Effects of synthetic craniofacial materials on cerebral microcirculation.

Four groups were studied to look at effects of synthetic materials on the pial vasculature. Using Sprague-Dawley rats, an open pial window approach was used in which there was a control group, a hydroxyapatite cement group mixed with sodium phosphate, a methylmethacrylate slow-set, and a methylmethacrylate fast-set group. There were 10 animals with 20 vessels studied within each group. The permeability leakage outside the vessel was evaluated to determine the vascular albumin leakage, and the number of rolling and adherent leukocytes was studied within each group. It was seen that the control group was significantly different compared with the fast-set methylmethacrylate group during a 2-hour period in regard to the percentage leakage, as well as a number of rolling and adherent leukocytes. This is one of the first studies to demonstrate the effects of synthetic craniofacial materials on the underlying pial vasculature.

Endoscopic treatment of carpal tunnel syndrome: a critical review.

OBJECT: The goal of this paper is to present a critical review of the endoscopic procedures currently in use for the treatment of carpal tunnel syndrome. Endoscopic techniques and outcomes are discussed. METHODS: An extensive review of published articles on the subject of endoscopic carpal tunnel release surgery is presented, encompassing six endoscopic techniques used to treat carpal tunnel syndrome. Since the first report in 1987, 7091 patients have undergone 8068 operations. The overall success rate has been 96.52%, with a complication rate of 2.67% and a failure rate of 2.61%. The mean time to return to work in patients not receiving Workers' Compensation was 17.8 days, ranging between 10.8 and 22.3 days. The most common complications were transient paresthesias of the ulnar and median nerves. Other complications included superficial palmar arch injuries, reflex sympathetic dystrophy, flexor tendon lacerations, and incomplete transverse carpal ligament division. In many studies in which open and endoscopic techniques were compared, it was reported that patients in the the latter group experienced significantly less pain and returned to work and activities of daily living earlier. CONCLUSIONS: Success and complication rates of endoscopic carpal tunnel release surgery are similar to those for standard open procedures.

Effect of 4-aminopyridine and single-dose methylprednisolone on functional recovery after a chronic spinal cord injury.

The demyelination process is an important factor contributing to long term sensory and motor impairments after spinal cord injury (SCI). Exposure of axonal K+ channels after demyelination may contribute to blockage of action potentials across the injury site. A K+ channel blocker, 4-aminopyridine (4-AP), has been effective in restoring some sensory and motor impairment in incomplete SCI patients. The long-term effect of this compound in chronic model of SCI is not known. In this study, after a compression injury of 50 grams in rats, a randomized treatment was initiated 3 weeks after the initial injury which was followed by daily administration of 4-AP at 2 mg/kg (n = 8), 4 mg/kg (n = 8), and 6 mg/kg (n = 8) for 4 weeks. A group of methylprednisolone (MP)-treated (30 mg/kg, n = 8) and non-treated animals (n = 8) were included for comparison. The functional motor outcome was measured in each animal at regular time points up to 4 weeks post-treatment. All animals receiving 6 mg/kg developed generalized seizure and were excluded from the study. In the other animal groups, analysis of the behavioral outcome and neuro-pathological changes were essentially similar and did not show any significant effect of treatment. Our data indicate that daily administration of 4-AP, over 4 weeks of treatment period, lacks any significant effect on axonal function in chronically injured rats. This could be due to (a) lack of significant numbers of demyelinated axons which could improve the functional outcome and (b) a treatment regimen that was not adequate to contribute to a better functional outcome. One time bolus-administration of MP at 30 mg/kg also did not ensure a better functional outcome.

Endoscopic treatment of carpal tunnel syndrome: a critical review.

An extensive review of published articles on the subject of endoscopic carpal tunnel release surgery is presented, encompassing six endoscopic techniques used to treat carpal tunnel syndrome. Since the first report in 1987, 7091 patients have undergone 8068 operations. The overall success rate has been 96.52%, with a complication rate of 2.67% and a failure rate of 2.61%. The mean time to return to work in patients not receiving Workers' Compensation was 17.8 days, ranging between 10.8 and 22.3 days. The most common complications were transient paresthesias of the ulnar and median nerves. Other complications included superficial palmar arch injuries, reflex sympathetic dystrophy, flexor tendon lacerations, and incomplete transverse carpal ligament division. All studies in which open and endoscopic techniques were compared reported that patients in the latter group experienced significantly less pain and returned to work and activities of daily living earlier. The reported success and complication rates of endoscopic carpal tunnel release surgery are similar to those for standard open procedures. Endoscopic techniques and outcomes are discussed.

The effects of methylmethacrylate's hyperthermic polymerization on cerebral vascular permeability.

This study was undertaken to analyze the effects of significant hyperthermia (> 100 degrees C) associated with the polymerization of polymethlymethacrylate (PMM) on the permeability of the cerebral vasculature in rats. The method used to visualize the pial vasculature included the open pial window technique and epifluorescence microscopy. Results indicated that there is a significant increase in cerebral vascular permeability following in situ polymerization of PMM over the craniectomy site.

Radiofrequency as a lesioning model in experimental spinal cord injury.

Many models have been developed to study spinal cord injury (SCI), such as cryogenic lesioning, hot water injury, scalpel lesioning, compressive trauma using clips, electromechanical devices, extradural cuffs, and weight-drop techniques. In this study, the radiofrequency (RF) lesion was used for inducing an experimental SCI in cats. The neuropathology was correlated with the MRI. In this model, 4 cats were injured at the thoracic spinal cord (T11-T12) with a lesion of 65 degrees C for 1 min using a micromanipulated penetrating RF electrode. The MRI of the lesions after 2, 3, 5, and 6 weeks post-injury as well as the correlative histological changes were obtained. The RF-induced lesion was discrete with little spreading across the spinal cord. There was a good correlation between the histopathology findings and the MRI. We conclude that experimental RF lesioning of the spinal cord can produce a consistent lesion with predictable histopathological changes in experimental animals. A 65 degree C injury for 1 min induced a clinical picture of an incomplete SCI. The RF lesioning should be considered as a new model to study SCI, particularly those with a penetrating component.