Cause Analysis Of Unsuccessful Myelography Of Patients With Spontaneous Intracranial Hypotension

Objective:1. To calculate the failure rate of the myelography in spontaneous intracranial hypotension(SIH) patients.2. To analyse the imaging findings of unsuccessful myelography include CT myelography(CTM) and gadolinium-enhanced MR myelography(Gd-MRM) in SIH.3. To analyse the clinical and imaging characteristics of SIH patients with unsuccessful myelography and to discuss the reason of those unsuccessful myelographies.4. To explore the value of CT-guided CTM in those SIH patients with unsuccessful myelography.Methods:1. Imaging findings of unsuccessful myelography in spontaneous intracranial hypotension:Myelography examinations of121patients with SIH between January2012and July2014were retrospectively reviewed, failure rate of the myelography was calculated and the image features of those unsuccessful myelography were analysed.2. Clinical and imaging characteristics of SIH patients with unsuccessful myelography:Imaging information of121patients with SIH between January2012and July2014was collected and the patients was divided into two groups. Patients with failure myelography experience were brought into A group and those with myelography examinations all successful were brought into B group. Extent of pachymeningeal enhancement, subdural fluid collection and downward displacement of the brain, Course,CSF pressure, BMI, dimensions and area dural sac on puncture level, CSF leaks and extradural CSF collections of the two groups were detected and compared.3. A preliminary study on CT-guided CTM in spontaneous intracranial hypotension:Radiology information of121patients with SIH between January2012and July2014was retrieved. Five patients underwent CT-guided CTMs. The process and images obtained from exams were retrospectively reviewed.Results:1. Imaging findings of unsuccessful myelography in spontaneous intracranial hypotension:128myelography examinations was done in these121patients with SIH. Contrast media was accidently injected into the epidural space in33examinations. The failure rate of the myelography in SIH was25.7%. In these33unsuccessful myelography examinations, spinal nerve roots on both sides of the dural sac passed through contrast media in33(100%) examinations, the anterior and posterior roots passed through contrast media can not be seen in33(100%) examinations, cauda equina passed through contrast media can not be seen in29(87.9%)examinations, contrast media can not diffuse into cisterns and ventricles in26(78.8%) examinations, contrast at cervical and thoracic level was not continuous in16(48.5%), contrast density or signal intensity in intraspinal canal was heterogeneous in10(30.3%), inner contour of contrast was not smooth in4(12.1%).2. Clinical and imaging characteristics of SIH patients with unsuccessful myelography:In these121SIH patients,32patients were brought into A group (with failure myelography experience) and89patients were brought into B group (with myelography examinations all successful). The differences of CSF pressure, pachymeningeal enhancement and subdural fluid collection between these two groups were significant (P<0.05). CSF pressure in A group was lower, pachymeningeal enhancement was more obvious and subdural fluid collection more severe.While no significant differences were observed with course, BMI, downward displacement of the brain, dimensions and area dural sac on puncture level, CSF leaks and extradural CSF collections (P>0.05).3. A preliminary study on CT-guided CTM in spontaneous intracranial hypotension:In the5patients with CT-guided CTM, collapse of the dura sac and focal indentation under the needle tip were observed in three cases. In two cases of these three cases, the needle failed to penetrate the dura matter, leading to failure of the myelographic procedure.Conclusion:1. The failure rate of the myelography in spontaneous intracranial hypotension(SIH) patients was25.7%which is relatively high.2. According to the imaging features of unsuccessful myelography, correct judgment of the success or failure of CTM and Gd-MRM in SIH can rapidly made.3. Low pressure of the dural sac and low tension of the dura which induce focal indentation of dura under the needle tip are key reasons why lumbar puncture could be challenging in patients with SIH and why the incidence of unsuccessful myelography is comparatively fairly high.4. While CT-guided CTM can enable better observations of needle positioning, dural sac shape, and the lumbar puncture process, unsuccessful myelography may still occur.