Vertical Parasagittal Hemispherotomy.

Hemispherotomy is a surgical procedure aimed at the treatment of hemispheric epilepsy. Hemispherotomy disconnects the commissural fibers, projecting fibers, and limbic system while preserving most of the brain parenchyma, unlike conventional hemispherectomy.1 Hemispherotomy is one of most complicated operations currently used in epilepsy surgery and requires a high-level understanding of the intrinsic neuroanatomy. Generally, 2 main techniques are applied in hemispherotomy: lateral hemispherotomy and vertical hemispherotomy.2,3 Vertical hemispherotomy was developed after the lateral technique. Despite a deeper, narrower surgical corridor, vertical hemispherotomy requires a smaller craniotomy and a shorter disconnection line and allows easier disconnection of the insula than the lateral approach.1 In performing vertical hemispherotomy, 2 options are available: the interhemispheric approach4 and the parasagittal approach.3 With the parasagittal approach, the lateral ventricle is opened and entered via superior frontal gyrus. To ease the surgery and minimize the operation time, we apply "partial superior frontal gyrus removal." This procedure is useful to widen a shallower surgical field while skipping the need for interhemispheric dissection. Total callosotomy is then performed via the lateral ventricle. To disconnect limbic system, we used the technique following the falx and tentorial edge as a landmark.5 Here, we present our surgical steps for parasagittal hemispherotomy in a 5-month-old girl diagnosed as hemimegalencephaly (Figures 1-8).

A scoping review of seizure onset pattern in SEEG and a proposal for morphological classification.

BACKGROUND: Seizure onset pattern (SOP) represents an alteration of electroencephalography (EEG) morphology at the beginning of seizure activity in epilepsy. With stereotactic electroencephalography (SEEG), a method for intracranial EEG evaluation, many morphological SOP classifications have been reported without established consensus. These inconsistent classifications with ambiguous terminology present difficulties to communication among epileptologists. METHODS: We reviewed SOP in SEEG by searching the PubMed database. Reported morphological classifications and the ambiguous terminology used were collected. After thoroughly reviewing all reports, we reconsidered the definitions of these terms and explored a more consistent and simpler morphological SOP classification. RESULTS: Of the 536 studies initially found, 14 studies were finally included after screening and excluding irrelevant studies. We reconsidered the definitions of EEG onset, period for determining type of SOP, core electrode and other terms in SEEG. We proposed a more consistent and simpler morphological SOP classification comprising five major types with two special subtypes. CONCLUSIONS: A scoping review of SOP in SEEG was performed. Our classification may be suitable for describing SOP morphology.