Francis Boumphrey

Cervical myelopathy: a comparison of magnetic resonance and myelography

Fifty-seven patients with a strong clinical suspicion of cervical myelopathy were studied with body coil magnetic resonance (MR) and conventional myelography or CT myelography. Eight patients were believed to have normal studies with both modalities. There were six patients with syringomyelia; four with an intramedullary tumor; one with an arteriovenous malformation; 19 with cervical spondylosis at multiple levels; eight with cervical spondylosis at a single level; four with extensive rheumatoid arthritis; four with extradural neoplasm; two with trauma; and one patient with an epidural abscess. In this study, body coil MR was the superior examination for the evaluation of an intramedullary process. It was as diagnostic as myelography in one case of an extramedullary intradural lesion. In patients with extradural disease, body coil MR was the superior study in 45%, equivalent to myelography in 37%, and, although still diagnostic, inferior to myelography in 17%. In 8% of the cases, body coil MR was at best equivocal, whereas myelography was diagnostic. It appears that in technically adequate studies, MR is at least equivalent to myelography in its ability to delineate disease. A superior MR study provides a better appraisal of the size and character of the spinal cord as well as the degree of both anterior and posterior defects on the subarachnoid space and neural structures. In addition, MR is as good as conventional myelography for the identification of extrinsic cervical cord lesions producing cervical myelopathy. Finally, an additional small group of 30 patients were studied with a prototype surface coil to determine its advantages relative to body coil imaging. Each patient had correlative myelography. As with body coil MR, imaging with the surface coil was believed to be more informative than conventional myelography in four patients with intramedullary lesions. The remaining 26 patients suffered from cervical spondylosis. Surface coil MR was believed to be more informative than myelography in six cases (23%), equivalent to myelography in 19 (73%), and less diagnostic than myelography in one (4%). The improved spatial resolution with the use of the surface coil was believed to increase the accuracy of MR.

Effects of chemonucleolysis demonstrated by MR imaging

In a study designed to assess the diagnostic and prognostic usefulness of magnetic resonance (MR) imaging in patients to be treated with chymopapain, 39 patients with a clinicoradiographic picture of herniated lumbar disk were scanned. Twenty-one of these, who were actually treated, were re-scanned 3 months following the intradiskal administration of chymopapain. In both pretreatment and posttreatment scans sagittal T1 and T2 weighted spin-echo technique was used. Prior to therapy, disks that were later injected demonstrated narrowing of the intervertebral disk space (95% of cases); an extradural defect (86% of cases); diminished signal intensity on the T1 weighted images (50% of cases); and decreased signal intensity on the T2 weighted image when compared with normal controls (100% of cases). Additionally, the adjacent endplates of the injected disk showed increased signal intensity on the T1 weighted image in 32%; 18% of the cases displayed increased signal intensity on the T2 weighted image. Following chymopapain, 100% of injected disks demonstrated decrease in disk height; 36% of the extradural defects diminished in size and 9% increased; 91% of injected disks showed loss of signal intensity on the T1 weighted image; and 86% lost signal in the T2 weighted study with 14% remaining unchanged. Vertebral body endplates adjacent to the level of injection demonstrated a decreased signal intensity on the T1 weighted image in 32% of cases, and 40% demonstrated increased signal in the T2 weighted study. Even though these findings could not be correlated with clinical success or failure using the criteria in this study, six of the original 39 patients were diagnosed as having free disk fragments on the basis of their initial MR scans, a fact that does have management implications for the use of chymopapain in treatment of herniated disk disease.

MRI diagnosis of tuberculous vertebral osteomyelitis

Two patients with suspected tuberculous spondylitis and one patient with previous Potts disease were evaluated preoperatively with magnetic resonance imaging (MRI). The MRI provided more exact anatomic localization of vertebral and paravertebral tuberculous abscesses in multiple planes not previously available with more conventional diagnostic methods in the patients with suspected tuberculous spondylitis. This was helpful for localization in planning of surgical approaches. In the patient with previous Potts disease, spinal cord compression was detected using MRI, which showed no evidence of active tuberculosis. Two case reports are offered to show the benefit of using MRI as a diagnostic technique in preoperative evaluation and as a method of monitoring treatment response of tuberculous spondylitis. The third case shows the benefit of using MRI to rule out active infection and to detect other forms of spinal pathology.

Nuclear Magnetic Resonance of the Spine: Clinical Potential and Limitation

&NA; Magnetic resonance can visualize the vertebral bodies, discs, neural structures, cerebrospinal fluid (CSF), neural foramina, and extradural structures in the sagittal, axial, and coronal planes. The normal nucleus pulposus can be differentiated from the anulus and changes associated with degeneration. Infection, trauma, and neoplastic conditions can be identified. The signal intensity of the CSF relative to extradural and neural structures can be increased to provide evaluation of the size and configuration of the contents of the thecal sac without the use of an intrathecal contrast medium. Impingement by disc, tumors, fracture segments, and expansile masses can then be accurately evaluted, It is the most accurate modality for the evaluation of the foramen magnum, Chiari malformation, syringomyelia, infection, and degeneration of intervertebral discs. It can identify paravertebral soft tissue and bony changes when plain films and computed tomographic (CT) studies are negative or equivocal. Not only can lesions be localized, but significant information regarding the nature of the process can be obtained. Using variations of the spin‐echo technique with appropriate T1 and T2‐weighted images, magnetic resonance can produce tissue contrast distinctions not possible with CT scans or conventional angiography. (Neurosurgery 15:583‐592, 1984)

Computed tomography scanning after chymopapain injection for herniated nucleus pulposus. A prospective study.

Fifty consecutive patients treated with chymopapain injection for a clinical and radiographic diagnosis of herniated nucleus pulposus were evaluated prospectively. All patients had a prechymopapain computed tomography (CT) scan and a threemonth postinjection CT scan. In addition, ten patients (20%) had a six-month postinjection CT scan. All scans were interpreted blindly. Only six patients (12%) had obvious changes in the size of the disc when preinjection and three-month postinjection CT scans were compared. By six months, however, seven of ten patients (70%) had obvious changes in their CT scan. Seven patients (14%) were considered chymopapain treatment failures and were later treated with surgical discectomy. Only two of these seven patients (30%) had obvious changes in their three-month CT scan. Chymopapain injection did not alter the size of the herniated portion of the disc during the first three months after chymopapain injection. A decision to operate for presumed chymopapain failure should therefore be based on clinical grounds, rather than on the three-month CT appearance of the herniated disc.