Weakness

Weakness is a topic covered in the 5-Minute Emergency Consult.

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Basics

Description

  • Defined as a decrease in physical strength or energy
  • Patients will use “weakness” to describe many different symptoms and presentations
  • May represent neuromuscular weakness, fatigue, malaise, presyncope, or other symptoms
  • History and physical is key to help narrow diagnosis and workup
  • Often multifactorial
  • Distinguish neuromuscular disorder/focal neurologic process vs. nonneuromuscular disorder
  • Distinguish focal weakness vs. bilateral or generalized weakness
  • Categories of neuromuscular disorders:
    • Upper motor neuron (UMN) lesions:
      • Deep tendon reflexes (DTR) increased
      • Plantar reflexes upgoing
      • Increased muscle tone
      • Muscle atrophy absent
    • Lower motor neuron (LMN) lesions:
      • DTRs decreased to absent
      • Plantar reflexes absent or normal
      • Decreased muscle tone
      • Muscle atrophy present
      • Fasciculations
    • Neuromuscular junction (NMJ) lesions:
      • DTRs normal
      • Plantar reflexes normal or absent
      • Decreased muscle tone
  • Categories of nonneuromuscular disorders:
    • Neurologic
    • Infectious
    • Traumatic/structural
    • Endocrine
    • Metabolic
    • Cardiac
    • Rheumatologic
    • Toxicologic
    • Other
    • Psychiatric

Etiology

  • Neuromuscular disorders:
    • Multiple sclerosis (UMN)
    • Amyotrophic lateral sclerosis (mixed)
    • Transverse myelitis (UMN)
    • Guillain–Barré syndrome (LMN)
    • Myasthenia gravis (NMJ)
    • Lambert–Eaton syndrome (NMJ)
    • Periodic paralysis (can be familial)
  • Neurologic:
    • TIA/CVA
    • Seizure (Todd paralysis)
    • Malignancy
  • Infection/sepsis:
    • UTI
    • Pneumonia
    • Meningitis
    • Mononucleosis
    • HIV
    • Arboviruses
    • Botulism (NMJ)
    • Diphtheria
    • Epidural abscess (often seen with IV drug use)
    • Poliomyelitis
  • Traumatic/structural:
    • Intracranial hemorrhage
    • Spinal cord injury/lesion
    • Malignancy
    • Cauda equina
    • Impingement syndromes
  • Endocrine:
    • Hypothyroidism
    • Adrenal crisis
    • Vitamin deficiency
  • Metabolic:
    • Dehydration
    • Hypoglycemia
    • Electrolyte abnormalities
  • Cardiac:
    • Myocardial ischemia
    • Arrhythmia
    • Presyncope
  • Rheumatologic:
    • Systemic lupus erythematosus
    • Polymyalgia rheumatica
    • Myositis
  • Toxicologic:
    • Seafood toxins
    • Tick paralysis (NMJ)
    • Carbon monoxide poisoning
    • Heavy metal poisoning
    • Drugs of abuse
    • Alcohol
    • Organophosphates and carbamates (history of pesticide exposure)
  • Anemia
  • Pregnancy
  • Psychiatric causes of weakness (diagnoses of exclusion):
    • Anxiety/depression
    • Dependent personality
    • Hypochondriasis
    • Chronic fatigue syndrome
    • Fibromyalgia
    • Malingering

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Basics

Description

  • Defined as a decrease in physical strength or energy
  • Patients will use “weakness” to describe many different symptoms and presentations
  • May represent neuromuscular weakness, fatigue, malaise, presyncope, or other symptoms
  • History and physical is key to help narrow diagnosis and workup
  • Often multifactorial
  • Distinguish neuromuscular disorder/focal neurologic process vs. nonneuromuscular disorder
  • Distinguish focal weakness vs. bilateral or generalized weakness
  • Categories of neuromuscular disorders:
    • Upper motor neuron (UMN) lesions:
      • Deep tendon reflexes (DTR) increased
      • Plantar reflexes upgoing
      • Increased muscle tone
      • Muscle atrophy absent
    • Lower motor neuron (LMN) lesions:
      • DTRs decreased to absent
      • Plantar reflexes absent or normal
      • Decreased muscle tone
      • Muscle atrophy present
      • Fasciculations
    • Neuromuscular junction (NMJ) lesions:
      • DTRs normal
      • Plantar reflexes normal or absent
      • Decreased muscle tone
  • Categories of nonneuromuscular disorders:
    • Neurologic
    • Infectious
    • Traumatic/structural
    • Endocrine
    • Metabolic
    • Cardiac
    • Rheumatologic
    • Toxicologic
    • Other
    • Psychiatric

Etiology

  • Neuromuscular disorders:
    • Multiple sclerosis (UMN)
    • Amyotrophic lateral sclerosis (mixed)
    • Transverse myelitis (UMN)
    • Guillain–Barré syndrome (LMN)
    • Myasthenia gravis (NMJ)
    • Lambert–Eaton syndrome (NMJ)
    • Periodic paralysis (can be familial)
  • Neurologic:
    • TIA/CVA
    • Seizure (Todd paralysis)
    • Malignancy
  • Infection/sepsis:
    • UTI
    • Pneumonia
    • Meningitis
    • Mononucleosis
    • HIV
    • Arboviruses
    • Botulism (NMJ)
    • Diphtheria
    • Epidural abscess (often seen with IV drug use)
    • Poliomyelitis
  • Traumatic/structural:
    • Intracranial hemorrhage
    • Spinal cord injury/lesion
    • Malignancy
    • Cauda equina
    • Impingement syndromes
  • Endocrine:
    • Hypothyroidism
    • Adrenal crisis
    • Vitamin deficiency
  • Metabolic:
    • Dehydration
    • Hypoglycemia
    • Electrolyte abnormalities
  • Cardiac:
    • Myocardial ischemia
    • Arrhythmia
    • Presyncope
  • Rheumatologic:
    • Systemic lupus erythematosus
    • Polymyalgia rheumatica
    • Myositis
  • Toxicologic:
    • Seafood toxins
    • Tick paralysis (NMJ)
    • Carbon monoxide poisoning
    • Heavy metal poisoning
    • Drugs of abuse
    • Alcohol
    • Organophosphates and carbamates (history of pesticide exposure)
  • Anemia
  • Pregnancy
  • Psychiatric causes of weakness (diagnoses of exclusion):
    • Anxiety/depression
    • Dependent personality
    • Hypochondriasis
    • Chronic fatigue syndrome
    • Fibromyalgia
    • Malingering

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