Application Of Optical Coherence Microscopy In The Diagnose Of Tight Filum Terminal Syndrome

BackgroundTight filum terminale syndrome(TFTS)was a special kind of tethered cord syndrome(TCS)that easily missed diagnosis and misdiagnosis.It means that the filum terminale(FT)had pathological changes like fibrosis or adipose infiltration,which resulted in the dragging to the conus medullaris,then the conus medullaris was ischemic and hypoxia,finally resulted in nervous lesion,which led to the bowel and bladder dysfunction,deformity of the lower limbs and sensory dysfunction.Many children present the cutaneous stigmata of spinal dysraphism at sacrococcygeal,MRI showed the FT shorter,thicker,fatter and low-lying conus medullaris.While some children only had neurological damage symptoms,the diagnose was difficult by MRI examination,and delayed treatment may result in clinical symptoms deterioration.Histological changes of the FT could not be directly diagnosed before surgery,mainly depends on the postoperative pathology,which is currently the problem to be solved.OCT was a novel imaging technique that performs non-invasive and high-resolution fast images of the internal microstructure in materials and biologic systems.It has been applied to the clinical diagnosis of ophthalmology,gastrointestinal,cardiovascular and skin diseases.The advantage was that it could be checked in vivo,rapid intraoperative diagnosis,make up for deficiencies of current inspection.Optical coherence microscopy(OCM)is an imaging technique that combines the advantages of OCT and confocal microscopy to achieve cell resolution.At present,the study of TFTS is mainly based on MRI,electron microscopy,light microscopy,immunohistochemistry and other morphological observation,There was no report on the application of OCM to TFTS.ObjectiveIn this study,OCM was used to scan in vitro FT specimens of children with TFTS and fetus without spinal cord neurological diseases.The internal structure images of the FT were obtained and compared with routine examination.We hope that OCM could replace conventional histopathological examination in some respects to a certain extent.And to provide the basis for the clinical application of OCM in vivo in the diagnosis of TFTS and confirm the extent of surgical resection.MethodFifteen children who were diagnosed as TFTS in the Third Affiliated Hospital of Zhengzhou University during the period from December 2015 to June 2016 and five new birth died fetuses without spinal cord disease were included in the study.All the patients and fetus underwent whole spinal MRI examination preoperative.The FT in vitro were collected for OCM scanning,and then the routine histopathological examination.The coincidence degree of the two methods was analyzed,and the results of routine examination of normal FT and TFTS were compared.Results1.General observation: The FT of eight children with abnormal MRI performance had adipose degeneration and shorter,thicker,the diameter of the starting point of FT was?2mm,the color was pale or yellow and elasticity decreased,the end of the CM was below L2.Seven FT had normal diameter and level,but the FT was bow-like tension.The diameter of fetus FT were below 1.5mm and the CM was above L2,the appearance was slightly redness.2.Routine histopathological examination outcome:A large amount of adipose cell was observed under the light microscope,and the number of blood vessels in the interstitial was increased.Fibrous degeneration and nerve cells was seen in some FT.Those changes mentioned above were still exhibited in the TFTS with normal appearance,but slightly relatively.The middle and distal FT of fetus was loose connection tissue that was composed of bulk fibers and sparse micrangiums,there was no adipose cell.3.OCM scanning outcome: OCM scanning could clearly showed the internal structure of the FT and had highly coincidence degree with routine examination.The lesion FT of TFTS showing a large number of adipose cells with loose mesh-like structure,during which vascular-like tissue,nerve cells and disordered fibrous tissue could be seen.In the fetus FT showed strong refraction fiber bundles,fiber bundles between interstitial refraction weak.The results of OCM scan and routine histopathological examination showed statistical significance in finding the pathological changes of the FT,and the image of the two methods was highly coincide.Conclusion1.OCM scanning could clearly show the internal structure of the FT and significantly distinguish the pathological changes of lesions filum terminale and normal filum terminale.Partial OCM scan images were highly consistent with pathological findings.2.The positive rate of OCM scan for the diagnosis of FT was in agreement with the routine histopathological examination outcome.