Schwannoma of extraocular nerves: survey of literature and case report of an isolated third nerve schwannoma

Oculomotor nerve schwannoma: case series and literature review

Oculomotor nerve schwannomas are rare benign cranial nerve tumors. There are only a limited number of reports on this pathology in the literature, and there are currently no established management guidelines that aid providers in deciding on surgical versus nonsurgical management. We assess the published literature on the topic to identify indications for treatment as well as outcome measures (e.g., local control rates, survival rates, and complication rates) that have been reported as associated with the various treatment modalities. We attempt to develop an algorithm for evaluation and treatment of oculomotor nerve schwannomas in order to establish consensus on how these tumors should be treated.

Prognosis Factor in Oculomotor Schwannoma: A Case of Endoscopic Endonasal Approach and Systematic Review of the Literature

BACKGROUND

We report the first case of oculomotor nerve (ON) schwannoma treatment through an endonasal endoscopic approach. We also review the literature to determine prognosis factors of ON function after treatment.

METHODS

A complete MEDLINE search was undertaken for all articles reporting data for oculomotor schwannoma. We divided the patient population into 2 groups; Group I: patients who conserved or recovered good ON function and Group II: patients with either new, worsening, or unchanged third-nerve palsy at the last available follow-up. We conducted a comparative statistical analysis of data between the 2 groups.

RESULTS

We identified 55 reported cases of ON schwannoma, all of whom were treated with open transcranial surgery, stereotactic radiosurgery, or observation. There were 22 patients in group I and 33 in group II. At admission, 29 patients had complete oculomotor nerve palsy (34.7% in group I and 67.7% in group II; P = 0.02). Surgical treatment was performed in 36 cases. Radiosurgery was performed in 3 cases. Among patients with good preoperative ON function, 34.6% worsened at last follow-up (26.6% after surgery and 50% with observation; P = 0.03). In total, 31% of patients with total or near-total palsy at admission had an improvement of their ON function (all after surgical resection; P = 0.05).

CONCLUSIONS

ON function at admission and surgical resection of schwannoma appears to be a predictive factor of favorable prognosis regardless of location and tumor size. The endonasal endoscopic approach can be used to biopsy tumors in cases in which open surgery is considered too risky, such as cavernous sinus schwannomas.

Oculomotor Schwannomas: A Systematic Review and Report of Two Pediatric Cases Treated with Fractionated Cyberknife Stereotactic Radiotherapy

OBJECTIVE

Pediatric oculomotor nerve schwannomas are rare and challenging lesions due to the high morbidity associated with surgical intervention and their proximity to critical structures limiting the opportunity for stereotactic radiosurgery. We aim to report and review the novel use of fractionated Cyberknife (Accuray, Inc., Sunnyvale, California, USA) stereotactic radiotherapy in pediatric patients with oculomotor schwannomas.

METHODS

A systematic review of PubMed, Embase, and Cochrane was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two patients, ages 8 and 10 years, with tumor volumes of 0.1 cm³ and 0.2 cm³, respectively, were treated with fractionated Cyberknife radiotherapy at our institution. A total dose of 45-50 Gy was administered over 25 fractions (1.8-2.0 Gy per fraction) to the 82%-84% isodose line. Serial magnetic resonance imaging was obtained for long-term follow-up (56-58 months).

RESULTS

We found 14 articles published between 1982 and 2018 that reported a total of 18 pediatric patients with intracranial oculomotor schwannomas. No previously described cases of pediatric intracranial oculomotor schwannomas were treated with radiation therapy. In both of our patients, radiographic tumor control was achieved at a mean follow-up of 57 months, with 1 patient displaying a decrease in tumor volume. Neither patient exhibited any worsening of their presenting symptoms, nor did either patient develop any new neurocognitive deficits following treatment.

CONCLUSIONS

Fractionated Cyberknife radiotherapy is an effective and well-tolerated treatment option for intracranial oculomotor nerve schwannomas with excellent tumor control rates, similar to surgical and radiosurgical techniques, while sparing critical surrounding structures.

[Oculomotor nerve neurinomas. Case reports and a literature review]

Oculomotor nerve neurinoma not associated with neurofibromatosis type II is an extremely rare pathology. According to the topography, cisternal, cisternocavernous, cavernous, orbitocavernous, and orbital tumor groups are distinguished. The clinical picture of the disease is characterized mainly by either oculomotor disorders or pyramidal symptoms, depending on the tumor localization. Neurinomas of the oculomotor nerve rarely occur without oculomotor disorders. However, in some patients with these tumors, the third nerve function remains intact. In this paper, we present clinical cases of two patients with oculomotor nerve neurinomas and analyze the relevant literature.

Atypical teratoid/rhabdoid tumor (ATRT) arising from the 3rd cranial nerve in infants: a clinical-radiological entity?

Atypical teratoid/rhabdoid tumor (ATRT) is a rare embryonal tumor of the central nervous system with preponderance in very young children, the majority of whom are younger than 3 years of age at diagnosis. Historically, outcomes of this aggressive disease, even with extensive multimodal therapy, have been dismal. Recent improvements have come from therapies directed exclusively towards ATRT, but misdiagnosis or delays in the correct diagnosis lead to significantly worse survival rates. ATRTs most commonly occur supratentorially but have been described in virtually all central nervous system locations, including the cerebellopontine angle cistern, meninges, and spinal canal, and extradural locations. ATRTs originating from cranial nerves are rare. Here, we describe three cases of solitary ATRT arising from the 3rd cranial nerve (CN III) or close to its origin in the midbrain, all of which presented in patients within 6 months of birth, with isolated unilateral oculomotor nerve palsy and strikingly similar magnetic resonance imaging (MRI) features. These MRI features include IV contrast enhancement, relative T2 hyposignal, and restricted water diffusion on apparent diffusion coefficient images, findings which are consistent with angiogenesis and high cellularity, and hence, suggestive of malignancy. We conclude that ATRT should be placed high on the differential diagnosis list when encountering a young infant presenting with isolated, unilateral 3rd nerve palsy and a small, solitary tumor arising from CN III that demonstrates malignant conventional and diffusion-weighted imaging features on MRI.

Oculomotor nerve schwannoma associated with acute hydrocephalus: case report

A 37-year-old woman presented with an extremely rare large oculomotor schwannoma associated with acute hydrocephalus manifesting as semicoma and anisocoria. Brain computed tomography and magnetic resonance imaging revealed a tumor in the oculomotor cistern. Cerebral angiography revealed separation of the posterior cerebral artery (PCA) and superior cerebellar artery (SCA). The tumor was removed subtotally by two stage surgery. Histological examination revealed ordinary schwannoma. The diagnosis of oculomotor nerve schwannoma was based on the intraoperative finding of the tumor origin in the oculomotor nerve. Oculomotor nerve schwannoma can cause acute hydrocephalus and manifest as impaired consciousness. The angiographical separation of the PCA and SCA was very useful for the preoperative diagnosis of oculomotor nerve schwannoma.

Oculomotor nerve schwannoma associated with acute hydrocephalus: case report

A 37-year-old woman presented with an extremely rare large oculomotor schwannoma associated with acute hydrocephalus manifesting as semicoma and anisocoria. Brain computed tomography and magnetic resonance imaging revealed a tumor in the oculomotor cistern. Cerebral angiography revealed separation of the posterior cerebral artery (PCA) and superior cerebellar artery (SCA). The tumor was removed subtotally by two stage surgery. Histological examination revealed ordinary schwannoma. The diagnosis of oculomotor nerve schwannoma was based on the intraoperative finding of the tumor origin in the oculomotor nerve. Oculomotor nerve schwannoma can cause acute hydrocephalus and manifest as impaired consciousness. The angiographical separation of the PCA and SCA was very useful for the preoperative diagnosis of oculomotor nerve schwannoma.

Pediatric isolated oculomotor nerve schwannoma: a new case report and literature review

Isolated schwannoma arising from the oculomotor nerve occurs rarely, and only 12 children with oculomotor nerve schwannoma without neurofibromatosis have been sufficiently documented. This article presents a 3-year-old boy in which a large isolated parasellar oculomotor nerve schwannoma causing parent nerve dysfunction. Complete resection of the tumor was achieved via a right pterion approach, but he developed complete palsy of the third nerve postoperatively, which had an incomplete recovery in 12-month follow-up. We review the pertinent literature about pediatric oculomotor nerve schwannoma and discuss its clinical features and management.

Surgical management of nonvascular lesions around the oculomotor nerve

OBJECTIVE

Schwannomas originating from the oculomotor nerve are extremely rare. We report our experience in the management of oculomotor schwannomas and other lesions mimicking them, and discuss operative strategy for these rare tumors emphasizing oculomotor nerve preservation.

METHODS

The clinical records of our patients and all those reported in the literature focusing on oculomotor schwannomas were reviewed and analyzed. The clinical presentations, operative approaches, complications, and results were studied.

RESULTS

Between 1983 and 2010, six patients with primary oculomotor nerve lesions were treated. Three of them had schwannomas. Two others had pathologies that mimicked an oculomotor schwannoma and one was suspected as schwannoma. In the literature there were 55 previous cases of oculomotor schwannomas reported (surgical treated, 41 cases; observed, 9; gamma knife surgery treated, 2; autopsy, 3). Patients presented most commonly with diplopia, followed by headache and ptosis as initial symptoms. Out of 55 patients including the present 3 cases (3 autopsy cases were excluded), 30 patients (54.5%) finally developed oculomotor nerve palsy. Fifteen of 44 patients (34.1%) who underwent surgery developed persistent postoperative oculomotor palsy. Among them, 6 patients developed total palsy after surgery. Five of 12 patients (41.7%) who did not undergo surgery also developed oculomotor palsy. Oculomotor schwannomas most often grow its cisternal segment (48.3%) followed by intracavernous (39.6%) and cisternocavernous segments (12.1%).

CONCLUSION

The microsurgical resection of oculomotor schwannomas carries a risk of worsening preoperative oculomotor nerve function; however, this is often transient. Considerable technical training and microanatomical knowledge of the region is required to optimize outcome.

Management of oculomotor nerve schwannomas in two different locations: surgical nuances and comprehensive review

Rare tumors with anecdotal reportage, oculomotor schwannomas are most often seen in the oculomotor cistern close to the anterior clinoidal region. Adding to the small series of reported cases of this unusual lesion, we report two male patients in their second decade who presented with different degrees of oculomotor palsy. The location of the lesion was caverno-cisternal in one case and orbito-cavernous in the other. Intricate neurovascular relationships of this lesion, especially in non-cavernous locations, are discussed. The risk of damage to nerve rootlets enmeshed within the lesion is high with attempts at near-total excision, rendering the anatomical preservation of the nerve an arduous exercise. The authors review literature pertaining to this unusual lesion and elucidate surgical nuances which may have a bearing on outcome.

Large oculomotor schwannoma presenting as a parasellar mass: A case report and literature review

Background:

Large schwannomas arising from the oculomotor nerve are very rare. The common site of tumor occurrence in this nerve is the segment within the interpeduncular cistern and the cavernous sinus.

Case description:

We report a case of a large left-sided oculomotor nerve schwannoma with minimal clinical signs and symptoms of oculomotor nerve involvement resembling a large parasellar mass. The radiological features of the mass were more consistent with a medial sphenoid wing meningioma causing brain stem compression. Complete resection of the tumor was achieved via a left pterional approach. The patient developed complete third nerve palsy postoperatively.

Conclusion:

The management of these large benign tumors with brain stem compression includes surgical resection. Intraoperative anatomical preservation of the third nerve was impossible given its course in the tumor. We discuss the pertinent literature and management of large oculomotor schwannomas.

Oculomotor nerve schwannoma located in the oculomotor cistern

BACKGROUND

OSs are extremely rare tumors, most often located in the interpeduncular cistern or the CS. We report an OS located predominantly within the oculomotor cistern, the arachnoid sac that surrounds the nerve for a short distance in the roof of the CS. We discuss a possible growth pattern for cavernous OSs.

CASE DESCRIPTION

We report the case of a 34-year-old woman presenting with a right oculomotor nerve palsy. Magnetic resonance imaging revealed a mass within the borders of the roof of the CS extending forward toward the superior orbital fissure. A right pterional approach was undertaken, and the roof of the CS was opened just above the oculomotor nerve toward the superior orbital fissure. Although the part of the OS inside the oculomotor cistern was excised completely while preserving the anatomical continuity of the nerve, a subtotal removal was performed for the more anterior part of the tumor toward the superior orbital fissure. At 5 months follow-up, her third nerve paresis had improved dramatically.

CONCLUSIONS

Resection of cavernous OSs within the oculomotor cistern, where the third nerve is clearly separated from the adjacent neurovascular structures, is feasible with functional preservation of the nerve. The chance of occurrence of the nerve palsy may increase as the resection proceeds more anteriorly toward the superior orbital fissure.

Oculomotor nerve schwannoma associated with ophthalmoplegic migraine

PURPOSE

To describe a patient with an oculomotor nerve schwannoma who had symptoms of ophthalmoplegic migraine.

METHODS

Case report.

RESULTS

A 23-year-old woman had a history of recurrent headache accompanied by transient right oculomotor palsy since age 7 years. Ophthalmoplegic migraine was diagnosed. She was subsequently found to have a structural lesion of her right oculomotor nerve on magnetic resonance imaging. The magnetic resonance image characteristics were consistent with schwannoma originating from the oculomotor nerve.

CONCLUSIONS

This case illustrates that an intrinsic lesion of the oculomotor nerve (schwannoma) may be associated with a painful relapsing-remitting oculomotor palsy mimicking the clinical syndrome of ophthalmoplegic migraine.