vestibular schwannoma in otolaryngology

1. VESTIBULAR SCHWANNOMA
Maj Md Sayaduzzaman
Trainee in otolaryngology

2.  vestibular schwannoma (VS) is an encapsulated benign tumour
arising from abnormally proliferative schwann cells.
 The commonest nerve of origin is the superior vestibular nerve,
followed by the inferior vestibular and then rarely, the cochlear
nerve
 Acoustic neuroma represents 8% of all intracranial tumours and
80% of cerebellopontine angle tumours.
 The medial portions of the cranial nerves are covered with glial
stroma. VS originate at the junction of the glial and Schwann cells,
which for the vestibular nerve is usually within the internal
auditory meatus
vestibular schwannoma

3. CEREBELLOPONTINE ANGLE (CPA)
 CPA – Irregularly shaped potential space in the posterior fossa of
the brain
Boundary-
 Anteriolaterally – Petrous part of temporal bone
 Posterior – Cerebellum
 Superior – Pons Cerebellar peduncles
 Inferior – Cerebellar tonsils
 Medial – Lateral surface of the brainstem

4. Content of CPA
 CSF
 Cranial nerves and their associated vessels
Superior:5th cranial nerve.
7th and 8th nerve
 Inferior : 9th,10th,11th nerves
Anterior inferior cerebellar artery
Superior petrosal veins

5. EPIDEMIOLOGY
 Both sexes are equally affected
 Age presentation is common between the ages of 40 and 60
 Majority of these tumours are unilateral, and bilateral (5%) are
seen in neurofibromatosis type 2 (NF2)
 Mean growth rate – 1.1 mm /year

6. Tumor pathogenesis
 Owing to mutations in the gene for the tumor
suppresor protein MERLIN located on chromosome
22q12
 Macroscopically the tumour appears as a firm
yellowish encapsulated mass with the nerve splayed
out on its surface.
 Histologically the tumour consists of packed sheaves
of connective tissue cells with intercellular vacuoles
and cysts (reticular pattern). Haemorrhage can occur
(particularly in the reticular type), leading to a sudden
increase in size.

7. Classification Of Vestibular Schwanoma

8. TUMOR DEVELOPMENT
Develops in nerve sheath
Compresses rather than invading the nerve
Gradually fills all the IAC & Extrameatal expansion
Tumour extend into cerebellopontine angle
Tumour compress on CN V
tumour compressing on CN V, IX, X, XI
Pressure over brainstem and cerebellum

9. Clinical features
Clinically, two phases can be recognized
 Otological phase in which a small tumour compresses structures in
the meatus
 Neurological phase as the tumour expands medially into the
cerebellopontine angle.

10. Otological symptoms
 Gradual and progressive unilateral deafness is the usual
presenting symptom (90%).
 The deafness is often associated with tinnitus (70%). Sudden
onset hearing loss can occur (10%).
 Some patients have normal hearing (5%).
 Vertigo is an unusual complaint

11. Neurological symptom
 5th CN: Earliest sign is impaired corneal reflex. Motor functions are
affected rarely. Facial pain, numbness and paraesthesiae may occur.
 7th CN: Sensory first; loss of sensation in the postero-superior aspect
of EAC called (Hitselberger sign).
 9th and 1oth CN: hoarseness with dysphagia .palatal, pharyngeal and
laryngeal paralysis.
 Late symptom: Ataxia and unsteadiness develop with progressive
brain stem displacement and cerebellar involvement.

12. INVESTIGATIONS

13. Radiological investigations.
 magnetic resonance imaging (MRI) with gadolinium enhancement is
the gold standard for diagnosis of VC
 Medium-sized tumors (3 cm) resemble an ice cream cone on MRI
 These tumors enhance intensely with contrast
 CT-scan; can not detect intermeatal tumors. but should only be used
when MRI is unavailable

14. Other investigation
 Pure tone audiometry - PTA shows assymmetric , down sloping ,
high frequency SNHL in almost 70% of patients
 Speech discrimination score (SDS)
 Acoustic reflex decay
 ABR test- ABR is partially or completely absent , or there is a delay
in latency of wave V on the affected side
 Evoked response audiometry (BERA)- It is very useful in the
diagnosis of retrocochlear lesions.
 CSF examination

15. Treatment option
 Patient’s age and medical condition
 Size and the location of the tumor
 Auditory and vestibular function of the tumor side and the
contralateral side.
 Tumor progression
 Surgeon’s preference

16. Treatment option
Observation With Serial Imaging
 Stereotactic Radiation
 Microsurgeries

17. OBSERVATION
 Age >65years, preferred
 Patients with vestibular shwannoma in the only hearing ear with
serviceable hearing and no imminent risk to brainstem function.
 Tumour growth is monitored .
 Serial imaging at 6 months interval is done , if no growth is
seen then yearly

18. STEREOTACTIC RADIATION
 A high dose of radiation can be delivered to a defined region,
usually within a well- immobilized system that conforms closely
to the target volume.
 Various modalities are:
Gamma knife
LINEAC: Linear Accelerator Photon Radiation Therapy
Proton Beam Therapy

19. Surgery
 Translabryinthine
 Middle cranial fossa approach
 Sub occipital (retro sigmoid) approach
 Combined

20. Surgical approach

21. THANK YOU