Slides prepared and compiled by highly experienced ENT teacher, Dr. Krishna Koirala from Nepal , for teaching undergraduate and postgraduate ENT students in the field of otorhinolaryngology.
A clear and concise explanation of the basic concepts in the subject matter concerned.
He is the Head of department with a sound knowledge in the field of ENT to teach both undergraduate and postgraduate ENT students
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
6.
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
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)
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.
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
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
27.
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
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
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
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