What could you ask a patient to assess the functioning of their olfactory nerve?
“Have you noticed a change in your sense of smell or taste?”
Give some causes of anosmia.
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
5 things must be tested when assessing the function of the optic nerve. What are they?
- Acuity (Snellen chart)
- Colour vision (Ishihara chart)
- Fundoscopy
- Visual fields
- Pupillary reflexes
List some features of VIIth nerve palsy which would lead you to suspect the cause was Bell’s Palsy i.e. idiopathic
- Acute onset e.g. overnight
- Complete unilateral facial weakness between 24-72 hrs
- Ipsilateral numbness or pain around ear
- Decreased taste
- Hypersensitivity to sounds
What is Rinne’s test?
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.
What is Weber’s test?
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.
List some causes of conductive hearing loss
Wax, otosclerosis, glue ear, otitis media
What is the treatment of Bell’s palsy?
Prednisolone but no aciclovir
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)?
CT head with contrast
What are the causes of a bilateral facial nerve palsy?
Guillian Barre
Sarcoidosis
Lyme disease
What are the causes of a medical IIIrd nerve palsy?
Diabetes
Stroke
Hypertension
What are the causes of a surgical IIIrd nerve palsy?
Aneurysm (PICA or internal carotid)
Space occupying lesion
Intracranial haemorrhage
What is the difference between a medical and a surgical IIIrd nerve palsy?
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.
If you’re testing the IIIrd nerve, apart from eye movements what is it important that you test?
Pupils (?medical or surgical palsy)
What is the appearance of a IIIrd nerve palsy?
Ptosis
Proptosis
Eye looks ‘down and out’ due to unopposed lateral rectus and superior oblique action
Fixed pupil dilatation in surgical IIIrd nerve palsy
Which muscles are supplied by the IIIrd nerve?
Superior, medial, inferior rectus
Inferior oblique
Levator palpebrae superior
Short ciliary muscles
Which muscle(s) are supplied by the IVth nerve?
Superior oblique
Which muscle(s) are supplied by the VIth nerve?
Lateral rectus
What are the features of a VIth nerve palsy?
Diplopia in horizontal plane (lateral gaze)
Failure of abduction of the eye
What are the features of a IVth nerve palsy?
Diplopia on looking down and in...the patient might notice this when descending stairs Head tilting (ocular torticolis) compensates for this
List some causes of a Ist nerve palsy
Parkinson’s disease
Trauma
Viral URTI
What is the primary cause of a IVth nerve palsy?
Trauma
Which side does the tongue deviate in a XIIth nerve palsy?
Tongue deviates towards the side of the problem
What is the nerve supply to the tongue?
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
What are the features of optic neuritis?
Painful around eye, especially on eye movements
Loss of vision - Subacute, usually unilateral
Reduced colour vision and red desaturation
RAPD
What is the treatment for optic neuritis?
IV methylprednisolone high dose for 72 hours, then prednisolone for 11 days
What are the causes of optic neuritis?
Idiopathic
Multiple sclerosis
Viral
Systemic disease: Sarcoidosis, syphilis, diabetes
What are the signs of optic neuropathy?
Pale optic disc Loss of visual acuity RAPD Loss of colour vision Central scotoma
What might be the underlying cause in a patient with a relative afferent pupillary defect?
Damage to optic nerve itself (optic neuropathy) e.g. in MS, ischaemia
Damage to retina
Describe what you see in a patient with a relative afferent pupillary defect
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.
List some causes of VIIth nerve palsy
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
What are the causes of a VIth nerve palsy?
Raised ICP
Lateral sinus thrombosis
Basal skull trauma
What are the causes of ptosis?
Bilateral: Myasthenia gravis, myotonic dystrophy
Unilateral: Horner’s, 3rd nerve palsy
What is a bulbar palsy?
Problem with CN IX to XII in the medulla, causing LMN signs
What is a pseudobulbar palsy?
An UMN problem with the corticospinal tracts
What are the signs of a bulbar palsy?
LMN signs: Tongue fasciculation Weakness of tongue Weakness of trapezius and sternocleidomastoid muscles Absent jaw jerk Quiet, hoarse, or 'nasal' speech
What are the causes of a bulbar palsy?
Motor neurone disease (Progressive bulbar palsy) Guillian Barre Myasthenia gravis Polio Central pontine myelinolysis
What are the signs of a pseudobulbar palsy?
UMN signs: Hyper-reflexic jaw jerk Slow tongue movements slow speech Labile affect
What are the causes of a pseudobulbar palsy?
MS
Motor neurone disease
Stroke
Central pontine myelinolysis
What are the branches of the trigeminal nerve?
Ophthalmic
Maxillary
Mandibular
Dysfunction of CN III, IV, Va and VI might lead you to suspect what diagnosis?
Cavernous sinus thrombosis
Superior orbital fissure lesions
What are the branches of the facial nerve?
Temporal Zygomatic Buccal Marginal mandibular Cervical