ABSTRACT
Trigeminal schwannomas (TS) are rare. Only a couple of series involving a large number of cases have been reported. In the present study we aimed to analyse the clinical characteristics of TS, the surgical approaches used to treat TS, and the outcomes for patients undergoing surgical treatment for TS via retrospective analysis of departmental records. Data for 68 patients treated for TS in the Department of Neurosurgery at the All India Institute of Medical Sciences between January 1993 and December 2005 were analysed. Most patients were in the fourth decade of life, with the duration of symptoms ranging from 1 month to 13 years. Twenty-nine TSs were classified as type A, 13 as type B and 26 as type C, depending upon size. A skull base approach was used in every surgically treated case. Of the 46 patients for whom radiological follow-up data were available, complete tumour excision was achieved in 35 cases (76%). Follow-up ranged from 3 months to 12 years (mean 62 months). One patient died and nine (15%) had permanent morbidity in the form of corneal opacity (5) or facial (2) or trochlear (2) nerve palsy. We conclude that trigeminal neuromas are best treated by total surgical resection, which yields acceptable results with low rates of mortality and permanent morbidity.
Subject(s)
Cranial Nerve Neoplasms/surgery , Neurilemmoma/surgery , Trigeminal Nerve Diseases/surgery , Trigeminal Nerve/surgery , Adolescent , Adult , Cranial Fossa, Middle/pathology , Cranial Fossa, Middle/physiopathology , Cranial Fossa, Middle/surgery , Cranial Nerve Neoplasms/pathology , Cranial Nerve Neoplasms/physiopathology , Craniotomy/methods , Decompression, Surgical/methods , Facial Nerve Injuries/mortality , Facial Nerve Injuries/prevention & control , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Neurilemmoma/pathology , Neurilemmoma/physiopathology , Neurosurgical Procedures/methods , Postoperative Complications/etiology , Postoperative Complications/mortality , Postoperative Complications/physiopathology , Radiosurgery/methods , Retrospective Studies , Trigeminal Nerve/pathology , Trigeminal Nerve/physiopathology , Trigeminal Nerve Diseases/pathology , Trigeminal Nerve Diseases/physiopathology , Trochlear Nerve Diseases/mortality , Trochlear Nerve Diseases/prevention & controlABSTRACT
OBJECTIVE: To describe the anatomy of the cisternal segment of the trochlear nerve as seen through different neurosurgical approaches. METHODS: The cisternal course of ten trochlear nerves was observed in five cadaveric embalmed heads, through the view afforded by the median infratentorial-supracerebellar, the extreme-lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. The relationships of the trochlear nerve with the surrounding neuro-vascular structures were analyzed. RESULTS: We identified 3 segments of the cisternal trochlear nerve: quadrigeminal, ambient and tentorial. The median infratentorial-supracerebellar approach allowed exposure of the quadrigeminal segment, including the origin of the nerve. The extreme-lateral supracerebellar and the combined presigmoid-subtemporal transtentorial approaches provided visualization of the ambient and tentorial segments of the nerve. The tentorial segment runs in a dural canal contained in the free edge of the tentorium, surrounded by its own arachnoidal sleeve. CONCLUSION: The trochlear nerve is a very delicate structure that can be easily injured during approaches to the tentorial incisura. Accurate knowledge of its anatomy as seen through different operative windows is helpful in maintaining its integrity during surgery.
