Cellular Schwannoma of the Greater Superficial Petrosal Nerve Presenting With Abducens Nerve Palsy and Xerophthalmia

Abstract

The abducens nerve palsy improved completely in the follow-up period, but the decreased tear secretion did not resolve. CS is one of the subtypes of ordinary schwannomas and exhibits malignant features on microscopic examination, although it has a good clinical prognosis. No adjuvant treatment was applied because of the tumor's benign character. The greater superficial petrosal nerve schwannoma should be considered in the differential diagnosis of the abducens nerve palsy and petrous apex mass.

Greater Superficial Petrosal Nerve Schwannoma: 3 Case Reports and Review of Literature

“…Contrast-enhanced MR images usually demonstrate homo-to heterogeneous enhancement. Carotid angiography has been advised if tumor is in close proximity or abutting petrous carotid artery [1,2,10,13,20]. In none of our case it deemed necessary.…”

“…In previously reported cases only 6 patients had xerophthalmia [1,[12][13][14]. Other reported manifestations include diplopia due to abducens nerve palsy [1], trigeminal nerve involvement [15], seizure [12], eye pain, headache etc. One of our patient had xerophthalmia, all three had facial paresis.…”

“…Facial nerve schwannomas are rare and comprise about 0.8% of all intrapetrous mass lesions [1,2,3,4]. In order of decreasing frequency these schwannomas in petrous bone, can arise from tympanic, vertical, labyrinthine, geniculate, and meatal segment of the facial nerve [5].…”

“…Xerophthalmia, although pathognomonic of GSPN schwannoma may not be there in all patients and only present if parasympathetic nerve fibers have been destroyed by the tumor [7][8][9][10][11]. In previously reported cases only 6 patients had xerophthalmia [1,[12][13][14]. Other reported manifestations include diplopia due to abducens nerve palsy [1], trigeminal nerve involvement [15], seizure [12], eye pain, headache etc.…”

“…It is usually isodense to gray matter with homo-to heterogeneous post-contrast enhancement containing cystic or calcified foci on CT scan [3,6,[16][17][18]. MRI may show tumor iso-to hypointense relative to gray matter on T1WI and hetero-to homogenously hyperintense on T2WI [1,4,19]. Contrast-enhanced MR images usually demonstrate homo-to heterogeneous enhancement.…”