| Objective: Cervical spondylotic myelopathy(CSM) refers to the spinal cordand its accompanying vessels been oppressed or stimulated by outstandingintervertebral disc and osteophyte, Which can cause sensorimotor disorderunder the damage plane. The symptoms and signs of CSM includednumbness weakness of limbs, sense of walking on cotton, increased muscletone and tendon hyperreflexia, pathological character, etc. CSM is seen mostfrequently in50-70years old elderly patients, its pathogenesis is mainlyinclude congenital factors, dynamic factors, mechanical factors and vascularfactors, cervical instability is one of the dynamic factors of CSM. Lowcervical instability refers to cervical vertebral instability on or underC2-3section，which is one of the performance of cervical degeneration. Atpresent, it is generally believed that the cervical instability is a stage in theprocess of CSM. We chose two groups of patients, one group for themono-segmental CSM with cervical instability(unstable group), the othergroup for the mono-segmental CSM without cervical instability(stable group).Through the comparison of unstable and stable group, we want to investigatethe relationship between the mono-segmental CSM associated with instabilityof lower cervical spine and cervical MRI signal change and prognosis.Methods: Date of109cases patients with CSM who visited our hospitalbetween January2005and June2008were retrospectively analyzed, and theywere underwent anterior cervical disectomy and fusion (ACDF). Mean patientage was66.0±6.2years (range,47-78years). All the patients were performedcervical AP, lateral and extension-flexion X ray and magnetic resonanceimaging (MRI) examination. According to the existence of cervical instabilitypoints divided the patients into two groups: the CSM patients with cervicalinstability were classified as unstable group, while without cervical instability were classified as stable group. It is the standard of judging cervical instabilitythat translatory distance beyond3mm or angle changes beyond10degrees inlateral or extension-flexion X ray(Figure1).Using the Japanese orthopaedicassociation (JOA)17points scoring criteria, we evaluated patients ofpreoperative and postoperative neurologic status and compared the two groupswith the rate of postoperative JOA recovery, postoperative JOA recovery rate=(postoperative JOA score-preoperative JOA score)/(17-preoperative JOAscore)*100%. Comparing the two groups with the rate of postoperative JOArecovery, MRIT2weighted imaging spinal cord high signal level and theincidence rate, the number of returned patients and the time they came backdue to repeated symptoms or new symptoms caused by spinal cordcompression. JOA score of preoperative and6month after surgery,duration ofdisease, sensory hypoesthesia or disappear, Hoffmann sign, Babinski sign andtendon reflexes were recorded.Application of SPSS13.0statistical software for statistical analysis, allmeasurement data underwent F and normality test. The comparing of twogroups on age,preoperative JOA score, the rate of postoperative JOA recovery,duration, the degree of spinal cord compression and the number of signsapplied Mann-Whitney U nonparametric test because they did not obeynormal distribution. The comparing of two groups on gender and the incidencerate of spinal cord high signal in MRIT2weighted imaging using chi-squaretest. Multivariate linear regression was applied to analyze the correlation ofpostoperative JOA recovery rate with gender, age, preoperative JOA score,course of disease, the number of physical signs and high signal level of spinalcord. Inspection level of alpha=0.05.Results: There were35patients in unstable group and74patients in stablegroup. The former contained19male patients and16female patients, meanpatient age was (58.8±7.8) years, the latter contained41male patients and33female patients, mean patient age was (59.4±7.5) years, there was nosignificant difference of the gender or age between the two groups(P>0.05).Mean course of the disease of unstable group was (26.9±15.1) months, which was (17.0±9.9) months in unstable group, significant differences were shownbetween unstable group and stable group (Z=-5.623,P<0.001). Meanpreoperative JOA score of unstable group was (10.0±2.5) degrees, which was(11.2±2.4) degrees in unstable group, there were significant differences ofpreoperative JOA score between two groups (Z=-3.772,P<0.001). The rate ofpostoperative JOA recovery of unstable group was (55.6±14.9)%, which was(69.0±18.0)%in stable group, there were significant differences of the rate ofpostoperative JOA recovery between two groups (Z=-6.454,P<0.001). Inunstable group, there were30patients appear symptom of sensoryhypoesthesia or disappear,28cases showed sign of Hoffmann sign,17casesshowed sign of Babinski sign, there were65cases appeared sign of tendonreflex hyperfunction. Each patient at the same time accompanied by thenumber of signs for1in2cases,2in10cases，3in12cases and4in11cases.By the Mann Whitney U test of two independent samples, there weresignificant differences of the numbers of signs between two groups(Z=-4．779，P<O.001). Unstable group with high cord signal occurrence ratewas74．3％, while41．9％in stable group, the cervical spinal cord with highsignal on MRIT2weighted incidence between the two groups showedsignificant difference(χ2=21.535，P<0．001). In unstable group, the number ofreturned patients and the time they came back due to repeated symptoms ornew symptoms caused by spinal cord compression were that21months of1case,23months of1case,25months of1case,29months of1case,31months of1case,35months of1case and40months of1case. A total of7patients visited hospital again, the rate of visiting again was20%, the averagetime of visiting again was28.7months. While in stable group, the numbersand time of patients who visited hospital again were that42months of1caseand73months of1case, a total of2patients visited hospital again, the rate ofvisiting again was2.6%, the average time of visiting again was57.5months.By the Mann Whitney U test of two independent samples, there weresignificant differences of the time of the patients visiting again between twogroups (Z=-13.653, P<0.001). By applying of multivariate linear regression analysis, we get that the rate of postoperative JOA recovery is related withpreoperative JOA score, the course of disease and the numbers of clinicalsigns. The rate of postoperative JOA recovery is negatively related withpreoperative JOA score, which is positively related with the course of diseaseand the numbers of clinical signs.Conclusion: Patients suffering from cervical spondylotic myelopathyaccompanied by lower cervical instability, have higher incidence of highsignal in spinal cord in MRIT2WI, longer course of disease, more physicalsigns, and poorer postoperative recovery rate. |
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