Acoustic neuroma surgery—Shanghai experience Hao Wu Department of Otolaryngology-Head and Neck Surgery Xinhua Hospital, Shanghai Second Medical University

McBumey (1891): unsuccessful Balance (1894): first successful

Cushing Era Surgical mortality: 80% Cushing –partial removal

Dandy Era（1917–1961） Total removal: mortality↓(22.1%) Atkinson (1949): AICA Total facial paralysis

1960 Mortality rate in California: 43.5% Olivecrona (Sweden)：414 cases small tumors: 4.5% large tumors: 22.5% Facial paralysis: 50%

Dr. W. House （1961-） Middle fossa approach (1961) Traslab approach (1962)

Origin Development in the internal acoustic meatus from the schwann cells of the vestibular ganglion (Sterkers JM et al., Acta Otolaryngol., 1987) Arachnoid sheet enveloping the tumour during its expansion to the CPA.

Epidemiology 6 to 8 % of all intracranial tumours The most frequent (80 to 90%) of the CPA tumours Sporadic, and solitary in 95 % of cases Associated with NF2 in 5 % of cases Estimated incidence in USA and Western Europe: 1 for 100,000 individuals per year (Kurlan et al., J neurosurg, 1958 ; Nestor JJ et al., Arch Otlaryngol Head Neck Surg, 1988)

REASON FOR CONSULTATION Moffat et al., 1998 n = 473 . Expected symptom: 80.7 % (progressive HL,tinnitus,unsteadiness) Sudden hearing loss: 9.6 % Atypical presentation: 10 % . .

MRI diagnosis Isosignal on T1, and variable aspect en T2 views Constant gadolinium enhancement Intratumoral cysts in large neurinomes No adjascent meningeal enhancement Enlarged IAM Extension predominantly posterior to IAM

Differential diagnosis Other neurinomas in the CPA: 5th, 7th, or caudal cranial nerve neurinomas Other lesions: Most frequent: Meningiomas Cholesteatomas Rare lesions :lipomas, metastases, hemangiomas, medulloblastomas etc…..

Unilateral or asymetrical audio-vestibular signs : Hearing loss, vestibular syndrome, tinnitus Neurotological examination Audiometry+ABR+VNG Normal ABR and VNG Abnormality Age < 60 years > 60 years MRI + Gadolinium MRI + Gadolinium Follow-up Audio-vestibular work-up In 6 months

Decisionnal factors Tumor volume Age Hearing function

Therapeutic options Conservative managament Radiotherapy Surgery Varaiable tumor growth According to age and tumor size < 1,5 cm MRI in 6 months and then once a year Conservative managament Radiotherapy Gamma-knife, LINAC Volume stabilisation Hearing loss and facial paresis Under evaluation Surgery

Goals of the surgery 1- Minimal vital and neurological risks 2- Total removal 3- Facial function preservation 4- Hearing preservation

Approaches Middle cranial fossa (MCF) Retrosigmoid (RS) Translabyrinthine (TL)

Acoustic Neuromas CPA> 20 mm Translabyrinthine or transotic Intracanalar or CPA < 20 mm > 70 years: Conservative management < 70 years: Surgery Poor general condition: Irradiation Hearing Serviceable Unserviceable MCF retrosigmoid translabyrinthine

Population 1999.1-2004.3: 100 VS operated on Mean age: 49 years (range: 20-79) Sex ratio: 0.8 Tumor stages : Stage 1: 3 % Stage 2: 11 % Stage 3 : 71 % Stage 4 : 15 % II < 15 mm III : 15-30 mm IV > 30 mm I

Approaches Translabyrinthine : 77 % Transotic: 6 % Retrosigmoid: 12 % Middle cranial fossa: 5 % 17% attempt to hearing preservation

Intraoperative monitoring ABR

Direct cochlear nerve potential

Resection quality Complete removal in 98 cases Subtotal removal in 1 cases (1 %) In cases with subtotal removal : 1 MRI images demonstrate to be stable (1 %) 1 case surgically revised (1 %)

Postoperative facial function in translabyrinthine or transotic approach Stages Cases 　　　　Facial function 　1　　2　　3　　4　　5　　6 总计 83 31 15 13 12 8 4

Hearing preservation Hearing preservation attempts by middle cranial fossa or retrosigmoid approach (n=17): Class C: 24 % Class D: 40 % Class B: 24 % Class A: 12 % Class A+B: 36%

Complications CSF leaks: 6%(all in first 39 cases) Neurological: 3% Infectious: 1 % Miscellaneous: 3 %

Translabyrinthine approach

Translabyrinthine removal of VS after radiosurgery 5 cases； Difficult in facial nerve dissection； Results：total removal in all cases facial function: grade II in 1 case grade III in 2 cases grade IV in 2 cases grade VI in 1 case

Transotic removal of VS with chronic middle ear infection 3 cases； Results：total removal in all cases facial function: all with gradeI-II no postoperative infection

Fallopian bridge technique

Middle fossa approach

Retrosigmoid-IAM approach

Facial nerve repair after interruption end-to-ent anastomosis Reroute technique Bridge technique Facial-hypolingual ana.

Hearing rehabilitation in acoustic neuroma surgery NF2 and Auditory Brainstem Implant

NF2 DIAGNOSIS Bilateral vestibular schwannoma (VS) NF2 familial history and - unilateral VS - or 2 among : meningioma, glioma, neurofibroma,schwannoma,subcapsular lens opacity

NF2 NF2 gene on chromosome 22 (1993) Tumor suppressor gene

Auditory pathway

Nucleus 21 Channel Auditory Brainstem Implant Removeable magnet CI22M receiver-stimulator Monopolar reference electrode (plate) Microcoiled electrode wires T-shaped Dacron mesh Electrode array (21 platinum disks 0.7mm diameter)

Bone anchored hearing aide (BAHA) Single sided deafness; FDA approval;

Conclusions 1 In spite of modern image techniques, large VS acounts for most diagnosed cases in China. The translabyrinthine app. could be used in even largest VS with minival invasion.

Conclusions 2 The facial function is aceptable in most patients. The hearing preservation result should still be improved. Hearing rehabilitation techniques are available after tumor removal.

Thanks