Clinical Application And Experimental Study Of The Effects Of Radiofrequency Thermocoagulation On Cervical Intradiscal Pressure

PrefaceDiscogenic pain is caused by Intervertebral disc disorder such as the pain caused by intervertebral protrusion and rupture of fibrous ring.It is often related to the degeneration of intervertebral disc.Because of its high morbidity,it brings great burden to the social economy,and it has always been a tremendous challenge to medical workers.Traditionally we perform vertebral body fusion surgery,which is not only strictly confined to strict indications but also have a discrepancy on the effect(50-80%),on those failed to be cured by expectant treatment Although there are many researches on this issue,but there is not a long term follow-up observational report on it.Realizing the limitation of traditional therapy,a lot of intradiscal therapies aiming at reducing the intradiscal pressure were invented.Because of its virtues like diminutive wound,shortened surgery time,fast recovery and less complications,it is widely used to treat discogenic pain caused by intervertebral disc protrusion and the effective rate is 51～94%.As the target site is confined to certain area and the amount of vertebral pulp removed is hard to control,some cases showed signs of degeneration such as narrowed intervertebral space and lessened MRI signal after surgery.Radiofrequency themocoagulation is a new intradiscal technique comparing with those mentioned before.It was first used to treat low back pain by clinical doctors,because of its founction of denervation It is effective in more than 50-100% cases.It is easier to control than other minor wound techniques.The rearch found that keeping the central vertebral pulp not only improve the long term effect of intradiscal therapy,but also reduce the occurance of degeneration.The precision of RF themocoagulation in chosing target site makes it possible to keep the whole central vertebral pulp.Researches on the effect of temperature on intervertebral disc shows:when vertebral pulp heated become dehydrated.The intradiscal pressure will decrease.However,there is few research on the decompression effect of RF themocoagulation,especially research on the time dependent decompression effect.Our work is to evaluate the decompression effect on intradiscal pressure and its clinic potential through experiment and clinic research. Materials1.Experiment model10 fresh sheep cervical vertebral segments with intervertebral discs, each segment include 2 vertebrae and 1 intervertebral disc,5 of these segments were from＜2 years old goat,the rest were from＞5 years old.2.InstrumentsLeksell LNG30-1RF heat coagulation machine(ELERTA.Sweden),22G×14.4cm trocar(ELERTA.Sweden),2mmRF electrode client(ELERTA. Sweden),20G×15mm pressure measuring needle(Smith &nephew,USA),CDS system pressure measuring(Smith & nephew,USA).Methods1.GroupsVertebral segments from＜2 years old were labled as young group.Segments From＞5 years old were labeled as old group,which included 5 each.2.Experiment procedureExperiment model were fixed by the table clamp.Stab the pressure measure-ing needle with trocar into the wertebral nucleus,and connect with the CDS system pressure messuring machine,record the pressure as initial pressure after injecting 2ml saline water.Stab the RF thermocoagulation trocar into the vertebral pulp 2 cm alongside the measuring needle.Began thermocoagulation(85℃,120s),then plug out RF electrode needle,and record the pressure as treating pressure.It is needed to unload before pressure measuting.3 Statistics analyzationThe pressure level decreased is shown in percentage,formula as:pressure decreasion rate%=(initial pressure—treating pressure)/ initial pressure×100%,use t-test in SPSS 11.0 to analyze data aquired between groups,and the results are shown as(?)±S.P＜0.01are considered to be significant.ResultsThe percentage is 48.3600±0.64653 in young group,the old groups 32.3000±1.36565.The young group and the degenerated group are significantly different(P＜0.01).Conclusions85℃,120sRF thermocoagulation can decrease intradiscal pressure,but which is in negative correlation with the degeneration of intervertebral discs. Materials1.Animals9 sheep(2-3year),6 male,3 female.2.InstrumentsDSA(SHIMADZU,JAPAN),Leksell LNG30-1RF heat coagulation machine (ELERTA.Sweden),22G×14.4cm trocar(ELERTA.Sweden),2mmRF electrode client(ELERTA.Sweden),20G×15mm pressure measuring needle(Smith & nephew,USA),CDS system pressure measuring(Smith & nephew,USA).Methods1.Groups9 adult sheep were divided into 3 groups respectively named 2W,4W, 6W group.Each goat were performed RF thermocoagulation on two randomly chosen intravertebral discs which were divide into surgery and control groups.2.Preparing before performing RF heat coagulationAbsolute diet and water for 8h,Ketamine 10mg/Kg and Diazepamum 1 mg/kg before surgery.Shear off the hair around the neck(C1-Y1)and the right thigh.Confine the animal to be experimented on lying by one side.Take X-ray pictures for the cervical vertebrae(positions:normal,stretching,bending).Find 2 cervical intravertebral discs of normal intravertebral spaces.Then,take the dosal position, after local sterilization,fixed the RF circuit electrode on the right thigh.3.Measuring methodAfter local anaesthesia,puncture with pressure measuring trocar to the centre part of the disc(through about 2 third of the disc)between left carotid sheeth and trachea under the fluoroscopy.Then connect the measuring needle with CDS system pressure measuring machine,and began pressure measuring after injecting 2ml saline water. The pressure measured were recorded as primary pressure.Disc pressures were measured at 0 days,14 days,28 days and 42 days after RF electrodes were plug out(treating pressure).Each disc was measured for pressure only twice.4.RF thermocogulationAfter local anaesthesia,puncture with RF trocar to th centre part of the disc(near the pressure measuring needle)between right carotid sheeth and trachea under the fluoroscopy.perform thermocoagulation(85℃,120s)on the surgery group;perform all procedures except thermocoagulation on the control group.5.Statistical analysisThe pressure level decreased were shown in percentages.Formula:percentage of pressure decreasion%=(primary pressure-treating pressure)/prim-ary pressure×100%.The data aquired were analysed with t-test between groups,using SPSS11.0.the result were show in(?)±SD,P＜0.01 was considered to be significant.ResultsThe intrapressure of intravertebral discs decreased significantly in 6 weeks after performing RF thermocoagulation in surgery group.The percentage decreased is 21.55±0.81445%(at once),61.92±1.25033%(14d),55.17±1.43643%(28d),54.93±2.02574%(42d)respectively in surgery group;the control group are 4.88±0.98658%(at once),8.53±0.20000%(14d),30.89±1.06667%(28d),5.32±0.77675%(42d)respectively.Statistics analysis show the pressure change in between groups is significantly different(P＜0.01).ConclusionsRF thermocoagulation(85℃,120s)can effectively decrease the intrapressure of intravertebral disc in goat and maintain the pressure in 6 weeks. Materials and Methods1.Research targetsThere were 19 male and 12 female,tolal 31 Palients.The mean 46.1 years (range,26-64 years).The mean symptom duration was 14.5 months(3-60 months). The herniated cervical disc was 36,located in C_3-4(2),C_4-5(4),C_5-6(12), C6-7(9),C4-6(2),C5-7(2)respectively.2.InstrumentsDSA(SHIMADZU,Japan),Leksell LNG30-1RF heat coagulation machine (ELERTA.Sweden),22G×14.4cm trocar(ELERTA.Sweden),2mmRF electrode client(ELERTA.Sweden).3.Radiofrequency themocoagulationTake the lateral position,puncture with RF trocar between carotid sheeth and trachea under the fluoroscopy.If the protrusion are on the left or in the middle side,puncture should be on the right,if the protrusion is on the right side then the needle should follow the left pathway.place the trocar to the target position(the hinder margin of the vertebral body of the protruding disc)under the monitoring of C-arm X-ray machine,plug out the trocar,and place the electrode needle into the trocar sheeth,began the impedance test and the physiology test to make sure the electrode were placed into the vertebral pulp,and make sure no damage to the spinal cord.Perform radiofrequency therapy(92℃,180s).4.Evaluation methodsUsing the Visual Araloguse System(VAS)to evaluate pain intensity.Depending on improved Macnab standard to evaluate the curative effects,which are divided into 4 classes:excel-ent,good,mediocre,bad.The percentage of excellent and good to total cases is the satisfactoru rate.The degree of disc degereration and hernia size were evaluated by MRI.5.Staistical analysisThe datas were analyzed in spss11.0 soft-ware.The results were shown as (?)±s,using t test.P＜0.05 was considered to be singnificant.Results1.Clinical outcomeSymptom is improved at 29 cases after surgery at once.The VAS score befor surgery is 5.59±0.42.Decreased to 1.95±0.66 immediately after surgery,the difference was statistically(P＜0.01).After 3monehs follow-up,excellent and good rate is 87%.No side effects have been observed.2.Imaging outcomeThere are not remarkly change in grade of degenerate in 9 cases by MRI.Henia size are decreased in 6 cases.ConclusionsAlthough long term curative effects are to be evaluated through more experiments,the short term effects of Radiofrequency thermocoagulation is safe and effective way to cure cervical discal herniation.