Neurophysiological follow-up of patients with celiac disease on gluten-free diet: a TMS study

Background and aims: A recent investigation showed that Transcranial Magnetic Stimulation (TMS) might disclose a subclinical neurological involvement in patients with celiac disease (CD). Here we aim to compare TMS measures before and after the gluten-free diet in order to monitor the observed changes and to assess the impact on the diet cortical excitability. Methods: A sample of 13 patients from the original cohort of 20 was re-evaluated after approximately 2 years of an adequate course of gluten-free diet. Antibodies were still present in 3 and were borderline in 2. A screening for cognitive and neuropsychiatric symptoms was repeated as well as the evaluation of cortical excitability by means of single and paired-pulse TMS from the first dorsal interosseous muscle of the dominant hand. Results: Compared to baseline, patients showed a significant decrease of the median resting motor threshold (34 vs 35%, p<0.01) and a shorter central motor conduction time (3.8 vs 4.8 ms, p<0.01). Depressive symptoms, quantified with the Hamilton Depression Rating Scale, improved (2.8 vs 5.6, p<0.01). Conclusion: A global increase of cortical excitability together with a faster conductivity along the cortico-spinal tract was observed in gluten-free diet patients, without significant changes of the other TMS measures found at baseline. These findings may represent a neurophysiological evidence that immune system dysregulation might persist despite the alimentary therapy, although the diet seems to enhance the excitability and conductivity of the central motor pathways. The impact of the gluten-free diet on subclinical neurological abnormalities needs to be further explored.