What’s up with Acoustic Neuromas?

Nancy Fuller, M.D.

PCC September 27, 2006

Objectives:

-Recognize signs and symptoms of acoustic neuroma

-Identify treatment options and their risks

-no financial disclosures

• Patient #1: 2 year history of right sided hearing loss.

-sudden worsening: near total

deafness

• A diagnostic test was performed.

• Patient #2: history of migraine headaches; new onset dizziness after treatment for status migrainus.

• A diagnostic treatment was performed.

• MRI # 1: 12 x 4 mm intracanalicular enhancing lesion c/w acoustic schwannoma (acoustic neuroma)

• MRI #2: 11x 6 mm cerebellopontine angle enhancing lesion c/w acoustic schwannoma

Acoustic Neuroma

aka: Acoustic Schwannoma

Acoustic neurinoma

Vestibular schwannoma

Vestibular neurilemoma

Schwann cell derived tumor usually arising from vestibular portion of vestibulocochlear nerve, aka acoustic nerve (VIII)

• 1/100,000 person-years

• 8% of intracranial tumors

• 80-90% of cerebellopontine angle tumors

• Increasing frequency-

? Incidentalomas

? Exposure to loud noise

? Exposure to radiofrequencies (cell phones)

• Either superior or inferior branches of 8th nerve

• Variable natural history: approx. 2 mm growth per year BUT

-40 % of tumors-no growth or even shrinkage in serial imaging studies

• No predictive relationship between growth rate and tumor size

• Clinical presentation: due to cranial nerve involvement and tumor progression

• 95% acoustic nerve involvement (others facial nerve, etc)-95% hearing loss present, 63% tinnitus

• Acute sensorineural hearing loss is unusual in AN, but AN is a common cause of sensorineural hearing loss

• Vestibular portion of nerve: 61%

• Symptoms include unsteadiness, vertigo

• Other symptoms from compression of facial nerve and trigeminal nerve

• Diagnosis: asymmetric sensorineural hearing loss + MRI or CT, with audiometry showing speech loss out of proportion to decreased hearing

• PE: Rinne test-tuning fork to mastoid

Weber test-tuning fork to skull

• TX: Surgery Radiation Therapy Observation

-Surgery-usually collaboration between neurosurg and ENT

-big learning curve

-Only rarely does hearing improve after surgery; half of patients lose more hearing

-nearly 100% successful in eliminating tumor

-Radiation: ‘gamma knife’ or linear accelerator used

-good alternative especially for small tumors

-?scarring may complicate future surgery if needed, but overall outcome is similar

-fewer complications such as headaches, facial weakness, vestibular dysfunction

-Observation:

MRI q 6-12 months

Potential problem: observation may result in higher likelihood of hearing loss, so if hearing is still present, earlier treatment is preferred