Abstracts

The relationship betwen seizure types in hypothalamic hamartoma (HH) is poorly understood and remains controversial. It is suggested that repeated gelastic seizures (GS) may lead to or trigger focal or generalized non-gelastic seizures (NGS) which then occur independently. Previous descriptions of seizures combined patient histories with direct observations and employed various terminologies. This study aimed to systematically examine and describe seizures in patients with HH, using video-EEG and accepted terminology, to better understand epileptogenesis in this syndrome., Video-EEG was performed in 34 patients with HH. Videos were examined for clinical features using a modification of the ILAE glossary of descriptive terminology. Seizures were considered gelastic if they contained any motor manifestation of laughter or crying. NGS were classified by electroclinical type. Evolution of seizures was described according to Lüders et al. Ictal EEG was categorised by type and location. Correlation of clinical, EEG and imaging features was performed., GS (31 patients) were characterised by behavioral arrest or arousal at onset; increased respiratory motor activity; tonic lower facial contraction, lateralization of which correlated with side of predominant HH attachment ([Gamma] = -0.60, [italic]p[/italic] = 0.001); tachycardia and facial flushing; and hypermotor automatisms. Laughter-like vocalization was variable and could have congruous affective tone. EEG findings in GS were stereotyped, the usual pattern being diffuse desynchronization followed by low voltage fast activity, lateralization of which correlated with the side of predominant HH attachment ([Gamma] = 0.80, [italic]p[/italic] = 0.004). Various NGS were observed (26 patients), including focal NGS [versive (14 patients), complex motor (9), hypomotor (4)] and less often generalized NGS [myoclonic (4), tonic-clonic (2), atypical absence (2)]. Epileptic spasms were identified in 13 patients (38%) and bilateral tonic seizures in 8 patients. Seizure evolution was stereotyped for each patient and 65% of patients had only one pattern. When GS and NGS coexisted, focal NGS usually followed GS in the evolution. Generalized NGS occured from seizure onset, but epileptic spasms and bilateral tonic seizures (when present) usually followed on from GS or focal NGS., In HH syndrome, focal NGS usually follow GS and are likely to represent seizure spread from the HH. By contrast, generalized NGS begin without prior focal seizures and these may indicate an independent (possibly secondary) process. Epileptic spasms and bilateral tonic seizures usually follow GS or focal NGS and in this respect they are more like focal NGS than generalized NGS.,