Long-term seizure freedom following intracranial sEEG monitoring: Therapeutic benefit of a diagnostic technique

Abstract

Patients with treatment-resistant epilepsy often require surgery. It is very rare that patients with TRE can have sustained seizure freedom spontaneously, without undergoing further resection or neuro-modulation after invasive monitoring with sEEG. Of the 78 TRE cases monitored over last 5 years, we identified three patients who became seizure-free following sEEG monitoring without undergoing further resection or neuro-modulation. Seizure-freedom after sEEG is possible even without further intervention. In cases where seizures after the completion of the invasive monitoring are not observed, a longer observation period following electrode explantation prior to planned neuro-modulation or resection is warranted. This could be due to the disruption of the cortical–subcortical epileptogenic network due to focal area of tissue damage along and around the electrode tract.

Seizure freedom without seizure medication following stereoelectroencephalography implantation: a case report of drug-resistant post-traumatic epilepsy

“…While the literature acknowledges instances of sEEG monitoring resulting in seizure remission, these occurrences are particularly rare ( 5 ), with a previous study of epilepsy patients observing 0.5% remission rate following intracranial electrode placement. A previous case series described 3 patients with seizure remission following sEEG, however, these cases reported multiple seizures captured during the monitoring period ( 6 ), proving accurate targeting of the seizure onset zone with electrodes and suggesting the lesioning effect was not upon initial implantation but rather because of depth electrode removal or other delayed effects. In addition, none of the prior cases reported complete discontinuation of seizure medications.…”

Stereoelectroencephalography: a review of complications and outcomes in a new Australian centre

“…In one series of 78 cases of treatmentresistant epilepsy, two patients remained seizure-free at 2 and 5 years of follow-up following SEEG, with a third having an initial 1-year seizure-free period followed by a return of seizures, though much milder and more infrequent. 27 Another case in 161 children with invasive monitoring, including SEEG, showed seizure freedom in two children who had depth electrodes inserted. 28 While the mechanism for these outcomes has not yet been clearly elucidated, it is reasonable to suggest that some change induced by SEEG electrode insertion has interfered, lesioned or destroyed parts of the ictal network.…”

“…This phenomenon has been reported previously. In one series of 78 cases of treatment‐resistant epilepsy, two patients remained seizure‐free at 2 and 5 years of follow‐up following SEEG, with a third having an initial 1‐year seizure‐free period followed by a return of seizures, though much milder and more infrequent 27 . Another case in 161 children with invasive monitoring, including SEEG, showed seizure freedom in two children who had depth electrodes inserted 28 .…”

Cortical and thalamic electrode implant followed by temporary continuous subthreshold stimulation yields long-term seizure freedom: A case report

“…In addition, seizure freedom following invasive monitoring with sEEG has been reported in about 0.5% of cases [ 15 , 16 ]. Often there is evidence of damage along the depth electrode tracts which could indicate unintentional lesioning of the epileptogenic network and neighboring fibers responsible for seizure spread [ 17 , 18 ]. This can also be observed without imaging evidence of a parenchymal lesion [ 19 ] as microscopic changes in neural tissue after electrode insertion could disrupt epileptogenic neurons and fibers [ 20 ].…”