Acoustic neuroma and the eye

Neuro-Ophthalmic Complications of Vestibular Schwannoma Resection: Current Perspectives

Vestibular schwannomas (VSs), also called acoustic neuromas, are benign intracranial neoplasms of the vestibulocochlear (VIII) cranial nerve. Management options include “wait-and-scan,” stereotactic radiosurgery and surgical resection. Due to the proximity of the VIII nerve to the facial (VII) nerve in the cerebello-pontine angle, the VII nerve is particularly vulnerable to the effects of surgical resection. This can result in poor eye closure, lagophthalmos and resultant corneal exposure post VS resection. Additionally, compression from the tumor or resection can cause trigeminal (V) nerve damage and a desensate cornea. The combination of an exposed and desensate cornea puts the eye at risk of serious ocular complications including persistent epithelial defects, corneal ulceration, corneal vascularization, corneal melting and potential perforation. The abducens (VI) nerve can be affected by a large intracranial VS causing raised intracranial pressure (a false localizing sign) or as a result of damage to the VI nerve at the time of resection. Other types of neurogenic strabismus are rare and typically transient. Contralaterally beating nystagmus as a consequence of vestibular dysfunction is common post-operatively. This generally settles to pre-operative levels as central compensation occurs. Ipsilaterally beating nystagmus post-operatively should prompt investigation for post-operative cerebrovascular complications. Papilledema (and subsequent optic atrophy) can occur as a result of a large VS causing raised intracranial pressure. Where papilledema follows surgical resection of a VS, it can indicate that cerebral venous sinus thrombosis has occurred. Poor visual function following VS resection can result as a combination of all these potential complications and is more likely with larger tumors.

Ophthalmic Complications Following Acoustic Neuroma Resection

BACKGROUND

Past studies have shown high rates of ocular complications with the need for ophthalmic surgery following acoustic neuroma resection (ANR).

OBJECTIVE

To determine the rates of ophthalmic complications, referrals, and surgery following ANR, and the factors associated with poor outcomes.

METHODS

A retrospective study of ophthalmic outcomes in patients who underwent ANR was conducted, following institutional review board approval. Surgical approach, tumor size, tumor characteristics, completeness of resection, postoperative House-Brackmann grades, ocular complications, referrals to ophthalmology, and ophthalmic treatments were recorded.

RESULTS

Between 2007 and 2012, 174 patients underwent ANR. There were 3 surgical groups: retrosigmoid (n = 97), translabyrinthine (n = 59), and combined retrosigmoid and translabyrinthine (n = 18). Median tumor size was 2.2 cm. Postoperatively, 30% of patients had facial nerve dysfunction (House-Brackmann ≥3), which recovered to 19% by 1 mo and 8.6% by 1 yr following ANR. Fifty-six (32.9%) patients experienced ocular complications postoperatively, with lagophthalmos, dry eye, and blurry vision as the most common complications. Thirty-six (67.9%) of the patients who required ophthalmic treatment were managed nonsurgically, with just 13 (7.6%) patients requiring referral to an ophthalmologist. In total, only 9 (5.3%) patients received an ophthalmic procedure. Patients with tumors >2 cm, those undergoing combined retrosigmoid and translabyrinthine resection, and those with severe facial nerve dysfunction which did not improve in the first month following surgery were more likely to have poor ophthalmic outcomes.

CONCLUSION

We present lower rates of ophthalmic complications following ANR than previously reported. Improved surgical technique, better postoperative eye care, and facial nerve monitoring most likely accounted for the improved ocular outcomes.

The diagnosis and management of neurofibromatosis 2 in childhood

Neurofibromatosis 2 (NF2) is an autosomal-dominant condition that causes multiple benign nervous system tumors, especially vestibular schwannoma. Although frequently confused with the more common neurofibromatosis 1, NF2 presents a distinct set of diagnostic, genetic, and management issues. The presentation and natural history of NF2 differs in children and adults, with eighth nerve dysfunction often overshadowed by the effects of other tumors on the nervous system. Molecular diagnostics is an important tool for early recognition of NF2, and when performed in the context of appropriate counseling and follow-up, may lead to a better final outcome of the disease. Further research into the molecular genetic etiology of NF2 promises to broaden the possibilities of therapy for this devastating disorder.