The masseteric inhibitory reflex in the diagnosis of multiple sclerosis

In order to evaluate the reliability of the masseteric inhibitory reflex (MIR) as a screening method in the diagnosis of multiple sclerosis (MS), a series of 41 consecutive patients affected by clinically defined, long-duration forms (mean duration 10.9 years) of the disease was examined. In all cases magnetic resonance imaging and CSF isoelectrofocusing confirmed the diagnosis. Sensitivity of MIR, Blink Reflex and BAEPs were compared. Statistical analysis of data suggested the following considerations: 1) a significant concordance was found between MIR and the other neurophysiological tests performed (MIR vs. BAEPs in 78.4% of cases, p < 0.001; MIR vs. blink reflex in 68.3%, p < 0.02). 2) The S1 early component of MIR is a more reliable indicator than S2 late component. 3) In detecting brainstem lesions the sensitivity of MIR equaled that of the other neurophysiological tests. 4) Poor localizing concordance between neurophysiological tests and neuroimaging was found in our series. A possible utilization of MIR, as a part of a multimodal neurophysiological approach, even in patients affected by possible or probable MS is suggested.