Alternating Hemiplegia of Childhood (AHC)

Overview

Background.
Alternating hemiplegia of childhood (AHC) is a rare neurological disease of unknown aetiology characterized by recurrent paroxysmal attacks of side - alternating hemiplegias of variable duration associated withother paroxysmal dysfunctions. Paroxysmal attacks start in infants but neurological deficits become progressive with the age. 

Methods and Results.
During the last 20 years 8 patients (5 boys, 3 girls) with AHC were followed. Mean age at the time of diagnosis was 2.75 years, age range 2–5 years; mean follow up period 13.9 years (range 1 month-20 years) The diagnosis was based on clinical history and neurological findings, completed by neurophysiological and neuroimaging methods (SPECT, PET), and results of psychological and biochemical findings. Paroxysmal phenomena (occulo-motor, tonic, choreo-athetotic, autonomic) appearing at the age of 4.1±2.2 months and followed by repeated attacks of hemiplegia (age onset 16.3±13.0 months) were the first symptoms. Progressive neurological impairment covering spasticity, dyskinetic syndrome, cerebellar ataxia and intellectual deficit was present in all cases, epileptic seizures in 7 out of 8 patients. On ictal SPECT/PET examination hypoperfusion/glucose hypometabolism were demonstrated above affected hemispheres including basal ganglia, both thalami and cerebellar hemispheres. Improvement of hemiparesis was illustrated by nocturnal videomonitoring. 

Conclusions.
AHC is a chronic disease with progressive neurological deficit. A flunarizine therapy has a favorable effect on frequency and severity of paroxysmal attacks, but does not prevent a progressive neurological impairment. 

Key words:
alternating hemiplegia, paroxysmal attacks, diagnosis, neuroimaging methods, video-polysomnography, long-term follow-up, prognosis, therapy.