Multiple sclerosis. The problem of incorrect diagnosis.

Various neurologic disorders may be diagnosed incorrectly as multiple sclerosis (MS) since there is no test that is entirely specific for the disease. We report ten patients who met clinical criteria for probable or definite MS and who were given incorrect diagnoses. All of the patients were subsequently shown to have alternative diagnoses, three of which were directly treatable. From these illustrative cases, five characteristics were identified that alerted us to the possibility of an alternative diagnosis. We have called these characteristics "red flags," and suggest that they may be useful as features casting doubt on the diagnosis of MS if used judiciously in conjunction with clinical diagnostic criteria.