Use of contrast in MR imaging of the lumbar spine

Gadolinium chelates are often useful in sorting out different causes of lower back pain and lumbar radiculopathy. Gadolinium is particularly useful, for example, in distinguishing recurrent disc herniation from epidural scarring in the postoperative spine. Enhancement can demonstrate nerve roots in viral or inflammatory conditions (e.g., cytomegalovirus or Guillain-Barré syndrome), and define compression resulting from herniated discs or spiral stenoses. Gadolinium enhancement also is useful in diagnosing tumors in the intramedullary space (e.g., conus ependymoma), in the extramedullary space (e.g., drop metastases, meningioma, schwannoma), and extradural space (e.g., extraosseus extension of osseus metastases or infections).

Subcallosal striations: early findings of multiple sclerosis on sagittal, thin-section, fast FLAIR MR images

PURPOSE

To determine how sensitive and specific the magnetic resonance (MR) imaging finding of subcallosal striations is for multiple sclerosis (MS).

MATERIALS AND METHODS

In 18 patients with clinically suspected MS and 32 age-matched patients without MS, sagittal 2-mm fast fluid-attenuated inversion-recovery (FLAIR) imaging was added to the routine MR studies of the brain. The images were reviewed for the presence of subcallosal striations, that is, linear, 1-mm-thick foci of hyperintensity perpendicular to the ependyma, like a stack of coins. The images were masked to exclude the hemispheric white matter and were interpreted without knowledge of patient age or medical history.

RESULTS

Seventeen patients with clinical MS had subcallosal striations; one did not. Of the 32 patients without MS, five had subcallosal striations and 27 did not. Subcallosal striations were highly associated (P < .001) with clinical MS.

CONCLUSION

Subcallosal striations are thought to represent perivenular demyelination, that is, the same process that later produces the "ovoid" lesions visible on routine MR images. Subcallosal striations are not seen on routine axial MR images and can be seen only on 2-mm sagittal FLAIR images.

The application of the International Statistical Classification of Diseases to neurology: ICD-10 NA

Rapid advances in the clinical neurosciences in the last decade have led to considerable amplification of our ability to classify neurological diseases. For these classifications to be widely used, they must be compatible with the 'International Statistical Classification of Diseases and related health problems' (ICD) of the World Health Organization (WHO), which system is used throughout the world for classification of diseases and reasons of death. The 'Ninth' revision of the ICD (ICD-9), published in 1976, is currently in use in a number of Member States of the World Health Organization, including the United States. However, it is expected that by the end of this decade virtually all Member States will have introduced the 10th Revision of the ICD (ICD-10), published in 1992. An 'Application of ICD-10 to neurology' (ICD-10 NA) has been developed, with a specific coding system for virtually every neurological disease currently recognized. This article describes the structure and background of this work, that is offered as a definitive international classification of neurological disease to be used by clinical and research organizations, governmental and nongovernmental bodies, and for epidemiological and research purposes. It is concordant with the new and proposed classifications of subspecialty neurological organizations.

Relapses in the Guillain-Barré syndrome after treatment with intravenous immune globulin or plasma exchange

To clarify the question of whether Guillain-Barré syndrome (GBS) patients treated with intravenous immune globulin (i.v.IG) relapse at a higher frequency than those treated with plasma exchange (PE), 54 patients with GBS were studied retrospectively. A higher frequency of relapses was noted in the PE-treated patients than in those receiving i.v.IG. The presence of an associated medical condition correlated with an increased risk of relapses, while earlier onset of treatment resulted in a decrease of relapses of GBS. This study found no support for prior suggestions of increased relapses in patients with GBS treated with i.v.IG as opposed to those treated with PE.

Morphometric analysis of the peripheral neuropathy of AIDS

A morphometric study of the peripheral nervous system at autopsy was undertaken in 11 AIDS patients and 10 controls. The left L4, L5, and S1 dorsal root ganglia (DRG) and samples of the sciatic nerve at the buttock, tibial nerve at the knee, and sural nerve at the ankle were collected. Indices of neuronal/axonal degeneration and of segmental demyelination/ remyelination were measured at each level. The small number of cases and evidence of neuropathy in a number of the control cases resulted in statistical significance for only a limited number of comparisons. Nodules of Nageotte in the DRG were increased fivefold in AIDS cases compared with controls, and axonal degeneration in single-teased nerve fibers was increased 9-fold in the sciatic nerve, 28-fold in the tibial nerve, and 12-fold in the sural nerve. The ratios of AIDS to controls for the density of remaining DRG neurons and large myelinated axons were reduced to 0.71 in the DRG, 0.84 in the sciatic nerve, 0.84 in the tibial nerve, and 0.66 in the sural nerve. Axonal regeneration in single-teased nerve fibers was increased threefold at the sciatic nerve level in AIDS, but was markedly reduced at distal levels. Acute segmental demyelination in single-teased nerve fibers was present to a greater extent than in controls at all levels of the peripheral nerves in the AIDS cases. Remyelinating fibers were increased compared with controls only in the proximal sciatic nerve. No case showed the changes of cytomegalovirus infection. In a parallel immunohistochemical study of these AIDS peripheral nerves, T-cell and macrophage infiltration, with cytokine expression, was demonstrated. The pathological process in the neuropathy of terminal AIDS appears to be a multifocal immunologically mediated inflammatory disease, with increased density of macrophages and T cells at all levels of the peripheral nervous system, producing segmental demyelination and axonal degeneration. Reparative processes (axonal regeneration and remyelination) occurred only at the most proximal levels of the nerves.

Functional magnetic resonance imaging in macaque cortex

The ability to use fMRI in a monkey model would bridge the gap between the fMRI demonstration of cerebral activation in humans and the cumulative wealth of monkey data on the functional organization of the brain from single electrode mapping, radioisotope and histology studies. We report a new technique for fMRI in an awake co-operative rhesus macaque (Macaca mulatta) in a conventional clinical 1.5T MR scanner and present the first fMRI images from a macaque. Good resolution, signal-to-noise ratio and BOLD response (2.6-4.6%) have been achieved using the manufacturer's standard volume knee coil. T1 values of macaque gray and white matter (1490 ms, 1010 ms respectively) are higher than human brain, whereas T2 values are lower (55 ms, 48 ms respectively). An MR-compatible design for restraining the monkey is also described, along with a suitable EPI sequence for BOLD images, optimized for monkey T2, with voxel sizes from 29 to 61 microl, and MPRAGE sequence for anatomical studies with 0.8 mm isotropic resolution, optimized for monkey T1.

MRI of extracranial masses in children: the usefulness of gadolinium-chelate enhancement

OBJECTIVE

This study evaluated the usefulness of gadolinium (Gd) chelates in magnetic resonance imaging (MRI) of extracranial pediatric mass lesions.

MATERIALS AND METHODS

Seventy-five MRI studies were obtained on 60 children (mean age 5.06 years) with pathologically proven mass lesions. Post-contrast T1-weighted (T1W) images were compared with pre-contrast T1-weighted, T2-weighted (T2W) and both T1W and T2W images. They were evaluated for their ability to demonstrate lesion margins and extent, to add additional information, and to increase confidence in or change a diagnosis. In all patients post-contrast images were also evaluated for degree and pattern of enhancement.

RESULTS

Malignant lesions enhanced much more intensely than benign lesions (P<0.0005). Lack of enhancement was seen only in benign lesions. A heterogeneous pattern of enhancement was more frequently seen in malignancy (P<0.05). Additional information was provided on Gd-enhanced T1W images in 36% of cases compared to unenhanced T1 and T2W images. Diagnostic confidence was improved in 29%. The Gd-enhanced images changed the diagnosis correctly in 5% and incorrectly in 1%.

CONCLUSION

Post-contrast images clarified specific issues, better defined lesion extent and margins in a majority of cases, and gave additional useful information in selected cases.

First pass MRA of the abdomen: ultrafast, non-breath-hold time-of-flight imaging using Gd-DTPA bolus

The authors describe a new fast imaging sequence that can produce projection angiograms of the abdominal vessels at a rate of 2 to 3 frames per second. The result is a versatile imaging technique that can track the arrival of a bolus of contrast in major vessels. With very fast data acquisition, gross patient motion is not a problem, and routine vascular projection studies may be performed without the need for breath-holding. This method is compatible with later high-resolution three-dimensional gradient echo studies using contrast agents and may, in fact, be used as an accurate timing protocol to gauge the arrival time of contrast in various segments of the abdominal vessels. Compared with echo planar imaging, this method has the advantages of avoiding susceptibility artifacts and depicting retroperitoneum and other abdominal fat-containing landmarks and does not require extensive hardware modifications for a clinical system.

Quality improvement in neurology residency programs. Report of the Quality Improvement Committee of the Association of University Professors of Neurology

The neurology residency programs in the United States are facing a crisis of quality. The Association of University Professors of Neurology (AUPN) approved the Quality Improvement Committee to examine this situation and make recommendations, which have been accepted by the AUPN. The recommendations are (1) that the educational goals of neurology residency training be dissociated from patient-care needs in academic medical centers and (2) that minimum levels of quality be applied to residents in neurology residency programs and to these programs themselves. These minimum criteria should include minimum educational criteria for entry into the program, minimum criteria for advancement from one year to the next in the program, and minimum criteria for performance of the graduates of neurology residency programs for program accreditation. The implementation of these recommendations will require a shift of funding of the care of indigent patients from the graduate medical education budget to direct patient-care sources. These recommendations will significantly improve the quality of neurologists and neurologic care in the United States.

Marked improvement of severe polyneuropathy associated with multifocal osteosclerotic myeloma following surgery, radiation, and chemotherapy

We describe a patient with a 3 year history of progressive polyneuropathy that rendered him severely quadriparetic and bedridden. Work up revealed an IgG lambda monoclonal spike and multifocal osteosclerotic myeloma. Remarkable improvement followed combined treatment with surgical excision, radiation therapy, and chemotherapy using chlorambucil, danazol, and hydrocortisone. Hence, we believe that aggressive local therapy associated with systemic chemotherapy should be considered in severely affected patients with multifocal osteosclerotic myeloma and peripheral neuropathy.

Use of gadolinium chelates in MR imaging of the spine

Spinal disease can be divided into intramedullary, extramedullary-intradural, and extradural compartments. In the cord (intramedullary compartment), gadolinium chelates are useful to diagnose primary and metastatic tumors, inflammation, and demyelination, and to evaluate syringomyelia when a Chiari I malformation is not present. In the extramedullary-intradural compartment, gadolinium chelates are useful for the diagnosis of drop metastases, meningiomas, and schwannomas. In the extradural compartment, gadolinium chelates are most useful to distinguish recurrent disc herniation from epidural fibrosis in the postoperative back and may be useful to diagnosis the soft tissue component of osseous metastases.

Painful vasculitic neuropathy in HIV-1 infection: relief of pain with prednisone therapy

Painful distal sensory polyneuropathy (DSP) is the most common peripheral neuropathy in patients with human immunodeficiency virus-1 (HIV-1) infection. There is no specific therapy for DSP, and nonspecific treatment with pain blockers and narcotic agents generally fails to adequately control the symptoms. We report two patients who had subacute painful neuropathy in the B2 (formerly AIDS-related complex [ARC]) stage of HIV-1 infection. Neurophysiologic studies revealed predominantly axonal sensorimotor neuropathy. Sural nerve biopsy in both cases showed a necrotizing vasculitis. Treatment with corticosteroids resulted in rapid relief of pain, followed by arrest of the neuropathic process. Although not previously emphasized, vasculitic neuropathy must be considered among the treatable causes of painful sensory neuropathy in HIV-1-infected individuals.

High cervical myelopathy presenting with the numb clumsy hand syndrome

We report two patients with numb clumsy hands due to cervical spondylotic spinal cord compression. It is proposed that arterial insufficiency in the watershed area between the central and radial arterial systems of the cervical cord explains the sensory findings in the upper extremities with preservation of motor function. Although this is a rare conditions, its recognition is important since the prognosis is improved by early surgical decompression.

Improving the diagnostic accuracy of MR in the detection of infraspinatus tendon injuries

PURPOSE

Our goal was to determine the accuracy of MRI in the diagnosis of infraspinatus tendon injury and more specifically to determine if the antero-posterior extent of a rotator cuff tear is predictive of infraspinatus tearing.

METHOD

The MR images of 41 shoulders with surgically proven supraspinatus tears at surgery were retrospectively reviewed. The following were assessed for each of the 41 studies: the number of oblique coronal images on which a tendon defect could be seen, the angle subtended by the tear on axial images (the rotator cuff "axial angle"), and the extent of signal abnormality on sagittal images.

RESULTS

The rotator cuff axial angle was 75.6 degrees in patients with infraspinatus tendon tears (ITTs) versus 40 degrees in those without ITTs, and this difference was significant (p < 0.001, t = 3.06). The mean number of oblique coronal images (obtained with a 4 mm slice and 1 mm gap) showing signal abnormality was 5.4 in the ITT group versus 2.9 in those without ITTs, and this difference was also significant (p < 0.001, t = 4.45). The mean sagittal extent of the tendon abnormality was 24.6 mm in the ITT group and 11.6 mm in those without ITTs, but the difference was not significant (p > 0.05, t = 1.1364).

CONCLUSION

The axial angle and the number of oblique coronal images in which signal abnormality was present were significantly related to a higher incidence of infraspinatus tears.