Weakness Flashcards
How to describe clinical weakness:
First decide: Neuromuscular vs Non-NM cause
Global/ focal
Bilat/ unilat
Proximal/ distal
Patterns of:
UMN
LMN
NMJ
Myopathy
Strength (Gr 0-5)
Scale of motor strength:
5- Against full resistance
4- Against mild resistance
3- Against gravity
2- Gravity eliminated
1- Flicker
0- Nil
Features that differentiate:
- UMN
- LMN
- NMJ
- Myopathy
What is the ‘pyramidal’ pattern of weakness?
Suggests UMN.
Weakness of:
- Upper limb extensors
- Lower limb flexors
DDx of weakness:
NON-NEUROMUSC- subjective, global
- Anaemia
- Sepsis
- CCF
- SLE, fibromyalgia, chronic fatigue
- Hypothyroidism
- Electrolytes (Na, Ca, K)
NEUROMUSCULAR WEAKNESS- quantitative loss of strength
Brain
- Stroke
- SOL
- Multiple sclerosis
Cord
- Compression
- Infarct
- Stenosis
- Abscess
NMJ
- Myaesthenia gravis
- Lambert-Eaton (paraneoplastic)
Myopathy
- Statins
- Steroids
- Addison’s
- Cushing’s
- Thyrotoxicosis
- Myositis
- Muscular dystrophy
Toxic/toxin
Organophosphates
Botulism
Tetanus
Ciguatera
Paralysis tick
Blue-ringed octopus
Snake-bite (Taipan)
Bell’s Palsy: assessment and DDX
Facial nerve (CN VII) palsy
–> Facial weakness to whole half of face (incl forehead and eye).
–> Salivation
–> Tears
–> Taste on anterior 2/3 tongue
‘Bell’s is idiopathic
MUST LOOK FOR EAR VESICLES (Ramsay-Hunt) Prognosis much worse.
- Parotid mass
- Cholesteatoma
- Acoustic neuroma
- Brainstem event
Bell’s Palsy Mx:
PREDNISOLONE 1mg/kg for 7 days
(2mg/kg paeds)
+
- ACICLOVIR 10mg/kg PO 5x daily (if within 72 hours)**
(Cover for pre-rash Ramsay Hunt)
Eye drops/ ointments
Tape eye nocte
PROGNOSIS
- Most better by 3 months
Clinical features of Guillian-Barre:
Acute autoimmune neuropathy of nerve roots and peripheral nerves (LMN)
1- Demyeliation
or
2- Axonal
Follows < 3 weeks after a Resp or GI illness
- Campylobacter most common
- Mycoplasma, Hib, CMV, EBV.
Onset over days to weeks
Causes Symmetrical ASCENDING paralysis
- Flaccid, tendon reflexes absent
- ALL: limbs, trunk, resp
- MOST: cranial nerves, sensory
- SOME: eyes
- A FEW: autonomic dysregulation
Worst at 2-4 weeks.
Which GBS type is most common with Campylobacter?
Direct AXONAL neuropathy.
Diagnosis of Guillian-Barre:
Mostly clinical diagnosis
- Preceding resp/GI illness
- Symmetrical, ascending flaccid paralysis
Adjunctive:
- MRI C spine
- Lumbar puncture
–> Protein rise without WCC
- Resp and stool screen
- Lung functions tests (serial, to guide elective intubation)
- Evoked potentials (not ED)
Management of Guillian-Barre:
Focus on airway and ventilatory support
Manage secretions
Check lung function 2-hourly (VC, peak flow)
Intubate + ventilate for deteriorating:
- FVC (<15ml/kg)
- FEV1/FVC (<50% predicted)
- Peak flow (<250ml/min)
- NO SUX
- Will need mandatory mode (weak)
NIV NOT RECOMMENDED.
IVIG (2g/kg over 5days)
or
Plasma exchange
FASTHUGS
Mortality in Guillian-Barre:
Majority recover completely (but slowly)
20% will have persisting neuro deficit
Death usually resp failure or autonomic dysFx
What is the Miller-Fischer variant in GBS?
Cranial nerves FIRST.
Oculomotor palsy –> limb weakness.
Tetanus:
Opisthotonos and trismus
Resp failure +/- autonomic dysFx
Clostridium tetani (soil)
More common where no imm, poorly tended wounds (eg. homeless)
Supportive
Tetanus immunoglobulin
Periodic paralysis
Rare channelopathy causing periodic attacks of weakness that last minutes, up to 3 days before resolving suddenly.
Vary in severity and duration
Onset usually in childhood
Triggers:
- High carbs
- After strenuous exercise
- Stress/ excitement
- Sudden temp changes
Types:
- Hypokalaemic periodic paralysis- most common
- Hyperkalaemic
- Thyrotoxic
Mx:
- Supportive
- UEC/CMP- K+ NOT ALWAYS LOW
- Thyroid function
- Replenish K+
- Prophylaxis (eg. acetazolamide, diet)
Multiple Sclerosis: clinical features
Immune-mediated chronic demyelinating condition affecting brain and cord white matter (UMN)
Women
Tasmania
Age 15-45 at onset
Heat/fever can trigger relapse.
Relapses = almost anything:
- Optic neuritis + other visual COMMON
- UMN pattern weakness (spastic, prox)
- Painful shocks in legs
Multiple Sclerosis: Diagnosis
Lumbar puncture:
- High protein
- Pleocytosis with predominant lymphocytosis (mild)
- OLIGOCLONAL BANDS
MRIB
- Multiple white matter plaques on T2
–> Subcortical OR periventricular
Not visible during remissions
Multiple Sclerosis: Treatment
1g IV Methylprednisolone
or
Plamapharesis
Myaesthenia Gravis: Clinical features
Autoimmune attack on post-synaptic AcH receptors (LMN)
Idiopathic.
Exacerbations triggered by illness or stresses
Causes weakness, that is fatiguable and relieved by rest
- Usuallyfacial/ bulbar
–> Ptosis
–> Dysphonia
–> Dysarthria
‘Myaesthenic crisis’ = generalised weakness and resp compromise (20%)
Myaesthenia Gravis: diagnosis
Clinical features
Anti-AcH antibodies in blood
Myaesthethenia Gravis: management
Supportive
–> Unlike GBS, NIV is recommended option
IVIG
Plasmaphoresis
Steroids can make worse
Long term ‘stigmine
Eaton-Lambert syndrome:
Like the ‘opposite’ of myaesthenia
Autoimmune paraneoplastic syndrome, typically SCLC
Attack on PREsynaptic release of AcH.
IMPROVES with exercise
Only treatment, is to treat the cancer.
Motor neurone disease (ALS- amyotrophic lateral sclerosis)
Mixed UMN and LMN destruction. Rapidly progressive, death within 2-4 years.
Bulbar and respiratory weakness are most prominent:
–> Choke, aspiration
–> Resp failure
Mixed nature: often spastic weakness but with fasciculations
Most ED presentations will be resp (aspiration or failure). Management is supportive:
- Try to avoid NIV (aspiration, more WOB)- HFNP better
- NO opiates - resp drive depression
What is the ‘icepack test’
Patient with ptosis
Apply icepack to face for 2 mins
If immediately resolves- likely myaesthenia
Botulism:
Clostridium botulinum
In adults, toxins in food poisoning (partic home-canned). In infants, spores in honey.
Inhibits Ach at presynaptic
Starts with bulbar –> DESCENDING flaccid paralysis
Botulism antitoxin
