Intracranial nonvestibular neurinomas: Young neurosurgeons' experience

Abstract

Background and objectives: Neurinoma arising from other than nonvestibular cranial nerves is less prevalent. Here we present our experiences regarding the clinical profile, investigations, microneurosurgical management, and the outcome of nonvestibular cranial nerve neurinomas.

Materials and methods: From January 2005 to December 2011, the recorded documents of operated nonvestibular intracranial neurinomas were retrospectively studied for clinical profile, investigations, microneurosurgical management, complications, follow-up, and outcomes.

Results: The average follow-up was 24.5 months. Total number of cases was 30, with age ranging from 9 to 60 years. Sixteen cases were males and 14 were females. Nonvestibular cranial nerve schwannomas most commonly originated from trigeminal nerve followed by glossopharyngeal+/vagus nerve. There were three abducent nerve schwannomas that are very rare. There was no trochlear nerve schwannoma. Two glossopharyngeal+/vagus nerve schwannomas extended into the neck through jugular foramen and one extended into the upper cervical spinal canal. Involved nerve dysfunction was a common clinical feature except in trigeminal neurinomas where facial pain was a common feature. Aiming for no new neurodeficit, total resection of the tumor was done in 24 cases, and near-total resection or gross total resection or subtotal resection was done in 6 cases. Preoperative symptoms improved or disappeared in 25 cases. New persistent deficit occurred in 3 cases. Two patients died postoperatively. There was no recurrence of tumor till the last follow-up.

Conclusion: Nonvestibular schwannomas are far less common, but curable benign lesions. Surgical approach to the skull base and craniovertebral junction is a often complex and lengthy procedure associated with chances of significant morbidity. But early diagnosis, proper investigations, and evaluation, along with appropriate decision making and surgical planning with microsurgical techniques are the essential factors that can result in optimum outcome.

Keywords: Intracranial; microneurosurgical management; neurilemmomas; neurinomas; nonvestibular; schwannomas.

Figure 1

(a-c) Preoperative MRI of brain showing right-sided huge trigeminal schwannoma (axial, coronal, and sagittal views sequentially). (d-f) Postoperative MRI of brain showing the complete removal of tumor (axial, coronal, and sagittal views sequentially)

Figure 2

(a) Preoperative MRI of brain axial section showing right-sided trigeminal neurinoma and left-sided vestibular neurinoma. (b) Postoperative MRI of brain axial section showing complete removal of trigeminal neurinoma (right) and near-total removal of vestibular neurinoma (left)

Figure 3

(a) Magnetic resonance imaging of brain coronal view showing trigeminal schwannoma (inside the ellipse) (right mandibular division) coming out into infratemporal fossa through foramen ovale. (b) Computed tomography scan of skull base (bone window) showing dilated foramen ovale (arrow indicated) on the right side

Figure 4

(a) Preoperative MRI of brain axial section showing left-sided cavernous sinus sixth nerve schwannoma and left-sided vestibular nerve schwannoma (arrows marked). (b) Postoperative MRI of brain axial section showing complete removal of sixth nerve schwannoma and near-total removal of vestibular schwannoma (arrow marked)

Figure 5

(a) Preoperative MRI of brain axial section (T2W image) showing right cerebellopontine angle facial nerve schwannoma. (b) Postoperative contrast CT scan axial section showing complete removal of schwannoma. (c) Preoperative facial nerve paresis. (d) Preoperative pure tone audiometry showing bilateral normal hearing

Figure 6

Preoperative MRI of brain and neck (T1W images). (a and b) Axial view and (c and d) Sagittal view showing very large right jugular foramen schwannoma (JFS) extending from posterior cranial fossa to neck (up to common carotid artery bifurcation). Postoperative MRI of brain and neck (e and f) Axial T2W images. (g) Coronal T2W image and (h) sagittal contrast image showing complete removal of intracranial portion of JFS and subtotal resection of neck portion of tumor with grafted fat in tumor dead space

Figure 7

(a) Preoperative MRI of brain T2W axial image showing left-sided glossopharyngeal/vagal schwannoma. (b) Postoperative MRI of brain T2W axial image showing complete removal of tumor

Figure 8

(a) Preoperative MRI of brain contrast sagittal view showing craniovertebral (CV) junction accessory nerve schwannoma. (b) Postoperative MRI of brain contrast sagittal view showing complete removal of tumor

Figure 9

Comparative picture of operative views of CP angle after complete removal of (a) nonvestibular and (b) vestibular schwannomas. r: Cerebellar retractor; vcf: Vestibulo-chochlear-facial nerves complex; t: Trigeminal nerve; a: Abducent nerve; f: Facial nerve; iam: Internal acoustic meatus (drilled)