Vestibular schwannoma

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Key diagnostic factors

common

asymmetric hearing loss

Over 90% of patients exhibit unilateral or asymmetric sensorineural hearing loss. Such findings indicate need for an audiology workup.[2][38][45] Though definitions vary, asymmetric hearing loss is commonly defined by 2 or more contiguous frequencies with >10 dB asymmetry, or ≥15 dB at 1 frequency, compared with the contralateral ear on behavioral audiometry.[46] Some have reported that asymmetry at 3000 Hz is most sensitive.[47] Notably, many people with sudden sensorineural hearing loss will experience improvement, either spontaneously or following corticosteroid therapy. Improvement in hearing does not exclude the diagnosis of a vestibular schwannoma, and MRI should also be obtained in these cases.[42] Though variable, differences of >20% in word recognition should also prompt consideration for MRI screening. Approximately 3% of people with asymmetric hearing loss will have a vestibular schwannoma, or other retrocochlear lesions, identified on imaging, emphasizing that in most cases, asymmetric hearing loss is actually not due to a vestibular schwannoma.

progressive episodes of dizziness

Intermittent or brief imbalance, particularly with quick head turning, is common and results from unilateral vestibular hypofunction. Large tumors may result in dysmetria and ataxia related to cerebellar compression or hydrocephalus.

tinnitus

Tinnitus represents a phantom percept that results from cochlear deafferentation. Ipsilateral or bilateral tinnitus is a common symptom among patients with vestibular schwannomas and often coincides with hearing loss. Notably, tinnitus is highly prevalent in the general adult population and most people with tinnitus do not have a vestibular schwannoma.

Other diagnostic factors

common

difficulty localizing sounds

Significant ipsilateral hearing loss (typically >30 dB compared to the other ear) makes localizing sound and distinguishing voices in crowds difficult.

uncommon

headache

May occur with associated earache or pressure sensation. As headache is a ubiquitous symptom in the general population, separating out headache that is attributable to the tumor from other causes is often challenging. It is believed that most small and medium-sized tumors do not result in headache. Therefore, in most cases, headaches are diffuse and not localizing to the side of the head with the tumor.

facial numbness

Ipsilateral facial numbness often begins in a perioral distribution, although presentation is variable. Diminished or absent sensation, reduced blink reflex, or ipsilateral neuralgiform face pain may occur with tumors that are larger than approximately 2-3 cm in cerebellopontine angle dimension.

facial weakness

A late finding typically indicating a larger tumor.[48][13] The presence of ipsilateral facial weakness at diagnosis should raise the possibility of an alternative diagnosis, primarily a facial nerve schwannoma, or less commonly a malignancy, rather than a vestibular schwannoma.

diplopia on lateral gaze

Late finding, usually associated with nystagmus.

Rarely related to abducens weakness.