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Flashcards in Cranial Nerves for Finals Deck (42)
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1
Q

What could you ask a patient to assess the functioning of their olfactory nerve?

A

“Have you noticed a change in your sense of smell or taste?”

2
Q

Give some causes of anosmia.

A

Viral infection
Trauma
Idiopathic Parkinson’s Disease (about 80% of patients notice this as an early feature)
Rare: Refsum’s Disease, Olfactory Groove Meningioma, Kallmann’s Syndrome

3
Q

5 things must be tested when assessing the function of the optic nerve. What are they?

A
  • Acuity (Snellen chart)
  • Colour vision (Ishihara chart)
  • Fundoscopy
  • Visual fields
  • Pupillary reflexes
4
Q

List some features of VIIth nerve palsy which would lead you to suspect the cause was Bell’s Palsy i.e. idiopathic

A
  • Acute onset e.g. overnight
  • Complete unilateral facial weakness between 24-72 hrs
  • Ipsilateral numbness or pain around ear
  • Decreased taste
  • Hypersensitivity to sounds
5
Q

What is Rinne’s test?

A

Hold a tuning fork first in front of the ear (air conduction) then at the mastoid process (bone conduction) and ask the patient which they think is loudest. Negative = bone conduction > air conduction. Positive = air conduction > bone conduction.

6
Q

What is Weber’s test?

A

Hold a ringing tuning fork to the forehead and ask the patient which side is loudest. Conductive hearing loss = affected side loudest. Sensorineural hearing loss = contralateral side loudest.

7
Q

List some causes of conductive hearing loss

A

Wax, otosclerosis, glue ear, otitis media

8
Q

What is the treatment of Bell’s palsy?

A

Prednisolone but no aciclovir

9
Q

What is the investigation of choice in VIIth nerve palsy when the clinical picture suggests an upper motor neurone lesion (i.e. NOT Bell’s)?

A

CT head with contrast

10
Q

What are the causes of a bilateral facial nerve palsy?

A

Guillian Barre
Sarcoidosis
Lyme disease

11
Q

What are the causes of a medical IIIrd nerve palsy?

A

Diabetes
Stroke
Hypertension

12
Q

What are the causes of a surgical IIIrd nerve palsy?

A

Aneurysm (PICA or internal carotid)
Space occupying lesion
Intracranial haemorrhage

13
Q

What is the difference between a medical and a surgical IIIrd nerve palsy?

A

Surgical IIIrd never palsy causes compression of parasympathetic fibres which run along the outside of the nerve…This causes pupillary dilation because the parasympathetic fibres are responsible for constricting the pupil via the short ciliary muscles. In a medical IIIrd nerve palsy the parasympathetic fibres are spared so there is no involvement of the pupil.

14
Q

If you’re testing the IIIrd nerve, apart from eye movements what is it important that you test?

A

Pupils (?medical or surgical palsy)

15
Q

What is the appearance of a IIIrd nerve palsy?

A

Ptosis
Proptosis
Eye looks ‘down and out’ due to unopposed lateral rectus and superior oblique action
Fixed pupil dilatation in surgical IIIrd nerve palsy

16
Q

Which muscles are supplied by the IIIrd nerve?

A

Superior, medial, inferior rectus
Inferior oblique
Levator palpebrae superior
Short ciliary muscles

17
Q

Which muscle(s) are supplied by the IVth nerve?

A

Superior oblique

18
Q

Which muscle(s) are supplied by the VIth nerve?

A

Lateral rectus

19
Q

What are the features of a VIth nerve palsy?

A

Diplopia in horizontal plane (lateral gaze)

Failure of abduction of the eye

20
Q

What are the features of a IVth nerve palsy?

A
Diplopia on looking down and in...the patient might notice this when descending stairs
Head tilting (ocular torticolis) compensates for this
21
Q

List some causes of a Ist nerve palsy

A

Parkinson’s disease
Trauma
Viral URTI

22
Q

What is the primary cause of a IVth nerve palsy?

A

Trauma

23
Q

Which side does the tongue deviate in a XIIth nerve palsy?

A

Tongue deviates towards the side of the problem

24
Q

What is the nerve supply to the tongue?

A
Anterior 2/3:
Gross sensation = Lingual branch of trigeminal
Taste sensation = VIIth nerve
Posterior 1/3:
Gross sensation and taste = IXth nerve
Motor function of tongue = XIIth nerve
25
Q

What are the features of optic neuritis?

A

Painful around eye, especially on eye movements
Loss of vision - Subacute, usually unilateral
Reduced colour vision and red desaturation
RAPD

26
Q

What is the treatment for optic neuritis?

A

IV methylprednisolone high dose for 72 hours, then prednisolone for 11 days

27
Q

What are the causes of optic neuritis?

A

Idiopathic
Multiple sclerosis
Viral
Systemic disease: Sarcoidosis, syphilis, diabetes

28
Q

What are the signs of optic neuropathy?

A
Pale optic disc
Loss of visual acuity
RAPD
Loss of colour vision
Central scotoma
29
Q

What might be the underlying cause in a patient with a relative afferent pupillary defect?

A

Damage to optic nerve itself (optic neuropathy) e.g. in MS, ischaemia
Damage to retina

30
Q

Describe what you see in a patient with a relative afferent pupillary defect

A

Normally, when a light is shone in 1 eye, there is direct pupil constriction on that side, and consensual constriction on the other side. In an RAPD, there is damage to the afferent fibres - so when a light is shone in the affected eye, it is not detected so there is neither direct constriction on that side or consensual constriction on the other side.

31
Q

List some causes of VIIth nerve palsy

A

Idiopathic i.e. Bell’s palsy
Infective: Ramsay Hunt Syndrome (reactivation of VZV), Lyme disease, TB, HIV, polio
Brainstem lesions: Stroke, tumous, MS
Systemic disease: Diabetes, sarcoidosis, Guillian Barre
Acoustic neuroma

32
Q

What are the causes of a VIth nerve palsy?

A

Raised ICP
Lateral sinus thrombosis
Basal skull trauma

33
Q

What are the causes of ptosis?

A

Bilateral: Myasthenia gravis, myotonic dystrophy
Unilateral: Horner’s, 3rd nerve palsy

34
Q

What is a bulbar palsy?

A

Problem with CN IX to XII in the medulla, causing LMN signs

35
Q

What is a pseudobulbar palsy?

A

An UMN problem with the corticospinal tracts

36
Q

What are the signs of a bulbar palsy?

A
LMN signs:
Tongue fasciculation
Weakness of tongue
Weakness of trapezius and sternocleidomastoid muscles
Absent jaw jerk
Quiet, hoarse, or 'nasal' speech
37
Q

What are the causes of a bulbar palsy?

A
Motor neurone disease (Progressive bulbar palsy)
Guillian Barre
Myasthenia gravis
Polio
Central pontine myelinolysis
38
Q

What are the signs of a pseudobulbar palsy?

A
UMN signs:
Hyper-reflexic jaw jerk
Slow tongue movements
slow speech
Labile affect
39
Q

What are the causes of a pseudobulbar palsy?

A

MS
Motor neurone disease
Stroke
Central pontine myelinolysis

40
Q

What are the branches of the trigeminal nerve?

A

Ophthalmic
Maxillary
Mandibular

41
Q

Dysfunction of CN III, IV, Va and VI might lead you to suspect what diagnosis?

A

Cavernous sinus thrombosis

Superior orbital fissure lesions

42
Q

What are the branches of the facial nerve?

A
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical