Transcranial magnetic stimulation in Behçetʹs disease: a cross-sectional and longitudinal study with 44 patients comparing clinical, neuroradiological, somatosensory and brain-stem auditory evoked potential findings

Objectives: To compare neurological involvement in Behçetʹs disease as documented by transcranial magnetic stimulation (TMS) with clinical, neuroradiological, somatosensory (SEP) and auditory evoked potential (BAEP) findings. Methods: Forty-four patients were studied over an 8 year period. Nine patients had follow-up studies done. TMS central motor conduction (CMC) studies to upper and lower limb muscles, brain magnetic resonance imaging (MRI), SEP, and BAEP testing were conducted. Results: Thirty-nine patients had CMC slowing, decreased amplitude or absent motor evoked potentials (MEP); 5 of these patients were neurologically normal. Concordance of TMS results, clinical deficits, and MRI findings occurred in 36 of the 39 patients. SEP and BAEP testing proved non-complementary to MEP. Generally, follow-up studies revealed faster CMC and higher MEP amplitude. However, in two patients the CMC time to one target muscle became prolonged with diminished MEP amplitude over a period of 1.5–3 years. Conclusions: TMS can be useful in detecting and quantifying motor tract dysfunction in Behçetʹs disease and provides functional information complementary to imaging studies. TMS is more sensitive than either SEP or BAEP. Our longitudinal studies suggest that TMS studies may be valuable in monitoring disease activity or therapeutic response.