Data from: The epileptology of alternating hemiplegia of childhood

Objective: Report our experience and investigate five original hypotheses:
1) Multiple types of epileptic seizures occur in Alternating Hemiplegia of
Childhood (AHC) and these can be the initial presentation. 2) Epileptiform
abnormalities often appear well after clinical seizures. 3) Non-epileptic
reduced awareness spells (RAS) occur frequently. 4) Epilepsy is commonly
drug resistant but may respond to vagal nerve stimulation (VNS). 5) Status
epilepticus (SE) is common and is usually refractory and recurrent.
Methods: Analyze a cohort of 51 consecutive AHC patients. Results: 1)
Seizure types: 32/51 had epilepsy: Eighteen focal seizures, frontal more
frequently than temporal, then posterior. Eleven had primary generalized
seizures (tonic-clonic, myoclonic, and/or absence). Epileptic seizures
preceded other AHC paroxysmal events in eight (lag: 5.63±6.55 months;
p=0.0365). 2) EEG: In 7/32, initial EEGs were normal with the first
epileptiform EEG lagging behind by 3.53±4.65 years (p=0.0484). RAS
occurred equally in epilepsy (16/32) and non-epilepsy patients (10/19,
p=1.0). 28/28 video-EEG captured RAS showed no concomitant EEG changes. 4)
Therapies: Nineteen (59%) were drug resistant. VNS resulted in >50%
reduction in seizures in 5/6 (p<0.04). 5) SE: Twelve (38%) had SE
(9/12 multiple episodes), refractory/super-refractory in all
(p<0.001). 4/12 had regression after SE. Significance: Epilepsy in
AHC can be focal or generalized. Epileptic seizures may be the first
paroxysmal symptom. EEG may only become epileptiform on follow-up.
Epilepsy, though frequently drug resistant, can respond to VNS. RAS are
frequent and non-epileptic. SE often recurs and is, usually,
refractory/super-refractory. Our observations are consistent with current
data on AHC-ATP1A3 pathophysiology.