Acoustic neuroma Khairallah Aoucar PGY5 ENTUSEK UniversityGrand round 3-12-2016

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

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

Hearing classification scale

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

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

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

Management :no strict guidelines Observation: who is candidate?

Microsurgery :which approach ? total?

Radiosurgery :first line or second line?

Chemotherapy :the future?

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.

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.

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%.

Conservative management Contraindications:

Large or giant tumor =>compression brain stem Hydrocephalus Facial nerve dysfunction Failing balance

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.

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

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

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

MCF

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

Suboccipital or retrosgmoid

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).

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.

Translabyrinthine

Translab

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.

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

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%).

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.

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)

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).

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 .

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).

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.

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.

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.

ILS

Intracochlear schwannoma.

K.L. Salzman et al. AJNR Am J Neuroradiol 2012;33:104-109

©2012 by American Society of Neuroradiology

Current issues and controversies Management of small incidental tumors

Prediction of tumor growth

Hearing preservation surgery

Role of SRS

Sterotatic radiosurgery SRS1 of the 3 forms of high-energy radiation. Linear acceleratorGamma Knife unitCharged 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

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.

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.

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.

Post op care There is no consensus on the use of corticosteroids on

theday 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.

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.

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.

Cystic A.N:SRS August 2016

SRS in KOOS 4?

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 neuromamanagement: an evidence-based medicine approach. OtolNeurotol 23:534-541, 2002

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

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

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

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.

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.

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.

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?

Thank you