Spinal trigeminal neurons demonstrate an increase in responses to dural electrical stimulation in the orofacial formalin test

Primary headaches are often associated with pain in the maxillofacial region commonly classified under the term “orofacial pain” (OFP). In turn, long-lasting OFP can trigger and perpetuate headache as an independent entity, which is able to persist after the resolution of the main disorder. A close association between OFP and headache complicates their cause and effect definition and leads to misdiagnosis. The precise mechanisms underlying this phenomenon are poorly understood, partly because of the deficiency of research-related findings. We combined the animal models of OFP and headache—the orofacial formalin test and the model of trigeminovascular nociception—to investigate the neurophysiological mechanisms underlying their comorbidity. In anesthetized rats, the ongoing activity of single convergent neurons in the spinal trigeminal nucleus was recorded in parallel to their responses to the electrical stimulation of the dura mater before and after the injection of formalin into their cutaneous receptive fields. Subcutaneous formalin resulted not only in the biphasic increase in the ongoing activity, but also in an enhancement of neuronal responses to dural electrical stimulation, which had similar time profile. These results demonstrated that under tonic pain in the orofacial region a nociceptive signaling from the dura mater to convergent trigeminal neurons is significantly enhanced apparently because of the development of central sensitization; this may contribute to the comorbidity of OFP and headache

An easy schedule for postsurgical radioiodine administration in newly diagnosed differentiated thyroid carcinoma patients

OBJECTIVE: To validate the simplest approach to preparing patients with differentiated thyroid carcinoma (DTC) for (131) I-administration ((131) I-A), minimizing the impact of hypothyroidism. DESIGN: Panel study. PATIENTS: Ninety patients with DTC were enrolled in the study. Sixty (Group A) underwent total thyroidectomy (TT); L-T4 was not administered in preparation for (131) I-A planned for 3 weeks later. Thirty patients (Group B) with previous TT and (131) I-A stopped L-T4 in preparation for clinical evaluation, including whole-body scanning (WBS)/radioiodine therapy during thyrotrophin (TSH) stimulation planned for 3 weeks (or more) later. MEASUREMENTS: Thyrotrophin was measured the day before TT for group A, during L-T4 for group B (baseline-time 1) and then every week until it reached ≥ 30 mIU/l (time 2). Quality of life (QoL) was evaluated by Billewicz index. RESULTS: At week 3, 100% of patients in group A and 56.6% of group B exceeded TSH > 30 mIU/l. In group B, the cut-off was achieved in four patients at the fourth week (TSH 38.6 ± 8.7 mIU/l), in 3 at the fifth (53.2 ± 3) and in 6 at the sixth (42.3 ± 6.1). From time 1 to time 2, total QoL scores were less affected in group A (percentage decrease: 105%) than in group B (218%). At time 2, the total score was >+19 in group A in 46 patients and in 30 in group B. In group A, TSH levels in the higher tertile of QoL (61 ± 6 mIU/l) were not different from those in the lower tertile (62.3 ± 11.1)(P > 0.1); similar results were seen in group B (69.3 ± 13.3 vs 62.9 ± 13.1)(P > 0.1). There was a positive correlation between the time to obtain TSH ≥ 30 mIU/l and total QoL scores. CONCLUSIONS: Quality of life scores were not affected by thyrotrophin was measured the day before TT levels as absolute values. A longer time to obtain TSH ≥ 30 mIU/l was positively correlated with worse scores of QoL. We suggest 3 weeks without therapy can be used as an easy schedule in patients who undergo TT for DTC