A more basal approach in microvascular decompression for hemifacial spasm:The para-condylar fossa approach

Background. In iew of the fact that a basal craniectomy in microvascular de compression (MVD) for hemifacial spasm (HFS) can minimize cerebellar retrac tion and expose the facial nerve root exit zone (FNREZ) directly from below without placement of tension on the seventh-eighth cranial nerve complex, we used a more basal approach in 32 patients with typical HFS. Method. A slightly curved skin incision 5 cm in length and 2 cm posterior a nd parallel to the mastoid notch was made. The basal lateral occipital plat e including the lateral one-fourth of the condylar fossa and the posterior one-fourth of the jugular process were removed. For the early drainage of c erebrospinal fluid through a small dural hole, the basal occipital plate po steromedial to the condylar fossa was removed. With this basal craniectomy, minimum elevation of the cerebellar tonsil and flocculus could expose FNRE Z safely. Findings. Thirty one of 32 patients displayed complete disappearance of spa sm following surgery. One patient showed 70% decrease of spasm. Delayed tra nsient facial weakness occurred in one patient. Audiometries showed no post operative hearing decrease in any patient, even though no intra-operative m onitoring of the cochlear function was undertaken. Interpretation. Although this basal approach, the para-condylar fossa appro ach, is a slightly basal modification of the conventional procedure, it may minimize complications.