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