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1. ACOUSTIC NEUROMA

2. INDEX INTRODUCTION INCIDENCE PATHOLOGY ORIGIN OF TUMOR GROWTH OF TUMOR CLASSIFICATION CLINICAL FEATURES INVESTIGATIONS DIFFERENTIAL DIAGNOSIS TREATMENT

3. INTRODUCTION It is the most common benign tumor of Cerebro-pontine angle  Locally invasive "Acoustic Neuroma" - a Misnomer ! 1. Not Acoustic in Origin: The tumor doesn't arise from the acoustic portion (cochlear nerve) of the vestibulocochlear nerve. It originates from the vestibular portion, which is responsible for balance.  2. Not a Neuroma: "Neuroma" implies a tumor of nerve tissue. These tumors are actually schwannomas, meaning they arise from Schwann cells, which are the cells that make the myelin sheath (covering) of nerve fibers.  Vestibular Schwannoma : more accurate term because the tumor arises from Schwann cells in the vestibular nerve , which is part of the vestibulocochlear nerve 

4. INCIDENCE

5. INCIDENCE Tumour is mostly seen in age group of 40–60 years Both sexes are equally affected : M = F Sporadic: 95%

6. PATHOLOGY Benign , Encapsulated , Slow growing tumor of VIIIth Nerve Microscopically: elongated spindle cells with rod-shaped nuclei lying in rows or palisades. Antony A - Dense cell groups with small, spindle-shaped nuclei. Antoni B - Loosely arranged, vacuolated, pleomorphic cells Bilateral tumours are seen in patients with Neurofibromatosis.

7. ORIGIN OF TUMOR Arises from the Schwann cells of the vestibular division of VIII- th nerve within the Internal auditory canal (IAC)

8. “7 up, Coke down” Internal auditory canal (IAC)/ Internal acoustic meatus

9. AS IT EXPANDS: GROWTH OF TUMOR

10. CLASSIFICATION Depending on the size, the tumour is classified as: Intracanalicular (when it is confined to internal auditory canal) Small size - < 1.5 cm Medium size - 1.5 – 4 cm Large size - > 4 cm

11. CLINICAL FEATURES Cochleovestibular Symptoms: Progressive unilateral sensorineural hearing loss Tinnitus Marked difficulty in understanding speech - out of proportion to the pure tone hearing loss. Imbalance / Unsteadiness True vertigo is rarely seen  due to central compensation as it is a slow growing tumor MOST COMMON CHARACTERISTIC

12. CLINICAL FEATURES Cranial Nerve Involvement and its symptoms : V- th nerve: Earliest nerve to be involved (after VIIIth nerve) Reduced corneal sensitivity Numbness or paraesthesia of face Indicates that the tumour is roughly 2.5 cm in diameter and occupies the cerebellopontine angle

13. CLINICAL FEATURES VII- th nerve: sensory fibres affected first  then motor fibers ( more resistant) Hypoaesthesia of posterior meatal wall  Hitzelberger’s Sign (<25 % of patients ) Loss of taste (as tested by electro- gustometry ) ↓ lacrimation on Schirmer test Delayed blink reflex may be an early manifestation

14. CLINICAL FEATURES IX- th and X- th nerves: D ysphagia and hoarseness of voice due to palatal, pharyngeal and laryngeal paralysis D. Other cranial nerves: XIth , XIIth , IIIrd , IVth and VIth are affected when tumour is very large

15. CLINICAL FEATURES Brainstem Involvement: seen when long motor and s ensory tracts are involved. Ataxia Weakness Numbness of the arms and legs Exaggerated tendon reflexes Raised intracranial tension – late feature Headache, Nausea, vomiting Diplopia - VIth nerve involvement Papilloedema with blurring of vision.

16. CLINICAL FEATURES Cerebellar Involvement: Pressure symptoms revealed by- Finger-nose test Knee-heel test Dysdiadochokinesia Ataxic gait and inability to walk along a straight line with tendency to fall to the affected side

17. INVESTIGATIONS for work up of AN Pure tone audiometry Speech discrimination score Roll-over curve Stapedial reflex decay Evoked response audiometry MRI with contrast

18. INVESTIGATIONS Audiological Tests: Pure tone audiometry : SNHL - more marked in high frequencies . Speech audiometry : poor speech discrimination Roll-over phenomenon- reduction of discrimination score when loudness is increased beyond a particular limit Recruitment phenomenon is absent. Short Increment Sensitivity Index (SISI) test : 0–20%  in 70–90% of cases Threshold tone decay test – retro-cochlear type of lesion.

19. INVESTIGATIONS Stapedial Reflex Decay test: To detect VIII- th nerve lesion. If a sustained tone of 500 or 1000 Hz, delivered 10 dB above acoustic reflex threshold, for a period of 10 s, brings the reflex amplitude to 50% It shows abnormal adaptation and is indicative of VIII- th nerve lesion (stapedial reflex decay)

20. INVESTIGATIONS Vestibular test: Caloric test will show diminished or absent response in 96% of patients

21. INVESTIGATIONS Neurological Tests: Complete examination of Cranial nerves Cerebellar functions Brainstem signs of pyramidal and sensory tracts should be done Fundus is examined for blurring of disc margins or papilledema

22. INVESTIGATIONS Radiological tests: Plain X-rays : (Transorbital, Stenver’s, Towne’s and Submentovertical views) give positive findings in 80% of patients. Computed tomography (CT) scan: A tumour that projects even 0.5 cm into the posterior fossa can be detected ICECREAM CONE Appearance

23. INVESTIGATIONS Radiological tests: c ) MRI with gadolinium contrast: Gold standard Intracanalicular tumour , of even a few millimetres , can be easily diagnosed by this method. d) Vertebral angiography: H elpful to differentiate acoustic neuroma from other tumours of cerebellopontine angle when doubt exists.

24. INVESTIGATIONS BERA: CSF Examination : (Lumbar puncture usually avoided) - Protein level is raised

25. DIFFERENTIAL DIAGNOSIS Ménière’s disease

26. TREATMENT SURGERY: Treatment of choice The various approaches are: 1 . Middle cranial fossa approach. 2. Translabyrinthine approach. 3. Suboccipital ( retrosigmoid ) approach. 4. Combined translabyrinthine -suboccipital approach.

27. TREATMENT RADIOTHERAPY: X-knife or Gamma knife surgery: Stereotactic radiotherapy - Radiation energy is converged on the tumour , thus minimizing its effect on the surrounding normal tissue. causes arrest of the growth of the tumour and also reduction in its size used in patients who refuse surgery or have contraindications to surgery or in those with a residual tumour . X-knife surgery is done through linear accelerator Gamma knife through a Cobalt-60 source .

28. TREATMENT Cyber knife: Totally frameless and more accurate. Uses real-time image guidance technology through computer-controlled robotics. Conventional radiotherapy : No role in the treatment of acoustic neuromas due to low tolerance of the central nervous system to radiation.

29. Thank You