Bilateral hemifacial spasm might be cured by unilateral microvascular decompression

Tenth case of bilateral hemifacial spasm treated by microvascular decompression: Review of the pathophysiology

BACKGROUND

Bilateral hemifacial spasm (BHFS) is a rare neurological syndrome whose diagnosis depends on excluding other facial dyskinesias. We present a case of BHFS along with a literature review.

METHODS

A 64-year-old white, hypertense male reported involuntary left hemiface contractions in 2001 (aged 50). In 2007, right hemifacial symptoms appeared, without spasm remission during sleep. Botulinum toxin type A application produced partial temporary improvement. Left microvascular decompression (MVD) was performed in August 2013, followed by right MVD in May 2014, with excellent results. Follow-up in March 2016 showed complete cessation of spasms without medication.

RESULTS

The literature confirms nine BHFS cases bilaterally treated by MVD, a definitive surgical option with minimal complications. Regarding HFS pathophysiology, ectopic firing and ephaptic transmissions originate in the root exit zone (REZ) of the facial nerve, due to neurovascular compression (NVC), orthodromically stimulate facial muscles and antidromically stimulate the facial nerve nucleus; this hyperexcitation continuously stimulates the facial muscles. These activated muscles can trigger somatosensory afferent skin nerve impulses and neuromuscular spindles from the trigeminal nerve, which, after transiting the Gasser ganglion and trigeminal nucleus, reach the somatosensory medial posterior ventral nucleus of the contralateral thalamus as well as the somatosensory cortical area of the face. Once activated, this area can stimulate the motor and supplementary motor areas (extrapyramidal and basal ganglia system), activating the motoneurons of the facial nerve nucleus and peripherally stimulating the facial muscles.

CONCLUSIONS

We believe that bilateral MVD is the best approach in cases of BHFS.

Fatal complications following microvascular decompression: could it be avoided and salvaged?

Although the microvascular decompression (MVD) surgery has become an effective remedy for cranial nerve rhizopathies, it is still challengeable and may result in a fatal sequel sometimes. Therefore, the operative skill needs to be further highlighted with emphasis on the safety and a preplan for management of postoperative fatal complications should be established. We retrospectively analyzed 6974 cases of MVD. Postoperatively, 46 patients (0.66 %) presented decline in consciousness with a positive finger-nose test (or failure to be tested) after wake up from the anesthesia, whom were focused on in this study. Their surgical findings and intraoperative manipulation as well as computer tomography (CT) delineation were reviewed in detail. These cases consisted of trigeminal neuralgia in 37 and hemifacial spasm in 9. All these patients underwent an immediate CT scan, which demonstrated cerebellar hemorrhages in 38 and epidural hematomas in 6. A later magnetic resource image delineated cerebral infarctions in basal ganglia in 2. Eventually, 15 (0.2 %) died and 31 survived. Data analysis showed that the mortality is significantly higher in trigeminal cases with cerebellar hematoma and an immediate hematoma evacuation plus ventricular drainage could give the patient more chance of survival (p < 0.05). It appeared that the cerebellar hemorrhage was the predominant cause contributable to the postoperative consciousness decline, which occurred more often in trigeminal cases. To have a safe MVD, an appropriate surgical technique is the priority. It is very important to create a satisfactory working space before decompression of the cranial nerve root, which is obtained by a patient microdissection of the arachnoids rather than blind retraction of the cerebellum and hotheaded sacrifice of the petrous vein. Once a cerebellar hematoma is confirmed, an emergency surgery should not be hesitated. A prompt evacuation of the hematomas followed by a dual ventricular drainage via both the frontal horns may save the patient.