Root Entry Zone Of Facial Nerve Research Articles

Vertebral artery dolichoectasia leading to hemifacial spasm

A 45-year-old male presented to the ophthalmology clinic complaining of constant twitching in the left face for three years, associated with a moderate left temporal headache. He was noted to have tonic-clonic contractions of the left orbicularis oculi and oris muscles (Figure 1, Video 1). MR imaging through the posterior fossa (Figure 2) demonstrated compression of the pons at the facial nerve root entry zone by an ectatic left vertebral artery. The patient’s symptoms improved with botulinum neurotoxin injections. The most common etiology of hemifacial spasm is compression of the facial nerve as it emerges from the brainstem by ectatic vessels.

169 Microvascular Decompression for Hemifacial Spasm

INTRODUCTION:Hemifacial spasm (HFS) is a condition of debilitating, involuntary contractions of facial muscles with an estimated prevalence of 11/100 000. The potentially curative microvascular decompression surgery (MVD) aims to alleviate compression upon the facial nerve root entry zone (fREZ) by

Microanatomy and histological features of central myelin in the root exit zone of facial nerve.

ObjectiveThe aim of this study was to evaluate the microanatomy and histological features of the central myelin in the root exit zone of facial nerve.MethodsForty facial nerves with brain stem were obtained from 20 formalin fixed cadavers. Among them 17 facial nerves were ruined during preparation and 23 root entry zone (REZ) of facial nerves could be examined. The length of medial REZ, from detach point of facial nerve at the brain stem to transitional area, and the thickness of glial membrane of central myelin was measured. We cut brain stem along the facial nerve and made a tissue block of facial nerve REZ. Each tissue block was embedded with paraffin and serially sectioned. Slices were stained with hematoxylin and eosin (H&E), periodic acid-Schiff, and glial fibrillary acid protein. Microscopy was used to measure the extent of central myelin and thickness of outer glial membrane of central myelin. Thickness of glial membrane was examined at two different points, the thickest area of proximal and distal REZ.ResultsSpecial stain with PAS and GFAP could be differentiated the central and peripheral myelin of facial nerve. The length of medial REZ was mean 2.6 mm (1.6-3.5 mm). The glial limiting membrane of brain stem is continued to the end of central myelin. We called it glial sheath of REZ. The thickness of glial sheath was mean 66.5 µm (40-110 µm) at proximal REZ and 7.4 µm (5-10 µm) at distal REZ.ConclusionMedial REZ of facial nerve is mean 2.6 mm in length and covered by glial sheath continued from glial limiting membrane of brain stem. Glial sheath of central myelin tends to become thin toward transitional zone.

Hemifacial spasm patient with ipsilateral total absence of common carotid artery, vertebral artery and aneurysm of the contralateral internal carotid artery

We present a case of a 45-year-old male patient with left hemifacial spasm for 6 years. Magnetic resonance tomographic angiography confirmed that there were small vessels adjacent to the left facial nerve root entry zone, but the left internal carotid artery (ICA) was absent. Magnetic resonance angiography using three-dimensional time of flight technique showed the absence of the left ICA and vertebral artery, But the presence of a 6-mm aneurysm in the bifurcation of the right internal carotid artery. These abnormal arterial structures were further confirmed by angiogram. Aortic arch angiogram revealed a right-sided aortic arch and the Subclavian steal phenomenon. The left common carotid artery and the left Subclavian artery were absent. Right vertebral angiography showed retrograde filling of the left vertebral artery. The left upper limb was fed by this artery. The aneurysm was successfully clipped. Post-operatively, the hemifacial spasm was weakened. However, the operation did not change the neurovascular positional relationship, thus we advised follow-up visits. Cerebral artery anomalies should be taken into consideration when performing imaging and surgical corrections in patients with hemifacial spasm.