✓ The extent of the retrograde degeneration of corticospinal axons following transection of the spinal cord was studied in rats by labeling corticospinal axons with anterogradely transported horseradish peroxidase injected in the sensorimotor cortex. Axotomized corticospinal axons underwent progressive and continuing retrograde degeneration. In specimens examined 5, 14, 28, and 56 days after trauma, the tips of the transected corticospinal axons were seen to terminate at 181 ± 80 µm, 977 ± 203 µm, 1751 ± 344 µm, and 2559 ± 466 µm (mean ± standard deviation), respectively, from the site of transection. The rate of retrograde degeneration varied according to the interval after spinal cord transection, as follows: 36.2 µm/day during the first 5 days; 88.4 µm/day between 5 and 14 days; 55.3 µm/day between 14 and 28 days; and 28.8 µm/day between 28 and 56 days. These findings may serve as useful parameters for the objective assessment of therapeutic modalities in spinal cord injury research.
A quantitative study with anterogradely transported horseradish peroxidase
Roberto Pallini, Eduardo Fernandez and Alessandro Sbriccoli
Eduardo Fernandez, Roberto Pallini and Giuseppe Talamonti
✓ A patient with a long-recognized asymptomatic lipoma adjacent to the deep radial nerve developed paralysis of this nerve from a compression similar to the sleep palsy, or “Saturday-night palsy,” mechanism.
Eduardo Fernandez, Roberto Pallini and Giulio Maira
✓ A simple technique is described for protecting the cornea in patients with peripheral facial nerve palsy while waiting for recovery of nerve function. The application of an adhesive strip to the superior eyelid permits opening and closing of the eye, and provides good protection of the cornea.
Roberto Pallini, Eduardo Fernandez, Carlo Gangitano, Aurora Del Fà, Corrado Olivieri-Sangiacomo and Alessandro Sbriccoli
✓ Spinal cord tissue was obtained from 13- and 14-day embryonic rats and homologously grafted to the completely transected spinal cord of adult rats. Eight and 12 weeks after grafting, clinical, electrophysiological, histological, and neuroanatomical studies were performed. Motor performance of the hosts was assessed by the inclined-plane test. The conduction of nerve impulses across the lesion-transplantation site was evaluated by recording the spinal corticomotor and somatosensory evoked potentials. The survival, growth, differentiation, and parenchymal integration of the graft were documented histologically on semi-thin sections. The axonal interactions between the host spinal cord and the graft as well as the posttraumatic retrograde degeneration of corticospinal axons were investigated using the horseradish peroxidase (HRP) technique.
Clinical and electrophysiological assessments did not demonstrate any functional activity of the graft. On histological examination, grafted neurons showed a survival rate of 55%. Such neurons exhibited a limited degree of growth and differentiation. The extent of parenchymal integration between the host spinal cord and the graft varied considerably among different specimens and in the various regions of every specimen. The HRP investigations demonstrated that some axonal interactions between the host spinal cord and the graft had occurred. Regenerated axons arising from both the spinal cord and the dorsal root ganglia of the host entered the graft and elongated in it. Also, axons from the grafted neurons were able to grow for some distance in the host spinal cord. The phenomenon of the posttraumatic retrograde degeneration of corticospinal axons was not affected by this embryonic tissue grafting.