Anterior temporal lobectomy: A cross-sectional observational study of potential surgical candidates at a single institute

Abstract

Background: Epilepsy is a common neurological disorder, associated with serious cognitive, physical, and psychosocial burdens. Mesial temporal lobe epilepsy (mTLE) is the commonest form of focal epilepsy. The aim of this study was to establish the incidence of patients with electroencephalographic epileptiform discharges consistent with mTLE attending a tertiary hospital in South Africa, and determine whether these patients may be candidates for anterior temporal lobectomy.

Methods: This was a cross-sectional observational study of all patients receiving scalp electroencephalograms (EEG) performed at the Groote Schuur Hospital Neurophysiology laboratory during the period January 1, 2017-December 31, 2019. Where magnetic resonance imaging (MRI) brain scans had been performed, these were assessed for corroborative evidence of mTLE.

Results: Over the 3-year period, 4 342 EEGs were assessed. A total of 411 (11%) showed epileptiform discharges consistent with all epilepsy types. Of these, 327 (69%) were of focal onset and 108 (33% of all focal onset epilepsies) were consistent with mTLE. Of the patients with electroencephalographic features of mTLE, only 27 (25%) had had MRI brain scans performed according to an epilepsy surgery protocol. None of these patients had been considered for surgery.

Conclusion: Surgery, especially anterior temporal lobectomy, is widely acknowledged to be an efficacious and cost-effective intervention in patients with drug-resistant mTLE. The findings of our study suggest that patients with mTLE in our setting are under-investigated for potential surgery; and that it is under-utilized. These findings are in line with similar studies in both well-resourced and resource-constrained countries. Our study also highlights the utility of EEG as a practical screening tool to identify potential surgical candidates, as well as the establishment of an EEG and MRI database to assist in recognizing these patients.

Keywords: Anterior temporal lobectomy; Electroencephalogram; Mesial temporal lobe epilepsy.

Figure 1:

Coronal T2-weighted, and T1-weighted inversion recovery magnetic resonance imaging brain scan (Panel a and b respectively) of a study participant showing evidence of right-sided hippocampal atrophy (indicated by arrows).

Figure 2:

Histograms representing (a) the proportion of focal versus generalised epileptiform discharges, and (b) focal epileptiform discharges represented according to anatomical location.

Figure 3:

Histogram illustrating the age distribution of patients with anterior and/or middle temporal lobe epileptiform discharges on electroencephalogram consistent with a diagnosis of Mesial temporal lobe epilepsy.