What are the symptoms of acoustic neuroma?

Symptoms of Acoustic Neuroma

Unilateral sensorineural hearing loss is the hallmark symptom of acoustic neuroma, occurring in 94% of patients, followed by tinnitus in 83% of cases. 1

Primary Auditory Manifestations

The classic triad of symptoms centers on auditory dysfunction:

• Unilateral or asymmetric sensorineural hearing loss is the most common presenting feature, affecting 94% of patients, with characteristic asymmetry in the mid- to high-frequency range, particularly at 3000 Hz 1
• Tinnitus occurs in 83% of patients and is characteristically unilateral or asymmetric on the affected side 1
• The hearing loss pattern shows minimal fluctuation with steady or sudden declines and no interval improvements, which distinguishes it from Ménière's disease 1
• Sudden sensorineural hearing loss can be the initial presentation, though acoustic neuroma accounts for less than 3% of patients presenting with this symptom 1

Vestibular and Balance Symptoms

• Dysequilibrium and unsteadiness occur in 17-75% of patients, though these symptoms are likely underreported 1
• Unlike Ménière's disease, acoustic neuromas typically cause chronic imbalance rather than discrete episodic vertigo attacks 1
• Dizziness and instability are common early symptoms, particularly in younger patients 2, 3

Cranial Nerve Involvement

As tumors enlarge, additional cranial nerve symptoms emerge:

• Facial numbness (trigeminal nerve involvement) becomes more prominent with disease progression 2
• Decreased corneal reflex is one of the most frequently observed physical findings 2
• Facial hypoesthesia may be detected on examination 2
• Facial weakness can occur, particularly with larger tumors 2
• Atypical presentations include orofacial paresthesia, which may occur even without significant acoustic or vestibular symptoms 4

Symptoms Associated with Tumor Size

• Headaches become more prominent as the disease progresses and tumors enlarge 2
• Brainstem compression and hydrocephalus can occur with very large tumors 1
• Nystagmus may be observed on physical examination 2
• The mean tumor size at diagnosis has decreased over time due to improved screening protocols for asymmetric hearing loss and better MRI resolution 1

Critical Clinical Patterns and Pitfalls

Important distinguishing features:

• Physical findings other than hearing loss are uncommon in early disease; the most frequently observed are decreased corneal reflex, nystagmus, and facial hypoesthesia 2
• Bilateral acoustic neuromas are pathognomonic for neurofibromatosis type 2 (NF2), though 15% of NF2 patients may initially present with unilateral disease 1
• Approximately 13.5% of acoustic neuroma patients may have normal pure tone audiometry at diagnosis, making this a critical pitfall—these patients tend to be younger and may present with tinnitus, instability, sudden hearing loss with complete recovery, or vertigo 3
• About 10% of patients present with atypical symptoms including facial numbness, pain, or sudden hearing loss, and these patients tend to have larger tumors due to delayed investigation 4

Age Considerations

• Peak incidence occurs in the 65-74 year age group 1
• Patients with normal hearing at diagnosis tend to be significantly younger than those presenting with hearing loss 3

Red Flags Requiring Immediate Evaluation

Per the American Academy of Otolaryngology-Head and Neck Surgery guidelines, the following features suggest non-idiopathic causes and warrant urgent investigation 5:

• Bilateral sudden hearing loss
• Recurrent episodes of sudden hearing loss
• Focal neurologic findings (headache, confusion, diplopia, dysarthria, focal weakness, focal numbness, ataxia, facial weakness)
• Gaze-evoked or downbeat nystagmus
• Concurrent severe bilateral vestibular loss with oscillopsia