Hemifacial Spasm Caused by a Vein: A Case Report

Hemifacial spasm caused by the brainstem developmental venous anomaly: A case report and review of the literature

Background:

Hemifacial spasm (HFS) is usually caused by vascular compression of the root exit zone (REZ) of the facial nerve. Dual compression of the REZ by veins and arteries is also associated with HFS, but venous origin alone is rarely reported. We present a rare case of HFS caused by the brainstem developmental venous anomaly (DVA) treated with microvascular decompression (MVD).

Case Description:

A 30-year-old women presented with the left-sided HFS since the age of 18 years. The brainstem DVA was diagnosed by magnetic resonance imaging (MRI) and followed by two attempts of MVD at some other clinics without any improvement. At our hospital, MVD was performed through a left retromastoid craniotomy. Intraoperatively, after detaching the strong adhesions between the cerebellar hemisphere, petrosal dura and lower cranial nerves, and removing the Teflon sponge inserted during the previous operations, the compressing large vein was found, separated from facial nerve REZ and MVD was completed. The postoperative computed tomography angiography and MRI showed the thrombosis of the main trunk of DVA and decompression of the facial nerve REZ. Complete cessation of HFS with hearing preservation was observed with only slight weakness of mimic muscles which disappeared within 3 months after surgery.

Conclusion:

HFS associated with brainstem DVA is a very rare condition. MVD of the facial nerve REZ with transposition of the large draining vein should be considered as an effective treatment option.

Hemifacial Spasm Caused by Vascular Compression in the Cisternal Portion of the Facial Nerve: Report of Two Cases with Review of the Literature

Although primary hemifacial spasm (HFS) is mostly related to a vascular compression of the facial nerve at its root exit zone (REZ), its occurrence in association with distal, cisternal portion has been repeatedly reported during the last two decades. We report two patients with typical HFS caused by distal neurovascular compression, in which the spasm was successfully treated with microvascular decompression (MVD). Vascular compression of distal, cisternal portion of the facial nerve was identified preoperatively in the magnetic resonance imaging (MRI). It was confirmed again with intraoperative findings of compression of cisternal portion of the facial nerve by the meatal loop of the anterior inferior cerebellar artery (AICA) and absence of any offending vessel in the REZ of the facial nerve. Immediate disappearance of lateral spread response (LSR) after decompression and resolution of spasm after the operation again validated that HFS in the current patients originated from the vascular compression of distal, cisternal portion of the facial nerves. According to our literature review of 64 patients with HFS caused by distal neurovascular compression, distal compression can be classified by pure distal neurovascular compression (31 cases, 48.4%) and double compression (both distal segment and the REZ of the facial nerves, 33 cases [51.6%]) according to the presence or absence of simultaneous offender in the REZ. Eighty-four percent of 64 identified distal offenders were the AICA, especially its meatal and postmeatal segments. Before awareness of distal neurovascular compression causing HFS and sophisticated MRI imaging (before 2000), the rate of reoperation was high (58%). Preoperative MRI and intraoperative monitoring of LSR seems to be an essential element in determination of real offending vessel in MVD caused by distal offender.