Vestibular Schwannoma and glomus tumors with special focus for MBBS undergraduate students

1. Vestibular Schwannoma
(Acoustic Neuroma)
and Glomus Tumors
Dr. Krishna Koirala08/06/2020

2. Define Vestibular Schwannoma.
What is the commonest site of origin of
vestibular schwannoma?
Write two synonyms of vestibular schwannoma.
In which condition will you find bilateral
vestibular schwannoma?
Which is the most common tumor in CP angle ?

3. • Definition
– Benign, encapsulated, slow growing tumor arising
from Schwann cells of superior vestibular division
of VIII nerve within the internal auditory meatus
– Rarely arises from inferior vestibular or cochlear
division
• Synonyms
– Neurilemmoma, Acoustic Neuroma

4. • Most common tumor in the region of CP angle (85%)
• Bilateral in 10% (Multiple neurofibromatosis) NF2, also
called bilateral acoustic NF (BAN)
• NF1, also called von Recklinghausen NF or peripheral NF

5. Spread
• Tumor grows by expansion within internal auditory
canal and causes widening & erosion of I.A.C.
• Occupies the cerebello-pontine ( C.P. ) angle
• Progresses to involve V , VII, IX, X, XI cranial nerves
• Displaces the brainstem & cerebellum

7. Classification according to size
• Intra- canalicular : confined to I.A.C.
• Small : up to 1.5 cm
• Medium : 1.5 to 4 cm
• Large : > 4 cm

8. Briefly describe the stages of Vestibular
schwannoma
1. Otological stage : pressure on VIII nerve
2. Other Cranial nerve involvement
3. Brainstem + Cerebellar involvement
4. Raised intra-cranial tension
5. Terminal stage: failure of vital centers of brainstem &
cerebellar tonsil herniation

9. Otological Stage
• Progressive, unilateral sensorineural deafness
• Poor speech discrimination disproportionate to
hearing loss
• Tinnitus
• Nystagmus
• Vestibular symptoms including vertigo are
uncommon due to slow tumor growth & vestibular
compensation !

10. Stage of other cranial nerve involvement
• Trigeminal :
– First nerve to be involved , loss of corneal reflex, pain,
numbness and paresthesia of the face
• Facial : Hypoesthesia of posterior external auditory canal wall
(Hitselberger’s sign), facial weakness, loss of taste, ed
lacrimation
• Glossopharyngeal, Vagus & Spinal Accessory : Dysphagia,
hoarseness, nasal regurgitation, decreased gag reflex
• Abducent & Oculomotor : Diplopia

11. Stage of Brainstem and Cerebellar involvement
 Ataxia
 Weakness of arms & legs
 Tendon reflexes exaggerated
 Intention tremors
 Past-pointing
 Dysdiadochokinesia

12. Stage of Increased Intra-cranial tension
 Headache
 Projectile vomiting
 Blurred vision
 Papilledema
 Abducent nerve palsy

13. Investigations in Vestibular
schwannoma
• How will you investigate a case of vestibular
schwannoma?
• What is the gold standard investigation for
vestibular schwannoma?
• What are the ABR findings in vestibular
schwannoma?

14. Investigations
• Pure Tone Audiometry : asymmetrical high frequency
SNHL
• Speech audiometry : SD scores < 30%
• Tone decay test : +ve
• Stapedial Reflex : Decay > 50 % in 10 sec
• Caloric test : I/L canal paresis or no response

15. • A.B.R. (Selters and Brackmann)
– Wave I - V inter-wave interval : >4.4 ms
– Absolute latency of wave V : >6.3 msec
– Interaural Latency Difference of wave V : >0.3 ms
– Less sensitive for small lesions
• C.T. scan with contrast : helpful for tumor > 0.5 cm
• M.R.I. with Gd contrast : Tumor enhances (Gold
standard)

16. Pure Tone Audiogram
Left sided high frequency SNHL

17. MRI with Gd contrast

18. Treatment modalities
• Write down the treatment options available for
vestibular Schwannoma.
• What is gamma knife surgery? Mention its uses in
ENT.
• What are the different approaches to the
Vestibular schwannoma Surgery? Briefly describe
the advantages and limitations of each approach.

19. Treatment Modalities
1. Observation
2. Surgical removal
Approaches
– Translabyrinthine approach
– Retrosigmoid (Sub-occipital) approach
– Middle Cranial Fossa approach
– Combined approach
3. Proton Stereotactic Radiotherapy( Gamma knife surgery)
4. Brainstem Implant

20. Observation• Indications for observation
– Age > 60 years with small tumor & no symptoms
– Tumour in only hearing / better hearing ear
• Serial MRI to follow growth pattern
• Treatment recommended if
– Severe hearing loss
– Increasing tumor size

21. Surgical Approach : Protocol
• Intra-canalicular
– Middle cranial fossa approach
• Small (<1.5 cm)
– Retrosigmoid approach
• Medium (1 .5 - 4 cm)
– Hearing good: Retrosigmoid approach
– Hearing bad: Trans-labyrinthine approach
• Large (>4 cm): Trans-labyrinthine / Combined

22. Surgical Approaches

23. Trans-labyrinthine approach

24. Middle cranial fossa approach

25. Intra-operative

26. Stereotactic radiotherapy Gamma Knife
surgery)
• 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 : Linear accelerator
– Cyber-Knife : Robotic radio-surgery system
• Indications
– Surgery refused / contraindicated, Residual tumor

28. Glomus Tumours
1. Write down the differential diagnosis of pink lesion
behind the intact tympanic membrane (rising sun sign
behind the intact TM)
2. How do you diagnose glomus tumors in CT scan?
3. What are Browne’s and Phelp’s sign in glomus tumors?

29. • Commonest benign tumour of middle ear derived
from glomus bodies distributed along
parasympathetic nerves of head and neck
• Synonyms
– Chemodectoma
– Non - chromaffin paraganglioma
• Consists of paraganglionic cells derived from
embryonic neuroepithelium

30. Characteristics
• Histologically benign , locally invasive, highly
vascular, non-encapsulated, slow growing tumors
– 10 % tumors: familial
– 10 % tumors: multicentric
– 10 % tumors: functional (secrete catecholamines)
– 4 % tumors: metastatic

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

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

33. Spread

34. Symptoms
• Age : 40-60 yrs
• Female : male --- 5:1
• U/L deafness : conductive, progressive
• Tinnitus : Pulsatile, synchronous with pulse, decreases on
carotid pressure
• Blood stained otorrhea
• Ear ache & vertigo: rare

35. Signs
• Rising sun sign behind the intact TM : red reflex behind intact
TM on otoscopy
– Other conditions: ASOM, Organised hematoma, Hemangioma,
Aberrant carotid artery , Otospongoisis
• Browne’s sign : Positive pressure on Siegalization  tumor
blanches  pressure released  tumor engorges
• Aural mass that bleeds on touch
• Systolic bruit over mastoid on auscultation
• Neurological : IX, X, XI cranial nerve palsy

36. Rising sun sign

37. Blood-stained otorrhoea

38. Investigations
• Pure Tone Audiometry: Conductive deafness
• High resolution C.T. scan with contrast: erosion of
carotico - jugular spine (Phelp’s sign)
• Magnetic Resonance Imaging with Gadolinium
contrast: for soft tissue & intra-cranial extension
• M. R. Angiography
– For invasion of Internal jugular vein & internal
carotid artery compression

39. • Digital Subtraction Angiography
• Angiography
– Tumour blush , feeding arteries, contralateral
circulation
– Embolization (within 48 hours of surgery)
• 24 hour urine Vanillin Mandelic Acid level: > 7 mg 
Catecholamine secreting tumor
• Careful biopsy of mass in external auditory canal: rule
out malignancy

40. C.T. scan plain
Glomus Jugulare

41. M.R.I. with contrast

42. Pre & Post embolization

43. Fisch Staging
• Stage A: tumor limited to middle ear cleft
• Stage B: tympano -mastoid tumor sparing infra-labyrinthine
bone
• Stage C: tympano -mastoid tumor eroding infra-labyrinthine
bone
• Stage D1: Intra-cranial extension < 2 cm
• Stage D2: Intra-cranial extension > 2 cm

44. Surgical Treatment
• Anterior Tympanotomy: small stage A
• Extended facial recess approach: large stage A
• Modified Radical Mastoidectomy: small Stage B
• Combined Modified Radical Mastoidectomy + Fisch’s
Infratemporal fossa approach: large stage B, Stage C
• Subtotal temporal bone resection: Stage D1

45. Anterior Tympanotomy

46. Other Treatments
• Tele - Radiotherapy (4000 – 5000 rads) or Stereotactic
Radiotherapy
– Inoperable, residual or recurrent tumors
– Pt unfit for surgery or refuses surgery
• Observation : Pt > 70 yr with minimal symptoms
• Embolization:
– Before surgery : reduces vascularity
– After RT : for residual or recurrent tumor