Rosen & Barkin's 5-Minute Emergency Medicine Consult (308 page)

CODES

• 288.00 Neutropenia, unspecified
  
• 288.03 Drug induced neutropenia
  
• 288.09 Other neutropenia
  

BASICS

• Group of peripheral nerve disorders characterized by autoimmune demyelination and axonal degeneration of peripheral nerves leading to acute ascending paralysis
  
• Humoral and cellular immune mediated
  
• Leading cause of acute flaccid paralysis worldwide (since polio vaccination)
  
• Triggered by antecedent bacterial/viral infection
  
• Increasing incidence with advancing age, male gender
  
  • Average 1.1 per 100,000 per yr
    
• Weakness reaches nadir at 2–4 wk
  
• Spontaneous resolution occurs over weeks to months
  
  • 80% full recovery at 1 yr
    
  • 20% unable to walk at 6 mo
    
  • 5% die of complications (PE, infection, cardiac)
    
• Acute inflammatory demyelinating polyradiculoneuropathy (AIDP):
  
  • Most common form of Guillain–Barré syndrome (90% of all GBS cases)
    
  • Demyelination sometimes accompanied by axonal loss
    
• Other forms of GBS:
  
  • Acute motor axonal neuropathy (AMAN):
    
    • Pure motor axonal involvement
      
    • 67% seropositive for
      Campylobacter jejuni
      
    • Recovery often rapid
      
    • Often pediatric patients
      
  • Acute motor sensory axonal neuropathy (AMSAN):
    
    • Degeneration of myelinated motor and sensory nerves without significant inflammation or demyelination
      
    • Similar to AMAN, but also involves sensory nerves
      
  • Acute panautonomic neuropathy:
    
    • Very rare
      
    • Involves sympathetic and parasympathetic nerves
      
    • Postural hypotension, dysrhythmias, tachycardia, hypertension
      
    • Blurry vision, dry eyes, anhidrosis
      
    • Recovery gradual, often incomplete
      
  • Miller Fisher syndrome:
    
    • Rare
      
    • Rapidly evolving ataxia, areflexia, and ophthalmoplegia without weakness
      
    • Demyelination and inflammation of cranial nerves II and VI, spinal ganglia, and peripheral nerves
      
    • Resolves in 1–3 mo
      

• Postinfectious:
  
  • 2/3 with antecedent illness, usually respiratory or GI
    
  • Different autoantibodies associated with different subtypes
    
  • 1–3 wk between prodromal illness and neurologic symptoms
    
  • C. jejuni
    most common antecedent bacterial infection
    
  • Cytomegalovirus
    most common antecedent viral infection
    
  • Epstein–Barr virus, VZV, HIV, mycoplasma also associated
    
• Relationship to vaccines is questionable
  
  • Slight increased risk ascribed to 1976 swine flu vaccine, no other vaccines have same risk
    

DIAGNOSIS

• Rapidly evolving, symmetric, ascending paralysis
  
• Absent or mild sensory symptoms (e.g., paresthesias of fingertips or toes)
  
• Pain, commonly of pelvis, shoulder girdles, posterior thighs
  
• Cranial nerve involvement may affect swallowing, facial muscles, eye movements
  
• Preceding bacterial or viral infection
  
• Progression of symptoms over 8 wk not consistent with GBS, but chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)
  

• Ascending symmetric weakness, legs more affected than arms
  
• Loss of deep tendon reflexes
  
• Look for cranial nerve involvement
  
• Respiratory insufficiency (25% patients)
  
• Normal sensory exam
  
• Other subtypes:
  
  • Autonomic dysfunction:
    
    • Hypertension
      
    • Orthostatic hypotension
      
    • Ileus
      
    • Dysrhythmias
      
    • Urinary retention
      
  • Miller Fisher variant:
    
    • Ataxia
      
    • Areflexia
      
    • Ophthalmoplegia
      
    • Mild limb weakness
      
• Features that suggest alternative diagnosis:
  
  • Fever
    
  • Normal reflexes
    
  • Upper motor neuron signs
    
  • Asymmetric neurologic deficits
    
  • Sharply demarcated sensory level
    

• Diagnosis is generally made on clinical grounds
  
• Lab and imaging tests can assist with diagnosis and rule out other causes of symptoms
  

• Electrolytes (some patients have SIADH)
  
• Lumbar puncture:
  
  • Albuminocytologic dissociation-increased protein with few or no WBCs
    
  • Protein typically 55–350, may be present only after 7–10 days as disease and blood–brain barrier dysfunction progress
    
  • WBCs >10–50 suggests other etiology
    
  • Normal opening pressure
    

CT or MRI to rule out cord compression

Electrophysiologic studies will be abnormal (nerve conduction confirmatory)

Polyneuropathies:

• Acute intermittent porphyria
  
• Chronic heavy metal poisoning
  
• Diphtheria
  
• Lyme disease
  
• Paraneoplastic disease
  
• Poliomyelitis
  
• Sarcoidosis
  
• Tick paralysis
  
• Vasculitis
  

Spinal cord disorders:

• Cord compression
  
• Transverse myelitis
  

Neuromuscular junction disorders:

• Botulism
  
• Eaton–Lambert syndrome
  
• Myasthenia gravis
  

Muscle disorders:

• Acute polymyositis
  
• Critical illness myopathy
  

Other:

• Hypokalemia
  
• Psychogenic, malingering
  

TREATMENT

Attention to airway management

Airway assessment and management:

• Progression to respiratory failure can be rapid
  

• Airway management:
  
  • ∼30% will need ventilatory support.
    
  • May need intubation within 24–28 hr of onset
    
  • Frequent monitoring of respiratory parameters:
    
    • Forced vital capacity (FVC) or negative inspiratory flow (NIF) helpful
      
    • ICU admission if FVC <20 mL/kg or NIF <30 cm H
      ₂
      O
      
    • Intubation recommended if FVC <15 mL/kg
      
• Watch for autonomic dysfunction
  
• Supportive therapy
  
• Early neurology consult
  

• Plasmapheresis or IV immunoglobulin (IVIG), in conjunction with neurologic consultation:
  
  • Unclear benefit for Miller Fisher or mild GBS
    
• IVIG: 400 mg/kg/d for 5 days
  
• Pain control:
  
  • Acetaminophen: 500 mg PO q6h; not to exceed 4 g/24h
    
  • Ibuprofen: 400–800 mg PO q8h
    
  • Gabapentin: Start 300 mg PO per day
    
• Steroids not beneficial for pain or deficits:
  
  • Oral steroids delay recovery
    
  • IV steroids with no benefit
    

FOLLOW-UP

• All patients with GBS or suspected GBS warrant admission for close observation
  
• ICU admission for those with signs of respiratory compromise, autonomic dysfunction or need for frequent monitoring for progression of illness