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: 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
