A total of twenty-one patients operated by the author in the last 6 years were reviewed. All the patients had hemifacial spasm since few years. All had tried medical management in the form of carbamazepine, gabapentin and pregabalin at other hospitals, but the spasms were not controlled. The first patient had a history of treatment by botox injection resulting in a mild facial palsy.
MRI of the brain with 3D CISS/FIESTA images was done to identify the vessel compressing the facial nerve root entry zone and to rule out other causes of hemifacial spasm-like tumour, AVM, aneurysm and demyelinating conditions like multiple sclerosis. It is important to differentiate primary hemifacial spasm caused by atraumatic pulsatile vascular compression from secondary hemifacial spasm and other conditions like blepharospasm and fasciculation, as treatment strategy for both is different. If surgery is carried out for hemifacial spasm seen in demyelinating lesions, fascinations seen in Bell’s palsy, blepharospasm, etc. then is bound to fail.
Only patients with primary hemifacial spasm were included in this study.
Out of a total of 21 patients, four were male, and seventeen were females. Thirteen had right-sided spasm while eight had spasm on the left side. The responsible vessel was anterior inferior cerebellar artery (AICA) in eighteen cases, posterior inferior cerebellar artery (PICA) in two cases and veins in one case.
The age distribution was as under (Table 1).
All the patients were operated by the retromastoid approach under general anaesthesia in supine position (Video 1). The head was turned to the opposite side by 90°, and the ipsilateral shoulder elevated by sandbag. The vertex of the head was dropped by 10–15° towards the floor. This is important as it improves the visualisation of the facial nerve from the inferior angle. A standard retromastoid craniotomy was done, and dura opened. The cerebellum is then gently pressed on the inferior-lateral aspect with the suction cannula over a cottoned patty, so as to release CSF from the cerebello-medullary cistern. We avoid using self-retaining retractors for cerebellar retraction as this leads to a greater chance of traction injury to the eighth nerve and consequent hearing loss [5,6,7]. As CSF is drained, the lower cranial nerves come into view. A small vein drain from the cerebellum to the inferior petrosal sinus may get ruptured. Hence, forceful retraction should be avoided. We usually do not cauterise the vein. The lower cranial nerves are followed back to their origin from the brainstem by cutting the arachnoid adhesions between the nerves and the cerebellum sharply by micro-scissors. Once the brainstem is visualised, attention is directed to the arachnoid between the 8th nerve and the cerebellum. These are cut sharply leading to further visualisation of the 7–8th nerve complex. Next, the lower cranial nerves are visualised at their point of entry into the brainstem. Then, the angle of microscope is turned slightly upwards, and the flocculus and the choroid plexus are visualised. All these steps can be done without using self-retaining retractors. Gentle pressure on the cottonoid with a suction provides sufficient retraction to carry out the dissection. The facial root exit zone is best visualised through the infra-floccular approach lifting the cerebellar rostrally. At this stage, it may be necessary to use the thin 3-mm blade of self-retaining Leyla retractor to gently retract the flocullus. The root entry zone of the facial nerve comes in the view. The vascular loop indenting the facial nerve can now be seen. The loop is gently separated from the facial nerve. Any arachnoid adhesions restricting the movement of the loop are cut sharply with micro-scissors. The goal of the surgery is to reorient the axis of the vessel and changes its course away from the facial nerve, rather than simply “push” Teflon between the vessel and the nerve. Soft Teflon felt is now inserted between the nerve and the vessel loop to prevent re-adhesion.
After confirming adequate hemostasis, dura is closed in watertight fashion. Muscles and skin are closed in standard fashion, and dressing applied.
Postoperatively, the patient is kept in an ICU for few hours. Antiemetics, analgesics and IV fluids are continued for 24 h as postoperative transient, vertigo and ataxia, and vomiting may occur. Patient is usually discharged on the second or third postoperative day. Stitches are removed on the eighth or ninth postoperative day.
