Updated on 05/01/2024
Radiologically isolated syndrome (RIS) is the term used to describe the lesions detected incidentally on brain or spinal cord magnetic resonance imaging (MRI), performed for a different reason, without any relevant history or symptoms, which raise suspicion of multiple sclerosis (MS). The MRI is typically performed for an unrelated cause such as headache or trauma.
Further investigations are not necessary at the time of MRI in such individuals. However, it is important to monitor the development of clinical signs suggestive of MS. Some experts recommend cerebrospinal fluid analysis through lumbar puncture in some individuals to assess for MS.
Individuals with radiologically isolated syndrome have a risk of developing multiple sclerosis; however, limited information is available on this topic. Risk factors for the development of MS include:
1. Young age
2. Male gender
3. Lesions in the neck and back regions of the spinal cord
4. Temporal dissemination on MRI (i.e., presence of new lesions or lesions enhancing with contrast)
5. High lesion burden on MRI
6. Lesions in the cortical regions of the brain on MRI
7. Presence of oligoclonal bands in cerebrospinal fluid
8. Abnormal visual evoked potentials
9. Impairment of cognitive functions such as information processing speed and attention
Approximately 30% of individuals with radiologically isolated syndrome develop MS. Among them, 12% have the primary progressive type of MS.
Findings suggestive of alternative diagnoses include migraine or chronic headaches, epileptic seizures, recurrent symptoms, psychiatric symptoms, significant cognitive impairments, and head trauma. In such cases, there should be suspicion regarding the diagnosis of RIS, and detailed differential diagnostic investigations should be conducted.
The individual should undergo detailed neurological examinations every 6 months or whenever there are any symptoms, and be followed up with an annual MRI for a duration of 5 years.
Olec M.J, Howard J. Management of clinically and radiologically isolated syndromes suggestive of multiple sclerosis. Up to Date 2021