Acoustic neuroma surgery —Shanghai experience

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

2. McBumey (1891): unsuccessful • Balance (1894): first successful

3. Cushing Era • Surgical mortality: 80% • Cushing –partial removal

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

5. 1960 • Mortality rate in California: 43.5% • Olivecrona (Sweden)：414 cases • small tumors: 4.5% • large tumors: 22.5% • Facial paralysis: 50%

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

7. 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.

8. 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)

9. 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 % . .

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

11. 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…..

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

13. Decisionnal factors • Tumor volume • Age • Hearing function

14. Therapeutic options 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

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

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

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

18. I II < 15 mm III : 15-30 mm IV > 30 mm 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 %

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

20. Intraoperative monitoring ABR

21. Direct cochlear nerve potential

22. Resection quality • Complete removal in 98 cases • Subtotal removal in 1 cases (1 %) • In cases with subtotal removal : • 1 MRI imagesdemonstrate to be stable (1 %) • 1 case surgically revised (1 %)

23. Postoperative facial function in translabyrinthine or transotic approach

24. 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%

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

26. Translabyrinthine approach

27. 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

28. 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

29. Fallopian bridge technique

30. Middle fossa approach

32. Retrosigmoid-IAM approach

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

34. Hearing rehabilitation in acoustic neuroma surgery NF2 and Auditory Brainstem Implant

35. NF2 DIAGNOSIS • Bilateral vestibular schwannoma (VS) • NF2 familial history and - unilateral VS - or 2 among : meningioma, glioma, neurofibroma,schwannoma,subcapsularlens opacity

36. NF2 • NF2 gene on chromosome 22 (1993) • Tumor suppressor gene

37. Auditory pathway

38. 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)

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

41. 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.

42. 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.

43. Thanks