Specificity of Barkhof criteria in predicting conversion to multiple sclerosis when applied to clinically isolated brainstem syndromes

Background: Barkhof criteria have been adopted to demonstrate dissemination in space in the new multiple sclerosis diagnostic criteria because of their high specificity for predicting conversion to multiple sclerosis. One of the 4 Barkhof criteria is the presence of an infratentorial lesion. In clinically isolated syndromes (CIS) of the brainstem (CISB), the infratentorial criterion does not demonstrate dissemination in space, raising the possibility that the criteria may be less specific in CISB, as compared with specificity in other CIS, in which all 4 criteria demonstrate dissemination in space. Objective: To compare the validity indices of Barkhof criteria in CISB with those in other CIS. Design: Inception cohort with median follow-up of 34 months for CISB and 40 months for other CIS. Setting: Institutional ambulatory referral center. Patients: A sample of 51 patients with CISB and 102 patients with other CIS (46 with myelitis and 56 with optic neuritis) was analyzed. Barkhof criteria, with a cutoff of 3 of 4, were applied to magnetic resonance imaging performed at baseline. Four combinations each containing 3 parameters were also applied, with a cutoff of 2 of 3. Main Outcome Measure: Specificity of unmodified Barkhof criteria and of the 4 combinations to predict conversion to clinically definite multiple sclerosis. Results: The specificity of the criteria in CISB was 61% against 73% in other CIS. The combinations that retained the infratentorial lesion parameter had lower specificities in the CISB group; in analysis of the group with other CIS, no such differences were found. Conclusion: The infratentorial lesion criterion is responsible for the lower specificity of Barkhof criteria in CISB.