Surgical Amenable Magnetic Resonance Imaging Lesions In Africans With Active Convulsive Epilepsy: An Observational Study

Résumé

Background: Focal epilepsy is common in low and middle-income countries and may be amenable to surgery. However, the frequency and nature of possible underlying structural brain abnormalities that are amenable to surgical correction have not been fully assessed.  Methods: We evaluated the possible structural causes of epilepsy in 331 people with epilepsy (240 from Kenya and 91 from South Africa), identified from community surveys of active convulsive epilepsy. Magnetic Resonance Imaging (MRI) scans were acquired on 1.5-tesla scanners. We estimated the prevalence of these abnormalities using Bayesian priors (from an earlier pilot study) and observed data (from this study). We used a mixed-effect modified Poisson regression approach with site as a random effect to determine the clinical features associated with neuropathology. Results: MRI abnormalities were found in 140/240 (modelled prevalence=59% (95%CI:53%-64%)) of people with epilepsy in Kenya, and in 62/91 (modelled prevalence=65% (95%CI:57%-73%)) in South Africa, with a pooled modelled prevalence of 61% (95%CI:56%-66%). Abnormalities were common in those with a history of adverse perinatal events (15/23 (65% (95%CI:43%-84%))), exposure to parasitic infections (83/120 (69% (95%CI:60%-77%))) and focal electroencephalographic (EEG) features (97/142 (68% (95%CI:60%-76%))), but less frequent in individuals with generalized EEG features (44/99 (44% (95%CI:34%-55%))). Most abnormalities were potentially epileptogenic (167/202 (82%)), of which mesial temporal sclerosis (MTS) (43%) and gliosis (34%) were most frequent. Abnormalities were associated with generalised non-convulsive seizures (relative risk (RR)=1.12 (95%CI:1.04-1.25)), lack of family history of seizures (RR=0.91 (0.86-0.96), status epilepticus (RR=1.14 (1.08-1.21)), frequent seizures (RR=1.12 (1.04-1.20)) and reported use of anti-seizure medication (RR=1.22 (1.18-1.26)). Conclusion: MRI identified pathologies that are common in people with epilepsy in Kenya and South Africa, most of which may be amenable to surgical correction for instance MTS. Investment in access to MRI services may not only have a diagnostic value in rural Africa, but also a prognostic role.