Diagnosis of multiple sclerosis.

There is no pathognomonic symptom, sign, or paraclinical result that provides an unfailingly accurate diagnosis of multiple sclerosis (MS), and hence, MS remains largely a clinical diagnosis. However, being a clinical diagnosis does not mean that the diagnosis of MS is one of exclusion. Increasingly sophisticated guidelines and objective paraclinical findings are generally sufficient to allow the clinician to confirm or rule out the diagnosis with confidence. This article presents the most recent guidelines for using clinical, radiological, and other paraclinical information and the red flags that should alert the clinician to investigate other diagnostic possibilities.