Abstracts

Rationale: Central nervous system (CNS) events, including stroke, transient ischaemic attacks (TIA) and seizures are common in sickle cell anemia (SCA). Stroke may be predicted by high internal carotid and/or middle cerebral artery velocities (ICA/MCAV) on transcranial Doppler (TCD) ultrasound screening, and long term prophylactic transfusion for those with ICA/MCAV>200 cm/sec prevents stroke. Seizures are approximately 10 times commoner in patients with SCA than in the general population but semiology has not been well described. In addition, it is not clear whether they are associated with sleep-disordered breathing (SDB) or cerebrovascular disease diagnosed on TCD or magnetic resonance angiography (MRA) or with overt or covert ('silent') stroke. There are therefore no evidence-based guidelines for management. Methods: We had ethical permission to study neurological complications in an unselected hospital-based cohort of patients with SCA followed-up for up to 10 (median 4) years. Non-imaging TCD screening was routinely undertaken in clinic. Overnight pulse oximetry was undertaken at home and those over the age of 7 or with acute focal neurological signs underwent MR imaging (MRI) and MRA. Results: 20/207 (10%) had had a seizure at a median age of 9 years (range 7 days to 35 years) but only 3 developed recurrent seizures outside an acute illness. The majority of patients (n=15) had 1-3 generalized tonic-clonic convulsions, while 6 had focal clonic seizures, 2 had absences, 2 had tonic seizures and one had an episode with a Jacksonian march. The majority had focal slowing rather than discharges on EEG. Eight had other acute neurological events: 5 also had TIAs, 1 before and 4 after the seizure, 2 additional children had a stroke, both presenting with seizures, and one child died of acute cerebral edema after status epilepticus. In this group of patients with SCA and seizures, median ICA/MCAV on either side was 101 (range 0-179) cm/sec. Of the 11 who had MR studies, 5 had infarction on MRI and 6 had abnormal MRA. Eight of 13 who had overnight pulse oximetry had either low baseline (mean overnight saturation <94%; n=5) or evidence of obstructive apnea (>4 dips/hour of >4% oxygen saturation, n=3). Conclusions: Although high ICA/MCAV was not seen in this series, cerebrovascular disease and covert infarction are common in patients with seizures in the context of SCA, in addition to overt stroke and TIA, and should be actively excluded at presentation. As recurrent seizures are relatively uncommon, there is little justification for long term prophylactic anticonvulsants, although seizures and status epilepticus should be managed appropriately when they present acutely. Our data add to the evidence for a link between SDB and seizures[1]. Screening for and appropriate management of SDB, might be a safe and effective alternative to prophylactic blood transfusion for primary prevention of CNS events in SCA. [1] Chihorek AM, Abou-Khalil B, Malow BA. Obstructive sleep apnea is associated with seizure occurrence in older adults with epilepsy. Neurology 2007;69:1823-7.