16. ICU weakness Flashcards
List Potential Causes of Weakness
CNS
CNS
1. Coma / GCS low
not generating impulse
disease process / sedation
- Central pathology
- stroke
- ICH - Exacerbation pre existing
Parkinson’s
MS - NCSE / Post ictal
- GBS
- Alcohol abuse / vitamin defic
Spinal Cord
Trauma
disruption / ischaemia
Myelitis
S.C infarct
Infection
viral
polio / west nile v
CNS/PNS unction
Epidural mass effect
abscess
haematoma
compressing nerve @ ventral horn
PNS
Trauma - disrupting axons
Compression induced degeneration
- patient position
/ haematoma following trauma /line
Peripheral demyelination
GBS
Alcohol
NMJ
Receptor def (MG)
Accum NDMB - low clearance
Acquire / genetic deficiency
pseudocholinesterase post sux
hypo
K Mg Phos
Hypothermia
MSK
Crit illness myopathy
- necrotising
- cachectic
- acute rhabdo
- thick filament loss
Fracture / Dislocation
Compartment syndrome - NM Ischaemia
Other drugs
Other drugs
Steroids / Amingogly
Define Critical illness myopathy
Acute onset
Muscular weakness
Muscle inflammation and death
normal nerve conduction patter
- usually post week 1 ICU
Muscle not stimulated
(even w/ direct)
Affects distal limb
often a/w wasting
Respiratory & ocular muscles also
Critical illness polyneuropathy
Acute onset polyneuropathy
Normal muscle architecture & action
Axonal degen
predom motor
can affect sensory
Areflexia +- sensory deficit
Sim disturb to CIM
Onset usually 2-5
Invx to distinguish CIM and CIP
Electrophysiological
Direct muscle stimulation
Muscle biopsy
Serum CK
Electrophysiological
Nerve conduction
CIM - Normal
CIP
Low compound muscle action potential CMAP
and sensory Ap
& normal conduction velocity
DIrect Muscle stim
Diff CIP and CIM unconscious
CIP - low or absent CMAP follow tim
direct produces contraction
CIM CMPA
low or absent
both motor nerve stim
direct muscle stim
Muscle Bx
Invasive
slow to yield results
Sub class CIM excluded other dx
Serum CK
Variable raised
normal doesn’t exclude
Massively elevated ?other cause
