acoustic schwannoma treatment and management

1. Acoustic neuroma
Khairallah Aoucar PGY5 ENT
USEK University
Grand round 3-12-2016

2. Acoustic neuroma
 Most common tumor of the CPA (85%)
 M :F =2:3
 Sporadic in 95% of cases , peak incidence is in the 4th to 6th
decade
 Hereditary ,5%, NF2 (Autosomal dominant)22q,bilateral ,teens
and early adulthood
 Benign ,slow growing tumor
 Majority originate in IAC, rare are ILS

3. Acoustic neuroma
 Incidence ( number of newly diagnosed cases / year ) : 13 cases/million/year
Moffat et al. J. Laryngol Otol 1989 : 109 ; 51 - 59. Davis A. Proc. Acoustic Neuroma meeting
1995
 Prevalance :
-Leonard and Talbot 1970 - autopsy study : 0.8% ( 8000 /1,000,000 )
-Anderson et al 2000 : MRI study found an incidental 7 AN / 10,000 MRI studies => 700
cases / 1,000,000 population i.e large number asymptomatic / undiagnosed
 Number of patients attending ENT clinic with unilateral hearing loss due to AN : 3 - 7.5%
Ferguson et al 1996, Hollingworth et al 1998

6. Hearing classification scale

7. Growth rate
 To date no conclusive correlation between tumor size and
change in hearing threshold
 But relationship with tumor growth rate as demonstarted by
Massik et al .
 There was no correlations between growth rate and patient
,gender , initial volume ,side
 The only way to assess growth rate is MRI

8. Course
 3 separate growth patterns :
 (1) no or very slow growth even regression
 (2) slow growth (i.e., 0.2 cm/year linear growth on imaging studies)
 (3) fast growth (i.e., >1.0 cm/year).
 While most vestibular schwannomas grow slowly, some grow quite quickly
and can double in volume within six months to a year.
 Cystic vestibular schwannomas are sometimes capable of relatively rapid
expansion because of filling of their cystic component
Charabi S, Tos M, Thomsen J, et al: Vestibular schwannoma growth—long-term results. Acta Otolaryngol
Suppl 543:7-10, 2000

9. Incidence and growth pattern of vestibular schwannomas in a
Danish county, 1977 - 1988
 • Over 21 years 162 Acoustic neuromas diagnosed in county of Aarhus
 • Incidence increased over the years related to access to CT / MRI
 • 98 patients underwent surgery
 • 64 patients pursued Conservative Mx and surveillance imaging
 – 14 patients ( 22% ) regressed
 – 35 patients ( 55% ) did not grow / marginal growth ( < 1mm /yr )
 – 15 patients ( 23 % ) increased in size : growth rate > 1mm / yr
 Mirz F, Pedersen, Fitzgerald B, Lundorf E. Acta Otolaryngol 2000; 543 : 30 - 33

10. Management :no strict guidelines
 Observation: who is candidate?
 Microsurgery :which approach ? total?
 Radiosurgery :first line or second line?
 Chemotherapy :the future?

11. Conservative management
 elderly /short life expectancy
 medically infirm patients
 very small tumors in only hearing ear
 Repeat MRI scans over time : used to carefully monitor the
tumor for any growth.
 treatment is to be considered when there are signs of growth.

12.  Conclusions: Older patient age lowers the chance of hearing preservation but does not
affect facial outcomes. There is a trend toward a higher rate of cerebrospinal fluid leak in
older patients, but no increased risk of other complications.

13.  if extrameatal +1, if intrameatal 0
 if SSHL –1, if no SSHL 0
 if balance problems +1, if no balance problems 0
 if complaints hearing loss <2yr +1; if > 1yr or if no complaints 0
If the total score is <=0, the chance of tumor growth during the
first year is <10%.
If the score is 3, the chance of growth during the first year after
diagnosis is >70%.

14. Conservative management
 Contraindications:
 Large or giant tumor =>compression brain stem
 Hydrocephalus
 Facial nerve dysfunction
 Failing balance

15. Treatment :
 no randomized trials have compared radiosurgery with
microsurgery
Pollock BE. Vestibular schwannoma management: an evidence based comparison of stereotactic radiosurgery and microsurgical resection. Prog Neurol Surg
2008;21:222–227.

17. Surgical treatment:Aims
 No mortality
 Complete tumour excision
 No recurrence
 Preservation of facial nerve function
 Preservation of hearing
 No neurological morbidity
 CN 5,6,7,9,10
 No operative morbidity

19. Which approach ?
 PTA,SDS
 tumor size
 hearing status of both ears
 patient age and preference.
 Surgery practices vary in degree of experience and preferred
techniques

20. Surgical Approaches :
What we need to know from the Radiologist
 imaging directs preoperative management by addressing:
 tumor size
 extent of IAC penetration,
 cerebellopontine angle involvement
 Relationship of the tumor to cranial nerves
 Relevant anatomic variants

21. MCF

22. Mcf
 Brackman and House 1991
 – Nos : 106
 – Size : 0.4 – 2.0 cm
 – No deaths
 – Facial nerve preservation : 80 %
 – Hearing preservation : 59 %

25. Suboccipital or retrosgmoid

26.  Fundal involvement was identified in 38 of the 51 patients.
 Fundal involvement was identified in 38 /51
 Average tumor size: (+FE) was 6.8 ± 2.2 mm
 without fundal extension (-FE) was 8.2 ± 1.9 mm
 Average preoperative SDS was 91.6 %
 89% (34/38) of +FE patients had preserved hearing (Classes
A, B, or C) vs 11% percent of these patients did not (Class D).

27.  In contrast : 61%(8/13) of –FE patients had hearing preserved
(Classes A, B, or C) 39% did not (Class D).
 This difference was statistically significant, (p =0.006 Pearson chi-
square test).
 Conclusion: Hearing preservation rate following retrosigmoid
craniotomy for intracanalicular vestibular schwannomas may be
superior for tumors with fundal extension compared to tumors that
do not extend to the fundus. Tumors with fundal extension were, on
the whole, smaller than tumors without fundal extension. It is likely
this size difference that plays the largest role in hearing preservation
rates in intracanalicular tumors.

31. Translabyrinthine

32. Translab

35.  Facial nerve function decreases with increasing tumour size,
but even in giant tumours (>4cm) we found a high number of
patients with preserved normal nerve function (HB I and II:
78%) and only 11% had complete facial palsy postoperatively.

37. Total?near total?subtotal?
 >3.5 cm extracanalicular=large
 >4.5 cm=giant
 Over a 23-year period between
1986 and 2008, 59/784 AN cases
met inclusion criteria ,45 with
completed data

38. Management of large /giant tumor
 the extent of resection was classified into total (no tumor
remaining), near-total (95% tumor removal), and subtotal
(<95% tumor removal), based on postoperative imaging.
 Total excision was achieved in 14 patients (31.1%)
 Near-total in 26 patients (57.8%).
 subtotal in 5 patients (11.1%).

39. Total excision
 No recurrence: mean follow up 40 months
 12/14 had giant tumors
 All patients had normal facial nerve function preoperatively.
 The final facial nerve outcome deteriorated to HB grade III/IV
in six patients (42.8%).
 3 patients (21.4%) reported new ataxia postoperatively, but all
described it as ‘‘mild.’’
 No patient experienced new trigeminal deficits.

40. Near total excision
 No further growth in the residual tumor was observed in 15 out
of 26 patients (57.7%)(5 giant and 10 large)
 one patient: residual tumor showed regression over 3 years
following surgery.
 mean follow-up period was 63.7 months
 11 patients (42.3%) showed tumor regrowth(5 giant &6large)

41. Near total
 23/26 patients (88.5%) had normal facial nerve function before
surgery.
 the final facial nerve outcome deteriorated to HB grade III or
worse in 11 patients (47.8%)
 Of the 3 patients with preexisting facial nerve weakness:
 -one improved slightly (grade IV toIII)
 -one remained the same (grade II),
 -one deteriorated slightly (grade II to III).

42. Near total
 10 /11 received further treatment as their residual tumors
showed growth(mean interval is 60 months )
 6/10 gamma knife (stable with 87 month follow up)
 1/10 2nd surgery +adjuv GK (stable for 48 months)
 3/10 2nd surgery,2/3 needed GK at 2 and 6 years .

43. Subtotal
 5 large
 1/5 regrowth but observation (mean follow up 10 years)
 1/5 died from brain stem infarction
 3/5 no growth in 68 month of follow up
 All patients had normal facial nerve function preoperatively and
had excellent facial nerve functions subsequently (three grade
I and one grade II).

44.  43 tumors underwent total removal, and anatomical
preservation of the facial nerve was attained in 48 cases.
 1 facial nerve damage .
 In 12 out of 24 patients, who showed serviceable hearing
before surgery, this was preserved after tumor removal.
 Recently HD endoscope has been introduced into the clinical
practice, and not only 70 but also 90 and 120 degrees angle
endoscope is available.

45. Intralabyrithine A.N
 ILSs are defined as tumors arising primarily from within the
membranous labyrinth: cochlea, vestibule, or semicircular
canals.
 Surgical approaches and prognostic implications are affected.
 Hearing preservation surgery is not an option.
 Proper anatomic localization by the radiologist is essential in
the preoperative assessment of these patients.

46. ILS
 Primary ILS in the past has been considered a rare lesion in
isolation.
 However, these tumors are likely much more common than
previously thought.
 Improved imaging allows detection and characterization and
stresses the needs for a heightened sense of awareness
among radiologists to their presence.

47. ILS

48. Intracochlear schwannoma.
K.L. Salzman et al. AJNR Am J Neuroradiol 2012;33:104-109
©2012 by American Society of Neuroradiology

50. Current issues and controversies
 Management of small incidental tumors
 Prediction of tumor growth
 Hearing preservation surgery
 Role of SRS

51. Sterotatic radiosurgery SRS
1 of the 3 forms of high-energy radiation.
Linear accelerator
Gamma Knife unit
Charged particle proton beam
The Gamma Knife device was invented by Leksell, a Swedish
neurosurgeon, in Sweden in 1951. It was the first device used to
deliver SRS

52. SRS
 Effective alternative to surgical removal of small to moderate-
sized A.N
 Goals :
 prevent further tumor growth
 preserve cochlear and other cranial nerve function where
possible
 maintain or improve the patient’s neurological status.

53. Dose Prescription
 In Gamma Knife® :dose of 12–13 Gy is typically prescribed to the
50% (or other) isodose line that conforms to the tumor margin.
 This dose is associated with a low complication rate and yet
maintains a high rate of tumor control.
 Lower radiosurgery doses may be a better management strategy for
patients with bilateral NF2 vestibular schwannomas or patients with
contra-lateral deafness from other causes, for whom hearing
preservation may be more critical.

54.  For LINAC :total dose may be divided into 3–5 delivery
sessions
 typically prescribed to the 80% isodose line, using a total mean
dose ranging up to 17 Gy.
 The higher dose is an issue as the risk of complications is
directly related to the dose and treatment volume.

55. Post op care
 There is no consensus on the use of corticosteroids on the
day of radiosurgery.
 Some do not use steroids at all before,during or after
radiosurgery.
 Patients are observed for a few hours in the same day surgery
unit and are usually discharged within 24 hours.

56. Post-Radiosurgery Evaluations
 After radiosurgery, all patients are followed up with serial
gadolinium-enhanced MRI :at 6 months, 12 months, and 2, 4, 8
and 16 years.
 All patients who have some preserved hearing are advised to
obtain audiological tests (PTA and SDS) near the time of their
MRI followups.

57. POTENTIAL BENEFITS:
 Minimally invasive approach
 High rates of tumor growth control (95–98%), serviceable hearing
preservation (60–70%), facial nerve preservation (>95%) and
trigeminal nerve preservation (>95%).
 The medical literature has documented the cost savings benefit of
stereotactic radiosurgery versus open surgical procedures and the
lower risk potential of bleeding, anesthesia problems, infections and
side effects which may result intransient or permanent disabilities
from open surgery.

58. Cystic A.N:SRS
 August 2016

59. SRS in KOOS 4?

60. Comparison of MS vs RS
 no level 1 or 2 evidence to support either surgical resection or
radiosurgery and highlighted the need for properly designed studies.
 Several carefully performed retrospective studies have compared
the results of microsurgery and stereotactic radiosurgery
Nikolopoulos TP, O’Donoghue GM: Acoustic neuroma
management: an evidence-based medicine approach. Otol
Neurotol 23:534-541, 2002

61. MS vs RS
 Myrseth et al 2005
 Retrospective review 189 patients tumors ≤3cm
 86 by microsurgery vs. 103 by GK
 5.9 year mean follow up
 Local control rates of 89.2% Surgery vs 94.2% GK
 HB 1-2 in 79.8% Surgery vs 94.8% GK p=0.0026
 Quality of life significantly lower in surgery group
 compared to gamma knife group

62. MS vs RS
 Pollock et al. 2006
 Prospective cohort of 82 patients unilateral VS <3cm
 36 Surgery vs 46 GK
 Average follow up of 42 months
 Local control 96% Surgery vs 100% GK p= 0.50
 HB 1/2 in 75% Surgery vs 96% GK p<0.01
 Hearing Preserved 5% Surgery vs 63% GK p<0.001
 Quality of life all statistically better for GK
 -Physical functioning
 -Bodily pain scores
 - Dizziness Handicap Inventory

63.  Régis et al 2002 :97 RS vs 110 MS
 The mean hospitalization stay:3 daysGKvs 23 MS
 The mean time away from work:7 days GK vs 130 MS
 Among patients whose preoperative hearing level was Class 1:
70% preserved functional hearing GK vs 37.5% MS

65. Recommendations
 SRS : first management option in patients with small to
medium size tumors (without symptomatic
 brainstem compression).
 It is also used to control growth of recurrent or residual tumor
after surgical resection.
 May be especially suitable for patients who desire preservation
of neurological function (cochlear, facial nerve) and a high rate
of tumor growth control.

66. Recommendations
 Patients with large tumors causing symptomatic brainstem
compression should be managed with surgical decompression of the
tumor.
 Residual tumor can be treated by radiosurgery.
 Patients with hydrocephalus but without symptoms of brainstem
compression can have a shunt inserted prior to radiosurgery,
especially if the patient is aged or medically infirm and consequently
not a good candidate for resection.

67. Chemotherapy
 Tumors with high levels of VEGF expression considered as suitable for
bevacizumab treatment
 Because vestibular schwannomas express VEGF-1 NF2 patients with
imminent total hearing loss because of tumor progression may benefit from
bevacizumab treatment
 At the 2008 NF conference in Bonita Spring, Florida, preliminary results
from an ongoing treatment of NF2 patients using bevacizumab were
presented by the group of Dr Scott Plotkin (Massachusetts General
Hospital, Boston, Massachusetts), demonstrating potential efficacy of this
drug for vestibular schwannomas.

69. Fig. 3. Cranial MRI for patient 2 before (A) and 3
months after (B) treatment. The cystic component of
the right vestibular schwannoma regressed
substantially, whereas mitigation of the associated
brain stem compression was clearly seen.
Bevacizumab was given to each patient as an infusion
every 2 weeks at a dose of 5.0 mg/kg body weight.
Erlotinib?

70. Thank you