Abstract
IntroductionThe use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure. Currently a new surgical technique allows surgeons to work in safer conditions. ObjectiveTo report the results with endoscope-assisted retrosigmoid approach for facial nerve microvascular decompression in hemifacial spasm due to neurovascular conflict. The surgical technique is described. MethodsWe carried out a prospective study in a tertiary referral center observing 12 (5 male, 7 female) patients, mean age 57.5 years (range 49–71) affected by hemifacial spasm, that underwent to an endoscope assisted retrosigmoid approach for microvascular decompression. We evaluated intra-operative findings, postoperative HFS resolution and complication rates. ResultsHemifacial spasm resolution was noticed in 9/12 (75%) cases within 24h after surgery and in 12/12 (100%) subjects within 45 days. A significant (p<0.001) correlation between preoperative historical duration of hemifacial spasm and postoperative recovery timing was recorded. Only 1 patient had a complication (meningitis), which resolved after intravenous antibiotics with no sequelae. No cases of cerebrospinal fluid leak, facial palsy or hearing impairment were recorded. Hemifacial spasm recurrence was noticed in the only subject where the neurovascular conflict was due to a vein within the internal auditory canal. ConclusionsThe endoscope assisted retrosigmoid approach technique offers an optimal visualization of the neurovascular conflict thorough a minimally invasive approach, thus allowing an accurate decompression of the facial nerve with low complication rates. Due to the less invasive nature, the procedure should be considered in functional surgery of the cerebellar pontine angle as hemifacial spasm treatment, specially when the procedure is performed by an otolaryngologist.
Highlights
The use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure
Magnetic Resonance Imaging (MRI) T2 sequence is the most sensitive in identifying the vessels impinging the facial nerve8---24 in the cerebellopontine angle (CPA) root exit zone (REZ) and more rarely in the entry of the porus
A constant association between Hemifacial spasm (HFS) side and neurovascular conflict (NVC) site was noticed, which confirms the concept that a contact between a vessel loop and the facial nerve is responsible for facial spasm (Fig. 6)
Summary
The use of surgical decompression of facial hemispasm due to the loop in the internal auditory canal is not always accepted due to the risk related to the surgical procedure. Objective: To report the results with endoscope-assisted retrosigmoid approach for facial nerve microvascular decompression in hemifacial spasm due to neurovascular conflict. Two possible theories of HFS pathophysiology have been reported in the literature: the ‘‘central’’ and the ‘‘peripheral’’ hypotheses. According to the former one, the facial nerve injury, due to the neurovascular impingement, would have a regressive action on facial nucleus, causing neural hyperexcitability. On the contrary, according to the ‘‘peripheral’’ hypothesis, clinical symptoms would result from ectopic impulse generation and transmission alteration due to facial nerve demyelization.[4] Even though no definite evidence has been reported on which theory is the accurate one, both mechanisms likely contribute together to the onset of HFS
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