Diagnosis and differential diagnosis of multiple sclerosis.

No single test to diagnose multiple sclerosis is available, and its cause is unknown. The diagnosis relies on recognition of the clinical patterns of the disease as well as exclusion of other possible mimics. Waxing and waning neurologic deficits that localize to the CNS are the hallmark of the disease in most patients. The diagnosis can be supported by laboratory studies, including MRI of the brain and spinal cord, analysis of CSF, and evoked-potential studies of the visual and somatosensory pathways.