Woman, 22, With Dizziness and Headache

NF2 is diagnosed using the following criteria:

1) Bilateral vestibular schwan­nomas

2) Diagnosis of a family member with either NF2 or unilateral vestibular schwannoma, and

3) Juvenile posterior subscapular lens opacities.^9,12,13

Because schwannomas grow slowly, the vestibular system can adapt to the slow destruction of CN VIII. For this reason, patients typically present with unilateral deafness or hearing impairment rather than dizziness.¹¹ Many patients also present with tinnitus and/or vertigo.^14,15

Some vestibular tumors remain stable or even regress; others progress, in some cases causing life-threatening complications.¹⁶ An extremely rare complication of a vestibular schwannoma was reported in one patient: an intratumoral hemorrhage that led to acute neurologic deterioration and death.¹⁷

Since the case patient underwent immediate surgical intervention, it appears she was experiencing significant involvement and it was likely anticipated that without surgical intervention, clinical progression would occur. Her young age could be considered a risk factor for a faster-growing neuroma.¹⁸

Clinical Presentation and Diagnosis
Primary care clinicians commonly see patients with complaints of dizziness, lightheadedness, faintness, or a sensation of spinning or tilting. Vestibular schwannoma should be considered in the differential diagnosis of the patient who presents with these complaints, as well as tinnitus or hearing loss.⁹ The patient with vestibular schwannoma may also have a history of headache, unsteady gait, facial pain, and numbness.¹⁹ A partial differential diagnosis is listed in the table^20,21). The astute clinician will systematically rule out many of these conditions, since certain other features that may be present (eg, rapid onset, vomiting, fever) do not typically occur in the patient with vestibular schwannoma.

Because the symptoms typically associated with vestibular schwannoma are likely to occur bilaterally in patients with other conditions, unilateral symptoms should alert the clinician to investigate further. The patterns and growth rates of vestibular schwannomas are highly variable and currently unpredictable¹⁸ (according to Fortnum et al,¹⁴ at least 50% of tumors do not grow within several years after diagnosis); thus, no clear predictors of tumor growth have been identified to assist in the evaluation of an affected patient,¹⁶ although faster tumor growth rates have been reported in young patients, and Baser et al¹⁸ have called for additional research involving younger persons with vestibular schwannomas.

Standard testing is audiometry followed by MRI, which is considered the most effective means to confirm a diagnosis of vestibular schwannoma.^5,14,22

Treatment for Vestibular Schwannoma
Treatment, whether with surgery or radiation, is associated with significant morbidity and possibly decreased quality of life.¹⁶ Therefore, distinguishing patients whose tumors will grow and pose a threat to them from those whose tumors are likely to remain stable is central to appropriate management.²³

Treatment modalities are considered based on tumor size, growth, presence or absence of tinnitus, and the patient’s preferences and life expectancy.²³ In most cases, decision making is complex and should be customized to meet the patient’s individual circumstances. Patients with similar clinical scenarios have been reported to opt for different treatment choices.²⁴

Four treatment options are currently available for patients with vestibular schwannoma:

Serial observation with periodic MRI studies. Since vestibular schwannomas are benign and slow-growing, conservative manage­ment can be a reasonable option, particularly if the patient is elderly, the tumor is small, and/or little hearing loss has taken place. However, use of observation is associated with a risk for progressive and permanent hearing loss.² Between 15% and 50% of patients who opt for serial observation will undergo subsequent surgical intervention, particularly in cases involving worsening tinnitus, balance problems, or hearing loss.^23-25

Chemotherapy. Agents including bevacizumab (a humanized monoclonal antibody against vascular endothelial growth factor)^8,26,27 and erlotinib (an epidermal growth factor receptor inhibitor) may delay progression or even facilitate regression of vestibular schwannomas.²⁸ Hearing improvement has also been reported in patients with NF2 who were treated with bevacizumab⁸; research is ongoing.²⁶

Fractionated radiotherapy. Hearing may be preserved in 60% to 95% of patients, depending on levels of dosing to the cochlea, but 3% to 7% of patients will need further treatment.^29-31 Radiation treatment is a likely choice in patients with tumors measuring 2.0 cm or less. Larger tumors are considered a surgical disease, and directed radiotherapy may be administered postoperatively (as in the case patient) for residual portions of the tumor.¹⁶

Microsurgery. Compared with other treatment modalities, the emphasis of microsurgery is on removing tumors (particularly larger tumors) rather than controlling their growth.²⁹ The three common approaches are retrosigmoid, middle fossa, or translabyrinthine.^32-34 Preservation of hearing is reportedly better following retrosigmoid or middle fossa microsurgery, compared with a translabyrinthine procedure (because in the latter, the tumor cannot be exposed without damage to the inner ear).^32,35