Schwannoma of the VC Nerve

Question 1

What is tinnitus?

Answer 1

Sensation of sound with no external auditory stimulus.
Ringing, buzzing, roaring or humming noice.
Can be constant/intermittent, unilateral/bilateral.

Question 2

What is objective tinnitus?

Answer 2

Sound can be detected by an observer.
Can be a neuromuscular cause.
Can be a vascular cause e.g. Sound generated by turbulent blood flow are conducted to the auditory system in a pulsatile manner.

Question 3

What is subjective tinnitus?

Answer 3

Noise perception with no stimulation of the cochlea.
Usually intermittent and high-pitched.
Can be caused by aspirin, nicotine or caffeine.
Impacted cerumen is also a cause.
Can be caused by abnormal firing or auditory receptors, dysfunction of cochlear neurotransmitters or ionic balance, or alterations in central processing of the signal.

Question 4

What is Vertigo?

Answer 4

The illusion of motion or loss of balance due to vesicular dysfunction.

Question 5

What is objective vertigo?

Answer 5

When the person is ‘moving’ and environment is stationary.

Question 6

What is subjective vertigo?

Answer 6

When the person is stationary and the environment is ‘moving’.

Question 7

What is the difference between central and peripheral vertigo?

Answer 7

Central - results from issues with the cerebellum and other brainstem centres. It is usually mild and constant.

Peripheral - Usually VC problems. More severe and episodic.

Question 8

Describe the symptoms of vertigo?

Answer 8

Malaise, nausea, vomiting, dizziness.

Autonomic signs - Decreased BP, tachycardia, sweating, hyperventilation, postural hypotension.

Question 9

What is Menieres Disease?

Answer 9

A disorder of the inner ear due to distention of the endolymph compartment. It causes a triad of vertigo, tinnitus and hearing loss.
This could be due to;
- Increased endolymph production.
- Decreased perilymph accompanied by a compensatory increase in endolymph.
- Decreased endolymph production.

Question 10

What can cause Menieres disease?

Answer 10

Infection e.g. syphilis
Trauma
Endocrine e.g. hypothyroidism
Vascular Disorders.

Question 11

What is a Schwannoma of the VC nerve?

Answer 11

A benign tumour of the schwann cells on the VC nerve.

Question 12

How do symptoms relate to schwannoma of the VC nerve?

Answer 12

Hearing loss and tinnitus - due to compression of the cochlear nerve or interfering with blood supply to the cochlea.
Vertigo - compression of the vestibular nerve.
If it grows large enough, it can compress the facial nerve in the internal acoustic meatus and cause facial numbness, slow blink, altered taste and tearing.
Nystagmus and gait abnormalities can also occur in large tumours.

Question 13

What could result from a schwannoma of the VC if left untreated?

Answer 13

Hydrocephalus due to compression of the 4th ventricle.

Question 14

How is a schwanoma of the VC treated?

Answer 14

Chemo/radiotherapy.
Surgery - Sub-occipital Rectosigmoid approach where part of the occipital bone behind the ear is removed and the surgeon must go under the sigmoid sinus to reach the internal acoustic meatus.

Question 15

How does Schwannoma of the VC symptoms differ to Menieres?

Answer 15

Constant hearing problems rather than intermittent.

Symptoms get worse as tumour grows.

Question 16

Define Neoplasm?

Answer 16

Abnormal mass of unco-ordinated growth that exceeds that of normal tissues.

Question 17

Describe features of a benign tumour?

Answer 17

Expansive growth but localised
Capsule 
Slower growth rate 
Resembles tissue of origin
Normal nuclei and uniform cells.

Question 18

Describe features of a malignant tumour?

Answer 18

Infiltrative growth with metastases
No capsule 
Rapid growth 
Loses resemblance to tissue
Pleomorphism and dyplasia. 

Malignant tumours breach the BM and have the ability to metastasise.

Question 19

Describe the sequelae of space occupying lesions?

Answer 19

Tissue of the CNS get compressed and distorted as the brain and spinal cord are enclosed in bone.
SOL’s can cause atrophy of adjacent tissue if slowly enlarging.
Rapid enlargement can cause and increased in pressure (>15mmHg) and cause tissue to herniate into areas of lower pressure.

Question 20

Describe the course of the Facial nerve?

Answer 20

Attached between the pons and medulla.
It has a larger motor root and smaller sensory root.
Both roots cross the cranial fossa and leave via the internal acoustic meatus, then enter the facial canal in the temporal bone.
In the facial canal, the nerve enlarges to form the Geniculate ganglion.
It exits via the stylomastoid foramen and enters the parotid gland to give its terminal branches (T, Z, B, MM, C).

Question 21

List the functions of the facial nerve?

Answer 21

Motor: Muscles of facial expression, digastric, stylohyoid and stapedius.
Sensory: A small area around concha of auricle.
Special sensory: Taste to anterior 2/3rds of tongue (Chorda tympani).
Parasympathetic: Submandibular and sublinual salivary glands (chorda tympani).
Nasal, palatine and pharyngeal mucous glands (greater petrosal).
Lacrimal glands (greater petrosal).

Question 22

Describe the course of the VC nerve?

Answer 22

Attaches between the pons and medulla.
Emerges from internal acoustic meatus and splits in 2 to form the vestibular and the cochlear nerve and crosses the posterior cranial fossa.
It then forms the vestibular ganglion which gives off branches to the semicircular ducts, utricle and saccule.
The cochlear nerve forms the spiral ganglion which innervates receptors in the spiral organ.

Question 23

What is Tarsorrhaphy?

Answer 23

If facial palsy occurs and orbicularis oris is affected, it will be difficult to close the eyelid. This can cause the eye to become dry and unprotected, leading to ulceration.
This procedure involves the eyelids being partially sewn together to narrow the eyelid opening.

Question 24

What symptoms are seen in facial palsy?

Answer 24

Weakness of facial muscles.
Loss of taste.
Voluntary eye closure may not be possible.
Difficulty eating as buccinator helps hold food in the oral cavity.

Question 25

How would the facial nerve be affect in UMNL’s compared to LMNL’s?

Answer 25

UMNL: Upper facial muscles are spared due to alternative pathways in the brainstem. Patient can wrinkle forehead and there is less sagging.

LMNL: Final common pathway to the muscles is destroyed so they cannot wrinkle forehead. Lesion is either in pons or outside the brainstem.

Question 26

Describe symptoms of Menieres disease?

Answer 26

1. Fluctuating vertigo (lasting more than 5 mins).
2. Fluctuating hearing loss.
3. Fluctuating tinnitus.
4. Fluctuating feeling of fullness in affected ear.