Vestibular schwannoma

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

Key diagnostic factors

common

asymmetrical hearing loss

Over 90% of patients exhibit unilateral or asymmetrical sensorineural hearing loss. Such findings indicate need for an audiology work-up.[2][38][45] Though definitions vary, asymmetrical 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 behavioural 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 asymmetrical hearing loss will have a vestibular schwannoma, or other retrocochlear lesions, identified on imaging, emphasising that in most cases, asymmetrical 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 tumours may result in dysmetria and ataxia related to cerebellar compression or hydrocephalus.

tinnitus

Tinnitus represents a phantom percept that results from cochlear de-afferentation. 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 localising sounds

Significant ipsilateral hearing loss (typically >30 dB compared to the other ear) makes localising 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 tumour from other causes is often challenging. It is believed that most small and medium-sized tumours do not result in headache. Therefore, in most cases, headaches are diffuse and not localising to the side of the head with the tumour.

facial numbness

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

facial weakness

A late finding typically indicating a larger tumour.[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.