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