Article
Greater superficial petrosal nerve schwannoma
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Published: | May 30, 2008 |
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Only 0.8% of petrous mass lesions are facial schwannomas; among these, greater superficial petrosal nerve (GSPN) schwannomas are very rare. Only 6 cases have been reported in the literature. Frequent clinical symptoms of GSPN schwannoma include facial palsy and hearing difficulties with extension of the tumour into the tympanic cavity.
This 32-year-old man was admitted with a six months history of slow progressive hearing loss on the right side associated with occasional low pitched tinnitus. On examination a decreased conductive hearing on the right was detected with no signs of facial palsy. On MRI, a 27 x 22 mm, round, well defined mass was evident in the right middle cranial fossa. It was hypo-intense on T1-weighted images without contrast and hyperintense on T2-weighted images. There was homogeneous enhancement after intravenous gadolinium.
The patient underwent complete surgical removal of the mass throw a right subtemporal extradural approach; previous, a lumbar spinal drain was positioned. After the retraction of the temporal lobe, an extradural, yellowish, well defined mass was visible. After the reduction of mass, the origin was localised in the petrous bone. The middle ear was open, as its roof was destroyed by tumour. After removal of tumour, the auditory ossicles were seen. The intact facial nerve and its geniculate ganglion were identified and also the GSPN, which was the origin of the mass. Histology showed a schwannoma. Post operative course was characterized by a complete facial palsy (°III H&B). After 6 months follow-up, the facial palsy was unchanged. There was no further deterioration of hearing on audiometry.