Abstracts

Rationale: Ring chromosome 20 syndrome (r20s) is a rare disorder characterized by prolonged episodes of refractory non convulsive status epilepticus. Other features are: brief motor seizures, mental retardation and occasionally dismorphic changes and behavioural disturbances. Ictal EEG during non convulsive status shows continuous paroxysmal activity with generalized slow delta waves and spike discharges. Until now, there are very few studies of functional neuroimaging in these patients. Methods: We present the case of a 44 years old woman with no dysmorphic features diagnosed with r20s. Her first seizure occurred at the age of nine. At this time she started cognitive decline. The seizures consist in prolonged episodes (30-180min) of marked slow response with occasionally winking. She also had generalized tonic-clonic seizures (GTCS). Despite multiple antiepileptic drugs trials only GTCS were controlled. Intellectual coefficient is now (actually en vez de now?)56. Interictal EEG showed an 8-9 Hz alpha wave rhythm with frequent anterior dominant 5-6 Hz waves with spikes. EEG during non convulsive status epilepticus showed long lasting, high voltage slow waves with occasionally spike predominantly frontal and clinically severe bradipsichia and some winking. Other type of seizures showed recruiting spike activity followed by theta activity predominantly over frontal areas and 2-3Hz generalized high voltage slow waves with spikes during 10-20 seconds, clinical manifestation consist in staring and aphasia. Ictal SPECT with 99Tc-EDC during non convulsive status and interictal SPECT and PET with F18-FDG (fluoro-dexosiglucose) were performed Results: Interictal SPECT showed hypoperfusion over left temporal area. SPECT performed during a non convulsive status epilepticus showed also hypoperfusion in left temporal area but also (in a less degree) in right temporal lobe comparing with interictal study. Interictal PET showed hypometabolism in medial and neocortical structures of right temporal lobe. Conclusions: Episodes of decreased consciousness are the major feature of r20s. The temporal lobe has been considered an important structure in regulation of consciousness. During temporal epileptic seizures consciousness is found to be impaired in almost all of patients with bilateral seizure activity. Our findings suggest that there is a dysfunction of temporal lobe activity related to consciousness in r20s. When bilateral dysfunction occurs simultaneously prolonged episodes of impaired consciousness occur. Aphasia during the brief seizures suggest also a possible involvement of temporal dominant lobe, but until now it has not been possible to make functional neuroimaging study during this type of seizures.