Evaluation of Posterior Hippocampal Epileptogenicity During Epilepsy Surgery For Temporal Lobe Cavernoma by the Occipital Approach.
BACKGROUND
Cavernomas frequently are associated with intractable epilepsy. When cavernomas located in the temporal lobe are associated with intractable epilepsy, the hippocampus also may have an epileptic focus. The objective in the present study was to clarify the importance of evaluation of the posterior hippocampal epileptogenicity during epilepsy surgery for posteromedial temporal lobe cavernoma.


METHODS
In this study, we describe 2 rare cases of medically intractable epilepsy in patients with posteromedial temporal lobe cavernomas who underwent surgery via the occipital approach. Using longitudinal insertion of depth electrodes into the hippocampus, we evaluated epileptogenicity in both patients from the cavernoma cavity and its surrounding hemosiderin, as well as from the posterior hippocampus near the cavernoma. We show that the transoccipital approach to the posteromedial temporal lobe is compatible with depth electrode insertion and subdural electrode placement on the temporal lobe, enabling an accurate evaluation of potential epileptogenic zones in the posterior part of the hippocampus. Both patients did not experience any seizures and had no postoperative neurologic deficits, and their cognitive functions were intact.


CONCLUSIONS
The transoccipital approach enables the optimization of the extent of posterior hippocampectomy while avoiding unnecessary resection for seizure control. We suggest resecting the posterior part of the hippocampus in addition to the cavernoma and surrounding areas in patients with medically refractory epilepsy due to a posteromedial temporal cavernoma. Tailored systematic resection guided by intraoperative electrocorticography and electroencephalography with a depth electrode was important and necessary in the present cases.
Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan.
Yukinori
Y
Akiyama
Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan.
Kengo
K
Suzuki
Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan.
Satoko
S
Ochi
Department of Neurosurgery, Kyoto University School of Medicine, Kyoto, Japan.
Susumu
S
Miyamoto
Department of Neurosurgery, Sapporo Medical University School of Medicine, Sapporo, Japan. Electronic address: mikunin@sapmed.ac.jp.
Nobuhiro
N
Mikuni
D000328:Adult; D001932:Brain Neoplasms / Q000601:surgery*; D000069279:Drug Resistant Epilepsy / Q000601:surgery; D004567:Electrodes, Implanted; D004569:Electroencephalography; D004827:Epilepsy / Q000503:physiopathology* / Q000601:surgery*; D006392:Hemangioma, Cavernous / Q000601:surgery*; D006624:Hippocampus / Q000601:surgery; D006801:Humans; D008297:Male; D019635:Neurosurgical Procedures / Q000379:methods*; D009778:Occipital Lobe / Q000601:surgery*; D013702:Temporal Lobe / Q000601:surgery*; D016896:Treatment Outcome
Epilepsy; Hippocampus; Temporal Cavernoma; Transoccipital Approach