Multiple Sclerosis Mimics

Abstract

Although the course of the disease in all MS patients is different, most MS patients present in fairly straightforward manner, so that the diagnosis is usually made soon after first presentation to a neurologist. However, sometimes the diagnosis is incorrect, either because the patient has another disease process and MS is mistakenly diagnosed, or less commonly because the patient has MS and another diagnosis is erroneously made. This chapter discusses the diseases that most commonly mimic MS. The confusion usually occurs at the time of the first neurological event, clinically isolated syndrome (CIS), rather than in patients who have had previous events. CIS, as previously discussed in Chaps. 4 and 5, is the sudden development of a demyelinating and inflammatory event, consistent with a first attack of MS, that does not meet criteria for clinically definite MS. Thus, optic neuritis or myelitis or a hemisensory syndrome in a young, previously healthy individual might be CIS or one of the other diseases outlined in the chapter. If the patient with CIS develops new MRI lesions or has new attacks, the diagnosis of MS is much less difficult. Some issues and difficulties involved in differential diagnosis of the CIS patient are highlighted in a recent clinical review of six German patients with CIS [2]. Some examples of diseases that have clinical, imaging, or CSF characteristics similar to MS are summarized in Table 6.1. Finally, not all symptoms localizing to the CNS in patients with known MS should automatically be assumed to be a new attack of MS, as exemplified by the patient in Inset 6.1.