acoustic neuroma: an overview… · acoustic neuroma benign, intracranial tumor slow-growing...

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Acoustic Neuroma: An Overview

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Moderator:Carolyn Smaka, Au.D., Editor-In-Chief

Jill Messina, Au.D., CCC-A, & Robert A. Battista, M.D., F.A.C.S., The Ear Institute of Chicago

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Acoustic Neuroma: An Overview

Robert A. Battista, MD, FACSAssistant Professor

Northwestern University Medical SchoolNorthwestern University Medical School

Jill Messina, AuD, CCC-A

Ear Institute of Chicago, LLCHinsdale/Chicago/Elk Grove Village, IL

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Acoustic Neuroma

Benign, intracranial tumor

Slow-growing

Originate: schwann cells of vestibular nerve Originate: schwann cells of vestibular nerve

“Vestibular schwannoma”: most accurate term

Ear Institute of Chicago, LLC

Acoustic Neuroma: Epidemiology

6 - 8% of intracranial tumors

Incidence: 10‡ - 20*/1,000,000

2 500 3 500 new cases/year ~ 2,500 - 3,500 new cases/year

‡Nestor JJ, et al. Arch Otolaryngol Head Neck Surg 1988; 114:680.

*Stangerup SE, et al. J Laryngol Otol 2004;118:622-7.


Acoustic Neuroma: Types

Two Forms Sporadic: 95%

Neurofibromatosis 2 (NF2): 5%


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Acoustic Neuroma: Symptoms

Unilateral sensorineural hearing loss > 95%

Unilateral tinnitus

Dysequilibrium 50%y q

Facial Anesthesia ~ 5 - 20%

Vertigo 19%

Facial twitching/weakness < 5%

Headache

Acoustic Neuroma: Diagnosis

Audiogram: screening

ABR: screening

MRI Brain/Internal Auditory Canal with MRI Brain/Internal Auditory Canal with gadolinium


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Acoustic Neuroma: Hearing Loss

History 90%: Slowly progressive sensorineural hearing

loss

~10%: Sudden, SNHL

Type of Hearing Loss ~2/3: High-frequency SNHL

1/3:

Low-frequency SNHL

Mid-frequency SNHL

Normal hearing

Ear Institute of Chicago, LLC Northwestern Universit

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Acoustic Neuroma: Treatments

A. Observation (Serial radiologic evaluation) Relatively asymptomatic Age > 65 yrs

B. Stereotactic radiosurgery Elderly/Infirm Tumor < 3cm Residual/Recurrent tumor Patient preference

C. Microsurgical removal All other cases


Considerations for Management

Patient’s age

Medical status

Size of tumorS e o tu o

Tumor related symptoms and signs

Patient’s reliability and attitude

Tumor growth rate


A. Observation: Risks

Cranial nerve dysfunction

Brainstem compression

(Death) (Death)


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B. Stereotactic RadiosurgeryB. Stereotactic Radiosurgery

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Translabyrinthine

Retrosigmoid (Suboccipital)

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Microsurgical Approaches

Hearing Loss Translabyrinthine

Hearing Preservation (potential) Middle Fossa Retrosigmoid


Surgery: Hearing Preservation Positive Prognostic Indicators

Tumor: < 1.5 cm

Audiogram: <50 dB PTA/ >50% WRS

ABR: Normal ABR: Normal

VNG caloric: Reduced

VEMP: normal


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Caloric

VEMP

•Reduced/Absent Caloric•VEMP: normal

•Normal Caloric•VEMP: reduced/absent

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Conventional Audiometry

- Most common abnormality is an asymmetric high frequency hearing loss


Right LeftFrequency (Hz) Frequency (Hz)

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HL % HL %

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9665/M

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Speech

SRT

L 25 33

PTA

R 15 15

Stim Ear R L R LMeas. Ear L R R L

500 Hz1000 Hz 2000 Hz4000 Hz

Acoustic Reflex Thresholds (dBHL)R LEquivalent Volume (cm3)Peak Pressure (daPa)Static Admittance (mmhos)

Tympanometry

DNT

DNT

Conventional Audiometry

Normal hearing or even symmetric hearing does NOT exlude an acoustic neuroma


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Speech

SRT

L 5 7

PTA

R 10 7


500 Hz 90 80 80 901000 Hz 80 75 80 852000 Hz 80 80 75 854000 Hz 90 80 85 85

Acoustic Reflex Thresholds (dBHL)R LEquivalent Volume (cm3) 1.5 1.6Peak Pressure (daPa) 30 25Static Admittance (mmhos) 0.9 0.8

Tympanometry

Audiometric Testing

Acoustic Reflexes

Speech Discrimination Often worse than expected; rollover (decreased

ability to understand words with increased volume)


ABR Testing For Acoustic Neuroma

Less sensitive/less expensive than MRI

Characteristic findings:

Wave I, no waves III or V

Delayed I-III latency

Delayed wave V latency

High false-positive/false-negative rates (pts with small tumors can have normal ABR’s)


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ABR Testing, cont.

Tumor Size: more predictive than location

> 1.5 cm : ABR = 92-98% accuracy

< 1.5 cm : ABR = 60-70% accuracy


Schmidt et.al (2001)

ABR Testing, cont.

ENG/VNG Testing

Most pt’s with an AN have a unilateral caloric weakness (however, weakness could be from other causes)

ENG/VNG not specific


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ENG/VNG Testing, cont.

Example:

VEMP testing

VEMPs absent or decreased amplitude in approximately 80% if patients with vestibular schwanomma (Murofushi et. al., 1998)

Saccule innervated by inferior vestibular nerve



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10045

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Speech

SRT

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PTA

R 15 25


500 Hz NR NR NR 851000 Hz NR NR NR 852000 Hz NR NR NR 854000 Hz NR NR NR 95

Acoustic Reflex Thresholds (dBHL)R LEquivalent Volume (cm3) 1.4 1.3Peak Pressure (daPa) 25 25Static Admittance (mmhos) 1.4 1.1

Tympanometry

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Case Study #2

59 y.o. male

Left-sided tinnitus, hearing loss (5 year history), and vertigo

MRI showed intracanalicular small acoustic neuroma (1.1 cm mass)


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Inte

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10065/M

84

Speech

SRT

L 35 32

PTA

R 15 10


500 Hz DNT DNT 75 801000 Hz DNT DNT 80 802000 Hz DNT DNT 80 804000 Hz DNT DNT 80 80

Acoustic Reflex Thresholds (dBHL)R L

Equivalent Volume (cm3)Peak Pressure (daPa)Static Admittance (mmhos)

DNT

Case Study #2, cont.

ABR: Abnormal (prolonged latencies)

VNG: Normal

Retrosigmoid craniotomy and removal of the Retrosigmoid craniotomy and removal of the acoustic tumor with attempted preservation of the seventh and cochlear division of the eighth nerve


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10075/55

76

Speech

SRT

L 55/40 57

PTA

R 10 13


500 Hz1000 Hz 2000 Hz4000 Hz


Equivalent Volume (cm3)Peak Pressure (daPa)Static Admittance (mmhos)

DNT

DNT

Case Study #3

58 y.o. female

Sudden right hearing loss, tinnitus, and dizziness

Similar incident on left side 20 years ago



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Speech

SRT

L 85 80

PTA

R 80 72


500 Hz NR NR NR NR1000 Hz NR NR NR NR2000 Hz 100 NR 100 NR4000 Hz NR NR NR NR


Equivalent Volume (cm3) 1.8 1.7Peak Pressure (daPa) 25 25Static Admittance (mmhos) 2.2 3.8

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Case Study #3, cont.

MRI revealed 4 x 6.5 mm acoustic neuroma on the LEFT side

Patient underwent translabyrinthine removal of LEFT acoustic neuroma

Two months later patient was implanted with cochlear implant on RIGHT side



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Inte

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CC

C CC

C

C

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HL % HL %

Speech

SRT

L

PTA

R


500 Hz1000 Hz 2000 Hz4000 Hz

Acoustic Reflex Thresholds (dBHL)R LEquivalent Volume (cm3)Peak Pressure (daPa)Static Admittance (mmhos)

Tympanometry

DNT

DNTDNT

Bibliography

Nestor JJ, et al. The incidence of acoustic neuromas. Arch Otolaryngol Head Neck Surg 1988; 114:680.

Murofushi T, Matsuzaki M, Mizuno M. Vestibular evoked myogenic potentials in patients with acoustic neuromas. Arch Otolaryngol Head Neck Surg 1998; 124: 509 512Otolaryngol Head Neck Surg. 1998; 124: 509-512.

Schmidt R, Sataloff R, Newman J, et al. The sensitivity of auditory brainstem response testing for the diagnosis of acoustic neuromas. Arch Otolaryngol Head Neck Surg. 2001; 127: 19-22.

Stangerup SE, et al. Increasing annual incidence of vestibular schwannoma and age at diagnosis. J Laryngol Otol 2004;118:622-7.

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acoustic neuroma: an overview… · acoustic neuroma benign, intracranial tumor slow-growing...

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