Acoustic Neuroma

The area of the brain where the 8th and 7th nerve connect is important for?

Basic Life sustaining functions (heart rate, blood pressure, respiration)

Gd-contrast MRI can detect what?

Tumors as small as 1/10 of an inch Technique of choice since mid 1980's

VII cranial nerve?

(Facial) also passes through IAC

How many cranial nerves?

12

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When is the average age of presentation for AN?

50 years

What kind of tumor is an acoustic neuroma?

Benign tumor, more displacement than invasion

CT scan can detect what?

Can detect tumors slightly larger than 1/2 inch in size

AN are fast growing. True of False?

False. Slow and progressive

Retrosigmoid/suboccipital approach (AN treatment)?

Hearing preservation possible, less exposure of IAC, cerebellar retraction

Middle Fossa Approach (AN treatment)?

Hearing preservation possible, small intracanalicular tumors only, poor access to CPA, inferior IAC

AN treatment: Stereotactic Radiation Therapy?

Large does of radiation is delivered to the tumor in a single session Preservation of hearing 38-75% Facial nerve paralysis low, increases with tumor size

VIII cranial nerve?

Lies deep within the skull bases and connects the inner ear to the brainstem. Passes through a bony channel, the IAC, before making connections at brainstem

Acoustic Neurom originates from where?

Nerve sheath (covering of the 8th cranial nerve, schwan cells, encapsulated)

Translabyrinthine approach (AN treatment)?

No serviceable hearing, easiest approach, wide exposure, least amount of complications, total hearing loss

Where is the origin of an vestibular schwannoma (acoustic neuroma)?

Origin usually within the internal auditory canal. Occasionally medially near the brain stem

AN treatment is based on what?

Size of tumor, residual hearing, age/general health of patient

AN treatment based on Observation?

Slow growth rate, elderly patients, patients unable or unwilling to undergo surgery, tumor is present in the only hearing ear

Where do acoustic neruomas arise from?

The vestibular portion of the 8th nerve