Acoustic Neuroma causing hearing loss.pptx

1. ACOUSTIC NEUROMA
Dr. Imran Khan
Assistant Professor
Department of ENT KMC-KTH

2. ACOUSTIC NEUROMA
Vestibular Shwanomma
Arise from 8th C.N
Benign, encapsulated
Slow growing
Constitutes 80% of all CP angle tumours and
10% of all the brain tumours.

3. CEREBELLOPONTINE ANGLE
• Acoutic Neuroma 80%
• Meningiomas 20%
• Facial Nerve Neuroma
• Vascular tumor
• Lipoma
• Metastatic lesions

4. INTERNAL AUDITORY CANAL

5. RISK FACTORS
• No apparent risk factors
BUT
• Exposure to high-dose ionizing radiation?
• Cell Phone Radiations?
• Neurofibromatosis type 2

6. ORIGIN
• Schwann cells of the vestibular Nerve 95%
• But rarely from the cochlear Nerve <5%
• Within Internal Auditory canal

7. GROWTH
• Arise in IAC
• Expands to CP angle
• In later stages, causes displacement of
brainstem, pressure on cerebellum and raised
intracranial tension

8. GROWTH PATTERNS
• No growth
• Slow growth (i-e, 0.2 cm/y on imaging studies)
• Fast growth (i-e, ≥ 1.0 cm/y on imaging studies)
Although most acoustic neuromas grow slowly, some grow
quite quickly and can double in volume within 6 months
to a year.

9. CLINICAL FEATURES

10. CLINICAL FEATURES
• Age… 40 to 60
• Gender… Both sexes are equally affected
• Progressive unilateral SNHL, often accompanied by
tinnitus, is the presenting symptom in majority of cases
• Difficulty in understanding speech, out of proportion
to the pure tone hearing loss.
• Vestibular symptoms… Imbalance or unsteadiness.

11. CLINICAL FEATURES
Cranial Nerves Involvement:
• 8th
• 7th Nerve : Sensory fibres are affected early.
Hitzelberger’s sign (hypoaesthesia of posterior meatal
wall)
loss of taste and reduced lacrimation on Schirmer test
• 5th Nerve
Involvement of this nerve indicates that the tumour is
roughly 2.5 cm in diameter and occupies the
cerebellopontine angle.

12. CLINICAL FEATURES
• 9th and 10th Nerve: Dysphagia and hoarseness
due to palatal, pharyngeal and laryngeal
paralysis.
• Other cranial nerves. 11th, 12th , 3rd, 4th and
6th are affected when tumour is very large.

13. CLINICAL FEATURES
• Brainstem Involvement. Ataxia, weakness and
numbness of the arms and legs with
exaggerated tendon reflexes.
• Cerebellar Involvement. Pressure symptoms
on cerebellum are seen in large tumours.
• This is 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.

14. CLINICAL FEATURES
• Raised Intracranial Tension. This is also a late
feature.
There will be headache, nausea, vomiting,
diplopia due to VIth nerve involvement and
papilloedema with blurring of vision.

15. Classification
Depending on the size, the tumour is
classified as:
• 1. Intracanalicular (when it is confined to
internal auditory canal)
• 2. Small size (up to 1.5 cm)
• 3. Medium size (1.5–4 cm)
• 4. Large size (over 4 cm)

16. INVESTIGATIONS
• Audiological Tests:
o PTA: will show SNHL, more marked in high
frequencies.
o Speech audiometry shows poor speech
discrimination and this is disproportionate to
pure tone hearing loss.
o Roll-over phenomenon, i.e. reduction of
discrimination score when loudness is increased
beyond a particular limit is most commonly
observed

18. INVESTIGATIONS
o Recruitment phenomenon is absent.
o Short Increment Sensitivity Index (SISI) test will
show a score of 0–20% in 70–90% of cases.
o Threshold tone decay test shows retrocochlear
type of lesion.
o Stapedial Reflex Decay Test
o Vestibular Tests. Caloric test will show diminished
or absent response in 96% of patients.
o Neurological Tests. Complete examination of
cranial nerves

19. INVESTIGATIONS
• BERA: Delay of > 0.2 ms in wave V
• CSF Examination

20. RADIOLOGICAL TESTS
• PLAIN X-RAYS
Transorbital,
Stenver’s,
Towne’s and
Submentovertical views)
• CT SCAN
A tumour that projects even 0.5 cm into the
posterior fossa can be detected by a CT scan.

21. RADIOLOGICAL TESTS
• MRI WITH CONTRAST
Superior to CT scan
Gold standard
Intracanalicular tumour, of even a few
millimetres, can be easily diagnosed
• VERTEBRAL ANGIOGRAPHY
This is helpful to differentiate acoustic neuroma
from other tumours of cerebellopontine angle
when doubt exists.

25. TREATMENT
• Wait & See
• Stereotactic Radiation therapy
• Surgical excision

26. Wait & See
• Elderly patients
• Small tumors with good hearing
• Patients with medical conditions
• Patients who refuse treatment
• Patients with a tumor on the side of an only
hearing ear

27. STEREOTACTIC RADIOTHERAPY
• X-knife or Gamma knife surgery
• Cyber knife

28. SURGICAL APPROACHES
1. Middle cranial fossa approach.
2. Translabyrinthine approach.
3. Suboccipital (retrosigmoid) approach.
4. Combined translabyrinthine-suboccipital
approach.