Sources of error in the diagnosis of Guillain-Barre syndrome.

A careful monitoring of the accuracy of diagnosis in six cases of Guillain-Barre syndrome has shown that a substantial proportion of these patients initially diagnosed as having Guillain-Barre syndrome on the basis of characteristic clinical findings and an elevated level of protein in the spinal fluid had a neuropathy caused by another etiology. The pitfalls in the laboratory and clinical diagnosis of disorders that were confused with Guillain-Barre syndrome were several: the pattern of neurological dysfunction in the Guillain-Barre syndrome was not unique to that disorder; no specific laboratory test existed to confirm the diagnosis of Guillain-Barre syndrome; and the laboratory diagnosis of other causes of similar neurological disorders (especially heavy metal intoxication) depended upon tests that are very unreliable.