893 Posterior Location of the Facial Nerve in Vestibular Schwannoma: Report of a Rare Case and a Brief Literature Review

Abstract

Abstract Background The commonest location of the facial nerve on the surface of a vestibular schwannoma (VS) is ventral. The posterior location of the facial nerve on the surface of a VS is extremely rare and is reported to be between 0.6-3.8%. In this illustrative case report, we present a case of a large VS with posterior location of the facial nerve on its surface. The surgical strategy in this situation to preserve the facial nerve both anatomically and physiologically is discussed. Ours is the first illustrative case of the posterior location of the seventh nerve on these tumours. Case Description An elderly man presented with right cerebellopontine (CP) angle syndrome. MRI showed a partly cystic and partly solid right CP angle lesion extending to the internal auditory meatus. Electrophysiological stimulation of the tumour showed that the facial nerve was located on the posterior surface of the tumour. Under the microscope, the facial nerve was identified on the posterior surface of the tumour. Partial excision of the tumour was done with preservation of the facial nerve both anatomically and physiologically. Conclusions This case reiterates the fact that even though rare, surgeons should anticipate the posterior location of the facial nerve on the surface of VS. Electrophysiological stimulation of the posterior surface of the tumour should be done before tumour resection in all cases to look for the posterior location of the facial nerve. Careful microsurgical dissection should be done to achieve maximal cytoreduction of the tumour, preserving the facial nerve.