25. Weakness Flashcards
differential for weakness
Brain
- MS
- Stroke (and think about stroke mimics hypoglycaemia, todd’s paresis, migraine, bell’s palsy)
- Space occupying lesion
- Psychogenic
Spinal Cord
- MS
- Motor neuron disease
- Myelopathy
- Any spinal cord disorder affecting the corticospinal tract eg subacute combined degeneration,
Nerve roots
- Radiculopathy
Peripheral nerves
- Motor neuron disease causing LMN signs
- peripheral neuropathy - motor loss
Neuromuscular junction
- Myasthenia gravis and lambert eaton
Muscle
- Muscular dystrophy
- Muscular breakdown eg rhabdomyolysis
Muscle inflammation and damage eg rhabdomyolysis, polymyositis, dermatomyositis, statin-induced, corticosteroid induced, cushings, addisons
History taking weakness
PC: weakness = onset? where in the body, has the pattern changed? worse at any point in the day? how does it affect ADLs?, improved by rest or movement?
screening for weakness elsewhere: eyelid weakness? double vision? lazy eye? change in vision (eg homonymous hemianopia), facial expression weakness? difficulty getting up from a chair? clumsy? difficulty swallowing?speaking?
associated symptoms: headache, n&v, LOC, changes to voice? dizziness? vertogo? palpitations
MHx: AF, migraines,
DHx: anticoagulants, statins, COCP,
Examination weakness
UL neuro, LL neuro
- any UMN signs?
- pattern of weakness?
Cranial nerve exam
- eye movements?
- visual field defect?
- forehead sparing?
- swallowing issue?
GCS
cerebellar exam
ABCDE
check glucose!! can cause stroke mimic!
UMN signs
Minimal muscle atrophy
Weakness
Hyperreflexia of deep tendon reflexes- as no UMN regulating that reflex
Absent superficial reflex - babinski positive
Hypertonia + or - clonus
Pronator drift
causes of LMN lesions
ALS (may also have UMN)
Peripheral neuropathy motor loss (guillain barre, charcot-marie tooth)
Spinal cord disorders (should also have UMN) that involve:
Injury to axons leaving spinal cord
Injury to anterior horn/grey matter of spinal cord
causes of UMN lesions
Stroke
Infection
Tumour
Damage to white matter/corticospinal tract eg myelopathy, MS
ALS
Injury to brain stem
LMN signs
Muscle atrophy
Flaccid paralysis
No plantar response
Absent tendon reflexes
Fasciculations (single muscle fibres of uninjured LMN stimulated)
test for conversion disorder weakness
hoovers sign
causes of peripheral muscle weakness? signs?
guillian barre
Charcot-marie tooth
lead poisoning
Ascending weakness
“Tripping over feet”
Foot drop
Hyporeflexia
causes of proximal muscle weakness
Corticosteroid-induced proximal myopathy
Statin-induced myopathy
Cushings
Rhabdomyolysis
Polymyositis
Dermatomyositis
Addisons
Muscular dystrophy
Presentation polymyositis and dermatomyositis
Symmetrical, proximal muscle weakness
Raynaud’s
As the disease progresses, other muscles may also become involved, resulting in the following:
Pharyngeal or oesophageal muscles leading to dysphonia and dysphagia.
Respiratory muscles can lead to poor ventilation with type 2 respiratory failure.
Dermatomyositis causes the above plus skin changes eg
Heliotrope rash -which is a lilac discolouration of the eyelid skin in addition to periorbital oedema
first line invetsigation ?inflammatory myopathy
creatinine kinase
invetsigations ?polymypositis/dermatomyositis
creatinine kinase
nerve conduction studies = Electromyography (EMG)
muscle biopsy for definitive
may want to look for underlying malignancy
what enzymes are elevated in demratomyositis and polymyositis
DM and PM turn your muscles into CLAAA (clay):
Creatine kinase
Lactate dehydrogenase
Aldolase
ALT
AST
management polymyositis/dermatmyositis
Corticosteroids
are the mainstay of treatment. They are started at high doses initially, creatanine kinase is then monitored to guide the rate of tapering the dose.
Many patients need an additional immunosuppressant such as methotrexate or azathioprine as a steroid-sparing agent.
Hydroxychloroquine occasionally helps with skin disease in dermatomyositis.
As well as pharmacological therapy, physiotherapy is essential to rehabilitate patients.
define stroke
‘rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 hours or leading to death with no apparent cause other than that of vascular origin
define TIA
a transient episode of neurologic dysfunction caused by focal brain, spinal cord, or retinal ischaemia, without acute infarction
Approach to acute assessment of ?stroke
ABCDE
A
B - is there increased RR? (get blood gas as may be hyperventilating causing resp alk) maintain O2 sats
C - BP- monitor this- in haemorrhagic this is sometimes lowered. Get ECG (may have AF)
D - Don’t forget glucose!!!, reduced GCS may indicate haemorrhagic
E
Focused UL, LL, cranial nerve examination and cerebellar exam
should BP be managed during stroke
ischaemic - usually no, except if:
hypertensive encephalopathy
Hypertensive nephropathy
Hypertensive cardiac failure/myocardial infarction
Aortic dissection
Pre-eclampsia/eclampsia
haemorrhagic - sometimes yes, consult local guidelines
what is the ROSIER score
score used in ?stroke to help ddx between stroke and stroke mimics
a score > 0 means stroke likley
what scoring sytem will you use when assessing ?stroke
ROSIER
what is part of rosier score
LOC -1
seizure -1
asymmetric facial weakness +1
asymmetric arm weakness +1
asymmetric leg weakness +1
speech disturbance +1
visual field defect +1
A stroke is likely if > 0
first line for investigation ?stroke
- non contrast CT
what can a non-contrast CT show you in stroke
ischaemic
- hyperdense artery (often visible immediately)
- low density in grey/white matter (takes time to develop)
haemorrhagic
- hyperdense material (blood) surrounded by low density (oedema)
if a non-contrast CT shows ishcameic stroke/rules out haemorrhage, what other scans might you get?
CT angiography particularly if thrombectomy is being considered
MR angiography
CT perfusion scan or diffusion weighted MRI if looking for salvagable brain tissue
risk factors for ischaemic stroke
OCP is a risk factor
Migraine is a risk factor
AF is a risk factor
Antipsychotics is risk factor
Polycythaemia vera (raised RBC - hyperviscosity)
management ischaemic stroke <6hrs onset
- Aspirin 300mg orally or rectally should be given as soon as possible if a hemorrhagic stroke has been excluded. Continue for 2 weeks.
+ Thrombolysis with alteplase if <4.5 hours since symptom onset
+ Thrombectomy if <6 hours (together with Thrombolysis with alteplase if <4.5 hours) and confirmed occlusion of the proximal anterior circulation demonstrated by CTA or MRA
management of strokes presenting >6 hours after onset of symptoms
- aspirin 300mg orally or rectally should be given as soon as possible if a hemorrhagic stroke has been excluded. Continue for 2 weeks.
CT perfusion or diffusion-weighted MRI
+ thrombectomy if between 6 hours and 24 hours (including wake-up strokes) if there is the potential to salvage brain tissue,
+ consider if proximal posterior circulation
stroke patient. what do you do to manage complications and assess other aspects
DVT risk management: pressure stockings, IPCDs, not dalteparin as it could cause hemorrhagic transformation
SALT referral for swallow screen - make nil by mouth in the meantime
Disability is most commonly measured using the Barthel index (BI)
ECG for ?AF
If AF, ‘anticoagulants should not be started until brain imaging has excluded haemorrhage, and usually not until 14 days have passed from the onset of an ischaemic stroke’
when monitoring stroke pts what are important things to do?
24hr after thrombolysis do another CT to check you haven’t caused haemorrhagic transformation
Young person more likely to get raised ICP as their brain isn’t atrophied so no space t swell - be alert for decrease in GCS
absolute contraindications to thrombolysis
- Previous intracranial haemorrhage
- Seizure at onset of stroke
- Intracranial neoplasm
- Suspected subarachnoid haemorrhage
- Stroke or traumatic brain injury in preceding 3 months
- Lumbar puncture in preceding 7 days
- Gastrointestinal haemorrhage in preceding 3 weeks
- Active bleeding
- Pregnancy
- Oesophageal varices
- Uncontrolled hypertension >200/120mmHg
pharmacological secondary prevention of stroke and TIA
- Clopidogrel
- Aspirin plus modified-release (MR) dipyridamole
- MR dipyridamole
if the cholesterol is > 3.5 mmol/l patients should be commenced on a statin. Atorvostatin 80mg. Many physicians will delay treatment until after at least 48 hours due to the risk of haemorrhagic transformation
If AF, ‘anticoagulants should not be started until brain imaging has excluded haemorrhage, and usually not until 14 days have passed from the onset of an ischaemic stroke’
surgical considerations for secondary prevention of stroke/TIA
consider carotid artery endarterectomy:
- if stroke/tia in carotid territory (eyes, ACA, MCA) and they are not severely disabled
- should only be considered if carotid stenosis > 70% according ECST** criteria or > 50% according to NASCET*** criteria
- Don’t operate on completely blocked as it is sealed so doesn’t embolize and cause strokes
Don’t operate on a asymptomatic carotid
what are anterior circulation strokes? total vs partial
strokes involving the anterior cerebral artery / middle cerebral artery
they cause:
- Unilateral hemiparesis +/- hemisensory loss of 2 of: face, arm and leg
- Homonymous hemianopia
- High cognitive dysfunction eg dysphasia
Total anterior circulation - all 3 of above criteria
Partial anterior circulation - 2 of above criteria
how to differentiate between anterior cerebrala nd middle cerebrala rtery strokes
Anterior cerebral artery - contralateral hemiparesis + sensory loss (LL worse than UL)
Middle cerebral artery - contralateral hemiparesis + sensory loss (UL worse than LL)
whata re posterior circualtion strokes? broad terms
Involve the vertebrobasilar (posterior cerebral, cerbellar arteries, basilar arteries) arteries and presents with one of:
- Cerebellar or brainstem syndromes
- Loss of consciousness
- Isolated homonymous hemianopia
list the different types of posterior circulation stroke
- Posterior cerebral artery
- Weber’s syndrome (branch of PCA→ midbrain)
- Anterior inferior cerebellar artery AICA (lateral pontine syndrome)
- Posterior inferior cerebellar artery PICA (lateral medullary/wallenberg)
- Basilar artery
- Lacunar infarct
presentation posterior cerebral artery stroke
contralateral homonymous hemianopia with macular sparing with visual agnosia
presentation webers syndrome
ipsilateral CN 3 palsy, contralateral weakness of upper and lower extremity
presentation AICA
(lateral pontine syndrome) - ipsilateral facial paralysis, deafness, vertigo and vomiting
presentation PICA
(lateral medullary/wallenberg) - ipsilateral facial pain and temperature loss, contralateral limb/torso pain and temp loss, ataxia, nystagmus
presentation basilar artery stroke
locked in syndrome
quadriplegia
presentation lacunar infarct
1 of:
unilateral weakness of ⅔ of face,arm,leg(+/- sensory defecit),
pure sensory stroke,
ataxic hemiparesis. Often causes by HTN.
arteries/territories affected by lacunar infarct?
involves the perforating arteries around the internal capsule, thalamus and basal ganglia.
cause normally of alcunar infarct
HTN
Management ?TIA
immediate antithrombotic therapy
- Give aspirin 300mg unless:
–> pt has a blleeding disorder or taking anticoag (need CT to exclude ahemorrhage)
–> pt already taking low dose aspirin (contnue current dose)
–> aspirin contarindicated (discuss with specialist urgently)
Specialist review
- admit if crescenddo TIA or ?carotid stenosis or ?cardioembolic
- within 24 hours if happene din past 7 days
- within 1 week if symptoms were more than a week ago
when you have organised specialist review for TIA, what else do you need to advise the patient
Advise the person not to drive until they have been seen by a specialist
presentation of haemorrhagic stroke
Similar to ischaemic stroke or reduced consciousness
Nausea
Vomiting
Headache
Reduced GCS
causes of haemorrhagic stroke
Metastasis
Vascular malformations (AVLs)
Sinus venous thrombosis
Hypertension (most common)
management of intracerebral haemorrhage
stop anticoagulants and antithombotics. consider reversal
neurosurgical consult
name 4 stroke mimics
Hypoglycaemia
Todd’s paresis
Migraine
Bell’s palsy
what is bells palsy
Bell’s palsy may be defined as an acute, unilateral, idiopathic, facial nerve paralysis. The aetiology is unknown although the role of the herpes simplex virus has been investigated previously. The peak incidence is 20-40 years and the condition is more common in pregnant women.
forehead sparing means?
STROKE
bells palsy has 5 branches so hand on face = it all so not forehead sparing
lower motor neuron facial nerve palsy - forehead affected
in contrast, an upper motor neuron lesion ‘spares’ the upper face
patients may also notice post-auricular pain (may precede paralysis), altered taste, dry eyes, hyperacusis
management of bells palsy
- Oral prednisolone within 72 hours of onset of Bell’s palsy
- seek specialist advice about use of antivirals
follow up bells palsy
if the paralysis shows no sign of improvement after 3 weeks, refer urgently to ENT
a referral to plastic surgery may be appropriate for patients with more long-standing weakness e.g. several months
prognosis bells palsy
most people with Bell’s palsy make a full recovery within 3-4 months
if untreated around 15% of patients have permanent moderate to severe weakness
what is myasthenia gravis
Myasthenia gravis is an autoimmune disorder resulting in insufficient functioning acetylcholine receptors. Antibodies to acetylcholine receptors are seen in 85-90% of cases*. Myasthenia is more common in women (2:1)
key feature of myasthenia gravis
The key feature is muscle fatigability -
muscles become progressively weaker during periods of activity and slowly improve after periods of rest:
extraocular muscle weakness: diplopia
proximal muscle weakness: face, neck, limb girdle
ptosis
dysphagia
symptoms myasthenia gravis
extraocular muscle weakness: diplopia
proximal muscle weakness: face, neck, limb girdle
ptosis
dysphagia
what drugs may exacerbate myasthenia gravis
Beta-blockers — should be avoided if possible in patients with myasthenia gravis
lithium
phenytoin
antibiotics: gentamicin, macrolides, quinolones, tetracyclines
penicillamine
quinidine, procainamide
investigations ?myasthenia gravis
AChR antibodies (acetylcholine receptor antibody)
single fibre EMG (stimualtion of single fibres) high sensitivity (92-100%)
CT thorax to exclude thymoma
management of myasthenia gravis
- long-acting acetylcholinesterase inhibitors
pyridostigmine is first-line
(too tired to get to top of pyramid)
+ immunosuppression such as prednisolone
+ thymectomy
management of myastehnic crisis
- plasmapheresis
- intravenous immunoglobulins
implications for anaesthesia myasthenia gravis
suxamethonium (muscle relaxant) normal doses won’t work
Suxamethonium is a depolarising NMBD - it acts by binding to and activating the receptor, at first causing muscle contraction, then paralysis. Due to a decreased number of available receptors, MG patients are typically resistant to depolarising NMBDs and may require significantly higher doses.
what drugs may cause proximal myopathy? will CK be raiseD?
statins - CK will be raised
steroids - CK raised if acute, not raised if chronic
what is rhabdomyolysis
Rhabdomyolysis is caused by skeletal muscle breakdown.
This causes the release of intracellular contents such as myoglobin and potassium into the blood stream.
Excess myoglobin can precipitate in the glomerulus causing renal obstruction, direct nephrotoxicity and acute kidney injury.
triad rhabdomyolysis - symptoms
dark urine, generalised weakness and myalgia.
features of rhabdomyolysis blood tests etc.
acute kidney injury with disproportionately raised creatinine
elevated creatine kinase (CK)
myoglobinuria
hypocalcaemia (myoglobin binds calcium)
elevated phosphate (released from myocytes)
hyperkalaemia (may develop before renal failure)
metabolic acidosis
causes of rhabdomyolysis
seizure
collapse/coma (e.g. elderly patients collapses at home, found 8 hours later)
Ischaemia: embolism, surgery
ecstasy
crush injury
McArdle’s syndrome
drugs: statins (especially if co-prescribed with clarithromycin)
diagnosis of rhabdomyolysis
A creatine kinase >5x the normal range is typically diagnostic.
management rhabdomyolysis
IV fluids to maintain good urine output
Correction of electrolyte disturbances
urinary alkalinization is sometimes used
electrolytes in rhabdomyolysis
Hyperkalaemia (liberated from the damaged muscle)
Hyperphosphatemia (liberated from the damaged muscle)
Hyperuricaemia (liberated from damaged muscle)
Hypocalcaemia (calcium is taken into the damaged muscle by several mechanisms).
what endocrine things may cause proximal muscle weakness
cushings
hypoadrenalism
what is muscualr dystrophy
umbrella term for genetic conditions that cause gradual weakening and wasting of muscles.
what pattern of weakness presents in muscualr dystrophy? what sign is this
Children with proximal muscle weakness use a specific technique to stand up from a lying position. This is called Gower’s sign.
To stand up, they get onto their hands and knees, then push their hips up and backwards like the “downward dog” yoga pose. They then shift their weight backwards and transfer their hands to their knees. Whilst keeping their legs mostly straight they walk their hands up their legs to get their upper body erect. This is because the muscles around the pelvis are not strong enough to get their upper body erect without the help of their arms.
management muscualr dystrophy
Supportive
Management is aimed at allowing the person to have the highest quality of life for the longest time possible. This usually involves input from occupational therapy, physiotherapy and medical appliances (such as wheelchairs and braces) as well as surgical and medical management of complications such as spinal scoliosis and heart failure.
genetics duchenne
defective gene for dystrophin on the X-chromosome
X-linked recessive condition
if a mother is a carrier of defective dystrophin gene, what is the liklihood of her children being carriers/affected
50% chance of being a carrier if they are female
and 50% chance of having the condition if they are male.
presentation duchenne
Boys with Duchenne’s present around 3 – 5 years with weakness in the muscles around their pelvis. The weakness tends to be progressive and eventually all muscles will be affected. They are usually wheelchair bound by the time they become a teenager.
presentation beckers
The clinical course is less predictable than Duchennes. Symptoms only start to appear around 8 – 12 years. Some patients require wheelchairs in their late 20s or 30s . Others are able to walk with assistance into later adulthood. Management is similar to Duchennes.
genetics beckers
the dystrophin gene is less severely affected and maintains some of its function
key feature of myotonic dystrophy
Prolonged muscle contractions
This may present in exams with a patient that is unable to let go after shaking someones hand, or unable to release their grip on a doorknob after opening a door. When doing an upper limb neurological examination always shake the patients hand and observe for difficulty releasing their grip.
how to determine where horners syndrome lesion is??
Horner’s syndrome - anhydrosis determines site of lesion:
head, arm, trunk = central lesion: stroke, syringomyelia 1st order
just face = pre-ganglionic lesion: Pancoast’s, cervical rib 2nd order
absent = post-ganglionic lesion: carotid artery 3rd order
imaging
eye drops to determine site of lesion- apraclonidine to confirm horners followed by hydroxyamphetamine to determine site of lesion
