Cauda equina syndrome, diskospondylitis, and a paravertebral abscess caused by Rhodococcus equi in a foal.

A 4-month-old male Quarter Horse was referred for evaluation of urinary incontinence. Physical examination revealed clinical signs consistent with cauda equina syndrome. Radiography revealed diskospondylitis of S2 through S4. Infected bone was surgically curretted, and drainage was established for an associated paravertebral abscess. Rhodococcus equi was isolated from specimens of bone and from fluid samples obtained from the paravertebral abscess. Bethanechol was administered to stimulate urination. Erythromycin and rifampin were administered for 120 days. The foal's neurologic dysfunction resolved completely. Two years after discharge, the horse remained neurologically normal and did not have apparent effects as a result of its previous disorder.

Immunohistochemical localization of seven different peptides in the human spinal cord.

It is necessary to study the normal chemical contents in the human spinal cord in order to understand neurochemical changes that might occur under pathological conditions. In the present study, the comparative distribution of seven peptides was examined immunohistochemically in four levels (cervical, C; thoracic, T; lumbar, L; sacral, S) of the human spinal cord by means of the peroxidase-antiperoxidase technique. The peptides examined included bombesin (BOM), substance P (SP), cholecystokinin (CCK), somatostatin (SOM), methionine-enkephalin (M-ENK), vasoactive intestinal polypeptide (VIP), and thyrotropin releasing hormone (TRH). Among the seven peptides examined, four (BOM, CCK, SOM, and TRH) have never been described in the human spinal cord and the present work clearly demonstrates their existence in specific patterns. The terminals that were immunostained for BOM and CCK were localized in high concentration in the superficial dorsal horn (laminae I-II), in moderate amounts in the lateral part of laminae V and VII, and lesser amounts in the intermediate gray (lamina VII) and the dorsal part of the central gray (lamina X). Whereas BOM showed a similar distribution pattern at all spinal levels, CCK was mainly found in thoracic and lumbar levels. The SOM terminals were localized in the superficial dorsal horn (the highest density in lamina II but very few in lamina I), the intermediolateral cell column, intermediate gray, and central gray. This peptide was more widely distributed in the sacral cord with its terminal field extending into the ventral horn. The TRH terminals were mainly located in the ventral horn. Frequently, TRH terminals were seen adjacent to large ventral horn neurons. Furthermore, many neurons in the ventral and intermediate gray and Clarke's column demonstrated TRH immunoreactivity. The other three peptides (SP, M-ENK, and VIP) have been previously demonstrated in the human spinal cord and the present study confirmed their general spinal distribution with minor differences.

Evidence for unmyelinated sensory fibres in the posterior columns in man.

The human posterior columns are generally described as a myelinated fibre pathway. The present study demonstrates that more than 25% of the component axons are unmyelinated. Many of these unmyelinated axons are labelled by antibodies to calcitonin gene-related peptide (CGRP), a substance found in sensory cells, axons and terminals. On this basis we suggest that there are significant numbers of unmyelinated primary afferent axons in the human posterior columns. These results indicate that unmyelinated sensory axons are more widespread than previously thought, and that they should be taken into account when considering stimulation of the posterior columns to relieve pain.

Calcitonin gene-related peptide (CGRP) in the human spinal cord: a light and electron microscopic analysis.

The distribution of CGRP immunoreactivity in the cervical, thoracic, lumbar, and sacral levels of the human spinal cord was mapped at the light microscopic level with the aid of a rabbit-generated antiserum against human calcitonin gene-related peptide (CGRP). CGRP-positive fibers formed a dense plexus in lamina I, II, the reticulated region of lamina V, and the tract of Lissauer at all spinal cord levels. The distribution of fibers showed some variations dependent on the cord level analyzed. At the light microscopic level, intervaricose fiber diameters consistently measured 1.0 micron or less, and two types of CGRP varicosities were observed: a small (1 to 2 microns in diameter), relatively round profile and a larger, (3 to 4 microns in diameter) oval or oblong profile. At the electron microscopic level, immunostained varicosities contained a mixture of round clear vesicles and vesicles that contained dense cores. The CGRP immunoreaction product was often associated with vesicles containing dense cores. The reaction product was also seen associated with clear round vesicles or in the cytoplasmic matrix. Postsynaptic elements included dendritic spines, small and large diameter dendritic shafts and vesicle containing profiles. The presence of CGRP in the superficial dorsal horn of human spinal cord is highly suggestive of a role in primary afferent transmission as postulated in lower vertebrates. This study establishes the distribution of CGRP at four different spinal levels in human cord and will serve as a basis for future studies related to the pathologic conditions affecting sensory systems.

Computed tomogram-guided stereotactic brain biopsy in the pediatric patient.

Experience with computed tomogram-guided stereotactic biopsy is described with special reference to technical considerations important to the application of the Brown-Roberts-Wells system in pediatric patients. Eleven procedures were performed in 9 patients aged 9 months to 16 years of age. In all cases, the lesion was either deep seated or related to deficit prone areas making open biopsy hazardous. Since the stereotactic frame may interfere with intubation, it is important to apply it only after the patient has been anesthetized and intubated. In very small children, special attention is required to avoid over tightening of the fastening pins and to avoid excessive pressure when making the calvarial opening. In an effort to reduce the risk of hemorrhage, vasculature at the entry site was visualized and avoided by making a standard burr hole opening. Improved imaging of the vasculature at the deep biopsy site was obtained in most cases by intra-arterial contrast enhancement. No complications of the procedure were encountered and a diagnosis was obtained in all cases, although in 2 cases the procedure was repeated before adequate tissue was obtained. In 3 cases the procedure was therapeutic as well as diagnostic in that a tumor cyst or abscess could be drained.