Rosen & Barkin's 5-Minute Emergency Medicine Consult (783 page)

TREATMENT

Treatment is geared to the underlying cause of weakness.

• Supplemental oxygen
  
• IV access
  
• Finger-stick glucose determination
  
• Consider endotracheal intubation in patients with severe respiratory distress.
  

• Supplemental oxygen
  
• IV access
  
• Endotracheal intubation for impending ventilatory failure
  

• Neurology consult if needed
  
• When the diagnosis is determined, specific therapies can be applied:
  
  • TPA for CVAs meeting criteria
    
  • Plasma exchange and/or IV immunoglobulin (IVIG) for Guillain–Barré syndrome
    
  • Hydrocortisone for adrenal insufficiency
    
  • Potassium supplementation for hypokalemia
    
  • Dextrose for hypoglycemia
    
  • Antibiotics for infectious etiologies
    
  • Specific antidotes for botulism and diphtheria
    
  • Digibind for digoxin toxicity
    

FOLLOW-UP

• All patients with new-onset neuromuscular disorders should be admitted for definitive diagnosis.
  
• Any evidence of impending ventilatory or circulatory compromise warrants ICU admission.
  

• Resolution of symptoms
  
• Stable vital signs
  
• Definitive diagnosis and correction of abnormality
  

• Discharged patients with non-neurologic etiologies should have follow-up with their PCP.
  
• Discharged patients with neurologic etiologies should have urgent neurology follow-up.
  

• Identify early and aggressively treat patients at risk for respiratory compromise due to Guillain–Barré, botulism, myasthenia gravis.
  
• Identify elderly patients with ACS or infection presenting as weakness.
  
• Consider endocrine causes of weakness, including adrenal insufficiency and hypothyroidism.
  

• Anderson RS Jr, Hallen SA. Generalized weakness in the geriatric emergency department patient: An approach to initial management.
  Clin Geriatr Med.
  2013;29(1):91–100.
  
• Chew WM, Birnbaumer DM. Evaluation of the elderly patient with weakness: An evidence based approach.
  Emerg Med Clin North Am
  . 1999;17(1):265–278.
  
• Losman E. Weakness. In: Marx J, ed.
  Rosen’s Emergency Medicine: Concepts and Clinical Practice.
  7th ed. St. Louis, MO: Mosby; 2009:87–92.
  
• LoVecchio F, Jacobson S. Approach to generalized weakness and peripheral neuromuscular disease.
  Emerg Med Clin North Am
  . 1997;15(3):605–623.
  

CODES

• 728.2 Muscular wasting and disuse atrophy, not elsewhere classified
  
• 728.87 Muscle weakness (generalized)
  
• 780.79 Other malaise and fatigue
  

BASICS

Infectious agent is an arbovirus, an RNA member of the
Flaviviridae
family.

• Vector-borne virus
  
• Transmitted by infected mosquitoes in late summer/early fall
  
• Wild birds are primary reservoir hosts; humans are infected by cross-feeding mosquitoes.
  
• Introduced to Western Hemisphere in 1999; became more widespread owing to vector of
  Culex
  mosquito and is now endemic in North America
  
• Infection after blood transfusion and solid-organ transplant can occur.
  
• There are case reports of occupational exposure and infection of lab workers via percutaneous inoculation.
  
• Following recovery, immunity is considered lifelong. Reoccurrence is rare
  
• The 2011 outbreak had a mortality rate of 4–5%. Cases were reported in 48 states.
  

Infection via transplacental transmission and breast-feeding has been reported.

DIAGNOSIS

• Variable severity of illness:
  
  • 80% asymptomatic
    
  • 20% mild symptoms, flu-like illness
    
  • ∼1/150 with CNS involvement (encephalitis, meningitis)
    
• Incubation period is usually 2–6 days but can be up to 14 days in average patient and up to 21 days in immunocompromised patient.
  
• Symptoms have a sudden onset and last <1 wk with mild infection.
  
• Mortality rate in severe cases is estimated at 7%.
  
• Severity of illness is related to degree of CNS invasion by virus. Risk is enhanced with increased age and immunosuppression
  
• Immunocompromised patients have prolonged viremia, delayed development of antibody, and increased likelihood of severe disease.
  
• Persistent symptoms of fatigue, memory impairment, weakness, and headache have been reported to last for 1–2 mo
  

• Patients >60 yr, if infected, are at higher risk for developing more severe disease and neurologic consequences.
  
• Advanced age is the most important risk factor for death.
  

• General:
  
  • Fever
    
  • Malaise
    
  • Anorexia
    
  • Headache
    
  • Acute phase resolves within several days but fatigue and weakness may persist for weeks
    
• Neurologic:
  
  • Altered mental status (change in level of consciousness, confusion, agitation, irritability)
    
  • Severe, diffuse muscle weakness; may be asymmetric and involve the face
    
  • Flaccid paralysis, which may resemble poliomyelitis-like syndrome, associated with anterior horn cell injury. Cranial nerve and bulbar abnormalities have been reported
    
  • May resemble Guillain–Barré syndrome
    
  • Seizures
    
  • Encephalitis more commonly reported in adults and meningitis in children
    
• GI:
  
  • Nausea, vomiting, diarrhea, anorexia
    
  • Abdominal pain
    
• Musculoskeletal:
  
  • Myalgia
    
  • Arthralgia
    
  • Back pain
    
• Respiratory:
  
  • Cough
    
  • Sore throat
    
• Ophthalmologic:
  
  • Photophobia
    
  • Eye pain
    

• General:
  
  • Temperature >38°C (>100°F)
    
  • Transient maculopapular rash
    
  • Rhabdomyolysis
    
• Neurologic:
  
  • Altered mental status
    
  • Hyporeflexia, areflexia
    
  • Ataxia
    
  • Extrapyramidal signs
    
  • Cranial nerve palsies, paresis
    
  • Myoclonus
    
  • Profound motor weakness
    
  • Flaccid paralysis
    
• GI:
  
  • Hepatosplenomegaly, hepatitis, pancreatitis
    
• Musculoskeletal:
  
  • Nuchal rigidity
    
• Hematologic:
  
  • Lymphadenopathy
    
• Dermatologic:
  
  • Rash (maculopapular or morbilliform on neck, trunk, extremities) usually lasting <1 wk
    
• Cardiovascular:
  
  • Myocarditis (rare)
    
• Ophthalmologic:
  
  • Optic neuritis
    
  • Vitritis
    
  • Chorioretinitis
    

• Most sensitive screening test is serologic testing of CSF and serum for IgM antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA) and culture.
  
• Centers for Disease Control and Prevention (970-221-6400)
  
• Can be detected during 1st 4 days of illness, nearly all tests are positive by day 7–8; may remain positive up to 1 yr after infection
  
• Procedures for submitting samples vary by state.
  
• Refer to local public health department for guidelines.