Limb Weakness Flashcards
What other symptoms may limb weakness be confused with?
Ataxia (clumsy limbs)
Reduced sensation in limbs
Painful limbs
What are the two most important factors to consider when establishing the cause of limb weakness?
Time course
Location of lesion
List some cause of limb weakness based on their time course:
Sudden-onset (seconds to minutes)
Subacute onset (hours to days)
Chronic onset (weeks to months)
- Sudden-onset (seconds to minutes)
Vascular problem (e.g. stroke, TIA)
Trauma (e.g. disc herniation, subarachnoid haemorrhage) - Subacute onset (hours to days)
Progressive demyelination (e.g. MS, Guillain-Barre syndrome)
Slowly expanding haematoma (e.g. subdural haematoma) - Chronic onset (weeks to months)
Slow-growing tumour
Motor neurone disease
List some causes of sudden-onset limb weakness based on the location of the lesion.
- Brain Ischaemic stroke TIA Haemorrhagic stroke Hemiplegic migraine Todd’s paresis Hypoglycaemia - Spinal Cord Spinal disc prolapse Others: spinal cord transection/infarction - Nerve Root Spinal disc prolapse Vertebral fracture - Peripheral Nerve Acute limb ischaemia Traumatic nerve injury
List some causes of subacute onset limb weakness based on the location of the lesion.
- Brain Multiple sclerosis Haematoma Tumour - Spinal Cord Multiple sclerosis Tumour Transverse myelitis - Nerve Root Guillain-Barre syndrome Poliomyelitis - Neuromuscular Junction Botulism Tetanus
List some causes of gradual-onset limb weakness based on the location of the lesion.
- Brain Tumour Motor neurone disease - Spinal Cord Spinal canal stenosis B12 deficiency (subacute combined degeneration of the spinal cord) - Peripheral Nerve Diabetes mellitus Vasculitides - Neuromuscular Junction Myasthenia gravis Lambert-Eaton syndrome - Muscle Myositis
What’s Todd’s paresis?
Post-seizure paralysis
List some important features of the history that you should ask about.
Exact time of onset Speech or visual disturbance Headache Seizure or loss of consciousness Neck or back pain Trauma
Why is the exact time of onset of the symptoms important?
There is a 4.5 hour window (following the onset of symptoms) within which you have to thrombolyse patients with confirmed ischaemic stroke
Which causes of limb weakness are associated with causing headaches?
Hemiplegic migraine
Subarachnoid haemorrhage
Intracranial mass (e.g. subdural haemorrhage) causes a gradual-onset headache
List some causes of limb weakness that are associated with seizures and loss of consciousness.
Todd’s paresis
Hypoglycaemia
What would neck or back pain associated with limb weakness lead you to suspect?
Spinal pathology (e.g. disc prolapse, traumatic spinal injury) NOTE: Guillain-Barre syndrome can also cause some back pain
Why is it important to ask whether the patient has experienced any trauma to the head?
Head trauma can result in a slowly-expanding subdural haematoma, which causes symptoms days/weeks after the head injury
Which risk factors should you enquire about in a patient presenting with limb weakness?
Previous stroke/TIA
History of atrial fibrillation
Atherosclerotic risk factors (e.g. hypertension, hypercholesterolaemia)
List the pattern of symptoms/signs seen in:
Upper motor neurone lesions
Lower motor neurone lesions
- Upper motor neurone lesions Hypertonia Hyperreflexia Clonus Upgoing plantars - Lower motor neurone lesions Hypotonia Hyporeflexia Fasciculations Wasting
Describe the pattern or symptoms/signs in the acute phase of an upper motor neurone lesion.
Reduced tone and reduced reflexes
State two types of language defects and the area of the brain affected.
1) Receptive Dysphasia
Patient speaks fluently (words may be jumbled) but cannot comprehend language
Damage to Wernicke’s area
2) Expressive Dysphasia
Patient can comprehend language and follow instructions
Patient cannot find words and speak fluently
Damage to Broca’s area
A lesion in which part of the brain causes hemispatial neglect?
Posterior parietal cortex
Which part of the visual pathway is damaged in:
Complete blindness in one eye
Homonymous hemianopia
- Complete blindness in one eye Optic nerve Globe itself - Homonymous hemianopia Between the optic chiasm and the lateral geniculate nucleus
Eye deviation from the side of limb weakness can help identify the location of the lesion. What do the following eye deviations suggest:
Deviation away from the weak side
Deviation towards the weak side
- Deviation away from the weak side
Cortical lesion - Deviation towards the weak side
Brain-stem lesion
In a weak limb with lower motor neurone signs, the presence of sensory signs can help distinguish the location of the problem. Which part of the neurological pathway is affected if:
Sensory signs are PRESENT
Sensory signs are ABSENT
- Sensory signs are PRESENT Nerve root lesion Peripheral nerve lesion - Sensory signs are ABSENT Neuromuscular junction lesion Muscular lesion
Explain how the hemiparesis differs based on whether a stroke is caused by an occlusion of the anterior cerebral artery or the middle cerebral artery.
Anterior cerebral artery – affects legs > arms
Middle cerebral artery – affects arms > legs
Which cerebral artery supplies the posterior parietal cortex?
Middle cerebral artery
What is the first line investigation for stroke?
CT Head
How soon after the onset of symptoms must you use thrombolysis on a patient with a confirmed ischaemic stroke?
4.5 hours
List some blood tests that may be useful in a patient with limb weakness?
FBC – check for polycythaemia or thrombocytosis (increased risk of ischaemic stroke) or thrombocytopaenia (increased risk of haemorrhagic stroke)
Blood glucose – hypoglycaemia can cause limb weakness
Clotting times – check for coagulopathy
Why might you do an ECG in a patient with limb weakness?
Check for AF – this might be a source of emboli
What percentage of strokes are ischaemic?
85%
How are haemorrhagic strokes managed?
Supportive treatment
Outline the management of ischaemic strokes following thrombolysis.
Antiplatelet drugs
Transfer to stroke unit
VTE prophylaxis
List two second-line investigations for ischaemic stroke.
Carotid Doppler Ultrasonography – check for carotid atherosclerosis
Echocardiogram – check for source of emboli
List some complications of stroke.
Pressure ulcers
Aspiration pneumonia
VTE
What are the components of a disability screen?
GCS Swallow assessment Speech and language Visual fields Gait
Patients who have suffered ischaemic strokes will be given three lifelong medications to take daily. What are they?
Antiplatelets (e.g. clopidogrel)
Statins
ACE inhibitor/thiazide diuretic
Which drug are all TIA patients started on?
Aspirin 300 mg daily
TIA patients will be referred to a specialist TIA clinic. Which scoring system is used to determine the urgency with which patients should be seen?
ABCD2 Score
Explain the difference between antiplatelets and anticoagulants.
- Anticoagulants are better for clots that form in conditions of stasis (e.g. AF, DVT). These clots are rich in fibrin and red blood cells so using anticoagulants (which impair fibrin generation) is the most effective option.
- Antiplatelets are better for clots that form because of endothelial activation of platelets (e.g. atherosclerotic plaque rupture). These clots are rich in platelets so using antiplatelets (which impair platelet function) is the most effective option.
The benefit of using anticoagulants to prevent strokes must be balanced with the increased risk of bleeding. Which two scoring systems are used to help make this decision?
CHADS-Vasc score – calculates the stroke risk in patients with AF
HAS-BLED score – calculates the risk of bleeding in anticoagulated AF patients
List some causes of cord compression.
Disc herniation
Spondylolisthesis
Space-occupying lesion (e.g. tumour)
Which investigation is used to investigate cord compression?
MRI spine
What is multiple sclerosis characterised by?
Central nervous lesions disseminated in time and space
Name two features that are strongly associated with multiple sclerosis.
Internuclear ophthalmoplegia – slow adduction of one eye when shifting gaze accompanied by leading eye nystagmus due to a lesion of the MLF
Optic neuritis – painful eye with blurred vision
List two specific signs of multiple sclerosis.
Lhermitte’s sign – shooting pain down the spine when the neck is flexed
Uhthoff’s sign – worsening of neurological symptoms when the body is overheated (e.g. after a hot shower)
List two investigations that would be useful in a patient with multiple sclerosis.
Lumbar puncture – perform electrophoresis to look for oligoclonal bands
MRI of brain and spinal cord – look for sclerotic plaques
Describe a clinical sign that is seen in Ulnar nerve palsy.
Froment’s Sign – ask the patient to pinch on a piece of paper in between their index finger and thumb. If you try and pull the piece of paper away, the patient will flex the interphalangeal joint of their thumb in order to maintain grip on the paper.
What is Brown-Sequard syndrome?
Hemisection of the spinal cord
List some causes of Brown-Sequard syndrome.
Intrinsic cord lesions (e.g. MS)
Penetrating trauma to the spinal cord or spinal fractures
Describe the arrangement of neurones in each half of the spinal cord.
Upper motor neurones of the corticospinal tract to the ipsilateral side
Sensory neurones of the dorsal columns to the ipsilateral side
Pain/temperature neurones of the spinothalamic tract to the contralateral side
What does ‘paraparesis’ mean?
Weakness of the lower limbs
