Subclinical Trigeminal Dysfunction in Multiple Sclerosis Detected by Pulp Sensibility Testing

Trigeminal involvement in multiple sclerosis (MS) may remain clinically silent despite measurable functional disturbance. Subclinical dysfunction of afferent pathways can precede overt neurological findings. We aimed to investigate whether pulp sensibility testing can detect subclinical trigeminal afferent dysfunction in patients with MS who have no clinical evidence of trigeminal neuropathy.

Thirty-nine patients with MS (19 relapsing-remitting and 20 progressive) and 27 healthy controls were included. Electric pulp testing (EPT) and cold stimulation were applied to the right maxillary central incisor in all participants. For EPT, sensory threshold values were recorded. For the cold test, response latency was measured in seconds. Correlation analyses were performed to assess associations with age and disease duration.

Compared with controls, patients with MS demonstrated higher EPT thresholds and prolonged cold response times. Within the MS cohort, both measures were greater in progressive disease. The difference reached statistical significance for cold testing (7.15±3.60 vs 4.89±2.58 s, p=0.038), whereas EPT values showed a similar but non-significant trend (9.80±4.15 vs 7.84±4.59, p=0.084). Age correlated weakly with cold response latency (r_s=0.321, p=0.046) and EPT values (r_s=0.326, p=0.043). Disease duration showed a weak correlation with EPT (r_s=0.334, p=0.037), but not with cold responses.

Despite the limitations of our study, our results indicate that pulp sensibility testing may provide meaningful information regarding the functional status of trigeminal afferent pathways. The more pronounced alterations observed in the progressive disease subgroup are consistent with cumulative conduction disturbance along the trigeminal system. Further studies directly comparing this approach with trigeminal SEP and high-resolution brainstem MRI are needed to better define its diagnostic value and clinical relevance.