Medicine 4 Flashcards
What is internuclear ophthalmoplegia and what is it caused by?
Caused by damage to the medial longitudinal fasciculus which is responsible for allowing communication between the ipsilateral CN3 (adduction) and contralateral CN6 (abduction).
This leads to failure of adduction of the ipsilateral eye. Nystagmus in the abducting eye may be noted.
It is most commonly caused by multiple sclerosis (and stroke in older patients)
What is the difference between bulbar and pseudobulbar palsy?
Bulbar: lower motor neurone palsy of CN 9 to 12.
Pseudobulbar: upper motor neurone palsy affecting CN 5, 7, 9-12.
Both cause dysphagia and dysarthria but pseudobulbar palsy will also cause lack of facial expression, difficulty chewing and emotional lability.
NOTE: key difference is that bulbar palsy causes LMN signs (e.g. tongue fasciculations) whereas pseudobulbar causes UMN signs (e.g. exaggerated gag reflex)
What are the different types of motor neuron disease?
Amyotrophic lateral sclerosis (50%) - UMN and LMN signs
Primary lateral sclerosis - mainly UMN signs (spastic leg weakness and pseudobulbar palsy)
Progressive bulbar palsy - only affects CN 9-12
Progressive muscular atrophy - LMN signs only, affects distal to proximal (best prognosis)
List some lower motor neurone signs.
Muscle wasting
Fasciculations
Hypotonia
Hyporeflexia
List some causes of LMN signs.
DISTAL: Charcot-Marie-Tooth disease, paraneoplastic, lead poisoning, GBS, botulism
PROXIMAL: muscular dystrophy, myositis, Cushing’s, thyrotoxicosis, diabetic amyotrophy, alcohol
UNILATERAL: polio, mononeuropathy
List some causes of peripheral sensory neuropathy.
Diabetes mellitus Alcohol abuse B12 deficiency Chronic renal failure Hypocalcaemia Vasculitis Drugs (e.g. isoniazid)
What features of diabetic neuropathy can be seen in the lower limbs?
Distal sensory loss (gloves and stockings)
Bilateral loss of ankle jerk (due to sensory neuropathy)
Mononeuritis multiplex (foot drop)
List some manifestations of autonomic neuropathy in diabetes mellitus.
Postural hypotension Gastroparesis Diarrhoea Urinary retention Erectile dysfunction
List the main features of Charcot-Marie-Tooth disease.
Pes cavus Symmetrical distal muscle wasting (claw hand, champagne bottle led) Thickened nerves High stepping gait Weak foot and toe dorsiflexion Absent ankle jerk Variable loss of sensation
List some differentials for bilateral ptosis.
Myasthenia gravis Myotonic dystrophy Congenital Senile Bilateral Horner's (RARE)
Describe the typical presentation of Guillain-Barre syndrome.
Symmetrical ascending flaccid paralysis and sensory disturbance (paraesthesia)
Can cause autonomic neuropathy (labile BP)
NOTE: Miller-Fisher variant is characterised by ophthalmoplegia, ataxia and areflexia
Which muscles are weak in a facial nerve palsy?
Fronatlis (raising eyebrows) Orbicularis oculi (scrunching eyes) Orbicularis oris (smiling)
NOTE: UMN lesion spares frontalis and orbicularis oculi - if UMN then it may be due to a stroke so do other neuro exams
List some causes of facial nerve palsy.
Idiopathic (Bell's palsy) - 75% Vascular (stroke) Multiple sclerosis Space-occupying lesion Vestibular schwannoma Meningioma Ramsay-Hunt syndrome Parotid tumour Sarcoidosis Lyme disease
NOTE: patients may complain of hyperacusis due to paralysis of stapedius and aguesia (loss of taste)
What causes Ramsay-Hunt syndrome?
Reactivation of VZV in the geniculate ganglion of CN7
List some causes of Horner’s syndrome.
Multiple sclerosis
Pancoast tumour
Trauma (central line, carotid endarterectomy)
Cavernous sinus thrombosis
What are the main features of oculomotor nerve palsy?
Ptosis (LPS)
Eye points down and out (unopposed superior oblique and lateral rectus)
Dilated pupils
May have ophthalmoplegia and diplopia
List some causes of third nerve palsy.
MEDICAL: mononeuritis (DM), MS, midbrain infarction, migraine
SURGICAL: raised ICP (transtentorial herniation), cavernous sinus thrombosis, posterior communicating artery aneurysm
What is a Holmes-Adie pupil?
Dilated pupil with no response to light and sluggish response to accommodation
Benign condition, more common in females
Also known as myotonic pupil and usually presents with sudden-onset blurred vision. Aetiology unknown.
What are Argyll-Robertson pupils?
Small, irregular pupils
Accommodation intact
Reaction to light is lost
Atrophied and depigmented iris
Causes include neurosyphilis and DM (lesion in pretectal lesion)
What is an RAPD (Marcus Gunn pupil)?
Minor constriction to direct light
Dilatation when moving light to abnormal light (due to defect in the afferent pathway)