PPT of acoustic neuroma for MBBS students.

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