Weakness

Background

Determine if patient has actual neuromuscular weakness (suggesting CNS dysfuction) or non-neuromuscular weakness.

Clincial Features

History

  • True motor weakness (neuromuscular weakness)? Bilateral or unilateral (distribution of weakness)?
    • Bilateral weakness:
      • Symmetric ascending paralysis? Guillain-Barre Syndrome
      • Weakness involving both central and peripheral nervous system? Inflammatory/Autoimmune or toxic/metabolic
      • Discrete sensory level and/or bladder dysfunction? Spinal Cord Lesion
      • Involvement of proximal > distal musculature? Myopathy
    • Unilateral weakness: CVA, TIA
  • If non-neuromuscular weakness then BROAD differential, obtain:
    • ECG, CBC, Chem10, LFTs, blood cultures, UA/urine culture, drug levels, CXR, Consider Head CT (focal deficit, altered, history of cancer, anticoagulation with minor trauma)
  • Onset of weakness sudden or gradual?
    • Sudden suggests vaso-occlusive etiology CVA/TIA
    • Gradual onset likely non-vascular
  • Significant event surrounding onset of weakness?
    • Seizure prior to weakness? Todd’s paralysis
    • Migraine headache? Complicated migraine
    • Sudden onset of severe headache? SAH
    • Trauma? Epidural or Subdural Hematoma
    • Severe migratory neck or chest pain? Arterial dissection syndromes
  • Temporal pattern to weakness? Fluctuating or fixed weakness?
    • Weakness with repetitive motions? Neuromuscular junction pathology like Myasthenia Gravis
  • Associated symptoms?
    • Headache: SAH, epidural/SDH, complicated migraines (young females), not usually stroke/TIA (unless high intracranial pressure)
    • Vision changes: Posterior circulation stroke, Myasthenia Gravis
    • Shortness of breath: cardiovascular etiology
    • Chest pain or neck pain: Acute arterial dissection, AMI
    • Abdominal or back pain:
    • Nausea/vomiting: sign of ↑ ICP, can lead to electrolyte imbalances
    • Rash: Dermatomyositis

Physical Exam

Focus on clarifying if patient has true loss of strength and determining distribution of deficits. Check for trauma, carotid bruits, thyroid enlargement, irregular rhythm, unequal pulses, rashes or ticks.

Location Weakness Bowel/Bladder Reflexes Sensory Pain
Upper motor neuron
Brain Variable Increased Diminished No
Brainstem "crossed" findings - ipsilateral cranial nerve weakness and contralateral hemiparesis
Cord Fixed level Yes Increased Diminished +/-
Lower motor neuron
Nerve Distal > proximal and ascends No Diminished Nl/parethesias No
End-plate/muscle
Motor end plate Ooccular,bulbar and descends, fatigable No Nl/diminished Nl/parethesias No
Muscle Proximal > distal No Nl/diminished Normal +/-

Differential Diagnosis

Weakness

Evaluation

Workup

On all patients:

Consider:

  • CK (mypoathies)
  • ESR
  • CXR and UA (if infectious symptoms or elderly)
  • FVC (if evidence of respiratory compromise, i.e. Myasthenia, GBS)
  • CT head (if focal findings, altered mental status, history of cancer, history of any trauma in patient on anticoagulation)
  • LP (CNS infection, GBS)

Management

Intubation Indications

  • Severe fatigue
  • Inability protect airway
  • Rapidly increasing PaCO2
  • Hypoxemia despite O2
  • FVC <12 mL/kg
  • Neg Insp Force <20 cm H2O

Disposition

  • Depends on process
    • If normal initial workup, make sure has no respiratory compromise

See Also

External Links

References