Abstracts

RATIONALE: Epileptic Spasms are generally regarded as an age-dependent epileptic syndrome with onset during the first year of life. The objective of the present study is to demonstrate that epileptic spasms can infrequently present after age 2 years.
METHODS: Four patients in our database did not develop epileptic spasms until after 2 years of age. Semiology of spasms and their electrographic presentation were analyzed by Video-EEG telemetry review. Spasms were characterized by brief muscle contraction lasting between 200-500 miliseconds having a myographic crescendo-decrescendo pattern. The muscle contraction temporally corresponded to an EEG finding of a large amplitude transient slow wave and/or attenuation of the background. Cognitive testing was done by the Weschler Intelligence Scales for Children III and Vineland Adaptive Behavior Scales.
RESULTS: The four patients identified had onset of spasms between 2.5 and 6 years (average 3.8 years). Epileptic spasms persisted until ages 9-10.5 years as documented by Video-EEG monitoring. When compared with the patients who were younger than two at spasm onset, the frequency of spasms was relatively low, averaging 14 per day. Clinically, spasm semiology was flexor in two cases and mixed (flexor-extensor) in the remaining two patients. During the spasm the EEG showed a slow transient wave form, followed by an attenuation of the background intermixed with low amplitude fast activity. Episodically, patients 1 and 3 had a polyphasic blunted sharp wave seen at the onset of the spasm, instead of a slow wave transient. Each patient had other seizure types, including complex partial, tonic, myoclonic and secondary generalized tonic-clonic seizures. Spasms were partially controlled, [gt] 50% reduction, by valproic acid and the ketogenic diet in one patient each, with the remaining 2 patients controlled by intravenous immunoglobulin. However, reduction in spasm activity only showed a transitory benefit for 3-12 months, with return of spasm frequency in all 4 patients. Mental retardation was present all cases. The range of severity varied between patients. Two patients were severely retarded, while one was profoundly affected, with the remaining patient only moderately retarded. Cognitive decline was documented in two cases.
CONCLUSIONS: Epileptic spasms can occasionally present [italic]de novo[/italic] after the second year of life. The EEG and clinical features in these late onset cases is similar to patients with [dsquote]infantile-onset[dsquote] spasms. Cases of late onset spasms tend to have significant cognitive deficits. Furthermore, cognitive decline can be progressive.