Weakness
Background
Acute/Generalized
Workup
- cbc
- chem 10 (esp. K, Mg, Ca, Phos)
- ecg
- +/- CK (r/o myopathy)
- +/- FVC (eval impending resp failure, i.e. Myasthenia)
- +/- ABG/CT/LP/TSH/UA (rhabdo)
Diagnosis
Upper Motor Neuron
- BRAIN
- Weakness - variable
- Bowel/Bladder -
- Reflexes - increased
- Sens - diminished
- Pain - no
- Asymmetric/unilateral
- BRAINSTEM
- "crossed" findings - ipsilateral cranial nerve weakness and contralateral hemiparesis
- CORD
- Weakness - fixed level
- Bowel/Bladder - YES
- Reflexes - increased
- Sens - diminished
- Pain - +/-
Lower Motor Neuron
- NERVE
- Weakness - distal > proximal and ascends
- Bowel/Bladder - NO
- Reflexes - diminished
- Sens - nl/paresthesias
- Pain - no
End-Plate/Muscle
- MOTOR END PLATE
- Weakness - occular,bulbar and descends, fatigable
- Bowel/Bladder - NO
- Reflexes - nl/diminished
- Sens - nl
- Pain - no
- MUSCLE
- Weakness - proximal > distal
- Bowel/Bladder - NO
- Reflexes - nl/diminished
- Sens - nl
- Pain - +/-
DDX
- UPPER
- Multiple Sclerosis
- Poliomyelitis
- ALS (upper & lower motor)
- CORD
- Painful
- Cord compression
- Painless
- Transverse Myelitis
- Spinal cord infarct
- Intramedullary tumor
- Painful
- NERVE
- Guillian-Barre
- Toxic neuropthy (Ciguatera)
- Tick paralysis
- Diabetic neuropathy
- Porphyria
- MOTOR END PLATE
- Myasthenia Gravis
- Botulism (descending)
- Organophosphate Poisoning
- Lambert-Eaton
- MUSCLE
- Painful
- Rhabdo
- Alcoholic
- Myopathy
- Polymyositis
- Dermatomyositis
- Toxins
- Hypophos
- Hypokalemia - post prandial/ family hx/ thyroid
- Polymyalgia rheum
- Painless
- Familial periodic paralysis
- Endocrine
- Painful
- MIXED
- Upper & Lower Motor Neuron
- Sensory & Motor
- Peripheral neuropathy
- NON-NEUROMUSCULAR
Emergent Threat/ED Workup
- CORD
- paralysis
- MRI, neurologist
- consdier steroids in high suspicion
- NERVE
- resp failure
- FEV1, airway mgt, ticks?, neurologist
- MOTOR END PLATE
- resp failure
- FEV1, airway mgt, Tensilon Test?
- MUSCLE
- Rhabdo
- urine myoglobin, serum CK, BUN/Cr
- serum K+
Intubation Indications
- Severe fatigue
- Inability protect airway
- Rapidly increasing PaCO2
- Hypoxemia despite O2
- FVC <12 mL/kg
- Neg Insp Force <20 cm H2O
Source
2/26/06 DONALDSON (adapted from Rosen, Lampe, Birnbaumer)
adapted from Hockberger