Ch33 Neuro-otology

Question 1

When was the House-Brackmann grading described?

Answer 1

1985

Question 2

What is the House-Brackmann grading?

Answer 2

1 - normal (score 8/8) 2 - mild dysfunction with slight weakness. Normal symmetry and tone (score 7/8). 3 - moderate dysfunction. Obvious but not disfiguring difference between the two sides. Noticeable synkineses. Complete eye closure with effort. (score 5-6/8) 4 - moderately severe dysfunction. Obvious weakness with disfiguring asymmetric. Incomplete eye closure. (score 3-4/8) 5 - severe dysfunction. Barely perceptible motion. Slight movement of the mouth. (score 1-2/8) 6 - total paralysis. (score 0/8)

Question 3

How did the original House & Brackmann (1985) paper propose standardisation of the grading scale?

Answer 3

Measuring the movement of angle of mouth and the eyebrow and comparing to the unaffected side. The difference is based on 2.5 mm gradations. The maximum score is 8 (4 for the mouth and 4 for the eyebrow),

Question 4

What is Dandy’s syndrome?

Answer 4

Oscillopsia secondary to bilateral vestibular injury / neurectomy

Question 5

What is the most common indication for selective vestibular neurectomy?

Answer 5

Meniere’s disease

Question 6

How does the vestibular nerve appear during surgery?

Answer 6

More gray than the cochlear and facial nerves due to less myelination

Question 7

Where is the endolymphatic sac?

Answer 7

Midway between the posterior edge of the IAM and the sigmoid sinus

Question 8

What is Meniere’s disease?

Answer 8

An increase in endolymphatic pressure causing vertigo, tinnitus and sensorineural hearing loss affecting lower frequencies. Surgical options for refractory cases include endolymphatic sac shunting or selective vestibular neurectomy. Arenberg shunt is to the mastoid cavity and performed where hearing is intact. Otherwise shunting to the subarachnoid space.

Question 9

What are the differences between an UMN and LMN facial nerve palsy?

Answer 9

In UMN cases the forehead is preserved as this is bilaterally represented and emotional facial expression may be maintained e.g. smiling at a joke

Question 10

What is Gubler-Millard syndrome?

Answer 10

Base of pons lesion causing CN7, CN6 and contralateral hemiplegia

Question 11

What is benedikt syndrome?

Answer 11

CN3 palsy with red nucleus involvement (coarse intention tremor) and contralateral hemiparesis. Dorsal midbrain lesion.

Question 12

What forms the facial colliculus?

Answer 12

Facial fibres passing around the abducens nucleus

Question 13

What are the segments of the facial nerve?

Answer 13

Brainstem

Cisternal

Petrous - geniculate ganglion gives off GSPN (dry eye)

Tympanic - nerve to stapedius (hyperacusis)

Mastoid - chorda tympani (loss of taste)

Question 14

What pathway control lacrimation (tearing)?

Answer 14

Superior salivary nucleus

Nervus intermedius

GSPN > Vidian

Sphenopalatine ganglion

Zygomatic and lacrimal nerves

Lacrimal gland

Question 15

What is crocodile tear syndrome?

Answer 15

Lesions of the facial nerve cause abberent connections in the pterygopalatine ganglion between mastication and lacrimation. Chewing therefore results in lacrimation when eating.

Question 16

Which nerve do fibres to the submandibular and sublingual glands run on?

Answer 16

Chorda Tympani

Question 17

What is the most likely underlying cause for Bell’s palsy?

Answer 17

Viral inflammatory demyelinating polyneuritis

Question 18

What features may be associated with Bell’s palsy?

Answer 18

Follows a distal to proximal pattern with motor loss first then

Facial and retroauricular pain (60%)

Dysgeusia (=altered taste) (60%) = chorda tympani

Hyperacusis (30%) = n to stapedius

Reduced tearing (17%) = GSPN

Question 19

What is the evidence for treatments of Bell’s palsy?

Answer 19

In patients with Bell’s palsy, early treatment with prednisolone significantly improves the chances of complete recovery at 3 and 9 months. There is no evidence of a benefit of acyclovir given alone or an additional benefit of acyclovir in combination with prednisolone. NEJM RCT 2007 Sullivan et al.

Question 20

What are the surgical treatment options for facial nerve injury?

Answer 20

1. Approximation if there is a transection via direct anastomosis or cable graft with sural nerve
2. Extracranial anastomosis (CN9/11/12
3. Facial suspension
4. Tarsorrhaphy

Question 21

What are the two types of hearing loss?

Answer 21

Conductive and sensorineural - distinguished using Rinne and Weber’s test

Question 22

What are the Rinne and Weber’s test findings in a normal patient?

Answer 22

Weber is central i.e. does not lateralize to one side

Rinne has AC>BC

Question 23

What is a positive Rinne’s test?

Answer 23

When AC>BC which is normal. If BC>AC this is a negative finding and suggests conductive hearing loss in that ear.

Question 24

How do you perform Rinne’s test?

Answer 24

512 Hz tuning fork on the mastoid bone.

When no longer heard it should be moved to the ear.

If it can then be heard again it is positive.

Question 25

How do you interpret Weber's tests?

Answer 25

A tuning fork in the center of the head does not lateralise if the hearing is normal. It lateralises to the side where there is a conductive hearing loss of the contralateral side if there is a sensorineural hearing loss.

Question 26

Interpret the following: Webers lateralises to the right Right Rinne's is negative (BC\>AC) Left Rinne's is positive (AC\>BC)

Answer 26

Right conductive hearing loss

Question 27

Interpret the following: Webers lateralises to the right Right Rinne's is positive (AC\>BC) Left Rinne's is positive (AC\>BC)

Answer 27

Left sensorineural hearing loss

Question 28

What causes sensorineural hearing loss?

Answer 28

Sensory - cochlear damage from noise exposure, drugs (gentamicin) and viral labyrinthitis. Neural - Compression of CN8 in the CP angle

Question 29

What tests help to distinguish conductive and sensorineural hearing loss?

Answer 29

PTA / tymps Otoacoustic emissions BSAER Stapedial reflex out of proportion to PTA suggests neural lesion

Question 30

What is the most reliable indicator of an acoustic neuroma from the BAER?

Answer 30

Increased intraaural latency in wave V. BAER sensitivity is 90%.

Question 31

What is Hitzelberger's sign?

Answer 31

Compression of nervus intermedius by a vestibular schwannoma causing numbness over the posterior aspect of the EAC

Question 32

Which nerve supply the external ear?

Answer 32

Pinna = Greater auricular C2/3 Back of ear = Lesser occipital C2 Anterior and superior ear = Auriculotemporal V3 Posterior inferior EAC and = Auricular branch of vagus (Arnold's nerve) Posterior inferior EAC = Facial nerve sensory branch via nervus intermedius

Question 33

What is the modiolus?

Answer 33

The conical central axis of the cochlea

Question 34

What is the mechanism behind caloric testing?

Answer 34

The cold water causes the endolymph to become dense and fall. This pulls the ipsilateral cupula away from the utricle, reducing the firing and causes nystagmus with the fast component to the left. Movement of the cupla towards to the utricle = ampulopetal; Away = ampulofugal.

Question 35

Describe the vestibular pathway

Answer 35

Cupula in each of the semicircular canals \> CN8 \> Vestibular nucleus int he medulla \> CN6 and 3 bilaterally via the MLF and control medial and lateral rectus coordination.

Question 36

How do you interpret tympanometry?

Answer 36

X axis is the static pressure and Y axis is the volume. A = Normal B = flattened curve suggestive of an compressible fluid in the middle ear C = Negative compliance suggesting a negative pressure in the middle ear which occurs with eustachian tube dysfunction

Question 37

What are the PTA findings with noise-injury hearing loss?

Answer 37

Sensorineural hearing loss at 4kHz

Question 38

What genetic condition causes haematuria and high frequency hearing loss?

Answer 38

Alport syndrome

Question 39

Names the structures

Answer 39

Question 40

What is the different ionic composition of endolymph and perilymph?

Answer 40

Endolymph has high K+ like intracellular fluid, Perilymph has a higher Na+ like extracellular fluid and CSF

Question 41

How do you use Rinne's and Weber's test to localise hearing loss?

Answer 41