Acute Weakness Flashcards

1
Q

What are the signs of neuromuscular respiratory failure?

A

Often patient does not show obvious signs of respiratory distress…

  • Orthopnoea - paralytic diaphragm means abdominal contents put pressure on thorax
  • Paradoxical breathing (chest moves in during inspiration and out in expiration)
  • Tachycardia
  • Weak cough
  • Rapid shallow breathing
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2
Q

Different patterns of weakness help to identify the level of the lesion, what does a monoplegia or hemiplegia indicate?

A

UMN lesion in the internal capsule or motor cortex.

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3
Q

Different patterns of weakness help to identify the level of the lesion, what does a diparesis and quadraparesis indicate?

A

Lesion in the spinal cord itself

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4
Q

Different patterns of weakness help to identify the level of the lesion, what does fatiguability indicate?

A

Lesion is at the level of NMJ e.g MG

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5
Q

Different patterns of weakness help to identify the level of the lesion, what does distal limb weakness indicate?

A

Lesion at the level of peripheral nerves

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6
Q

Different patterns of weakness help to identify the level of the lesion, what does proximal weakness indicate?

A

Lesion at the level of the muscle i.e. myopathy

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7
Q

What is the MRC scale for weakness?

A
0 = no contraction 
1 = flicker of muscle contraction 
2 = active movement without gravity 
3 = active movement against gravity 
4 = active movement against resistance and gravity 
5 = normal contraction
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8
Q

Why is FVC measurement important in those with neuromuscular failure?

A
  • FVC <15ml/kg is an indication to ventilate the patient

- Consider the need for additional respiratory support at FVC <30ml/kg

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9
Q

Vascular causes of weakness…

A
  • Cerebral: stroke, TIA, SAH

- Spinal: stroke

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10
Q

Trauma causes of weaknesses…

A
  • Cerebral: Haemorrhage, focal/ diffuse lesion
  • Spinal: acute cord compression, cord transection
  • Peripheral: compartment syndrome, penetrating injury
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11
Q

Infective causes of weakness…

A
  • Cerebral: encephalitis, meningitis, abscess
  • Spinal: abscess
  • Peripheral: Lyme disease, HIV, Polio
  • NMJ: Botulinum toxin
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12
Q

Autoimmune causes of weakness…

A
  • Cerebral: MS
  • Spinal: MS
  • Peripheral: MS, GBS, sarcoid , vasculitis
  • NMJ: Myasthenia gravis
  • Muscle: myositis, dermatomyositis
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13
Q

Metabolic causes of weakness…

A
  • Cerebral: encephalopathy (hepatic, Wernicke’s)
  • Peripheral: Diabetes, renal failure, hypothyroid, B12/B1 deficiency, drugs, toxins
  • Muscle: Hypothyroid, Cushing’s, rhabdomyolysis, drugs
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14
Q

Neoplastic causes of weakness…

A
  • Cerebral: space occupying lesion
  • Spine: malignant spinal cord compression
  • Peripheral: Paraneoplasia
  • NMJ: Lambert-Eaton syndrome (autoimmune disorder characterised by muscle weakness of the limbs)
  • Muscle: Paraneoplasia
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15
Q

What are the main different types of stroke?

A
  1. Ischaemic stroke - broken down further according to Bamford Classification
  2. Haemorrhagic stroke - broken down into intracerebral and subarachnoid
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16
Q

What are the main causes of an ischaemic stroke?

A

Mainly caused by events that either precipitate artherosclerosis or lead to emboli formation:
Artherosclerosis: hypertension, high cholesterol, diabetes, smoking
Emboli formation: AF, DVT, carotid artery disease
*Most risk factors are common with cardiovascular risk factors

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17
Q

Bamford Classification of Strokes…

A
  • Total anterior circulation strokes (TACS)
  • Partial anterior circulation stroke (PACS)
  • Lacunar stroke (LACS)
  • Posterior circulation stroke (POCS)
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18
Q

How does TACS present?

A
  1. Hemiparesis +/- hemisensory loss
  2. Homonymous hemianopia
  3. Cortical dysfunction e.g. dysphasia, dysarthria
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19
Q

How does PACS present?

A
2/3 of: 
- Hemiparesis 
- Hemisensory loss
- Homonymous hemianopia 
OR 
- Cortical dysfunction
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20
Q

How does LACS present?

A
  1. Pure motor, sensory or sensorimotor
  2. Ataxic hemiparesis
    NO CORTICAL DYSFUNCTION
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21
Q

How does POCS present

A
  1. Cerebellar or brainstem syndrome: dizziness, diplopia, ataxia, dysarthria (CN involvement)
  2. Loss of consciousness
  3. Isolated homonymous hemianopia
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22
Q

How will a haemorrhagic stroke present

A

Usually presents with more global symptoms e.g.

  • Drowsiness
  • Headache
  • Altered mental status
  • Nausea and vomiting
  • Seizures
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23
Q

What is the ROSIER score?

A

Recognition Of Stroke In the Emergency Room :
Used to identify actual stroke from stroke mimics
Score >0 = stroke likely
Score =/<0 = stroke unlikely - but cannot be ruled out

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24
Q

What is the NIHSS score?

A

NIH stroke scale (NIHSS) score = used to assess the severity of a stroke, has been found to correlate with clinical outcome when used within 48 hrs of presentation.
Grades: consciousness, orientation, gaze, visual fields, facial weakness, ataxia, sensation, dysarthria
Score < 4=favourable clinical outcome

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25
Q

What may a neurological exam reveal for a stroke patient?

A
  • Limbs: initially flaccid then later spastic, weakness, absent reflexes
  • Cranial nerve examination: facial paralysis, visual field defect (hemianopia)
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26
Q

What are the indications for urgent CT head in stroke patients?

A
  1. Likely candidate for thrombolysis
  2. On anticoagulation medication
  3. GCS <13
  4. Progressive symptoms
  5. Features of meningism
  6. Severe headache
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27
Q

Management of ischaemic stroke…

A
  1. Maintenance of homeostasis: SpO2 <95% ,blood sugar - normal levels, BP > 185/110
  2. Rule out haemorrhagic stroke with imaging (CT/ MRI)
  3. Presents < 4.5 hrs - thrombolysis with IV alteplase - 10% bolus, then 90% over 1hr infusion. This is followed by aspirin 24-48 hrs after
  4. Presents > 4.5 hrs - give 300mg aspirin - then continue for 2 weeks- switched to 75mg clopidogrel daily lifelong
  5. Physio and nutritional involvement: swallow assessment and nutrition screen using MUST tool
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28
Q

What are the contraindications for thrombolysis?

A
  • Seizure
  • Intracerebral/ subarachnoid haemorrhage
  • INR > 1.7
  • Uncontrolled hypertension
  • GCS <8
  • Abnormal BM
  • Head injury
  • Rapidly improving signs
29
Q

Management of haemorrhagic stroke…

A
  1. CT/MRI shows bleeding in the brain
  2. Small bleeds = no requirement for neurosurgical involvement
    Coagulation defects should be fixed - vitamin K or prothrombin complex
    Large bleeds = neurosurgical involvement for drainage
30
Q

Prevention of stroke…

A

Primary prevention:
- Modifiable risk factors: smoking, alcohol, obesity, diet
- Modifiable with drugs: hypertension, diabetes, hyperlipidaemia
Secondary prevention:
- Antiplatelet therapy: 1st line= clopidogrel
- BP control = ACEi and diuretic
- Statins for all patients
- Anticoagulation for AF
- Carotid endarterectomy (stenosis >70%)

31
Q

What is a TIA?

A

Focal neurological deficit that resolves within 24 hours

32
Q

Typical presentation of TIA…

A
  • Unilateral weakness/ sensory loss
  • Expressive dysphasia
  • Amaurosis fugax (sudden transient loss of vision in one eye)
  • Homonymous hemianopia
33
Q

What is the ABCD2 score?

A

Used to risk stratify stroke in TIA patients:

  • Age >60 =1
  • BP > 140/90 =1
  • Unilateral weakness =1 (+ speech disturbance =2)
  • Duration 15-60 mins =1 (>60 mins=2)
  • Diabetes = 1
34
Q

Management of TIA

A
  • Any pt with suspected TIA should have 300mg aspirin and be referred to TIA clinic
  • ABCD2 score < 4 : seen in clinic within 7 days
  • ABCD2 score =/>4: seen in clinic within 24 hrs
35
Q

What malignancies most commonly metastasise to bone?

A
  • Breast
  • Prostate
  • Lung
  • Myeloma
  • Lymphoma
36
Q

What is the commonest region of the spinal cord affected by MSCC?

A
  • Thoracic cord
37
Q

Signs and symptoms of complete cord compression…

A
  • Loss of all sensation below level
  • Bilateral UMN weakness below level
  • Bladder and bowel dysfunction
38
Q

Signs and symptoms of anterior compression…

A
  • Loss of pain and temp below level
  • UMN weakness below level
  • Bladder and bowel dysfunction
39
Q

Signs and symptoms of posterior compression…

A
  • Loss of vibration and proprioception

- Sparing of pain and temperature

40
Q

Signs and symptoms of lateral compression…

A
  • Contralateral pain and temp sensation loss
  • Ipsilateral loss of vibration and position
  • Ipsilateral UMN weakness.
41
Q

Signs and symptoms of cauda equina…

A
  • Back pain
  • Saddle anaesthesia
  • Urinary retention
  • Loss of anal sphincter tone
42
Q

Management of MSCC…

A
  • Urgent MRI within 24 hrs
  • 16-20mg dexamethasone PO (with PPI)
  • Urgent referral to oncology MDT
  • Radiotherapy to be given with 24h of MRI diagnosis
  • Surgical decompression can be used with radiotherapy depending on the diagnosis.
43
Q

What is the pathophysiology of MG?

A

Autoimmune disease where there are antibodies against nicotinic ACh receptors

44
Q

What are the characteristic features of MG?

A

Muscle weakness with fatiguability, improving at rest

45
Q

Clinical presentation of MG…

A
  • Clinical presentation will range from mild weakness of limited muscle groups to severe weakness of multiple muscle groups
  • Painless muscle fatigue e.g. voice becoming quieter the more it is used
  • Muscles affected include finger flexors, bulbar weakness leading to dysphagia, facial muscle weakness
  • Ptosis
  • Diplopia
46
Q

What are the main examination findings for MG?

A

Unlikely to find many positive findings unless movements are repeated which will lead to fatigue

47
Q

What is the most common pattern of disease in MG?

A
  • Ocular symptoms to generalised weakness within one year

- Takes around 40 years to progress to maximal weakness

48
Q

What is the common method of fatality in MG?

A
  • Neuromuscular respiratory failure which progresses eventually to acute respiratory failure
  • Important to monitor tidal volume, vital capacity and blood gasses
49
Q

What investigations can be carried out for diagnosing MG?

A
  • First line= ice test, where ice is applied over eyelids for 3 mins showing improvement of ptosis
  • Serology - nAChR and MuSK antibodies
  • Neurophysiology - single fibre EMG and repetitive nerve stimulation
  • Tensilion test - IV edrophonium used to provide improvement in muscle strength
  • CT thorax to rule out thymoma
50
Q

What are the risks of the tensilion test, what is an alternative?

A

Edrophonium carries the risk of causing bradycardia.

Pyridostigmine can be used instead.

51
Q

Management of MG…

A
  • 1st line = long acting Ach inhibitors e.g. pyridostigmine
  • 2nd line = steroids e.g. prednisolone (tapered off)
  • Immunosuppressants alongside steroids - azathioprine, methotrexate
  • Thymectomy can be used in resistant disease where medical management has not worked (even in absence of thymoma)
52
Q

What is a myasthenic crisis?

A
  • Acute muscle weakness leading to respiratory failure which requires intubation
53
Q

What is the management of a myasthenic crisis?

A
  • Intubation and ventilatory support will be required early on
  • Plasma exchange (50ml/kg for 10 days) and IV Ig (2g/kg for 5 days) with corticosteroids
54
Q

What are the characteristic features of GBS?

A
  • Acute, ascending, progressive polyneuropathy
  • Causes weakness, parasthesia, diminished reflexes
  • Usually infective prodrome affecting Resp/ GI tract 1-3 weeks before presentation
55
Q

What are the common causative organisms of GBS?

A
  • C jejuni
  • EBV
  • CMV
  • Mycoplasma
56
Q

Clinical features of GBS…

A
  • Weakness starting in lower extremities with sensory deficit
  • Other sx = neuropathic pain, autonomic sx, paraesthesia
  • Signs on examination = hypotonia, altered sensation, reduced reflexes
  • Max severity within 2 weeks
57
Q

Investigations for GBS…

A
  • Normally a clinical diagnosis - some tests can be helpful:
  • Nerve conduction tests = definitive diagnosis as it shows slowing of conduction
  • LP = elevated CSF protein
  • Urinalysis, CXR, stool sample - find causative infection
  • Spirometry - monitor resp muscle weakness and need for ITU admission
58
Q

Management of GBS…

A
  • IV Ig and plasma exchange
  • VTE prophylaxis - as GBS patients are at greater risk
  • 90% of patients make a full recovery
59
Q

What are the different types of MND, and their clinical features?

A
  1. Amytrophic lateral sclerosis (ALS) = commonest form, both UMN and LMN signs : LMN = muscle atrophy , UMN= hyperreflexia, weakness of lower limbs and trunk
  2. Progressive bulbar palsy= affects lower cranial nerves leading to speech and swallowing problems
  3. Progressive muscular atrophy = LMN only, much slower progression than ALS
  4. Primary lateral sclerosis = UMN only
60
Q

What is the usual presentation of ALS?

A
  • Progressive muscle weakness - normally starting in the upper limbs
  • Then spreads to bulbar, thoracic, abdominal muscles
  • May initially look like clumsiness, foot drop may lead to tendency of tripping
  • Bulbar symptoms = slurring of speech, tongue fasciculations, dysphagia
61
Q

Indicative signs of MND…

A
  • UMN and LMN signs
  • Absence of sensory loss
  • Asymmetrical distal weakness
  • Fasciculations
62
Q

How is the diagnosis of MND made?

A

*No specific diagnostic tests for MND
Presence of:
- LMN dysfunction evidenced by clinical or electrophysiological examination
- UMN dysfunction evidenced by clinical examination
- Progressive symptoms
Absence of:
- Electrophysiological evidence of other disease processes
- Neuroimaging evidence of other disease processes

63
Q

Management of MND…

A
  • Incurable condition - most patients survive 2-4 yrs post diagnosis
  • Riluzole (glutamase releasing inhibitor)- shown to increase LE by few months
  • Physiotherapy and speech therapy input
  • Nutritional support - NG tube when body weight loss of >10%
  • Respiratory support - NIV when resp function declines
  • Symptomatic relief e.g. hysocine to stop drooling, pain relief, antidepressants
64
Q

What is spinal cord infarction?

A
  • Ischaemia to one portion of the SC caused by lack of blood supply from the arteries supplying the spine
  • Usually caused by artherosclerosis within artery
  • Aortic dissection is also a cause
65
Q

How does spinal cord infarction present?

A
  • Sudden back pain with tightness
  • Followed by bilateral flaccid weakness and sensory loss
  • Pain and temperature sensation lost (anterior spinal artery typically affected leading to anterior cord syndrome)
66
Q

Management of spinal cord infarction…

A
  • Treatment tends to be supportive

- Can sometimes treat the cause e.g. aortic dissection

67
Q

What is critical illness neuropathy?

A

A syndrome of diffuse, flaccid muscle weakness that can occur in the critically ill patient - often seen in ICU settings.
Usually involves all extremities and the diaphragm.

68
Q

How does critical illness polyneuropathy present?

A
  • Muscle weakness seen in a generalised fashion- limb and respiratory muscles often affected
  • Respiratory difficulties can prolong weaning process of ventilatory support
  • Bilateral flaccid paralysis of arms and legs