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Y3 Oxford Cases > Limb Weakness > Flashcards

Limb Weakness Flashcards

1
Q

What does time course tell you about the possible cause of limb weakness

A

Sudden (within minutes): trauma (displaced vertebral fractures due to major trauma) or vascular insults (stroke, TIA)

Subacute (hours-days): progressive demyelination (GBS, MS) or slowly expanding haematoma (subdural)

Chronic (weeks to months): slow growing tumour or MND

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2
Q

What is the neuronal pathway for muscles

A 
Cerebral cortex
Corona radiata
Internal capsule
Pons 
Corticospinal tract + spinal cord
Nerve root
Peripheral nerve
NMJ 
Muscle
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3
Q

What are the differentials for sudden onset limb weakness

A 
Ischaemic Stroke
Transient ischaemic attack (TIA)
Haemorrhagic stroke
Hemiplegic migraine, Todd's palsy, hypoglycaemia
Spinal disc prolapse
Spinal cord transection or infarction
Vertebral fracture
Acute limb ischaemia
Traumatic nerve injury
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4
Q

What are the differentials for subacute onset limb weakness

A 
Multiple Sclerosis
Haematoma (subdural, extradural)
Tumour
Abscess
Guillain-Barré syndrome 
Transverse myelitis 
Poliomyelitis
Botulism
Tetanus
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5
Q

What are the differentials for chronic onset limb weakness

A 
Spinal canal stenosis 
Vitamin B12 deficiency 
Diabetes mellitus
Vasculitis
Myasthenia gravis
Lamber-Eaton syndrome
Myositis
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6
Q

What questions should be asked about limb weakness on presentation

A

Exact time of onset (stroke management)
Any speech disturbance or visual disturbance (suggests brain rather than peripheral pathology)
Headache? (SAH, hemiplegic migraine, intracranial mass)
Seizure or LOC? (Todd’s paresis)
Neck or back pain? (disc prolapse, traumatic injury to spine, discitis, spinal abscess)
Trauma? (slow expanding subdural haematoma)
Risk factors for stroke? (HTN, DM, hypercholesterol, FMHx, smoking)

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7
Q

What are the signs of UMN and LMN lesions

A 
UMN:
Hypertonia
Hyperreflexia
Upgoing plantars (Babinski's)
Clonus
LMN:
Hypotonia
Hyporeflexia
Fasciculations
Wasting and muscle atrophy
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8
Q

What do language defects in the presence of the limb weakness suggest about pathology

A

Pathology in the cortex of the dominant hemisphere (usually left)

Receptive dysphasia: patient speaks fluently but cannot comprehend language. Lesion in Wernicke’s area in the temporal lobe

Expressive dysphasia: patient can comprehend and follow instructions but cannot find words or speak fluently. Lesion in the Broca’s area in the frontal lobe

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9
Q

What do attention defects in the presence of limb weakness suggest

A

Parietal cortex lesion

Patient ignores half of the sensory world i.e. responding to cues only one side

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10
Q

What do eye signs in the presence of limb weakness suggest

A

Complete blindness: optic nerve (e.g. optic neuritis) or the globe

Homonymous hemianopia: lesion between the optic chiasm and visual cortex on the contralateral side

Eye deviation: eyes deviating away from the weak side - cortical lesion. Towards the weak side - brainstem lesion

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11
Q

What investigations should be ordered for suspected stroke

A

Urgent CT head (non-contrast)

FBC: may reveal cause for arterial occlusion (polycythaemia, thrombocytosis) or haemorrhage (thrombocytopenia)
Glucose: exclude hypoglycaemia
Clotting studies: exclude haemophilia or coagulopathy

ECG: look for AF (May cause emboli)

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12
Q

What is the acute management for ischaemic stroke

A

Antiplatelets (typically aspirin) as soon as haemorrhagic stroke has been excluded, but delayed 24h if the patient receives thrombolysis

VTE prophylaxis using LMWH or pneumatic compression devices to the calves

Transfer to stroke unit/specialist ward for specialist nursers, SALT, physiotherapists and social workers

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13
Q

What second line investigations should be done to patients after transfer to the stroke unit

A

Carotid doppler ultransonography: USS of the carotid arteries will identify or exclude carotid artery atheromas that may be the cause of emboli causing the stroke
Echo cardiogram: identify a cardiac source of emboli e.g. atrial thrombus from AF, recent MI, heart murmur | patents foramen ovale

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14
Q

What complications of stroke should you be worried about and what can you do to minimise the likelihood of them occurring

A

Pressure ulcers -> regularly move the patient or placing on an inflatable mattress that periodically varies the area of pressure

Aspiration pneumonia -> SALT carries out a swallowing assessment, consider a NG tube

VTE and recurrent ischaemic stroke: LMWH and pneumatic compression devices to the calves

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15
Q

What forms the disability screen for patients with suspected stroke

A 
GCS (uses the best side)
Swallow
Speech and language
Visual fields 
Gait
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16
Q

What does a carotid bruit suggest and how is the cause treated

A

Carotid artery stenosis due to atherosclerotic disease
Causes an embolus -> stroke

Have a duplex USS of the carotid arteries

Stenosis >70% - carotid endarterectomy

17
Q

What is the follow up management for patients who have had an ischaemic stroke

A

Stop smoking

Daily antiplatelets (clopidogrel)
Statins, even if cholesterol levels are normal
Daily ACEi and/or thiazide diuretic

GP should follow up on any risk factors

18
Q

What is the management for TIA

A

Establish the source of emboli and treat it
300mg daily aspirin
Referral to a specialist TIA clinic (urgency depends on ABCD2 score, which predicts risk of stroke in the 48h after a TIA)

19
Q

What screening is done at a TIA clinic

A

Smoking
Hypertension
Hyperlipidaemia: fasting lipid profile
Diabetes mellitus: random plasma glucose, fasting glucose, HbA1c
Carotid artery stenosis: Doppler i;trasound of the carotid arteries
Atrial fibrillation: ECG

20
Q

62M who has recent onset of leg weakness. Noticed the legs becoming weak a fortnight ago and he was unable to get out his chair. It progressed so that he had to use a walking frame and for the past 2 days he has not been able to walk.
Exam - increased tone and clonus
Reduced power (2/5 bilaterally on hip and knee flexion)
Brisk patellar and ankle reflexes
Upgoing plantars
Loss of vibration sensation before the hips and pinprick below the umbilicus
Anal sphincter tone and perianal sensation are normal and all other systems including upper limbs are normal

What is the diagnosis and what investigation should be ordered

A

UMN lesion + loss of sensation below the umbilicus (T10 dermatome)

Most likely cord compression (disc herniation, spondylolisthesis, SOL e.g. tumour, abscess, cyst, haematoma)

Order a spinal MRI

21
Q

What investigations should be ordered for Multiple Sclerosis

A

Lumbar puncture: Elevated IgG antibodies in the CSF - oligoclonal bands that is unmatched with the serum

MRI brain and spinal cord: looking for plaques

Visually evoke potentials: Delayed response to visual stimulation indicates slow electrical conduction and a lesion along the optic pathway

22
Q

What are the contraindications to thrombolysis for stroke

A

Onset cannot be confirmed as within 4.5 hours
Acute intracranial haemorrhage on CT
Seizure at onset of stroke
Symptoms suggest SAH
Stroke or serious head injury in the preceding 3 months
Major surgery or serious trauma within 2 week s
Previous intracranial haemorrhage
Intracranial neoplasm
Arteriovenous malformation or aneurysm
etc.

23
Q

What scale is used to grade limb weakness

A

MRC scale for power

0/5: No movement
1/5: flicker is perceptible in the muscle
2/5: Movement only if gravity is eliminated
3/5: can move the limb against gravity
4/5: Can move the limb against gravity and some resistance exerted by the examiner
5/5: normal power

24
Q

Where is the neurological lesion likely to be for hemiparesis

A

Weakness on one half of the body

Contralateral cerebral motor cortex (widespread stroke)
Contralateral corona radiata, internal cortex, pons e.g. stroke

25
Q

Where is the neurological lesion likely to be for limb hemiparesis

A

Weakness unilaterally in the limbs

Contralateral cerebral motor cortex e.g. stroke
Contralateral corona radiata, internal cortex, pons e.g. stroke
Ipsilateral spinal lateral motor tract e.g. cervical disc prolapse

26
Q

Where is the neurological lesion likely to be for isolated limb weakness

A

Contralateral cerebral motor cortex e.g. localised stroke
Contralateral corona radiata, internal cortex, pons e.g. stroke
Ipsilateral peripheral nerve root e.g. osteophyte
Ipsilateral peripheral nerve plexus e.g. trauma to brachial plexus
Ipsilateral peripheral nerve per se e.g. angiogram sheath injury

27
Q

Where is the neurological lesion likely to be for paraparesis

A

Weakness of the lower limbs

Bilateral cerebral motor cortex e.g. parasagittal meningioma
Bilateral motor spinal tracts e.g. cord compression
Cauda equina e.g. lumbar intervertebral disc prolapse
Bilateral lumbosacral plexus e.g. GBS

28
Q

Where is the neurological lesion likely to be for tetraplegia

A

Bilateral motor tracts of the cervical spinal cord

Peripheral nerves e.g. demyelinating disease, GBS

29
Q

Where is the neurological lesion likely to be for proximal muscle weakness

A

NMJ e.g. myasthenia gravis, Eaton-Lambert syndrome

Muscle e.g. polymyositis, dermatomyositis or secondary to hyperparathyroidism or drugs e.g. statins

30
Q

How can you differentiate between epilepsy and migraine

A

Both are associated with positive symptoms - tingling shaking, disturbances of vision

Migraine auras usually evolve over 20-30mins whereas epileptic seizures usually have onset over seconds

Y3 Oxford Cases (29 decks)

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