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Título

Dumbbel-shaped intra and extradural Hypoglossal Schwannoma: clinical presentation and microsurgical treatment in Brazil

RESUMO

51-year-old female presented with history of progressive dizziness for the past 2 years, associated with long date left tinnitus. The patient reported no nausea, gait disturbance, phonation or swallow difficulties. On examination, she was alert and oriented; her left hemi-tongue was atrophic and showed deviation to the left side on protrusion. The palate elevation and uvula contraction were normal, with vomiting reflex preserved, as well as hearing acuity and cerebellar function tests. MRI images showed a solid extra-axial lesion, homogeneus, with gadolinium enhancement, occupying the left lateral clivus and petrous bone, with extension to the left hypoglossal canal and jugular foramen, and also caudal extension. A cerebral angiography was also performed, showing left transverse and sigmoid sinuses stenosis, with predominant contralateral drainage and absence of tumour blush. After proper investigation, the patient was submitted to microsurgical resection of the lesion through a far lateral transcondylar approach. During the surgery it was observed that the tumour eroded the left occipital condyle, which was resected; the tumour had also an intradural extension, which could be removed with preservation of the hypoglossal nerve. It was not noticed any dural sinus involvement. The dura was by the end of the procedure sutured with a galeal patch to cover its defect. Intraoperative anatomopathological analysis demonstrated low grade neoplasia suggestive of Schwannoma, later confirmed by definite immunohistochemical analysis.
In the post-operative care, there was no development of any new neurological deficits and the patient noticed improvement of dizziness. The tongue symptons from hypoglossal paresia persisted. During the later 24 months of follow-up, there was no evidence of tumour recurrence on clinical examination and MRI images. The first case of Hypoglossal Schwannoma was described In 1933, with about one hundred new descriptions in the international literature since then. The proper treatment consists of surgical resection of the tumour as curative option, being the far-lateral transcondylar approach – used in this case - of great value. This approach enables the exposition of vertebral arteries and low cranial nerves, what facilitates the tumour resection with lower risk of damage to physiological vascular and nervous structures.

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