https://doi.org/10.14245/kjs.2017.14.4.133 KJS Print ISSN 1738-2262 On-line ISSN 2093-6729 CLINICAL ARTICLE Korean J Spine 14(4):133-138, 2017 www.e-kjs.org Myelography in the Assessment of Degenerative Lumbar Scoliosis and Its Influence on Surgical Management George McKay, Objective: Myelography has been shown to highlight foraminal and lateral recess stenosis more Peter Alexander Torrie, readily than computed tomography (CT) or magnetic resonance imaging (MRI). It also has the Wendy Bertram, advantage of providing dynamic assessment of stenosis in the loaded spine. The advent of weight-bearing MRI may go some way towards improving assessment of the loaded spine Priyan Landham, and is less invasive, however availability remains limited. This study evaluates the potential Stephen Morris, role of myelography and its impact upon surgical decision making. John Hutchinson, Methods: Of 270 patients undergoing myelography during 2006-2009, a period representing Roland Watura, peak utilisation of this imaging modality in our unit, we identified 21 patients with degenerative Ian Harding scoliosis who fulfilled our inclusion criteria. An operative plan was formulated by our senior author based initially on interpretation of an MRI scan. Subsequent myelogram and CT myelogram Department of Spinal Surgery, investigations were scrutinised, with any additional abnormalities noted and whether these im- Southmead Hospital, Bristol, United pacted upon the operative plan. Kingdom Results: From our 21 patients, 18 (85.7%) had myelographic findings not identified on MRI. Of Corresponding Author: note, in 4 patients, supine CT myelography yielded additional information when compared to George McKay supine MRI in the same patients. The management of 7 patients (33%) changed as a result Department of Spinal Surgery, of myelographic investigation. There were no complications of myelography of the total 270 Southmead Hospital, Southmead Road, Westbury-on-Trym, Bristol, analysed. BS10 5NB, United Kingdom Conclusion: MRI scan alone understates the degree of central and lateral recess stenosis. In addition to the additional stenosis displayed by dynamic myelography in the loaded spine, Tel: +44-117-950-5050 we have also shown that static myelography and CT myelography are also invaluable tools E-mail: [email protected] with regards to surgical planning in these patients. Received: August 2, 2017 Revised: October 25, 2017 Key Words: Degenerative, Deformity, Myelography, Imaging, Magnetic resonance imaging Accepted: November 6, 2017 sessment and preoperative planning4). More re- INTRODUCTION cently improved availability of computed tomo- graphy (CT) and magnetic resonance imaging The prevalence of degenerative lumbar sco- (MRI) has resulted in a reduction in the use of liosis (DLS) has been reported to range between myelography as a diagnostic tool. These imaging 3.14%-68%8,13,24,28,30), and is known to increase modalities provide cross sectional information with advancing age13,14,18,20). The clinical pre- and are often considered relatively ‘low risk’ sentation and demands of this patient cohort investigations by most clinicians. The available is broad, heterogeneous and often and asso- literature presents mixed conclusions on the ciated with complex local deformities (antero, value of myelography compared with these retro, lateral, and rotational listheses). Poten- other imaging modalities and will be discussed tially treatable, these can be mobile or fixed, in this work. and may cause dynamic or static stenosis. This We sought in particular to assess what, if makes decision-making and operative planning any, additional information that was conveyed by dynamic myelography and subsequent su- Copyright © 2017 by The Korean a complex challenge. Spinal surgeons must con- Spinal Neurosurgery Society sider the merits of limited versus extensive de- pine CT myelography when compared to find- This is an open access article distributed compression, whether to perform short or long ings obtained on supine MRI. Additional data under the terms of the Creative Commons fusion, and what combinations of these are ap- was collected regarding complications of mye- Attribution Non-Commercial License (http://creativecommons.org/licenses/by- propriate in each individual patient. lography, and how any additional findings of nc/4.0/) which permits unrestricted non- In the era before 3-dimensional imaging, myelography changed management. As a result commercial use, distribution, and reproduction in any medium, provided the myelography was historically described as “an of this we propose criteria for requesting mye- original work is properly cited. essential preoperative measure” for patient as- lography in the setting of degenerative scoliosis. Korean J Spine Volume 14 | Number 4 | December 2017 | 133 McKay G et al. investigation, recording also the position of the patient (supine, MATERIALS AND METHODS prone, weight bearing, and stress) in which the radiological find- ings where observed. We retrospectively reviewed the MRI lumbar spine and mye- The results of MRI scanning were then compared with the lography imaging of all patients in our practice between 2006 results of myelography in the MDT. Significant differences were and 2009, a period representing peak utilisation of this imaging noted, for example; absence of stenosis or spondylolisthesis on modality in our unit. Following identification of our patient co- MRI investigation but objective evidence on myelography. All hort the medical notes of each suitable patient were reviewed, patients undergoing dynamic myelography subsequently under- including electronic outpatient clinic letters and Multidisciplinary went supine CT myelography as part of our units’ myelography Team (MDT) meeting documentation. The study inclusion crite- protocol. Significant anatomical findings were also collated from ria were; patients older than 45 years of age, presence of a DLS, this CT and compared with MRI lumbar spine investigations patients with MRI lumbar spine and myelography investigations in a similar fashion to the plain film myelography. performed within 12 months of one another, and patients who Any change in this operative plan following myelography was following this received operative intervention. In addition, clear noted. If patients with intrusive symptoms were being inves- documentation regarding investigation findings and the decision tigated by myelography in search of a surgical target due to a pre- making process following MRI scan and then subsequent to mye- viously entirely “normal” MRI scan, this was also noted. lographic intervention was essential, and this was obtained by Each myelogram was performed or supervised by the con- thorough review of patient notes or electronic clinic letters. A sultant musculoskeletal radiologists within our department. Pati- surgical plan must have been clear at both of these time points. ents were fully consented, the procedure was explained to the This limited the number of patients included in the study signifi- patient including the commonest complications and side effects cantly, but this was offset by our ability to ensure that there (including; headaches, cerebrospinal fluid leak, infection, bleed- was a clear change to patient management due to the addition ing, amongst others). Written consent was obtained. A detailed of myelographic investigation. Nursing Procedure Care Plan was carried out and the details The presence of a DLS was determined by evidence of coronal were recorded. plain deformity of greater than 10° between the superior end- The procedure was carried out using fluoroscopic guidance plate of L1 to the superior endplate of S1 on the standing ante- with the patient positioned prone. Full aseptic technique was ro-posterior (AP) plain film lumbar spine radiograph. used. Local anaesthetic in the form of plain Lidocaine (1%) was For all of the patients in our cohort the indication for myelog- infiltrated to anaesthetise the skin. A 22-G spinal needle was ad- raphy was the presence of neurological symptoms not explained vanced between the spinous process at a level below the conus, by other available imaging modalities in the setting of DLS. All depending on review of previous imaging. Lateral view fluoro- patients were being considered as potential operative candidates scopic screening was performed to assess needle depth. Contrast during the period of investigation and all received operative inter- was injected to confirm needle position (Omnipaque 240). A total vention when investigations were complete. Since the indications of 8-mL contrast was then injected. for both myelographic investigation and MRI scanning predated Screening views were taken supine, supine right and left obli- our study, we did not require approval from our Institutional que, plus lateral. Then varying degrees rising for example 30 Review Board or Ethics Committee. Other indications for mye- and 45 degrees - supine, supine right and left oblique. This was lography in our unit include patients with metalwork in whom followed by erect supine, supine right and left oblique, then neural structures are not well seen due to artefact and rarely, bending right and left lateral, and finally sagittal view erect plus the unexplained radicular pain in the presence of a normal su- forward flexion and extension. pine static MRI and standing X-ray. Patients then proceeded to CT - (images plus reconstructions) In terms of the surgical decision making process, each case axial, coronal, sagittal.