Temporal lobe white matter pathways: clinical and anatomical examination related to surgery of drug-resistant structural focal epilepsy

Background . Detected temporal lobe focal cortical dysplasia (FCD) often results in developing drug-resistant epilepsy requiring surgical treatment. In turn, temporal lobectomy, despite its high efficiency, can cause a certain deficit associated with direct or indirect damage to the brain pathways. Objective : to describe the main anatomical features of temporal lobe brain pathways and clinical outcomes of surgical treatment of drug-resistant epilepsy that developed in temporal lobe FCD. Material and methods . A retrospective analysis of the treatment of 14 patients with drug-resistant structural focal epilepsy (temporal lobe FCD) who underwent surgery (anterior temporal lobectomy) was carried out. To localize the epileptogenic zone, specialists of the multidisciplinary group performed a comprehensive presurgical examination in all participants. The surgical material was examined by a neuromorphologist, the diagnosis was verified. In the postoperative period, patients underwent a series of control examinations at standard time points (after 3, 6, 12, 36 months). The minimum follow-up period was 12 months. As a part of the anatomical study, 6 brain hemispheres were investigated prepared for the white matter fibers dissection using Klingler technique. The main pathways that run within or near the temporal lobe were selectively examined: the lower longitudinal, medial longitudinal, lower fronto-occipital and uncinate fasciculi. Results . In the postoperative period, no complications were observed in 14.3% of patients after 4 cm resection of the temporal lobe subdominant hemisphere. Speech disorders (mostly transient) were detected in 35.7% of the subjects, visual field disorders (mainly transient) – in 21.4%, neuropsychiatric disorders – in 43.9%. Overall seizure control: 93% of patients achieved class I according to Engel Epilepsy Surgery Outcome Scale. Conclusion . Anterior temporal lobectomy can be considered as a highly effective method of surgical treatment of drug-resistant structural focal epilepsy with a high rate of achieving control over epileptic seizures in the postoperative period. However, the mandatory conditions for maintaining the quality of life for patients after such a surgical intervention include preoperative analysis of the risk of adverse effects performed by a multidisciplinary team as well as postoperative management and rehabilitation.