Acoustic neuroma, also known as vestibular schwannoma, is a benign tumor that develops on the vestibular nerve leading to the inner ear. It makes up 80% of cerebellopontine angle tumors and 10% of all brain tumors. The tumor originates from Schwann cells of the vestibular nerve and causes progressive unilateral sensorineural hearing loss. Diagnosis involves audiological tests, vestibular tests, neurological examination, and MRI with gadolinium contrast which is the gold standard. Treatment options include surgical removal via middle cranial fossa, translabyrinthine, or suboccipital approaches or stereotactic radiosurgery using techniques like gamma knife or cyberkn

1. Acoustic neuroma
Dr Ranjana D Telkar

2. • Acoustic neuroma: definition, histopathology
• Etiopathogenesis
• Classification
• Clinical features
• Management

3. Acoustic neuroma
• Definition:
Tumor of eight cranial nerve
• Eponyms
Vestibular schwannoma
Neurilemmoma
• Incidence
80% of cerebellopontine angle tumors
10% of all brain tumors

6. Pathology
• Gross:
Benign, Encapsulated, slow growing
• Microscopy:
Elongated spindle cells
Rod shaped nuclei in rows or palisades

9. Origin & growth
• Origin:
– Schwann cells of vestibular nerve, rarely from
cochlear nerve
• Growth:
– Causes widening and erosion of the canal and appears
in the CP angle
– Anterosuperior growth: 5th
– Inferior: 9th 10th & 11th
– Later stages: displacement of brainstem, pressure on
cerebellum and raised intracranial tension

10. Origin and growth

11. classification
Acoustic
neuroma
intracellular
Small size
<1.5cm
Medium size
1.5 – 4 cm
Large size
>4cm

12. Clinical features
• Age: 40 – 60 years
• Sex: M = F
• Symptoms:
– Progressive unilateral SNHL
– Tinnitus
– Marked difficulty in understanding speech
– Imbalance/Unsteadiness
– Vertigo
– Sudden hearing loss
– Fullness in the ear

13. Cranial nerve involvement
• 5th nerve: EARLIEST
Reduced cornea sensitivity, paresthesia of face
Involvement indicates: tumor size = 2.5cm &
occupies CP angle
• 9th & 10th: dysphagia & hoarseness due to palatal,
pharyngeal, laryngeal paralysis
• Other cranial nerves: affected only when tumor
size is very large

14. Cranial nerve involvement
• Facial nerve:
– Sensory fibres are affected early
– Hitzelberger’s sign: hypoaesthesia of posterior
meatal wall
– Loss of taste (Electrogustometry)
– Schirmer test: Reduced lacrimation
– Motor fibres: affected late
– Delayed blink reflex

15. Brainstem involvement
• Ataxia
• Weakness & numbness of arms & legs
• Exaggerated tendon reflexes
Raised intracranial tension
Headache, nausea, vomiting, diplopia (6th ) &
papillo-edema with blurring of vision

16. Cerebellar involvement
• Pressure symptoms on cerebellum are seen in
large tumors
• Revealed by
• Finger-nose test
• Knee-heel test
• Dysdiadochokinesia
• Ataxic gait
• Inability to walk along a straightline (tendency to
fall on the affected side

17. Investigations
• Audiological tests
– PTA
– Speech audiometry
– Recruitment phenomena: absent
– Short increment sensitivity index: 0-20%
– Threshold tone decay test: Retrocochlear type of
lesion

18. Vestibular tests
• Caloric test
– Diminished or absent
– Respone in 96% of patients
– Maybe normal when tumor is small

19. Neurological tests
• Complete examination of:
– Cranial nerves
– Cerebellar functions
– Brainstem signs of pyramidal and sensory tracts
– Fundus

20. Radiological tests
• Plain X-ray
– Positive in 80% of patients
– Different views
• Transornital
• Stenver’s
• Towne’s
• Submentovertical
• Vertebral angiography
– Helps in differentiating AN from other tumors

21. Radiological tests
• CT scan
– More sensitive than X-ray
– Can detect even intrameatal and posterior fossa
tumors
• MRI with Gadolinium contrast
– GOLD standard
– Can detect even intracanalicular tumors of few
mm

22. CT

23. MRI

24. Other tests
• BERA:
– A decay of >0.2ms in wave V between 2 ears in
case of 8th nerve tumor
• Stapedial reflex :delayed
• CSF examination:
– Protein levels raised, lumbar punture should be
avoided

25. Investigations
• Important tests for AN workup
– PTA
– Speech discrimantion score
– Roll-over curve
– Stapedial reflex decay
– BERA
– MRI with Gadolinium contrast

26. Differential diagnosis
• Meniere’s disease
• Tumors of CP angle:
– Meningioma
– Epidermoid
– Arachnoid cyst
– Schwannoma of other cranial nerves
– Aneurysm
– Glomus tumor
– Metastasis

27. Treatment
Treatment
Surgical Radiotherapy

28. Surgical Mx
• Approaches
• Middle cranial fossa approach
• Translabyrinthine
• Suboccipital
• Combined translabyrinthine suboccipital

29. Radiotherapy
• Conventional
• X knife / gamma knife surgery
• Cyber knife

30. Thank you