Direct correlation between the facial nerve nucleus and hemifacial seizures associated with a gangliocytoma of the floor of the fourth ventricle: A case report

Abstract

SUMMARYA dysplastic neuronal lesion of the floor of the fourth ventricle (DNFFV) causes hemifacial seizures (HFS) from early infancy. However, it is still controversial whether HFS is generated by the facial nerve nucleus or cerebellar cortex. In this study, we confirm a direct correlation between the rhythmic activities in the DNFFV and HFS using intraoperative electroencephalography (EEG) and electromyography (EMG) monitoring. Our results support the theory that a DNFFV provokes ipsilateral HFS via the facial nerve nucleus. KEY WORDS: Facial nerve nucleus, Hemifacial seizure, Dysplastic neuronal lesion, Floor of the fourth ventricle.There are several reports of hemifacial seizures (HFS) caused by dysplastic neuronal lesions of the floor of the fourth ventricle (DNFFV). Delalande et al. (2001) described theta or beta rhythmic activity in the DNFFV using a depth electrode inserted during surgery. However, there have been no reports elucidating a direct correlation between DNFFV and HFS or explaining the possible pathophysiology of a relationship between DNFFV and HFS. In this study, we sought to assess the pathophysiology of DNFFV and HFS by real-time monitoring of HFS during surgery. Case ReportThe patient was a 20-month-old boy who was born without perinatal problems. However, he had seizures with motion arrest and right eyelid contraction soon after birth. At 3 months of age, brain magnetic resonance imaging (MRI) demonstrated a mass lesion on the right side of the floor of the fourth ventricle, which showed isointensity to gray matter in both the T 1 -and T 2 -weighted images and was not enhanced by gadolinium injection. From 4 months of age, his seizures changed to intermittent closure of the right eye and right perioral contraction. Although the patient's psychomotor development was normal in infancy, he could not walk alone at 20 months. His seizures increased gradually and by 20 months of age were occurring every day at almost 20-s intervals while he was both awake and asleep.He underwent tumor resection at 20 months of age. An MRI study obtained for preoperative evaluation revealed a mass lesion the same as at 3 months of age (Fig. 1A). Written informed consent was obtained for intraoperative monitoring before the operation. Needle electrodes were inserted into the right upper and lower eyelids and the right orbicular muscle of the mouth to detect the hemifacial seizures during surgery. A muscle relaxant was not used. Sheet electrodes with 20 contacts were used for evaluating cerebellar cortices, and a strip electrode with four contacts was used within the fourth ventricle.During the surgery, although the sheet electrodes on the bilateral cerebellar cortices did not show any ictal findings related with eyelid twitching, the strip electrode on the tumor demonstrated rhythmic theta waves during eyelid twitching corresponding to electromyography (EMG) (Fig. 1B,C). At the moment of biopsy resection, aberrant EMG occurred with wild eyelid twitching, and then the patient's seizure disappeared soon after appro...

Cerebellar seizures

“…15 Since then there have been a number of cases demonstrating that cerebellar seizures can occur. [1][2][3][4][5][6][7][8][9][10][11]13,14,16,19 In this article we document 2 such patients. The first is a child with a hypodense lesion on MRI deep in the cerebellum resulting in complex partial seizures that were eventually medically controlled.…”

Dysplastic Cerebellar Epilepsy: Complete Seizure Control Following Resection of a Ganglioglioma

“…Furthermore, gangliogliomas are among the most common epileptogenic lesions in epilepsy centers [21], harboring a major propensity for spontaneous electrical discharges which probably explains the association of this lesion to this unique syndrome [22]. Not unexpectedly, histological studies of cerebellar or fourth ventricle lesions presenting with subcortical epilepsy were classified as ganglioglioma [2,4,9,10,12,[23][24][25][26][27], hamartoma [8,13,14,28], gangliomatous hamartoma [29], ganglioneurocytoma [30][31][32] or low-grade dense fibrillary astrocytoma [3,15]. Although many of these lesions may carry a developmental origin and actually represent a continuum with FCD, some are not intrinsically epileptogenic [33].…”

Tracking the source of cerebellar epilepsy: Hemifacial seizures associated with cerebellar cortical dysplasia

“…1D). Intralesional EEG recordings (Delande et al, 2001;Harvey et al, 1996;Yagyu et al, 2011) have been performed in some cases and have shown direct correlation between intralesional rhythmic activity and ipsilateral hemifacial seizures (Yagyu et al, 2011). Furthermore, DSI tractography, portrayed an anatomical disruption at the lesion level (Fig.…”

“…A recent study, using concomitant iEEG and electromyographic recordings, implied that hemifacial contractions originate in the ipsilateral cerebellar dysplastic area and propagate via the facial nucleus into the ventrolateral region of the inferior pons (Yagyu et al, 2011). In order for this to occur, aberrant cerebello-pontine connections are required as normal cerebellar output is rubro-cortical or thalamo-cortical.…”