What are the signs and symptoms of acoustic neuroma (acoustic schwannoma)?

Signs and Symptoms of Acoustic Schwannoma

The most common presenting symptoms of acoustic schwannoma (vestibular schwannoma) are unilateral sensorineural hearing loss (94%) and tinnitus (83%), with vestibular symptoms like vertigo and unsteadiness occurring in 17-75% of patients. 1

Primary Clinical Manifestations

Auditory Symptoms

• Unilateral sensorineural hearing loss

  • Progressive and often asymmetric
  • Typically affects mid to high frequencies (3000 Hz) 1
  • May fluctuate in some cases, but generally shows steady decline 1
  • Often the earliest and most common symptom

• Tinnitus

  • Present in up to 83% of patients 1
  • Usually unilateral, on the same side as the tumor
  • Can be persistent or intermittent

Vestibular Symptoms

• Vertigo and dizziness
  • Present in 17-75% of patients 1
  • Often underreported 1
  • May present as:
    • Episodic true vertigo
    • Chronic imbalance
    • Unsteadiness when walking
    • Cough-induced vertigo (rare presentation) 2

Cranial Nerve Symptoms (in larger tumors)

• Facial nerve dysfunction

  • Facial weakness or paralysis
  • Typically occurs in advanced cases with large tumors
  • Facial paresis is rare in early/medium-sized tumors 1

• Trigeminal nerve symptoms

  • Facial numbness or paresthesia
  • Decreased corneal reflex
  • Facial pain (uncommon)

Advanced Symptoms (with large tumors)

• Brainstem compression symptoms
  • Headache
  • Hydrocephalus
  • Gait ataxia 1
  • Nausea and vomiting

Special Considerations

Bilateral Vestibular Schwannomas

• Hallmark of Neurofibromatosis Type 2 (NF2) 1
• Consider NF2 screening when a patient presents with unilateral vestibular schwannoma at age <30 years 3
• About 4-6% of vestibular schwannomas are associated with NF2 1

Intralabyrinthine Schwannomas

• Can present with fluctuating hearing loss 4
• May cause intractable vertigo 4
• Ear fullness sensation 5

Diagnostic Approach

When acoustic schwannoma is suspected based on symptoms:

1. Audiometric evaluation to document the degree and type of hearing loss 3

2. MRI with dedicated internal auditory canal protocol is the gold standard for diagnosis 3

   • T1-weighted sequences before and after gadolinium administration
   • T2-weighted sequences
   • Thin slice spin echo or turbo spin echo T1-weighted sequences
   • Axial submillimetric heavily T2-weighted sequences

3. CT temporal bone may provide complementary information about skull base anatomy but is less sensitive than MRI for detecting small acoustic neuromas 3

Clinical Pitfalls to Avoid

• Misdiagnosis as Ménière's disease: Both conditions can present with hearing loss, tinnitus, and vertigo. However, Ménière's typically has more fluctuating symptoms and episodic vertigo attacks 1

• Delayed diagnosis: Symptoms may be subtle initially, leading to delayed imaging and diagnosis

• Missing NF2: Always consider NF2 in younger patients (<30 years) with vestibular schwannoma 3

• Relying solely on audiometry: While asymmetric hearing loss is suggestive, MRI is essential for definitive diagnosis 1

• Overlooking small intracanalicular tumors: These may be missed if appropriate MRI sequences are not used 3