'Subclinical MS': follow-up of four cases

Subclinical multiple sclerosis (S-MS) can be defined as the discovery of characteristic lesions at magnetic resonance (MR) or at autopsy, in the absence of clinical evidence consistent with MS. To describe four cases of S-MS cases followed-up with clinical and MR examinations.

The four patients were initially evaluated because of accidental MRI findings suggestive of MS that fulfilled the Barkhof criteria. At the moment of MR examination, patients were asymptomatic or complained of unspecific symptoms. The objective examinations as well as the clinical history were negative. An extensive diagnostic work-up excluded alternative diagnoses.

Case 1: 40-year woman undergoing MR examination due to trivial cervical trauma. The cerebrospinal fluid (CSF) analysis showed an IgG Index of 3.32 and presence of oligoclonal bands (OCB). New MR enhancing lesions were detected in the brain and cervical cord after 2 and 5 years. The patient remained clinically asymptomatic. Neuropsychological assessment (NPS) performed after 5 years revealed moderate deficits of attention/concentration and executive functions. Case 2: 35- year man, undergoing MR due to recent-onset headache. CSF analysis showed an IgG Index of 1.54 and presence of OCB. At baseline, NPS assessment revealed moderate deficit on complex attention tasks. New MR enhancing lesions were detected in the brain after 1 and 3 years. Four years after the first MR, the patient presented double vision with internuclear ophthalmoplegia. He fulfilled Polman's criteria for MS and he started interferon beta therapy. He remained stable at a 8-year follow-up. Case 3: 32-year man, undergoing MR due to brief loss of consciousness following neck hyperextension. CSF analysis showed absence of OCB and normal IgG Index. At baseline, NPS assessment revealed mild deficits of attention and executive functions. Over a 5-year follow-up the subject remained asymptomatic and MR was unchanged. Case 4: 40-year woman, sister of an MS patient. MR was required during a period of marked tiredness taking into account the family history. The patient did not present any relevant symptoms and MRI remained unchanged over a 6-year follow-up. NPS evaluation performed after 7 years showed moderate impairment of memory, attention and executive functions.

With the increased use of MR, S-MS cases can be identified more often. In our series, despite the absence of any typical symptoms, an NPS assessment detected cognitive impairments consistent with those reported in MS.