26. Limb Weakness Flashcards
How does the time course help you narrow down differentials for limb weakness?
Sudden: trauma, fractures, vascular insults
Subacute: Demyelination (GBS, MS) slowly expanding haematoma
Chronic: MND, slow growing tumour
What should you ask of someone who has presented with limb weakness?
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
What signs would you see in a UMN lesion?
Increased tone
Hyper-reflexia
Upgoing plantars
Sometimes clonus
What language defects should you look out for with limb weakness?
Receptive dysphasia: Wernicke’s (temporal), speaks fluently but can’t comprehend language
Expressive dysphasia: Broca’s (frontal), comprehends language but can’t speak fluently
What would you suspect if a patient is responding to cues on one side?
Lesion in parietal cortex
What eye signs should you look out for in someone with limb weakness?
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
Difference between ACA and MCA infarct?
ACA: weakness in the lower limb more than upper
MCA: weakness in upper limb more than lower
What are first line investigations for a stroke? Why?
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
How do you manage stroke acutely?
Antiplatelets e.g. aspirin
Admit to stroke unit
VTE prophylaxis e.g. LMWH
What second line investigations will a patient with a stroke need?
Carotid doppler: exclude carotid artery atheromas
Echo: identify cardiac source of emboli like atrial thrombus or patent foramen ovale
What are some medical complications of stroke and how can you reduce them?
Pressure ulcers: regular movement
Aspiration pneumonia: Swallowing assessment + NG tube if needed.
VTE: LMWH
How do you assess disability in stroke patients?
GCS Swallow Speech + language Visual fields Gait
What is seen in LMN lesions?
Decreased tone
Hyporeflexia
Fasciculations
Wasting
Give 2 time frames and 2 causes of limb weakness when the pathology is in the brain
Sudden: Ischaemic stroke, TIA
Subacute: MS, Haematoma
Give 3 time frames and causes of limb weakness when the pathology is in the spinal cord
Sudden: Spinal disc prolapse
Subacute: MS
Gradual: Spinal canal stenosis
Give 2 time frames and causes of limb weakness when the pathology is in the nerve roots
Sudden: Spinal disc prolapse
Subacute: GBS
Give 2 time frames and causes of limb weakness when the pathology is in the peripheral nerve/ nerve plexus
Sudden: Acute limb ischaemia
Gradual: Diabetes
Give 2 time frames and causes of limb weakness when the pathology is in the neuromuscular junction
Subacute: Botulism
Gradual: Myasthenia gravis
Give a time frame and cause of limb weakness when the pathology is in the muscle
Gradual: Myositis
What signs would you see in a LMN lesion?
Hypotonia
Hyporeflexia
Fasciculations sometimes
Wasting
Which columns are spared in an anterior spinal artery infarct? Which sensory modalities are therefore preserved?
Dorsal columns
Light touch, vibration, proprioception
How do UMN facial weakness and LMN facial palsy differ?
UMN has sparing of forehead wrinkling + blink
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?
Deep veins/ fibrillating atria
Rich in fibrin + erythrocytes
Drugs that inhibit fibrin mesh formation (anticoagulants) e.g. Warfarin, RIvaroxaban
Venous thromboembolism + atrial clots
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?
E.g. upon atherosclerotic plaque rupture
Rich in platelets
Drugs that inhibit platelet activation (antiplatlets) e.g. Aspirin, Clopidogrel
MI’s + primary ischaemic strokes
Distinguish between the suffixes -paresis and -plegia. What does the prefix para- mean?
-paresis: weakness (can still move)
-plegia: complete paralysis
Para-: Lower limbs
