Acoustic neuroma is a benign tumor of the eighth cranial nerve. The document discusses the definition, histopathology, etiology, classification, clinical features, investigations, differential diagnosis, and management of acoustic neuroma. The key signs and symptoms include progressive hearing loss, tinnitzus, imbalance, and cranial nerve involvement including facial numbness. MRI with gadolinium is the gold standard for diagnosis. Treatment options include surgical removal via middle cranial fossa, translabyrinthine, or suboccipital approaches or stereotactic radiotherapy using gamma knife or cyber knife.

2. Objectives
 Acoustic Neuroma:
definition,
histopathology
 Etiopathogenesis
 Classification
 Clinical Features
 Management
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3. FAQ’s in RGUHS
• Acoustic Neuroma
• Clinical features of acoustic neuroma
• Hitzelberger’s sign

4. Acoustic Neuroma
• Definition:
Tumour of eighth cranial Nerve.
• Eponyms:
Vestibular Schwannoma
Neurilemmoma
• Incidence:
80% of Cerebellopontine angle tumours
10% of all brain tumours

5. Pathology
• Gross:
Benign, Encapsulated,
Slow-growing
• Microscopy:
Elongated spindle cells
Rod-shaped nuclei in rows
or palisades.

6. Origin & Growth
• Origin:
Schwann Cells of Vestibular Nerve, rarely from
cochlear nerve
• Growth: (slow)
 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

7. Origin & Growth

8. Classification
Acoustic
Neuroma
Intracellular
Small Size
<1.5cm
Medium size
1.5-4cm
Large Size
> 4cm

9. Clinical Features
• Age : 40-60 years
• Sex: M=F
• Symptoms:
1. Progressive unilateral SNHL
2. Tinnitus
3. Marked difficulty in understanding speech
4. Imbalance/ Unsteadiness
5. Vertigo
6. Sudden Hearing loss
7. Fullness in the ear

10. Cranial Nerve Involvement
1. 5th nerve: EARLIEST
Reduced cornea sensitivity, paraesthesia of face
Involvement indicates : tumour size = 2.5cm &
occupies CP angle
2. 9th & 10th : dysphagia & hoarseness due to
palatal, pharyngeal, laryngeal paralysis
3. Other cranial nerves: affected only when tumour
size is very large

11. 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

12. Brainstem Involvement
• Ataxia
• Weakness & Numbness of arms
and legs
• Exaggerated tendon reflexes
Raised Intra-cranial tension
Headache, nausea, vomiting, diplopia(6th) &
papillo-edema with blurring of vision.

13. 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 straight line (tendency to
fall on the affected side)

14. Investigations
• Audiological tests:
1. PTA
2. Speech Audiometry
3. Recruitment
phenomena: Absent
4. Short Increment
Sensitivity Index: 0-20%
5. Threshold tone decay
test : Retrocochlear type
of lesion

15. Vestibular Tests
• Caloric test:
Diminished or absent
response in 96% of
patients
May be normal when
tumour is small

16. Neurological Tests
Complete examination of:
• Cranial nerves
• Cerebellar functions
• Brainstem signs of pyramidal & sensory tracts
• Fundus

17. Radiological tests
1. Plain X-ray:
• Positive in 80% of patients
• Different views:
1. Transorbital
2. Stenver’s
3. Towne’s
4. Submentovertical
2. Vertebral angiography:
• Helps in differentiating AN from other tumours

18. Radiological Test
3. CT scan:
• More sensitive than X-ray
• Can detect even intra-meatal and
posterior fossa tumors
4. MRI with Gadolinium contrast:
• GOLD Standard
• Can detect even intracanalicular
tumours of few mm

19. Stapedial reflex Decay Test

20. Other tests
• BERA:
A delay of >0.2ms in
wave V between 2 ears in
case of 8th nerve tumour
• CSF Examination:
Protie level raised, Lumbar
puncture should be
avoided

21. Investigations
Important tests for AN work-up:
• PTA
• Speech discrimination score
• Roll-over curve
• Stapedial reflex decay
• BERA
• MRI with gadolinium contrast

22. Differential Diagnosis
• Meniere’s Disease
• Tumours of CPangle:
1. Meningioma
2. Epidermoid
3. Arachnoid Cyst
4. Schwannoma of other cranial nerves
5. Aneurysm
6. Glomus tumour
7. Metastasis

23. Treatment
Treatment
Surgical Radiotherapy

24. Surgical
• Treatment of Choice
Approaches
Middle Cranial
Fossa
Translabyrinthine Suboccipital
Combined
translabyrinthine-
suboccipital

25. Radiotherapy
1. Conventional Radiotherapy
2. X-knife/ɣ-knife surgery
3. Cyber knife

26. X-knife/ɣ-knife surgery
• Stereotactic radiotherapy
• Advantages:
1. Minimal radiological effect
2. Causes reduction in tumour size &
growth.
3. Can be used in patients where surgery is
not feasible.
• Procedure : linear accelerator
ɣ-knife through cobalt-60

27. Radiotherapy
Conventional:
• Not prefered now due to low
tolerance of CNS to radiation
Cyber knife:
• Modified X-knife
• More accurate & frameless
• Method: real-time image
guidance technology through
computer controlled robotics.