Results of surgery in patients with bilateral independent temporal lobe spiking (BITLS) with normal MRI or bilateral mesial temporal sclerosis (MTS) investigated with bilateral subdural grids

Abstract

-Purpose: The introduction of new technologies in the clinical practice have greatly decreased the number of patients submitted to invasive recordings. On the other hand, some patients with refractory temporal lobe epilepsy have normal MR scans or bilateral potentially epileptogenic lesions. This paper reports the results of invasive neurophysiology and surgical outcome in such patients. Method: Sixteen patients were studied. Eleven had normal MRI (Group I) and five had bilateral mesial temporal sclerosis (Group II). All patients had BITLS and non-localizatory seizures on video-EEG monitoring. All patients were implanted bilaterally with 32-contacts subdural grids. They were submitted to a cortico-amygdalo-total hippocampectomy at the side defined by chronic electrocorticography (ECoG). Results: In Group I, seizures came from a single side in nine patients. In nine patients, seizures started at one side, spread to the ipsolateral contacts and contralaterally afterwards. On the other hand, in two Group I patients seizures started in one mesial region and spread to the contralateral parahippocampus and neocortex before spreading to ipsolateral contacts. All patients in Group II had seizures starting unilaterally with focal EcoG onset in the mesial regions. Eight Group I patients are seizure-free and three are in Engel's class II. Eighty percent of Group II patients are seizure-free after surgery and one patient is in Engel's class II. Conclusion: Good surgical results can be obtained in patients with BITLS. Patients with normal MRI seem to have a worse prognosis when compared to patients with unilateral or even bilateral MTS. Extensive subdural coverage is essential in patients with normal MRI.KEY WORDS: bitemporal epilepsy, surgery, subdural grids, outcome, MRI. Resultados cirúrgicos em pacientes com descargas bilaterais independentes do lobo temporal (DBILT) e ressonância magnética normal ou com esclerose mesial bilateral investigados com implante bilateral de grades subdurais.RESUMO -Introdução: A introdução de novas tecnologias na prática clínica tem diminuído em muito a necessidade do estudo com eletrodos invasivos em pacientes epilépticos refratários. Por outro lado, alguns pacientes com epilepsia do lobo temporal ainda possuem exames de imagem normais ou com lesões potencialmente epileptogênicas bilaterais. Este estudo relata os resultados da neurofisiologia invasiva e da cirurgia neste grupo de pacientes. Métodos: Dezesseis pacientes foram estudados. Onze possuíam RM normal (grupo I) e 5 esclerose mesial bilateral (grupo II). Todos possuíam DBILT e crises não-localizatórias após vídeo-monitorização. Todos foram implantados bilateralmente com placas subdurais de 32 contatos cada. Eles foram submetidos a córtico-amigdalo-hipocampectomia do lado definido pela neurofisiologia invasiva. Resultado: No grupo I, as crises originaram-se em somente um lado em 9 pacientes. Em 9 pacientes, as crises iniciavam-se em um lado, espraiandose para os contatos ipsilaterais e a seguir contralateralmente. Por outro la...

Efficacy of temporal lobe surgery for epilepsy in patients with negative MRI for mesial temporal lobe sclerosis

“…13 In this situation invasive recording should be considered prior to surgery. 25 However, with convincing scalp EEG findings we did not find that Phase II monitoring with invasive electrodes is essential in patients with nMRI and semiology suggestive of mesial TLE. This confirms previously published reports that the best outcome rates are in patients who do not require Phase II (invasive) monitoring.…”

“…14 Other published series suggest that this population may be less likely to achieve the same postoperative seizure control as those with MTS. 15,17,18,[23][24][25] Therefore we asked, ''Is temporal lobe surgery an effective treatment option for TLE in the setting of nMRI of the brain? ''…”

Is it worth pursuing surgery for epilepsy in patients with normal neuroimaging?

“…Although no previous studies have directly compared outcome from patients with normal and abnormal neuroimaging, our findings in patients with normal neuroimaging are largely in keeping with those of other investigators. [3][4][5][6][7][8] The answer to whether it is worth pursuing surgery in patients with normal MRI requires consideration of several factors apart from seizure control. If intracranial recordings are necessary in these patients, financial issues and the risk of complications from intracranial implantations should be considered.…”

Bilateral stereotactic radiofrequency amygdalohippocampectomy for a patient with bilateral temporal lobe epilepsy

“…About 20-35% of patients with temporal lobe epilepsy (TLE) have bilateral discharges (Cukiert et al, 2000), and in at least 10-20% of them, bilateral temporal lobe epilepsy (BTLE) has been confirmed (Spencer et al, 1990). If patients were proved as BTLE, bilateral resection would results in the complication of severe dysmnesia (Scoville & Milner, 2000).…”