Acoustic neuroma surgery

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Acoustic neuroma surgeryShanghai experience

• Hao Wu
• Department of Otolaryngology-Head and Neck
  Surgery
• Xinhua Hospital, Shanghai Second Medical
  University

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

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• Cushing Era
• Surgical mortality 80
• Cushing partial removal

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• Dandy Era(19171961)
• Total removal mortality?(22.1)
• Atkinson (1949) AICA
• Total facial paralysis

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

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• Dr. W. House (1961-)

• Middle fossa approach (1961)
• Traslab approach (1962)

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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.

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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)

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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
.
.
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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

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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..

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Unilateral or asymetrical audio-vestibular signs
Hearing loss, vestibular syndrome, tinnitus
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Decisionnal factors

1. Tumor volume
2. Age
3. Hearing function

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Therapeutic options
Varaiable tumor growth According to age and
tumor size lt 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

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Goals of the surgery

• 1- Minimal vital and neurological risks
• 2- Total removal
• 3- Facial function preservation
• 4- Hearing preservation

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Approaches
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Acoustic Neuromas
Intracanalar or CPA lt 20 mm
lt 70 years Surgery
Poor general condition Irradiation
gt 70 years Conservative management
Hearing
Serviceable
Unserviceable
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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

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Approaches

• Translabyrinthine 77
• Transotic 6
• Retrosigmoid 12
• Middle cranial fossa 5
• 17 attempt to hearing preservation

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ABR
Intraoperative monitoring
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Direct cochlear nerve potential
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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 )

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

• Hearing preservation attempts by middle cranial
  fossa or retrosigmoid approach (n17)

Class C 24
Class D 40
Class B 24
Class A 12
Class AB 36
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Complications

• CSF leaks 6(all in first 39 cases)
• Neurological 3
• Infectious 1
• Miscellaneous 3

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Translabyrinthine approach
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Translabyrinthine removal of VS after radiosurgery

• 5 cases
• Difficult in facial nerve dissection
• Resultstotal 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

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Transotic removal of VS with chronic middle ear
infection

• 3 cases
• Resultstotal removal in all cases
• facial function all with
  gradeI-II
• no postoperative infection

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Fallopian bridge technique
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Middle fossa approach
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Retrosigmoid-IAM approach
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Facial nerve repair after interruption

• end-to-ent anastomosis
• Reroute technique
• Bridge technique
• Facial-hypolingual ana.

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Hearing rehabilitation in acoustic neuroma surgery

• NF2 and Auditory Brainstem Implant

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NF2 DIAGNOSIS

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

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NF2

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

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Auditory pathway
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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)
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Bone anchored hearing aide (BAHA)

• Single sided deafness
• FDA approval

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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.

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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.

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Thanks