The Calcitonin Gene-related Peptide And Substance P In The Patients With Trigeminal Neuralgia

Objective: To investigate the neuropeptides role in the pathogenesis of the primary trigeminal neuralgia,we measured the level of the calcitonin gene-related peptide(CGRP)and substance P(SP)in serum and cerebrospinal fluid in patients with primary trigeminal neuralgia.Methods: A total of 50 patients with primary trigeminal neuralgia who underwent 3D CT-guided percutaneous radiofrequency thermocoagulation of trigeminal ganglion from March 2015 to August 2015 were enrolled in our study.Patients who had undergone invasive management(balloon compression,glycerol rhizotomy,gamma knife,microvascular decompression surgery)and patients with facial pain other than due to TN were excluded from the study.Routine blood investigations were done preoperatively in all patients.Blood routine,coagulation routine,blood urea,serum creatinine,MRI of head were also obtained.Approval for the study was obtained from our Institutional Ethics Committee,and consent was obtained from patients.3ml cubital vein blood and 3ml external jugular vein ipsilateral to pain were obtained during the attacks of trigeminal neuralgia.Blood was collected into tubes prepared with both 7.5%EDTA-Na2 30μl and aprotinin 1500 kiu,centrifuged at 4℃3000 r/min for 10 min,then the serum was aliquoted into vials and stored at-70℃ in a refrigerator.All patients underwent RFT by a single surgeon.The operation was performed under three-dimensional image reconstruction of computerized tomography guidance.Hartel’s markings were drawn over the face with marking pencil,and the point of entry of the needle was usually 3 cm lateral to the angle of mouth.Two other points are(1)medial margin of pupil(2)a point 2.5 cm anterior to tragus on the zygomatic arch to serve as planes for diverting needle to foramen ovale.Once the needle reached the skull base,screening head CT was performed and to achieved the threedimensional image to confirm the relationship of the localization of needle tip and the foramen ovale.According to the three-dimensional image,the needle would be adjusted to directing to the foramen ovale.In all cases the successful entry into foramen ovale was achieved.Cerebral spinal fluid 0.5ml in Meckel’s SAC was achieved in 21 patients.After operation,the external jugular venous blood was obtained again.Blood was collected into tubes prepared with both 7.5%EDTA-Na2 30μl and aprotinin 1500 kiu,centrifuged at 4 ℃ 3000r/min for 10 min,then take supernatant.Serum was aliquoted into vials and stored at-70 ℃ in a refrigerator.The patients were assessed with the VAS preoperatively and postoperatively.The content of CGRP and SP were determined by radioimmunoassay.SPSS17.0 software was used for all the data analysis.Results: The VAS score was 8.0±0.5 before operation,and the operations in all patients were performed successfully,postoperative VAS scores were 0.The concentration of CGRP in preoperative external jugular venous serum was(120±30)pg/ml,and reduced to(100±27)pg/ml after operation,the difference was statistically significant(P<0.01).The concentration of CGRP in preoperative cubital jugular venous serum was(90±29)pg/ml.There was no correlation between the concentration of CGRP in preoperative external jugular venous blood and in cubital venous.The concentration of CGRP in CSF was(137±25)pg/ml,there was a positive correlation between the concentration of CGRP in preoperative external jugular venous serum and in CSF(P<0.01).There was no correlation between the concentration of CGRP in preoperative cubital venous blood and in CSF.The concentration of SP in preoperative external jugular venous serum was(54±7)pg/ml,and reduced to(44±6)pg/ml after operation,the difference was statistically significant(P<0.01).The concentration of SP in preoperative cubital jugular venous serum(46±8)pg/ml,there was no correlation between the concentration of SP in preoperative external jugular venous serum and in cubital venous.The concentration of SP in CSF was(59±7)pg/ml,there was a positive correlation between the concentration of SP in preoperative external jugular venous serum and in CSF(P<0.01).There was no correlation between the concentration of SP in preoperative cubital venous serum and in CSF.There was no correlation between the concentration of CGRP and SP in preoperative external jugular venous blood.Conclusions: The preoperative concentration of CGRP,SP in external jugular venous serum was higher than that of postoperative.CGRP and SP indeed participate in the attack of trigeminal neuralgia.The concentration of CGRP,SP in preoperative external jugular venous serum can be tested for those in CSF.