Central nervous system trauma : journal of the American Paralysis Association最新文献

Transplantation of 11 day gestation rat fetal cortex and spinal cord into adult rat thoracic spinal cord is feasible. However, the techniques used at present for the implantation of the fetal transplant result in host spinal gray matter necrosis. One day after implantation the transplant is in a fluid-filled cyst in the host. The transplanted fetal tissue forms spherical neuroepithelia and unorganized cellular arrays. At Day 3 after transplantation the implant has sedimented to the ventral aspects of the fluid-filled cyst. By 10 days, there is an active neuroepithium with differentiating neurons and neuroglia lining the basal portion of the cyst. The transplant then proceeds to fill the cavity formed by host phagocytosis of the debris in the fluid-filled cyst.

Embryonic cerebellae were transplanted to the anterior eye chamber of normal and thyroidectomized adult rats and were left in the eye to mature for 5 weeks. The cerebellar grafts received adrenergic innervation from the sympathetic ground plexus of the host iris. The density of adrenergic fibers innervating the grafts was reduced by approximately 50% in all thyroidectomized groups, without any effect on the fluorescence intensity or the morphology of individual nerve fibers. The reduction in adrenergic ingrowth was entirely prevented in grafts raised in similarly thyroidectomized recipients, which were substituted daily with thyroxine (100 micrograms/kg, SC). Electrophysiologically, there was no difference between the groups in terms of spontaneous firing rate of Purkinje neurons, recorded extracellularly from cerebellar grafts. However, there was a 10-fold decrease in the potency of catecholamines to inhibit the spontaneous neuronal activity in thyroidectomized hosts as compared to controls when applied either locally by micropressure ejection or by superfusion. Similar to the observed histologic changes in catecholamine innervation, the abnormal responsiveness of hypothyroid cerebellar neurons to locally applied catecholamines could be prevented by daily substitution with thyroxine in these animals. It is thus concluded that there is both structural and functional impairment of the adrenergic innervation of intraocular cerebellar grafts that underwent development under conditions of thyroid hormone deficiency.

Studies on the experimental spinal contusion injury in animals confirm that posttraumatic ischemia contributes to central cystic necrosis or fibrosis occurring at the level of the spinal cord lesion. Hyperbaric oxygen (HBO) modifies the degree and extent of the pathology in the spinal cord of the experimental animals. HBO has been used for 45 patients with recent spinal cord injuries. The extent of recovery in 27 patients with upper motor neuron lesions treated with adequate HBO is reported. Fifteen of the 27 patients had useful functional recovery.

A major problem in spinal cord injury research is quantification of motor function in animals. Most investigators in the field currently use neurologic scoring systems, relying on subjective observations of complex behaviours and assigning scores based on arbitrary criteria. These scoring scales are prone to observer bias and are nonspecific. We describe here a simple, reproducible, noninvasive, and objective test of a limited aspect of spinal motor function in cats, based on a well-known involuntary response of animals to sudden free fall. Free fall responses, or FFRs, have been studied in many species, including man, and are thought to be carried in ventral and lateral column pathways, i.e., vestibulospinal, reticulospinal, and rubrospinal tracts. We recorded the FFRs from hind and forelimb muscles of 100 cats before and after thoracic spinal cord injury. Hindlimb FFRs were shown to have three quantifiable components: a fast synchronous activation (E1) followed by a short silent period during which spinal segmental reflexes are inhibited (I1) and a late desynchronized excitatory burst (E2). Thoracic spinal injury produced hindlimb FFR losses ranging from greatly reduced amplitude to complete absence of response. Residual FFRs correlated with the extent of ventral column preservation and locomotory ability. Individual FFR components can be preserved. For example, some injured cats exhibited only 11 responses. Our work suggests that FFRs are a reliable and sensitive test of motor recovery in spinal cord injury.

Calcium-induced myelopathy was produced in rats by dripping 1.0 ml of a 10% solution of CaCl2 at pH 7.4 upon exposed spinal cord. Changes in spinal cord proteins were examined following application of calcium. Analysis of proteins by SDS-PAGE revealed progressive losses of neurofilament, microtubular, and glial filament proteins over a period of 8 hours to 5 days. Large losses of myelin proteins were also evident. The protein alterations observed correlate well with ultrastructural changes and resemble those previously found with physical trauma. These observations indicate that Ca2+ plays a pivotal role, possibly by activating proteinase(s), in the degeneration of axons and myelin sheath in both Ca2+-induced myelopathy and spinal cord injury.

Computer-directed functional electrical stimulation that employs closed-loop (feedback) technology has been used for rehabilitation of spinal cord injured (SCI) patients. This paper summarizes the most recent developments in our laboratory. First, the design of an adaptive control system is described, and its resultant controllability is reviewed. Second, our current results with the isokinetic leg trainer are summarized with respect to muscular strength and mass and cardiovascular changes in paraplegics and quadriplegics. Third, our current results with the exercise bicycle ergometer are summarized regarding muscular endurance and cardiovascular changes in control, paraplegic, and quadriplegic subjects. Fourth, impact vibration is reviewed as a potential technique to reverse disuse osteoporosis, and clinical case studies are cited. Fifth and finally, thermoregulatory studies are presented for the first time on control, paraplegic, and quadriplegic subjects. Conclusions are drawn regarding mechanisms and recommendations made for exercise of SCI subjects in hot and humid environments.