25. Limb Weakness Flashcards by E E

What other symptoms may limb weakness be confused with?

Ataxia (clumsy limbs)
Reduced sensation in limbs
Painful limbs

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What are the two most important factors to consider when establishing the cause of limb weakness?

Time course

Location of lesion

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List some cause of limb weakness based on their time course:
a) Sudden-onset (seconds to minutes)

Vascular problem (e.g. stroke, TIA)
Trauma (e.g. disc herniation, subarachnoid haemorrhage)

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List some cause of limb weakness based on their time course:
b) Subacute onset (hours to days)

Progressive demyelination (e.g. MS, Guillain-Barre syndrome)
Slowly expanding haematoma (e.g. subdural haematoma)

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List some cause of limb weakness based on their time course:
c) Chronic onset (weeks to months)

Slow-growing tumour

Motor neurone disease

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List some causes of sudden-onset limb weakness based on the location of the lesion.
i) Brain

Ischaemic stroke 
TIA 
Haemorrhagic stroke 
Hemiplegic migraine 
Todd’s paresis 
Hypoglycaemia

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List some causes of sudden-onset limb weakness based on the location of the lesion.
ii) Spinal Cord

Spinal disc prolapse

Others: spinal cord transection/infarction

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List some causes of sudden-onset limb weakness based on the location of the lesion.
iii) Nerve Root

Spinal disc prolapse

Vertebral fracture

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List some causes of sudden-onset limb weakness based on the location of the lesion.
iv) Peripheral Nerve

Acute limb ischaemia

Traumatic nerve injury

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List some causes of subacute onset limb weakness based on the location of the lesion.
i) Brain

Multiple sclerosis
Haematoma
Tumour

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List some causes of subacute onset limb weakness based on the location of the lesion.
ii) Spinal Cord

Multiple sclerosis
Tumour
Transverse myelitis

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List some causes of subacute onset limb weakness based on the location of the lesion.
iii) Nerve Root

Guillain-Barre syndrome

Poliomyelitis

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List some causes of subacute onset limb weakness based on the location of the lesion.
iv) NMJ

Botulism

Tetanus

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List some causes of gradual-onset limb weakness based on the location of the lesion.
i) Brain

Tumour

Motor neurone disease

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List some causes of gradual-onset limb weakness based on the location of the lesion.
ii) Spinal Cord

Spinal canal stenosis 
B12 deficiency (subacute combined degeneration of the spinal cord)

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List some causes of gradual-onset limb weakness based on the location of the lesion.
iii) Peripheral Nerve

Diabetes mellitus

Vasculitides

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List some causes of gradual-onset limb weakness based on the location of the lesion.
iv) Neuromuscular Junction

Myasthenia gravis

Lambert-Eaton syndrome

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List some causes of gradual-onset limb weakness based on the location of the lesion.
v) Muscle

Myositis

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What’s Todd’s paresis?

Post-seizure paralysis

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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

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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

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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

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List some causes of limb weakness that are associated with seizures and loss of consciousness.

Todd’s paresis

Hypoglycaemia

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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

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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

Hypertonia Hyperreflexia Clonus Upgoing plantars

List the pattern of symptoms/signs seen in lower motor neurone

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/describe two types of language defects and the area of the brain affected.

Receptive Dysphasia Patient speaks fluently (words may be jumbled) but cannot comprehend language Damage to Wernicke’s area 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

Optic nerve | Globe itself

Which part of the visual pathway is damaged in 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 does eye deviation away from the weak side suggest

Cortical lesion

Eye deviation from the side of limb weakness can help identify the location of the lesion. What does eye deviation towards the weak side suggest

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

Nerve root lesion | Peripheral nerve lesion

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?

80%

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

25. Limb Weakness Flashcards

(65 cards)