Microvascular decompression for hemifacial spasm: technical notes on pontomedullary sulcus decompression.

BACKGROUND

Hemifacial spasm usually results from compression of facial nerve by offending vessels. During microvascular decompression, offending vessels at pontomedullary sulcus are obscured by the lower cranial nerve roots, making exposure and surgery difficult. This study discusses the techniques for decompression of offending vessels in this area.

METHODS

Of 213 patients who underwent microvascular decompression for hemifacial spasm, 34 patients had compression of the facial nerve at the pontomedullary sulcus by offending vessels. Details of the intraoperative exposure and the arrangement of the lower cranial nerve roots are reviewed. The handling of the vertebral artery (VA) and the protection of perforating vessels is also discussed.

RESULTS

Sixteen patients had the compact type of cranial nerve root arrangement, 13 had the loose type and five had the solitary type. Fifteen patients had compression by the VA. At 1 year after surgery, 30 patients had excellent results, two had good results and two had poor results.

CONCLUSIONS

Microvascular decompression for hemifacial spasm can be performed with satisfying results if there is full exposure and protection of the perforating vessels, appropriate use of the spaces between cranial nerve roots, and attention paid to the characteristics of offending vessels.