, with episodes typically decreasing in frequency and eventually resolving spontaneously as the child grows older. No specific treatment is generally required, though reassurance and monitoring are important components of management. The condition must be carefully differentiated from alternating hemiplegia of childhood (caused by ATP1A3 mutations), epilepsy-related hemiplegia, and other neurological disorders through thorough clinical evaluation including EEG and neuroimaging studies.

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