Acoustic Neuroma K. Kevin Ho, M.D. Faculty Advisor: Vicente A. - PowerPoint PPT Presentation

Acoustic Neuroma & Hearing Loss Acoustic Neuroma 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 K. Kevin Ho, M.D. Vicente A. Resto, M.D., Ph.D. Department of Otolaryngology University of Texas Medical Branch

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 Intracanalicular Cisternal Hydrocephalic Compressive Jackler RK. 2000, p. 180: Tumors of the Ear and Temporal Bone

Hearing Loss  Most frequent initial symptom  Most common symptom ~ 95% AN patients  Asymmetric SNHL  Down-sloping / High Frequency  Decreased Speech Discrimination

Serviceable Hearing SDS (%) 100 70 50 0 0 A P 30 T T B (dB) D 50 C

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 Shaan Lustig Magdziarz 1993 1993 1998 2000 AN 126 100 546 369 patients Normal 5 6 29 10 hearing (4%) (6%) (5%) (3%)

Tumor Size and Hearing Normal Hearing All ANs (29 Patients) (126 Patients) % Small 45 24 (< 1cm) % Medium 42 59 (1-3 cm) % Large 12 16 (> 3 cm) 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 B D A A B D Change in Tumor Volume (mm3) Change in Tumor Volume (mm3) PTA SDS Massick DD. Laryngoscope 2000: 110; 1843-9

Predicting Tumor Growth Side Gender Age Initial Volume Herwadker A. Otology and Neurotology 2005: 26; 86-92

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 (85-97% ; 94% )  Hearing Loss  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 Preoperative TEOAE Kim AH. Otol Neurotol. 2006 Apr;27(3):372-9

MRI Brain w. & w/o GAD T1 pre-Gad T2 T1 post-Gad  T1: Isointense to brain, hyperintense to CSF  T2: Hyperintense to brain, hypointense to CSF  T1+Gad: Enhancing

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

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