1. process is patchy and not all nerves are affected. Distal latencies may be increased to as much as three times normal. Use of F-wave responses often gives a good indication of slowing over proximal portions of the nerve trunks and roots. Up to 20 percent of patients will have normal conduction study results. Results of conduction studies may not become abnormal until several weeks into the illness.

  1. Features Casting Doubt on the Diagnosis

  1. Marked, persistent asymmetry of weakness.

  2. Persistent bladder or bowel dysfunction.

  3. Bladder or bowel dysfunction at onset.

  4. More than 50 mononuclear leukocytes/mm3 in CSF.

  5. Presence of polymorphonuclear leukocytes in CSF.

  6. Sharp sensory level.

  1. Features That Rule out the Diagnosis

  1. A current history of hexacarbon abuse (the volatile solvents n-hexane and methyl n-butyl ketone). This includes huffing of paint lacquer vapors or addictive glue sniffing.

  2. Abnormal porphyrin metabolism indicating a diagnosis of acute intermittent porphyria. This would manifest as increased excretion of porphobilinogen and d-aminolevulinic acid in the urine.

  3. A history or finding of recent diphtheritic infection, either faucial or wound, with or without myocarditis.

  4. Features clinically consistent with lead neuropathy (upper limb weakness with prominent wrist drop; may be asymmetrical) and evidence of lead intoxication.

  5. The occurrence of a purely sensory syndrome.

  6. A definite diagnosis of a condition such as poliomyelitis, botulism, hysterical paralysis, or toxic neuropathy (e.g., from nitrofurantoin, dapsone, or organophosphorus compounds), which occasionally may be confused with Guillain-Barré syndrome.

Vaccinations are an infrequent antecedent event in patients with GBS, probably occurring in less than 1 to 5 percent of all cases. In most large series of GBS, recent vaccination either is not mentioned or is described in an occasional person. Hankey (1987) noted that 5 of 109 subjects had recently been vaccinated (two with diphtheria and tetanus toxoids and pertussis vaccine [DPT] and one each with rubella vaccine, tetanus toxoid, and cholera and typhoid vaccines). Winer and colleagues (1988) noted six recent vaccinees in a series of 100 consecutive cases of GBS, but they also found five recent vaccinees in the 100 case controls.

Vaccinations have also had major public policy implications in relation to GBS. In the swine flu incident of 1976-1977 (Langmuir et al., 1984;

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