26. Limb Weakness

Question 1

How does the time course help you narrow down differentials for limb weakness?

Answer 1

Sudden: trauma, fractures, vascular insults
Subacute: Demyelination (GBS, MS) slowly expanding haematoma
Chronic: MND, slow growing tumour

Question 2

What should you ask of someone who has presented with limb weakness?

Answer 2

Exact time of onset? thrombolysis window 4.5 hrs
Speech / vision disturbances? problem more likely to be in brain
Headache? SAH, hemiplegic migraine, SOL
Recent trauma? SAH
Seizures/ LOC? Stroke mimics e.g. Todd’s paresis (post-seizure)
Neck or back pain? disc prolapse/ GBS
RF for stroke? hx of stroke, AF, smoking, FH, HTN, DM, dyslipidaemia

Question 3

What signs would you see in a UMN lesion?

Answer 3

Increased tone
Hyper-reflexia
Upgoing plantars
Sometimes clonus

Question 4

What language defects should you look out for with limb weakness?

Answer 4

Receptive dysphasia: Wernicke’s (temporal), speaks fluently but can’t comprehend language
Expressive dysphasia: Broca’s (frontal), comprehends language but can’t speak fluently

Question 5

What would you suspect if a patient is responding to cues on one side?

Answer 5

Lesion in parietal cortex

Question 6

What eye signs should you look out for in someone with limb weakness?

Answer 6

Complete blindness in 1 eye: optic nerve lesion
Homonymous hemianopia: lesion between optic chiasm + visual cortex on contralateral side
Deviation: if deviates to weak side= brain stem lesion. If deviates away from weakness= cortical lesion

Question 7

Difference between ACA and MCA infarct?

Answer 7

ACA: weakness in the lower limb more than upper
MCA: weakness in upper limb more than lower

Question 8

What are first line investigations for a stroke? Why?

Answer 8

CT head: exclude haemorrhagic stroke
FBC: reveal cause of arterial occlusion (polycythaemia/ thrombocytosis) or haemorrhage (thrombocytopenia)
Blood glucose: exclude hypoglycaemia
Blood clotting: if on warfarin + exclude haemophilia
ECG: for AF

Question 9

How do you manage stroke acutely?

Answer 9

Antiplatelets e.g. aspirin
Admit to stroke unit
VTE prophylaxis e.g. LMWH

Question 10

What second line investigations will a patient with a stroke need?

Answer 10

Carotid doppler: exclude carotid artery atheromas

Echo: identify cardiac source of emboli like atrial thrombus or patent foramen ovale

Question 11

What are some medical complications of stroke and how can you reduce them?

Answer 11

Pressure ulcers: regular movement
Aspiration pneumonia: Swallowing assessment + NG tube if needed.
VTE: LMWH

Question 12

How do you assess disability in stroke patients?

Answer 12

GCS
Swallow
Speech + language
Visual fields
Gait

Question 13

What is seen in LMN lesions?

Answer 13

Decreased tone
Hyporeflexia
Fasciculations
Wasting

Question 14

Give 2 time frames and 2 causes of limb weakness when the pathology is in the brain

Answer 14

Sudden: Ischaemic stroke, TIA
Subacute: MS, Haematoma

Question 15

Give 3 time frames and causes of limb weakness when the pathology is in the spinal cord

Answer 15

Sudden: Spinal disc prolapse
Subacute: MS
Gradual: Spinal canal stenosis

Question 16

Give 2 time frames and causes of limb weakness when the pathology is in the nerve roots

Answer 16

Sudden: Spinal disc prolapse
Subacute: GBS

Question 17

Give 2 time frames and causes of limb weakness when the pathology is in the peripheral nerve/ nerve plexus

Answer 17

Sudden: Acute limb ischaemia
Gradual: Diabetes

Question 18

Give 2 time frames and causes of limb weakness when the pathology is in the neuromuscular junction

Answer 18

Subacute: Botulism
Gradual: Myasthenia gravis

Question 19

Give a time frame and cause of limb weakness when the pathology is in the muscle

Answer 19

Gradual: Myositis

Question 20

What signs would you see in a LMN lesion?

Answer 20

Hypotonia
Hyporeflexia
Fasciculations sometimes
Wasting

Question 21

Which columns are spared in an anterior spinal artery infarct? Which sensory modalities are therefore preserved?

Answer 21

Dorsal columns

Light touch, vibration, proprioception

Question 22

How do UMN facial weakness and LMN facial palsy differ?

Answer 22

UMN has sparing of forehead wrinkling + blink

Question 23

Describe locations where and characteristics of clots can form due to blood stasis. What drugs are used for preventing these? What adverse outcomes do they prevent?

Answer 23

Deep veins/ fibrillating atria
Rich in fibrin + erythrocytes
Drugs that inhibit fibrin mesh formation (anticoagulants) e.g. Warfarin, RIvaroxaban
Venous thromboembolism + atrial clots

Question 24

Give an example of where clots can form due endothelial activation of platelets, what allows this? What drugs are used for preventing these? What adverse outcomes do they prevent?

Answer 24

E.g. upon atherosclerotic plaque rupture
Rich in platelets
Drugs that inhibit platelet activation (antiplatlets) e.g. Aspirin, Clopidogrel
MI’s + primary ischaemic strokes

Question 25

Distinguish between the suffixes -paresis and -plegia. What does the prefix para- mean?

Answer 25

-paresis: weakness (can still move)
-plegia: complete paralysis
Para-: Lower limbs