Para-condylar Foraminal Approach in Microvascular Decompression for Hemifacial Spasm

ABSTRACT

The ideal approach in microvascular decompression(MVD) for hemifacial spasm(HFS) should provide the shortest and perpendicular route to the facial nerve root exit zone(FNREZ) with minimal cerebellar retraction and early cerebrospinal fluid drainage to avoid surgical morbidity. Small basal craniectomy anterior, posterior and superior to the condylar foramen would be the ideal approach for HFS, because it is maximal basal route to FNREZ. We performed this approach in 15 patients with HFS. Slightly curved skin incision 5cm in length was placed from inferior nuchal line 2cm posterior to the mastoid notch toward the angle of the mandible and the neck muscles were splitted. Posterior condylar emissary vein was elevated from condylar fossa. Small basal craniectomy extending from the inferior nuchal line to the condylar foramen was made. Jugular process was drilled out along the superior margin of the occipital condyle to expose distal sigmoid sinus and the junction of sigmoid sinus and jugular bulb. Lateral margin of foramen magnum posteroinferior to the condylar foramen was removed for early drainage of CSF from lateral medullary cistern. Dura was opened in T-shaped manner. With minimal elevation of cerebellum, arachnoid around lower cranial nerves can be dissected and FNREZ can be identified easily and safely. In conclusion, para-condylar foraminal approach can be considered to be minimally invasive and maximally safe in MVD for HFS.