Neuroimaging in Selected Nigerian Epileptic Patients: A Decade of Experience
Background: There is currently a general agreement that in the evaluation and management of epilepsy brain computed tomography-CT and nuclear magnetic resonance imaging-MRI complement the clinical and electrophysiological information obtained. Most of the studies on CT and epilepsy are from elsewhere. The study sets out to highlight the relevance of neuroimaging in the management of epilepsy in selected Nigerian patients.
Objective: This study examines the incidence of cerebral abnormalities using optiminsed brain CT scanning in Nigerian patients with intractable epileptic seizures and relates these to clinical and electroencephalographic localisation of seizures.
Methods. A prospective descriptive study was undertaken on 344 consecutive Nigerian patients with various epileptic syndromes of whom only 238 (173 children and 65 adults) completed a follow-up of between 0.5 to 8.8 years. Of these, 87 (64 children and 23 adults) satisfied the defined selection criteria for neuroimaging, but only 33 patients were able to obtain the investigation which consisted of CT scan in 31 and MRI in 2 patients. The neuroimaging was done in various centres in Nigeria and abroad. For CT scanning, the Somatom-AR. T (Siemens system) total body scanner and its varieties were used, and for MRI, done in the United Kingdom, a 1.5 Tesla Siemens system with a 25cm circularly polarised head coil used as both transmitter and receiver was employed. All electroencephalography (EEG) was recorded with 8,12 or 16 channel EEG machines.
Results. Altropic changes dominated with neurimaging abnormalities in one-third of the patients scanned. The vast majority of patients with generalised tonic-clonic seizures (9 out of 12) had no demonstrable abnormalities, and the reverse was the case in complex partial seizures in which 9 out of 13 patients had demonstrable structural lesions on CT.
Conclusion: This study further supports the relevance of CT scanning whenever partial seizures are associated with abnormal neurological signs during the interictal period. Though CT abnormalities may not always be amenable to surgical correction or alter significantly clinical management, CT findings can definitely alter the initial clinical or EEG classification of type of epilepsy in a few patients leading to alteration of drug therapy with rewarding results. In additon, brain tumour, brain abscess and obstructive hydrocephalus are known conditions that are amenable to surgical correction and are detectable on CT. Computerised tomography is expensive and must be justifiable on clinical grounds, and reserved for patients whose epilepsy is unresponsive to drug treatment rather than for all patients at presentation.
Nigerian Quarterly Journal of Hospital Medicine Vol. 9, No. 2 (June 1999) pp. 104-111