Acoustic Neuroma & Glomus Tympanicum

1. Acoustic Neuroma & Glomus Tympanicum Dr. Vishal Sharma

2. Acoustic Neuroma

3. Introduction A.K.A.:vestibular schwannoma / neurilemmoma Benign, encapsulated, slow growing tumour arising from Schwann cells of superior vestibular division of 8th nerve within internal auditory canal Rarely from inferior vestibular or cochlear division

4. Tumour growth Tumor expansion within internal auditory canal  causes widening & erosion of I.A.C.  appears in cerebello-pontine angle (> 2.5 cm)  involves 5th, 7th, 9th, 10th, 11th cranial nerves  displacement of brainstem & cerebellum  raised intracranial pressure Involvement of 6th & 3rdcranial nerves

5. Classificationas per size 1. Intra-canalicular: confined to I.A.C. 2. Small: up to 1.5 cm 3. Medium: 1.5 to 4 cm 4. Large: over 4 cm

6. Tumor size

7. Intra-canalicular

8. Small

9. Medium

10. Large

11. Epidemiology • 10% of all brain tumors • 80% of all Cerebello-pontine angle tumors • Age: 40-60 yrs • Male : Female = 3:2 • Unilateral (90%); Bilateral (10%) • Bilateral = von Recklinghausen’s neurofibromatosis

12. Clinical Staging • Otological stage: due to pressure on 8th nerve • Other Cranial nerve involvement • Brainstem + Cerebellar involvement • Raised intra-cranial tension • Terminal stage: failure of vital centers of brainstem & cerebellar tonsil herniation

13. Otological symptoms & signs • Progressive, unilateral sensorineural deafness • Poor speech discrimination (disproportionate) • Tinnitus • Mild vertigo • Nystagmus Vestibular symptoms appear late due to slow tumor growth & vestibular compensation

14. Other Cranial nerve palsy Trigeminal: first nerve to be involved • Loss of corneal reflex • Pain, numbness and paresthesia of the face Facial: • Hypoaesthesia of posterior external auditory canal wall (Hitselberger’s sign) • Facial weakness, Loss of taste, ed lacrimation

15. Other Cranial nerve palsy Glossopharyngeal, Vagus & Accessory Spinal: • Dysphagia • Hoarseness • Nasal regurgitation • Decreased gag reflex Abducent & Oculomotor: • Diplopia

16. Brainstem involvement  Ataxia  Weakness of arms & legs  Tendon reflexes exaggerated Cerebellar involvement  Ataxic gait (fall on affected side)  Intention tremors  Past-pointing  Dysdiadochokinesia Increased Intra-cranial tension  Headache  Projectile vomiting  Blurred vision  Papillodema  Abducent nerve palsy

17. First Symptoms Hearing loss: 80-100 % Vertigo: 10-50 % Tinnitus: 5-10 % Ear ache: 5 % Sudden hearing loss: 5% Facial paralysis: 1-2 %

18. Investigations • Pure Tone Audiometry:high frequency SNHL • Speech audiometry:SD scores < 30% • Tone decay test:positive • Stapedial Reflex: Decay > 50 % in 10 sec • B.E.R.A.:wave V >4.2 ms; inter-wave V >0.2 ms • Caloric test:I/L canal paresis or no response • C.T. scan with contrast: for tumor > 0.5 cm • M.R.I. with gadolinium contrast:best

19. Pure Tone Audiogram

20. Speech Audiometry Roll over phenomenon

21. Calorigram

22. Brainstem Evoked Response Audiometry (B.E.R.A.)

23. Contrast C.T. Scan

24. Contrast M.R.I.: neuro-anatomy

25. Contrast M.R.I. : intra-canalicular

26. Contrast M.R.I. : small

27. Contrast M.R.I. : Medium

28. Contrast M.R.I. : Large

29. Bilateral tumor: small

30. Bilateral tumor: large

31. Treatment 1. Observation 2. Microsurgical removal: (partial or total) • Trans-labyrinthine approach • Retro-sigmoid or Sub-occipital approach • Middle Cranial Fossa approach • Combined approach 3. Proton Stereotactic Radiotherapy 4. Brainstem Implant: after B/L tumor excision

32. Observation Indications: • Age > 60 years with small tumor & no symptoms • Tumour in only hearing / better hearing ear Serial MRI used to follow growth pattern. Treatment recommended if hearing is lost or tumor size becomes life threatening.

33. House Ear Institute 1977

34. Incisions Middle cranial fossa Retro-sigmoid Trans-labyrinthine

35. Retro-sigmoid Approach

36. Sub-occipital approach

37. Trans-labyrinthine approach

38. Middle cranial fossa approach

39. Surgical Approach Protocol 1. Intra-canalicular: Middle cranial fossa approach 2. Small (<1.5 cm): Retrosigmoid approach 3. Medium (1.5 - 4 cm) a. Hearing fine**: Retrosigmoid approach b. Hearing bad:Trans-labyrinthine approach 4. Large (>4 cm): Trans-labyrinthine/ Combined **Pure Tone Average < 30 dB, S.D. Score >70%

40. Intra-operative photograph

41. Proton stereotactic radiotherapy Single high dose of radiation delivered on a small area to arrest or kill tumor cells. Minimal injury to surrounding nerves & brain tissue Gamma Knife: radioactive cobalt LINAC X-knife: linear accelerator Cyber-Knife: robotic radio-surgery system Indication: 1. Surgery refused / contraindicated 2. Post-operative residual tumour

42. Treatment Planning

43. Treatment Planning

44. P.S.R.T. in progress

45. Pre & Post treatment

46. Glomus Tumours

47. Synonym: Chemodectoma  Non-chromaffin paraganglioma Commonest benign tumour of middle ear derived from glomus bodies distributed along parasympathetic nerves of head & neck Consists of paraganglionic cells derived from embryonic neuroepithelium Introduction

48. Introduction Histologically benign but locally invasive, highly vascular, non-encapsulated, slow growing tumors 10 % tumors: familial 10 % tumors: multicentric 10 % tumors: functional (secrete catecholamines) 4 % tumors: metastatic

49. Histopathology Typical cellular groups ("Zellballen") surrounded by a capillary network

50. Types Glomus jugulare Arises along jugular bulb & superior vagal Ganglion, near floor of middle ear Glomus tympanicum Arises along tympanic plexus on promontory formed by tympanic branch of Glossopharyngeal nerve, near medial wall of middle ear