| Part one:The anatomic abnormality of cervical spinal canal in adult patients with Chiari I malformation and syringomyelia,and its relationship with syrinxsObjective:To compare the anatomic features of the cervical spinal canal in adults with Chiari I malformation and syringomyelia(CMS)versus age-and gender-matched controls,and to explore the relationship between syrinx size and the cervical spinal canal dimensions.Methods:A total of 48 adult CMS patients(21 males and 27 females;mean age,24.6 years,range 18～47 years)treated at our center between January 2008 and June 2015 were retrospectively reviewed.A cohort of 48 age-and gender-matched healthy adults were selected as the control group.Transverse images parallel to each cervical vertebral body were constructed using multiplanar reconstruction with 64-slice spiral CT.Cross-sectional area(CSA)of the spinal canal was measured at the middle level of each cervical segment,and a linear trend line was fit by least-square regression to calculate the taper ratio of the cervical spinal canal.Taper ratios as well as CSA of the spinal canal were compared between the two groups at each cervical level.In the CMS group,CSA of the syrinx was also measured at each cervical level on MR images,and the correlation between the CSAs of spine canal and the syrinx was analyzed.Results:Syringomyelia was most frequently located at the levels of C4 to C7 in patients with CMS.At each cervical level from C3 to C7,CAS of the spinal canal in the CMS group was significantly larger than in the control group,and a significant positive correlation was found between the area of syrinx and CS A of the spinal canal at each segment level(r=0.676～0.765,P<0.001).Taper ratios for C1-C4,C4-C7,and C1-C7 averaged-58.5±29.9,-0.1 ±7.3,-25.6±6.8 mm2/level,respectively,in the control group,compared to-54.7±33.2 mm2,8.8±13.5mm2,-15±16.4 mm2/level in the CMS group.The C1-C4 taper ratio did not differ significantly between the two groups,whereas C1-C7 and C4-C7 taper ratios were,respectively,smaller and greater in CMS patients as compared to their normal counterparts.Conclusion:Adults with Chiari I malformation have regional enlargement of the cervical spinal canal at the level of syrinx,along with steeper C4-C7 tapering as compared to healthy controls.The cross-sectional area of the spinal canal is significantly correlated with the size of syrinx at the same level,suggesting that syringomyelia may affect the development of the cervical spinal canal in patients with Chiari I malformation.Part two:Genetic analysis of posterior cranial fossa morphology in families of Chiari malformation type ⅠObjectives To explore if there are similar posterior cranial fossa abnormalities between Chiari malformation Type Ⅰ(CMI)patients with their parents,as compared to normal controls.Methods A total of 47 CMI families collected by our center from April 2010 to May 2016 were retrospectively reviewed,including 47 CMI patients(CMI group)and their 94 parents(CMI-P group).Another cohort of 50 asymptomatic adults was enrolled to serve as the control group.Patients with skull fracture or other diseases which can lead to secondary CMI were excluded.On mid-sagittal T2-weighted magnetic resonance(MR)imaging,four measurements were evaluated and compared between these three groups,including the length of cerebellar tonsillar descent,the area of posterior cranial fossa(PCF area),the area of the brain tissue in posterior cranial fossa(PCF tissue area),and the PCF crowdedness indexes(PCF tissue area/PCF area×100%).Results Totally 47 CMI patients(21 males and 26 females;mean age,16.4 years),94 parents(47 males and 47 females;mean age,39.2 years)and 50 controls(23 males and 27 females;mean age,22.3 years)were recruited in this study.Significant differences in all four indexes were found between CMI group and the control group.The length of cerebellar tonsillar descent were much bigger in CMI-P group than in the control group(1.8±1.6mm vs-0.9±1.1mm),with 7 cases reach the diagnostic criteria of Chiari malformation(≥5mm)and one with syingomyelia.Compared to the control group,CMI-P group had smaller PCF area,and its PCF crowdedness indexes averaged 90.6%as between the control group(85.9%)and the CMI group(93.9%).Conclusion In CMI families,parents have similar posterior cranial fossa abnormalities with their CMI children,presenting obviously narrow and crowded.Their PCF crowdedness indexes are between normal subjects and CMI patients,and their cerebellar tonsils are lower,even some parents are also CMI patients,suggesting genetic mechanisms involved in the development of CMI.Part three:The intraoperative neurophysiological monitoring abnormality in an achondroplasia patient with scoliosis and severe spinal stenosisThe importance of intraoperative neurophysiological monitoring(IONM)during orthopaedic spinal surgery is well recognized,however few study has report its application in achondroplasia patient.We report a case of successfully avoiding nerve injury in surgery of achondroplasia with scoliosis and severe spinal stenosis through the IONM dynamic monitoring.The patient is a 11 years old girl who underwent an initial posterior spinal correction and arthrodesis with instrumentation for achondroplasia with scoliosis.Preoperative CT and MRI showed that there were multiple segments of T12-S1 spinal stenosis.Then the whole operation procedure was performed under the IONM dynamic monitoring.The SSEPs and TCeMEPs amplitudes of both lower limbs significantly decreased and disappeared rapidly when we distracted the rod in concave side.Immediately,we performed T12-L5 whole laminectomy decompression,and then the SSEPs and TCeMEPs signals of both lower limbs returned to normal gradually.There were no neurological symptoms remained after surgery.This case suggested that we should fully evaluate the extent of spinal stenosis before performing orthopedic surgery in patients with achondroplastic spinal deformity.We recommend that the laminectomy should be performed with the orthopedic surgery in patients who have a marked imaging stenosis.In this case IONM effectively monitored the spinal cord and peripheral nerves and predicted the postoperative neurological function.So It has high application value in achondroplastic spinal deformity surgery. |
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