Guillian-Barre Syndrome
                        =======================
þ Bottom Line: Guillain-Barré Syndrome
 - The presence of normal reflexes effectively rules out the diagnosis
 - Mechanical ventilation is required in almost a third of patients
 - Bedside spirometry is easy to perform. Remember the “20/30/40” rule
   (VC<20, or NIF<30, or MEP<40)
   
þ Epidemiology
 - 95% of cases in North America and Europe
 - Incidence is 1 in 100,000
 - Most common cause of nontraumatic acute paralysis in industrialized 
   countries
 - Occurs at any age; Four times more likely in patients > 75

þ Etiology
 - Autoimmune attack on myelinated peripheral motor nerves due to cross-
   reactivity with infectious trigger
 - Antibodies to epitopes within the infectious trigger cross react with to GM1
   ganglioside, which is present in high concentrations in peripheral nerve 
   myelin
 - Acute inflammatory demyelinating polyradiculoneuropathy (AIDP)
 - Other variants involve axons (ie, acute motor axonal neuropathy)
   e.g., Fisher's Syndrome
   
þ Clinical Features
 - Antecedent viral illness (CMV, EBV, HSV, HIV), Mycoplasma pneumoniae or
   Campylobacter jejuni identified in two-thirds of patients. Usually within the
   preceding 6 weeks. C. jejuni is most common, occurring in one quarter of
   patients.

þ Features of Guillian-Barre Syndrome
 - ascending motor paralysis
 - may have autonomic dysfunction (arrhythmias, BP variations)
 - may present as Bell's palsy <N-Bell.TXT - Guillian>, sometimes bilateral
 - Classic: symmetric weakness of thighs, legs, and then arms and eventually
   involving all four limbs (“ascending paralysis”)
 - Symptoms peak in < 4 weeks with many cases presenting more rapidly
 - Numbness or tingling of the lower extremities with sensory complaints in 
   one third. Occasionally sharp-shooting pains.
 - Cranial nerve involvement in 50% and suggests more severe course
 - Variants: Miller Fisher Syndrome (partial or complete ophthalmoplegia, severe
   ataxia and areflexia)9. May also have overlap with limb weakness and 
   respiratory involvement. Other variants include isolated facial paralysis and 
   paresthesias, pharyngeal-cervical-brachial weakness, and pure ataxia
 - Normal sensory exam with absent reflexes. Presence of reflexes essentially 
   rules out GBS.
 - May be confused with acute flaccid paralysis of West Nile virus, which 
   frequently presents with fever, leukocytosis, asymmetric distribution, no 
   sensory deficits, concurrent encephalopathy, and pleocytosis in CSF

þ Differential:  Acute Polyneuropathy
 Infections:
 - mono
 - viral hepatitis
 - diptheria
 - Polio
 - West Nile
 Toxic:
 - thallium
 - DDT
 - shellfish
 - arsenic
 - lead
 - Botulism: descending rather than ascending
 Metabolic
 - porphyria
 - hyperinsulinism
 Tick Paralysis

þ Pulmonary Evaluation Triad for Guillian-Barre
 - Vital Capacity should be more than 1 liter
 - Negative Inspiratory Force
 - Intubation recommended by “20/30/40” rule
  + Vital capacity < 20 mL/kg
  + Negative inspiratory pressure < -30 cmH2O
  + Maximum expiratory pressure < 40 cmH2O
 - Alternatively, a reduction in any of these values by > 30% suggests the
   need for mechanical ventilation14,15.

þ Diagnosis of Guillian-Barre Syndrome
 - High CSF protein with normal glucose and cell count is seen =1 week from onset
   of symptoms. Protein is usually between 55 and 250 mg/dl.
 - Present in 80% of patients

þ Rx:
 - Plasmapheresis (4-5 50 mL/kg exchanges over 10-14 days). Improved outcome
   and more rapid recovery
 - IVIG (0.4 g/kg/day) for 5 days has similar efficacy and is the preferred 
   method because of greater convenience18-20. IVIG is also preferred in 
   pregnancy. Mechanism is thought to be antibody binding to anti-ganglioside 
   antibodies.
 - Plasma exchange or IVIG is indicated in patients that are unable to walk 
   unaided when therapy is initiated within 4 weeks
 - supportive (6-18 months)
 - Steroids debunked in recent study
 - gamma globulin as effective for plasma exchange