Walsh & Hoyt: Diagnosis

The diagnosis of clinically definite MS has traditionally required clinical documentation of two discrete demyelinating events separated in space and time. This clinical diagnosis is then supported by the results of neuroimaging and laboratory studies. The current diagnostic criteria for MS, developed by an international panel of experts, continue to require dissemination of lesions in time and space but formally incorporate specific MR imaging criteria of demyelination in the equation (the McDonald criteria). These diagnostic criteria may also be applied so that MS can be diagnosed in patients with a first clinical demyelinating event, called a clinically isolated syndrome. This term refers to an inflammatory, demyelinating syndrome of acute onset in the CNS, occurring in patients with no previous history suggestive of demyelinating events, and for whom appropriate investigations have excluded an alternative diagnosis. The most common types of clinically isolated syndromes are of great interest to neuro-ophthalmologists, and include acute optic neuritis and brainstem syndromes. Spinal cord syndromes are also a common form of clinically isolated syndrome. The identification of patients with clinically isolated demyelinating syndromes is highly relevant to neuro-ophthalmologic practice, particularly in light of evidence supporting early initiation of immunomodulatory therapy in this group of patients.