Morphology of the lateral fossa of the brain (sylvian valley): anatomo-radiological aspects and surgical application.

INTRODUCTION: The knowledge acquired on the lateral fossa of the brain (LFB) is heterogeneous and incomplete. Our goal was to provide a morphological description of the LFB and analyze the impact of these descriptions on the surgical approach of the region. METHODS: The morphology of LFB was studied on 40 cerebral hemispheres of 20 right-handed subjects aged 18-55 years with an MRI of 1.5 T. The anatomo-radiological identification of the two section levels preceded the description of the shapes of the LFB. From these landmarks, the forms presented by the LFB were identified and described on each of the transverse, sagittal and frontal planes. The comparison of the proportion of shapes made it possible to identify the typical shapes at each section level and on each section plane. RESULTS: The average age of the subjects was 33 years with extremes of 19 and 54 years including 7 women and 13 right-handed men. According to the plane and the level of section, 6 typical morphologies of the LFB have been described, 2 of which were identical. The forms did not vary according to the cerebral hemisphere or the sex of the subject. The set of typical morphologies made it possible to determine a reference subject called NSK which presented the greatest number of typical morphological characteristics. CONCLUSION: Knowledge of LFB anatomical imaging is of paramount importance in the pre-surgical evaluation of pathologies in this region. The reference subject will be used for our future biometric and three-dimensional manual reconstruction work in this region.

Predictive factors of long-term outcomes of surgery for mesial temporal lobe epilepsy associated with hippocampal sclerosis.

OBJECTIVE: The reasons for failure of surgical treatment for mesial temporal lobe epilepsy (MTLE) associated with hippocampal sclerosis (HS) remain unclear. This retrospective study analyzed seizure, cognitive, and psychiatric outcomes, searching for factors associated with seizure relapse or cognitive and psychiatric deterioration after MTLE-HS surgery. METHODS: Seizure, cognitive, and psychiatric outcomes were reviewed after 389 surgeries performed between 1990 and 2015 on patients aged 15-67 years at a tertiary center. Three surgical approaches were used: anterior temporal lobectomy (ATL; n = 209), transcortical selective amygdalohippocampectomy (SAH; n = 144), and transsylvian SAH (n = 36). RESULTS: With an average follow-up of 8.7 years (range = 1.0-25.2), seizure outcome was classified as Engel I in 83.7% and Engel Ia in 57.1% of patients. The histological classification of HS was type 1 for 75.3% of patients, type 2 for 18.7%, and type 3 for 1.2%. Two factors were significantly associated with seizure recurrence: past history of status epilepticus and preoperative intracranial electroencephalographic recording. In contrast, neither HS type, the presence of a dual pathology, nor surgical approach was associated with seizure outcome. Risk of cognitive impairment was 3.12 (95% confidence interval = 1.27-7.70), greater in patients after ATL than in patients after transcortical SAH. A presurgical psychiatric history and postoperative cognitive impairment were associated with poor psychiatric outcome. SIGNIFICANCE: The SAH and ATL approaches have similar beneficial effects on seizure control, whereas transcortical SAH tends to minimize cognitive deterioration after surgery. Variation in postsurgical outcome with the class of HS should be investigated further.

[Epilepsy surgery: when thinking about? Who are the good candidates?]. / Chirurgie de l'épilepsie : quand y penser ? Quels sont les bons candidats ?

Epilepsy surgery concerns any patient with pharmacoresistant partial epilepsy, responsible for disability. Children and adult patients can be candidates for epilepsy surgery. A presurgical evaluation, adapted to each patient, must identify the most precisely the cortical area, where the seizures originate, using converging data: the clinical and electroencephalographic semiology of the seizures, the structural and sometimes functional brain imagings, and evaluate if the removal of the epileptogenic focus may induce a neurological or cognitive deficit, using neuropsychological tests and sometimes functional brain imagings. Such therapeutical strategy should be evoked as soon as possible in patients for whom the epilepsy becomes pharmacoresistant, and these patients should be oriented in specialized centres. The results of epilepsy surgery vary according to the lobar origin of the epileptogenic focus and to the existence of a visible lesion on brain MRI. A multidisciplinary evaluation of the benefits and risks should be presented to the patient. Results of the surgery are usually excellent when a focus is clearly identified and the neuropsychological tests did not predict a deficit.