Acoustic Neuroma

K. Kevin Ho, M.D.

Vicente A. Resto, M.D., Ph.D.

Department of Otolaryngology

University of Texas Medical Branch

Acoustic Neuroma & Hearing Loss K. Kevin Ho, M.D.

Faculty Advisor: Vicente A. Resto, M.D., Ph.D.

The University of Texas Medical Branch

Department of Otolaryngology

Grand Rounds Presentation

December 6, 2006

Medieval Times

1912 Acoustic Neuroma Surgery

Jackler RK. 2000, p. 173: Tumors of the Ear and Temporal Bone

Historical Perspectives (cont’d)

1905 Dr. Harvey Cushing Meticulous dissection

Hemostasis: silver clips, bone wax, electrocautery

Mortality: 20 % (1917) 4% (1931)

1916 Dr. Walter Dandy Complete removal of AN

Mortality: 10%

Early 1960s Dr. William House Translabyrinthine approach using surgical

drill and operating microscope

Cerebellopontine Angle: Anatomy

Epidemiology

6 % of all Intracranial tumors

80 - 90% of CPA tumors

Incidence in US: 10 per million / year

Vast majority in adulthood

95% Sporadic (unilateral)

5% Neurofibromatosis type 2 (bilateral)

No known race, gender predilection

Pathogenesis

Neither Neuroma or Acoustic (auditory)

Schwannoma arising from vestibular nerve

Benign tumor. Malignant degeneration

exceedingly rare.

Majority originate within the IAC

Equal frequency on Superior and Inferior

vestibular nerves (controversial)

Jackler Staging System

Stage Tumor Size

Intracanalicular Tumor confined to IAC

I (small) < 10 mm

II (medium) 11-25 mm

III (Large) 25-40 mm

IV (Giant) > 40 mm

Phases of Tumor Growth

Intracanalicular:

Hearing loss, tinnitus, vertigo

Cisternal:

Worsened hearing and dysequilibrium

Compressive:

Occasional occipital headache

CN V: Midface, corneal hypesthesia

Hydrocephalic:

Fourth ventricle compressed and obstructed

Headache, visual changes, altered mental status

Phases of Tumor Growth

Jackler RK. 2000, p. 180: Tumors of the Ear and Temporal Bone

Intracanalicular Cisternal

Compressive Hydrocephalic

Hearing Loss

Most frequent initial symptom

Most common symptom ~ 95% AN patients

Asymmetric SNHL

Down-sloping / High Frequency

Decreased Speech Discrimination

Serviceable Hearing

100 70 50 0 0

30

50

A

D B

C

P

T

T

(dB)

SDS (%)

Distribution of Hearing in AN

Myrseth: Neurosurgery, Volume 59(1).July 2006.67-76

Pathophysiology of Hearing Loss

in Acoustic Neuroma

Exact etiology is unknown

Compressive effect on cochlear nerve

Vascular occlusion of internal auditory artery

Biochemical alterations inner ear fluids

Normal or Symmetrical Hearing in

Acoustic Neuroma

Selesnick

1993

Shaan

1993

Lustig

1998

Magdziarz

2000

AN

patients

126 100 546 369

Normal

hearing

5

(4%)

6

(6%)

29

(5%)

10

(3%)

Tumor Size and Hearing

Normal Hearing

(29 Patients)

All ANs

(126 Patients)

% Small

(< 1cm)

45 24

% Medium

(1-3 cm)

42 59

% Large

(> 3 cm)

12 16

Lustig LR. Am J Otology 1998: 19; 212-8

Tumor size & Hearing

Lack of conclusive correlation between tumor

size and hearing

< 20 mm > 20 mm

Stipkovits EM et al. Am. J. Otology 1998: 19; 834-9

Tumor Growth Rate

Battaglia et al. Otol Neurotol. 2006 Aug;27(5):705-712

Tumor Growth: Studies

N Follow-up No

Growth

(%)

-

Growth

(%)

+

Growth

(%)

Bederson 70 26 mo 40 7 53

Selesnick 558 3 yr - - 54

Charabi 126 3.8 yr 12 6 82

Raut 72 80 mo 42 19 39

Walsh 72 3.2 yr 50 14 37

Tumor Growth & Hearing

A

D B A

B

D

Massick DD. Laryngoscope 2000: 110; 1843-9

Change in Tumor Volume (mm3) Change in Tumor Volume (mm3)

PTA SDS

Predicting Tumor Growth

Herwadker A. Otology and Neurotology 2005: 26; 86-92

Side Gender

Initial

Volume

Age

Estimating Tumor Growth

Serial MRI with and without GAD

The only reliable study to

estimate tumor growth rate

Tumor Growth: Biomarkers

O’ Reilly BF et al. Otol Neurotoloty 2000: 25; 791-6

Fibroblast Growth Factor Receptor

O’ Reilly BF et al. Otol Neurotoloty 2000: 25; 791-6

Delayed Diagnosis

Duration of Symptoms Prior to Diagnosis

Symptoms Years

Hearing Loss 3.9

Vertigo 3.6

Tinnitus 3.4

Headache 2.2

Dysequilibrium 1.7

Trigeminal 0.9

Facial 0.6

Jackler RK. 2000. Tumors of the Ear and Temporal Bone

History and Physical

Hearing Loss

Vertigo

Dysequilibrium

Tinnitus

Headache

Nystagmus Early small lesion: Horizontal (vestibular)

Late large: Vertical (brainstem compression)

Cranial neuropathy CN V, VII

Lower cranial nerves (IX-XII)

Frequency of Symptoms

Hearing Loss (85-97% ; 94% )

Vertigo (5-70 % ; 39% )

Dysequilibrium (46-70% ; 56 %)

Tinnitus (56-70% ; 64 %)

Facial nerve (10-77% ; 38 %)

Trigeminal nerve (16-63% ; 26 %)

Headache (12-38% ; 25% )

Visual symptoms (1- 15 % ; 7% ) Lower cranial nerves: Dysphagia, Hoarseness, Aspiration,

Shoulder weakness (Jugular foramen syndrome)

Jackler RK. 2000, p. 182: Tumors of the Ear and Temporal Bone

Symptoms in AN patients with

Normal Hearing

Lustig LR. Am J Otology 1998: 19; 212-8

Sudden Sensorineural Hearing loss

Idiopathic

1-2 % SSNHL patients have AN

10- 26 % AN patients have a history of SSNHL

Most experts advocate obtaining MRI in all patients who present with SSNHL

Diagnosis

History and Physical Exam

Audiology testing:

Audiogram

ABR

OAE

Vestibular testings (eg. ENG, rotary chair, posturography) all lack diagnostic value

Radiography

MRI Gold Standard

CT

Pure Tone and Speech Audiometry

ABR: Retrocochlear Pathology

Increased interpeak intervals

I-to-III interval of 2.5 ms, III-to-V interval of 2.3 ms,

and I-to-V interval of 4.4 ms

Interaural wave V latency difference (IT5)

Greater than 0.2 ms

Poor waveform morphology ie. only some of the

waves are discernible

Absent waveform

ABR patterns in AN

10-20 % with only wave I and nothing thereafter

40-60 % with wave V latency delay

10-15 % have normal findings

Fraysse B et al. First International Conf. on Acoustic Neuroma. 1992

ABR: Diagnostic Efficiency

Generally, Efficiency increases with Size

Sensitivity: > 90 % for tumor > 3 cm

No response for severe/ profound SNHL (Rupa 2003)

False negative Rate:

15 % (Wilson 1992 – 6/40)

33 % (5/15) for Intracanalicular Tumor

False positive Rate:

> 80 % (Jackler 2005)

Positive predictive value:

15 % (Weiss 1990 – 4/26)

12 % (Walsted 1992 – 23/185)

ABR: Sensitivity & Tumor size

Gordon ML. American Journal of Otology. 1995; 16: 136-9

IT 5 & Tumor Size

Chandrasekhar SS et al. Am J Otol 1995;16:63-7

Stacked ABR

Attempt to improve detection rate in small < 1 cm ANs

“Stacking” of derived band response

Out of 25 ANs, 5 tumors less than 1 cm missed in Standard ABR were picked up by Stacked ABR.

Don M et al. Am J. Otology; 1997: 21; 148-151

OAE Reflect cochlear/ OHC / sensory hearing

Not primarily used as screening tool

Presence of OAE in SNHL ↔ Retrocochlear

However, 50 % AN demonstrate both cochlear and

retrocochlear hearing loss

Risk stratification for hearing preservation surgery

Kim AH. Otol Neurotol. 2006 Apr;27(3):372-9

Preoperative TEOAE

MRI Brain w. & w/o GAD

T1: Isointense to brain, hyperintense to CSF

T2: Hyperintense to brain, hypointense to CSF

T1+Gad: Enhancing

T1 pre-Gad T1 post-Gad T2

CT Brain with contrast

Heterogeneous

enhancement on contrast

Rare calcification

Contraindication to MRI

(metallic implants),

claustrophobic patients

May not be able to detect

small tumor < 1.5cm

Radiation

Treatment options

Observation

Surgery

Translabyrinthine

Retrosigmoid

Middle fossa

Radiotherapy

Conventional

Stereotactic

Conservative Management

Advanced age (> 65 )

Short life expectancy (< 10 years)

Slow growth rate

Poor surgical candidate / poor general health

Minimal symptoms

Only hearing ear

Patience preference

Observation: Raut 2004 Prospective cohort study of 72 patients

Age at presentation: 60.8 years

Mean follow-up: 80 months

Mean tumor size at diagnosis: 9.4 mm

Mean tumor growth rate: 1 mm/ year

87% growth rate < 2 mm/ year

Tumor growth + : 39 %

0: 42%

- : 19%

No correlation between growth and age, gender, size at presentation, or presenting symptoms

32 % failed conservative management

Raut V et a.: Clin Otolaryngol 29:505–514, 2004.

Preop Predictive factors for Hearing

Preservation Surgery

Rohit MS et al. Ann. Oto. Rhino. Laryng. 2006: 115 (1); 41-6

Loss of Serviceable Hearing during

Observation

Walsh RM et al. Laryngoscope 2000: 110; 250-5

Conclusions

Tumor size has no correlation with

audiovestibular symptoms in Acoustic

neuroma

Understanding tumor growth rate is important

for predicting symptom progression and

treatment planning

The study-of-choice to estimate tumor growth

is serial MRI

Thank You