What are the symptoms of acoustic neuroma?

Symptoms of Acoustic Neuroma (Vestibular Schwannoma)

The vast majority of patients with acoustic neuroma present with unilateral sensorineural hearing loss (94%) and tinnitus (83%), making these the cardinal symptoms that should prompt diagnostic evaluation. 1

Primary Auditory Symptoms

• Unilateral hearing loss is the most common presenting symptom, occurring in 80-94% of patients, typically following a progressive pattern in 90% of cases 1, 2
• Tinnitus affects 83% of patients and is characteristically unilateral or asymmetric 1
• The hearing loss is sensorineural in nature, with asymmetry typically in the mid- to high-frequency range (especially at 3000 Hz) 1
• Sudden sensorineural hearing loss can occur, though acoustic neuroma is found in less than 3% of patients presenting with this symptom 1
• Importantly, 13.5% of acoustic neuromas present with normal hearing, particularly in younger patients with smaller tumors 3

Vestibular Symptoms

• Vertigo and unsteadiness occur in 17-75% of patients, though these symptoms are likely underreported 1
• Dizziness and dysequilibrium are common early symptoms 4
• Unlike Ménière's disease, acoustic neuromas typically cause chronic imbalance rather than discrete vertigo attacks 1
• Ataxia accounts for 3.8% of initial presentations 2

Symptoms Associated with Larger Tumors

As tumors enlarge beyond the internal auditory canal, additional cranial nerve and brainstem compression symptoms emerge:

• Facial numbness (trigeminal neuropathy) is associated with larger tumors and occurs with an odds ratio of 3.0 for tumors >2.5 cm 1, 2
• Subjective facial weakness strongly predicts larger tumor size (odds ratio 5.3) 2
• Headache is associated with larger tumors (odds ratio 2.6) and becomes more prominent as disease progresses 4, 2
• Abnormal tandem gait on examination is the strongest predictor of larger tumor size (odds ratio 8.9) 2
• Brainstem compression and hydrocephalus can occur with very large tumors 1

Physical Examination Findings

• Decreased corneal reflex is the most frequently observed physical finding beyond hearing loss 4
• Nystagmus is commonly present on examination 4
• Facial hypoesthesia (reduced facial sensation) is a concerning sign for larger tumors 4, 2
• Most physical findings other than hearing loss are uncommon in early disease 4

Important Clinical Patterns and Pitfalls

Several critical patterns distinguish acoustic neuroma from other causes of auditory symptoms:

• The hearing loss typically shows minimal fluctuation with steady or sudden declines and no interval improvements, unlike Ménière's disease 1
• Speech discrimination scores are frequently lower than expected based on pure-tone thresholds, suggesting retrocochlear pathology 4
• Acoustic neuromas occur in 63-75% of patients presenting with unilateral tinnitus who undergo imaging, making this the most common retrocochlear cause 5
• Bilateral acoustic neuromas are pathognomonic for neurofibromatosis type 2 (NF2), though 15% of NF2 patients may initially present with unilateral disease 1

Temporal Trends in Presentation

• There is a downward trend in patients presenting with hearing loss and an increased proportion presenting with other symptoms, likely due to improved imaging access and earlier detection 2
• The mean tumor size at diagnosis has decreased due to improved screening protocols for asymmetric hearing loss and better MRI resolution 1
• Incidental diagnosis now accounts for approximately 2% of cases 2

Age-Related Considerations

• Peak incidence occurs in the 65-74 year age group 1
• Younger patients are more likely to present with normal hearing and smaller tumors 3
• Patients with normal hearing at diagnosis have a mean age that is significantly younger than those with hearing loss 3