Functional and sensory evaluation of patients with idiopathic trigeminal neuralgia: comparison with controls

Idiopathic trigeminal neuralgia (ITN) can be associated with orofacial and sensory comorbidities.

To evaluate the masticatory functional and sensory characteristics of patients with ITN compared with controls.

We enrolled 119 patients and 30 healthy controls. They were evaluated with a systematic protocol: clinical orofacial evaluation questionnaire; a systematic approach of the mandibular function and the investigation of musculoskeletal comorbidities by the research diagnostic criteria for temporomandibular disorders (RDC/TMD) and the Helkimo indexes; and quantitative sensory testing (corneal reflex and gustative, olfactory, thermal, mechanical and pain thresholds).

The study group had more loss of vertical dimension than the controls (p=0.011) and restriction of the maximum mouth opening (p=0.024); they had more pain on mandibular movements (p=0.001), limitation of mandibular function (p<0.001), masticatory discomfort (p<0.001) and myofascial pain (p=0.001). Occlusion Helkimo index was lower in controls than patients. The study group had high tactile (p=0.025), warm (p=0.020) and cold (p=0.003) thresholds.

ITN may cause severe mandibular limitations that can be associated with the pain episodes and with sensory abnormalities. These findings indicate the affection of small and large nerve fibers and support the neuropathic nature of ITN. Sensory alterations can be part of the natural history of ITN and can be associated with the previous treatments including medication. They cause a high impact in quality of life.