Biomedical subjects

B B Mullin

Publications and source records attributed to B B Mullin.

6 recordsLinked to original sources

PubMed1996

A quantitative spatial analysis of the blood-spinal cord barrier. II. Permeability after intraspinal fetal transplantation.

In previous experiments we utilized quantitative autoradiography to temporally describe vascular permeability of a radiolabeled vascular tracer following spinal contusion injury in the rat. In the present report we compare these findings with permeability assessments following fetal grafting in the contused rat spinal cord. At 10 days postinjury, Embryonic Day 14 spinal tissue was grafted into the lesioned spinal cord of Sprague-Dawley rats. At 7, 14, and 28 days postgrafting the alpha-aminoisobutyric acid (AIB) technique was used to assess blood-to-tissue transfer rates in graft and host tissue over several segments of the injured spinal cord. Regional changes in permeability were assessed using four distinct image analysis techniques. Using these methods, we have previously shown that contusion injury alone results in a chronic relapse in vascular permeability. The present data indicate that fetal transplants at 7 days postgrafting have AIB transfer rates that are significantly above uninjured control levels and are similar in magnitude to neighboring host spinal tissue. In addition, permeability in 14- and 28-day intraspinal grafts decreased relative to that of the 7-day transplant group, but remained significantly elevated at and rostral to the injury epicenter. Alternately, graft and host tissue in regions caudal to the injury epicenter (e.g., T10--L2) acquired a functional barrier to AIB as early as 14 days posttransplantation. These experiments suggest that graft development occurs in a different manner or at a different rate in segments of the injured spinal cord rostral and caudal to the injury site. Additionally, it appears that vascular permeability of the injured spinal cord can be influenced by the process of intraspinal transplantation.

Aminoisobutyric Acids↗

PubMed1996

A quantitative spatial analysis of the blood-spinal cord barrier. I. Permeability changes after experimental spinal contusion injury.

Blood-spinal cord barrier (BSB) permeability was measured using quantitative autoradiography following contusion injury to the rat spinal cord. Permeability was assessed by calculating blood-to-tissue transfer constants (Ki values) for the vascular tracer [14C]-alpha-aminoisobutyric acid (AIB) in injured (3, 7, 14, and 28 days postinjury), laminectomy control, and uninjured control animals. Permeability was quantitated using four separate imaging techniques in gray and white matter throughout the rostro-caudal extents of the forming lesion. Away from the epicenter, gray matter permeability was further differentiated within discrete spinal lamina using computerized templates. Regardless of the type of analysis used, increased AIB permeability (Ki values) was noted at all survival times in all tissue regions with respect to both uninjured and laminectomy control groups. The data indicate a large increase in individual Ki values throughout the dorsoventral axis of the spinal cord at 3 days postinjury (approximately 6-9 ml/kg/min). By 7 days, Ki values were quantitatively smaller (approximately 4-5 ml/kg/min) in all regions compared with 3-day tissues. Despite further attenuation of AIB uptake in the gray matter at 14 and 28 days postinjury, circumferential white matter tracts showed a secondary increase in permeability compared to 7-day tissue. Permeability in the white matter at 14-28 days postinjury (approximately 5-6 ml/kg/min) was comparable to that at 3 days postinjury (6-7 ml/kg/min). Measurements of the axial distribution of AIB permeability indicate increased BSB permeability over several segments rostral and caudal to the lesion epicenter (approximately 3 cm in both directions). Secondary elevations of AIB transfer in the spinal white matter between 14 and 28 days were colocalized with zones of immunohistochemically defined microglial clusters. The known plasticity of this cell type in response to changes in the extracellular microenvironment suggests that the spinal white matter at later survival times (14-28 days postinjury) is an area of dynamic vascular and/or axonal reconstruction. The implications of increased permeability to both tissue injury and neural regeneration are discussed.

Aminoisobutyric Acids↗

PubMed1996

The effect of postlaminectomy spinal instability on the outcome of lumbar spinal stenosis patients.

Between 1986 and 1990, 37 of 72 patients undergoing decompressive lumbar laminectomy with medial facetectomy for lumbar stenosis at The Ohio State University were seen in follow-up at a mean of 31 months (range, 14-63 months) after their laminectomy and were evaluated by questionnaire, detailed neurologic examination, and static and dynamic lumbar radiographs. Thirteen patients who had undergone fusion or who had extenuating medical circumstances were excluded, leaving 24 patients for whom laminectomy was the sole treatment for lumbar stenosis. Postoperatively, normal walking improved from 4 to 45% of patients, sensory deficits decreased from 63 to 25%, and ability to perform most or all desired activities increased from 25 to 70%. Urinary function was unchanged. Thirteen patients (54%) showed radiographic signs of instability. All patients who were declared radiographically stable could walk without a prosthetic aid or normally; 62% of the unstable patients required aid for walking. All of the patients with a poor ambulatory outcome were radiographically unstable. Compared with stable patients, unstable patients had a significant (p < 0.01) decrease in their ambulatory ability. There was a clear correlation between the degree of listhesis and postoperative ambulatory status (p < 0.01). The unstable patients with a poor ambulatory outcome followed one of three clinical courses: improvement with later deterioration, improvement with a plateau at a poor functional level, or failure to improve from a poor functional level. In conclusion, (a) although instability did not necessarily preclude a good outcome, a poor ambulatory outcome was always associated with instability; (b) laminectomy can effectively ameliorate the symptoms of lumbar stenosis; however, there is a subset of patients in whom laminectomy is associated with instability and a poor clinical course.

Adult↗

PubMed1994

Surgical treatment of greater occipital neuralgia: an appraisal of strategies.

The surgical treatment of greater occipital neuralgia often involves diagnostic anesthetic blockade, followed by chemical or surgical ablation of the greater occipital nerve. The anatomy of this region was studied in microdissections of 2 cadaver specimens. The diagnosis and management of a series of 5 patients with greater occipital neuralgia is discussed. Two patients were treated with atlanto-epistrophic ligament decompression of the C2 dorsal root ganglion and nerve; four patients had C2 ganglionotomy performed. All patients in this series had immediate complete relief of pain following surgery. Patients were followed for a mean of 24 months (range 7-33 months). One patient had a recurrence of her original pain after 26 months following atlanto-epistrophic ligament decompression and required re-operation in the form of bilateral C2 ganglionotomy. All patients experienced transient nausea and dizziness in the several days following surgery. One patient had an incisional cerebrospinal fluid leak. Microsurgical C2 gangliotomy is advocated as the preferred surgical treatment of greater occipital neuralgia of idiopathic origin.

Adult↗

PubMed1993

Occipitocervical fixation in nontraumatic upper cervical spine instability.

Ten patients requiring occipitocervical fixation were reviewed: five were unstable secondary to rheumatoid arthritis, one had Klippel-Feil, and four had neoplastic disease. Patients with nonneoplastic disease improved, having decreased pain, decreased paresthesias, and increased ambulation. Patients with neoplastic disease improved significantly after the surgery, but eventually died from different tumors. The technique found to be most efficient was the placement of an intraoperatively contoured Luque rectangle wired from the occiput to appropriate cervical spine levels.

Adult↗

PubMed1987

Microcomputer stereotactic atlas.

A stereotactic atlas to determine thalamic target sites has been incorporated into a microcomputer. Variability studies of the thalamus with mean and standard deviations of nuclear borders are depicted graphically for overlay onto operative images. Internal landmarks traditionally used to reference target points for functional stereotaxis may be determined by conventional ventriculography or derived from magnetic resonance scans. Modeling of polyline vertices established from gray scale contour mapping and atlas reconstructions further enhance the spatial understanding of relationships to midline structures. Computer integration of anatomic reference points, graphically depicted images and stereotactic atlas data into head frame coordinates can be accomplished. This method is consistent with established stereotactic techniques and allows the visual conceptualization of imaged and graphic data for functional stereotaxis.

Brain↗