MRI in management of suspected cervical spondyloticmyelopathy · MRI as the initial imaging technique. The aim was to discover if clinicians could manage patients with MRIalone, or

Journal of Neurology, Neurosurgery, and Psychiatry 1991;54:484-489

MRI in the management of suspected cervicalspondylotic myelopathy

P F Statham, D M Hadley, P Macpherson, R A Johnston, I Bone, GM Teasdale

AbstractOne hundred and two patients with sus-pected cervical spondylotic myelopathywere prospectively investigated usingMRI as the initial imaging technique.The aim was to discover if clinicianscould manage patients with MRI alone,or if they would find a second investiga-tion necessary. Eighty two patients weremanaged using MRI alone, 34 of whomwere treated surgically. Twenty patientshad a second investigation: a myelogramin 18 and a CT myelogram in two. Thiswas performed in nine patients to ex-

clude structural pathology in thethoracic or lumbar region (which was

not examined with MRI), and in 11 toobtain more specific information aboutthe cervical region. Only five of these 20patients had surgical treatment. Thediagnosis changed after the second in-vestigation in four patients, but man-

agement was not influenced in any ofthese. MRI is a satisfactory alternative tomyelography for most patients with sus-

pected cervical spondylotic myelopathy.

Institute ofNeurological Sciences,Southern GeneralHospital, Glasgow, UKP F StathamD M HadleyP MacphersonR A JohnstonI BoneG M TeasdaleCorrespondence to:P F Statham,Department of ClinicalNeurosciences, WesternGeneral Hospital, CreweRoad, Edinburgh EH4 2XU,UK.Received 31 July 1989and in final revised form10 October 1990.Accepted 15 November 1990

Traditionally patients in the UK suspected ofhaving cervical spondylotic myelopathy are

usually investigated by myelography, sup-plemented by axial CT. Side effects, such as

headache, nausea, vomiting or dizziness,occur after myelography in up to 48% ofpatients' and overnight hospital admission isconsidered necessary. MRI is reported to beequivalent to myelography and CT myelo-graphy in the identification of the cause ofcervical myelopathy,23 and may be preferredbecause it is non-invasive, and does notinvolve exposure to ionising irradiation. Apilot study in this Institute showed 92%agreement between MRI and myelography inthe level of maximum cord impingement in 57patients with spondylotic myelopathy.4 Wereport a prospective study to assess the use ofMRI as a replacement for myelography in theroutine management of patients with suspec-ted cervical spondylotic myelopathy.

Patients and methodsThe patients studied were referred to theNeuroradiological Department with a requestfor myelography to investigate suspectedcervical spondylotic myelopathy. To achieveconsistent recruitment to the study, potentialpatients were independently assessed byclinical examination, and had plain radio-

graphs of the cervical spine. Patients con-sidered to have myelopathy or radiculo-myelopathy with spondylotic changes on plainradiographs were included. Patients withcervical radiculopathy without myelopathy, orprovisionally diagnosed to have a syrinx,tumour or multiple sclerosis were excluded, aswere those who had had myelography withinthe last year.

Patients who fulfilled these criteria wereasked to accept MRI instead of undergoingmyelography. However, if circumstancesprevented this being performed in the follow-ing 24 hours (for example, during routineservicing) myelography was performed. Thisensured that all patients studied were thoughtclinically to merit myelography. After MRI areport was sent to the clinician managing thepatient, who was asked (in questionnaireform) the most likely final diagnosis (degen-erative, vascular, congenital, tumour, syrinx,unknown), the level(s) involved, the clini-cian's confidence in the diagnosis (based on alinear analogue scale of 0-100%) and theintended management (discharge, continuedreview, medical, surgical, other). The clini-cian was also asked if further imaging wasthought to be necessary, and if so, whetherthis was to obtain more information about thecervical region, or to exclude a structurallesion elsewhere in the spine. If further imag-ing was requested it was performed. With theradiological report the clinician received asecond questionnaire, asking how much fur-ther imaging had contributed to the final diag-nosis (definite, moderate, slight or none),about changes in the confidence in the diag-nosis (if any), and the relative contribution ofeach investigation. Finally, the clinicians wereasked to indicate their intended managementof the patient.The main end point of the study was the

number of patients who could be managedusing MRI as the only imaging technique,compared with the number who were judgedby the clinician to require a second investiga-tion. Additional questions concerned thechanges in diagnosis, the confidence in diag-nosis and the management that resulted fromperforming a second investigation.MRI was performed using a Picker Vista

0-15 Tesla resistive imager, with purpose builtsurface coils. In all patients three differentpulse sequences were used to highlight thedifferences between disc, osteophyte, CSF andcord (fig 1); 5 mm sagittal multislice balancedspin echo (SE)700/32, 7 mm sagittal slicemulti-echo SE 1660/26-78-156 with increas-ing T2 weighting, and oblique axial multislice

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MRI in the management of suspected cervical spondylotic myelopathy

Figure 1 Normalexamination: a) sagittalSE700/32 b) sagittal SE1660/156.

5 mm T, weighted SE 560/32. Myelogramswere performed by running up water solublenon-ionic contrast medium introduced in thelumbar region, and CT was performed using aPhillips Tomoscan 350 with 3 mm axial (disc-angled) slices. The examinations were pro-spectively and independently assessed by twoneuroradiologists, looking particularly at thelevel of maximum cord impingement and thenumber of levels involved. The assessment ofdisc impingement was based on a forcedchoice between normal, minimal, moderate orsevere indentation of the cord. A subsidiaryassessment of central or lateral (left or right)impingement was also made.An analysis of previous myelogram requests

in this department led us to expect 18 requestsper month, so that within six months we couldrecruit over 100 patients, about a third ofwhom would have surgical treatment. A totalof nine neurologists and six neurosurgeonswere involved in the study. Approval for thestudy was obtained from our Institute's ethi-cal committee, and written informed consentwas obtained from each patient having MRI.The data was analysed using Chi-square testswith one degree of freedom.

ResultsPatients studiedOne hundred and nine patients potentiallyeligible for entry into the study were identifiedbetween December 1987 and August 1988.One hundred and two of these had MRIperformed. Three patients were too claustro-phobic and one patient had an intracranialaneurysm clip which contra-indicated MRI.Three patients were overlooked in error. The102 patients entered were aged between 20 and80 years, the median age being 55 years. Fifty

Table I Pattern of neurological abnormality

Myeloradiculopathy 70 patientsMyelopathy 25 patientsCentral cord syndrome 5 patientsHemicord syndrome 2 patients

nine were male and 43 were female. Theduration of the patients symptoms ranged fromone month to over five years, and in most was atleast one year. The clinical features are sum-marised in table 1.During the period of the study, 396 myelo-

grams were also performed in the same depart-ment. In 335 cases the reason for myelographywas to investigate potential thoracic or lumbardisease, whilst in 34 it was to investigatecervical radiculopathy (without myelopathy).

Management after MRIEighty two patients were managed on the resultof the MRI (fig 2), and a request for additionalimaging was made for only 20 patients. Amyelogram was performed on 18 patients and aCT myelogram on two. In 11 of these 20patients the clinician wanted more specificinformation about the cervical region, but inthe remaining nine, the second investigationwas requested to exclude a structural lesion inthe thoracic or lumbar region, which was notincluded in the MRI examination. Although agreater proportion of those having a secondinvestigation had myelopathy without radi-cular symptoms or signs, no clinical featuresclearly distinguished patients who had a secondinvestigation from those who had MRI alone.

Result offurther imagingIn 18 of the 20 patients who had a secondinvestigation there was agreement betweenthe results of MRI and myelography or CTmyelography. In two patients there was adiscrepancy in the maximal level of cordcompression (fig 3). Both patients had multiplelevel spondylosis and had surgical treatment atmultiple levels. In six patients minor lateralindentation of a single nerve root wasdemonstrated on myelography but not MRI.The result of further imaging increased theconfidence in the diagnosis (assessed by theclinician managing the patient) by a median ofonly 3%, although in one patient it wasincreased by 60%. Management was notchanged as a result of the second investigation.

Variation between radiologistsThere was agreement between the two

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Figure 2 Severespondylosis with cordcompression by prolapseddisc at CV3/4 and 4/5shown by MRI. a) sagittalSE700/32 b) sagittalSE1660/26.

independent radiological reports in all but twopatients with major cord impingement. In onepatient there was a discrepancy in the degree ofcord compression reported on MRI. One

radiologist described severe indentation of thecord at C5/6, and the second described a largedisc protrusion adjacent to, but not impingingon, an atrophic cord. The latter report was

Figure 3 Multiple levelspondylosis a) myelogram,prone lateral: cordimpingement at CV4/5,5/6 and 6/7, maximal atCV5/6, b) sagittal MRISE1660/156 andcorresponding c) sagittalSE700/32 showing similarcord impingement by discand adjacent osteophytesbut interpreted as maximalat CB617.

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Table 2 Final diagnosis

Patients who hadPatients having additional imagingMRI only (82) after MRI (20)

Cervical spondyloticmyelopathy 52 10

Demyelination 8 1Tumour 5 0Infection 2 0Other* 8 2Unknown 7 7

*Congenital (3), rheumatoid arthritis (2), motor neuron disease(2), instability (1), post-irradiation (1), infarction (1).

Table 3 Operations performed

Patients who hadPatients having additional imagingMRI only after MRI

Total number ofpatients 82 20

Number who had anoperation 34 5

Type of operation:Anterior procedure 22 2Posterior procedure 8 2Other 4 1

accepted by the clinician, and he was treatedwithout operation. In one other patient therewas a discrepancy in the level of cord compres-sion seen at myelography. One radiologistdescribed partial obstruction to flow of contrastat C6/7, as well as cord indentation at C5/6.The second radiologist reported major im-pingement at C5/6 only, which had also beenreported on MRI by both radiologists. Thesingle level impingement was accepted by theclinician, and the patient proceeded to anteriorsurgery at C5/6 with good clinical effect.

Further investigations and diagnosisIn two patients the diagnosis was altered fromthat made after MRI as a result of subsequentinvestigation. In one patient the result of a testfor rheumatoid factor was positive, althoughthe myelogram was normal, and in anotherpatient the myelogram was thought to make thediagnosis of cord infarction more likely thancord atrophy. In 15 patients a CSF sample wasobtained for further diagnostic studies afterMRI. In seven patients CSF was taken at thetime ofmyelography, but eight patients neededa lumbar puncture to obtain CSF for immuno-logical studies. This was of definite diagnosticvalue in only three patients.The final diagnoses made are summarised in

table 2. Almost two thirds of the patients were

Examinations making a definite contribution to diagnosis

77 1021Myelogram \\\\\\\W5 201

CSF K3 141Pathology E

Figure 4 Investigations making a definite contribution to diagnosis. The shaded area

represents the number ofpatients in whom the clinician felt the investigation made a

definite contribution to the diagnosis, based on aforced choice between "definite","moderate", "slight" or "no" contribution. The total area represents the total number ofpatients undergoing the investigation.

confirmed to have cervical spondylotic myelo-pathy. The 40 other patients had a variety ofdiagnoses which included demyelination,tumours (neurofibroma in two, meningioma,astrocytoma , ependymoma), and paravertebralinfections (one staphylococcal, one tuber-culous). In 14 patients a diagnosis was notestablished. This was significantly more com-mon in those who had a second investigationcompared with those who had MRI alone (p <0 01). There was no other statistically sig-nificant difference between the two groups.

OperationsThirty nine patients had an operation afterimaging (table 3). In each patient the expectedfindings were confirmed, including the fivepatients with tumours and the two with para-vertebral infections. Ofthe 82 patients who hadMRI alone, 34 had surgical treatment. Of the20 patients who had a second investigation, fivehad an operation. In none of these had thefurther test changed the intended site ofopera-tion. One had rheumatoid atlanto axial diseasewith subaxial spondylosis. CT myelographywas requested to assess the position of theodontoid. This patient subsequently had trans-oral excision of the odontoid followed byposterior fixation. In two other patients therewas a discrepancy between the level ofmaximalcord compression shown by MRI and myelo-gram, but both had a cervical laminectomyperformed from C3 to C7. The discrepancytherefore was not crucial in management. Thefourth patient had predominantly radicularsymptoms and signs, with relatively mildmyelopathy. MRI showed cord compression atthe same level as that shown by myelography.The fifth patient had marked sensory symptomsin the trunk and legs. Although MRI showedsevere cord impingement at C5/6, a myelogramwas performed to exclude a coincidentalthoracic lesion. This confirmed C5/6 spondy-losis, although there was a discrepalncy in thedegree of compression at C6/7, describedabove.

Clinician's assessmentClinicians foundMRI made a definite contribu-tion to diagnosis in 77 ofthe 102 patients (76%)whereas myelography made a definite contribu-

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"Z ~ P~C\, ~ po' IC

Sequential cohort of 10 patients entered

Figure S The influence of the study on the requestfor asecond investigation. A comparison of the proportion ofpatients who had a second investigation per cohort of tenpatients entered consecutively into the study.

MR

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Statham, Hadley, Macpherson, Johnston, Bone, Teasdale

tion in only eight of the 20 patients (40%) inwhom it was performed after MRI. Histo-logical examination ofthe lesion made a definitecontribution in each of the five patients with atumour (fig 4). Other investigations were onlyof definite value in a few patients; CSF studies(3), visual evoked responses (2), cranial CT (1),plain films in flexion and extension (1).

Individual clinicians entered between oneand 20 patients to this study, the mediannumber being seven. The clinician with 20patients has a special interest in spinal surgery.Recruitment of patients to have a second inves-tigation was not influenced significantly by theexperience of previous patients in the study,with as many being recruited for a secondinvestigation at the end of the study as at thebeginning (fig 5).

DiscussionNew investigative technology should be asses-sed as rigorously as a new surgical technique ora new drug. After initial reports that MRI ofthe spine produced images of high quality,comparisons of technical performance of MRIwith that of conventional radiology werecarried out.2"lo

Studies in which patients are selected onradiological rather than clinical grounds,however, or are identified retrospectively canoverestimate the value of a new test and thusmisrepresent its acceptability to cliniciansmaking management decisions.' 12 Few studieshave attempted to answer reliably the nextcrucial question; if MRI produces acceptableimages, are they adequate for clinical man-agement of patients with cervical spondylosiswithout recourse to conventional radiology?Our results show that the use of MRI as an

alternative to myelography or CT myelographyfacilitated accurate diagnosis and managementand avoided invasive investigation in 80% of aseries of consecutive patients suspected ofcervical spondylitic myelopathy. Moreover,even when myelography or CT myelographywas performed after MRI it did not result in achange in patient management. We did notidentify a clinical subgroup of patients whowould have clearly benefited from myelographyas the initial investigation.The only adverse effect ofMRI reported was

claustrophobia, which occurred in threepatients (2-8%). This was more common thanour experience with 600 patients having MRIof the posterior fossa among whom the inci-dence was 1 %. Others, however, have re-ported this to occur in 3% of patients havingspinal MRI.'4Two thirds of the patients had a final diag-

nosis of spondylotic myelopathy. This is areflection of the patient population referred inroutine clinical practice. Clinically it can bedifficult to establish or exclude cervical spon-dylosis as the cause of a myelopathy withoutimaging the spinal cord. An appreciable pro-portion of patients referred for investigationprove not to have cervical spondylotic myelo-pathy requiring operation.The use of surface coils in MRI improves the

signal to noise ratio, but limits the size of theregion that can be examined in one scan. Thiswas a disadvantage in patients who did not haveclinical or plain radiographic features thatlocalised the cervical spine as the site of thepatients' disorder. In nine patients this left thediagnosis sufficiently uncertain after MRI thatthe clinician requested a myelogram to excludea thoracic or lumbar structural lesion. Each ofthese investigations was normal below thecervical cord.The design of our study meant that the

patients were investigated as an "in patient", sothat myelography could be done if MRI wasnot available. If this had not been the case,MRI could have been performed as an out-patient. Then, only those needing a lumbarpuncture for CSF studies would have requiredovernight hospital admission. Using our pulsesequences at 0-15 Tesla, MRI of the cervicalcord takes about one hour to perform, sig-nificantly longer than a run-up myelogram.However, the current use ofmore stable highermagnetic field strength imagers reduces thetime needed to obtain an image, because thesignal to noise ratio is higher, which neces-sitates fewer "averages" of information toproduce the same quality of image. In addition,thinner slices (<5 mm), 3D volume acquisi-tions, and low flip angle sequences can beobtained, resulting in faster imaging and betterimage quality.""17The resource implications of a change to the

use of MRI for investigation of cervical spon-dylotic myelopathy are being assessed inparallel with this study. The factors to beconsidered include, in addition to capital andrunning costs, the benefit of investigation as anoutpatient. Although an allowance must bemade for patients who may subsequently needovernight hospital stay for a myelogram orlumbar puncture, these will have a low diag-nostic yield. Overall it may be possible torelease appreciable in patient facilities for otheruses. On the other hand, the greater ease ofinvestigation as an outpatient may lead to anincrease in the number of patients beingreferred, and an increase in total costs.The decision to investigate a patient suspec-

ted of having cervical spondylotic myelopathyis based on the perceived balance of risks;investigation (at present myelography) andsurgical treatment, versus benefits; the estab-lishment of a diagnosis and institution ofappropriate management. Our study showsthat clinicians found MRI a satisfactory alter-native to myelography, providing sufficientinformation for appropriate management in80% of cases. With routine use of MRI therisk/benefit balance may favour earlier inves-tigation, and this may lead to more successfultreatment.

This study was financed by an MRC research grant 1 D81. Wethank Audrey Lawrence for statistical advice, all the clinicianswho contributed their time to this study, and Ann Semple fortyping the manuscript.

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859-66.10 Larsson EM, Holtas S, Cronquist S, Brandt L. Comparison

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13 Teasdale GM, Hadley DM, Lawrence A, et al. Computedtomography or magnetic resonance imaging for a possibleposterior cranial fossa lesion? A randomised prospectivestudy. BMJ 1989;299:349-55.

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MRI in management of suspected cervical spondyloticmyelopathy · MRI as the initial imaging technique. The aim was to discover if clinicians could manage patients with MRIalone, or