Juvenile xanthogranuloma of peripheral nerve: a report of two cases.

As a rule, juvenile xanthogranuloma (JXG) is a cutaneous lesion most often occurring in infancy. An inflammatory process of unknown etiology, it is self-limited and benign in nature. The spectrum of JXG has expanded to include adult examples, multifocal lesions, and ones arising at extracutaneous locations. Although a variety of extracutaneous sites may be affected, few reported lesions have involved cranial or peripheral nerves. Solitary examples have been reported in trigeminal nerve and spinal nerve root; affected individuals were children or adolescents. An optic nerve lesion has also been described. We describe two additional cases of JXG of nerve. One patient developed multiple dorsal nerve root lesions, as well as skin involvement. The other case featured isolated involvement of the left radial nerve. Both patients were adults with no known underlying systemic disorder. These cases further expand the spectrum of extracutaneous JXG, and underscore its consideration in the differential of nerve "tumors."

Heterotopic bone formation in male and female rabbits.

We performed mechanical induction of heterotopic ossification in the quadriceps of the right hind limb of six male and six female sexually mature New Zealand white rabbits of similar size. The effect of sex difference on heterotopic bone was assessed by analyzing plain radiographs of the femur. The results indicate that a male/female sex difference in heterotopic bone formation cannot be demonstrated.

Effect of two nonsteroidal antiinflammatory drugs on heterotopic bone formation in a rabbit model.

Using the model described by Michelsson, 24 mature New Zealand white rabbits underwent mechanical induction of heterotopic ossification in the quadriceps of the right hind limb. The rabbits were equally divided into four groups: indomethacin-treated, piroxicam-treated, and their respective controls. The effect of drug therapy on the production of heterotopic bone was assessed by analyzing plain radiographs of the femur using the grading system described by Scott. The results demonstrated that, while indomethacin is effective in decreasing the formation of heterotopic bone, piroxicam--when used in the dosage previously demonstrated to have no deleterious effect on healing bone--is not. The analysis of piroxicam blood levels demonstrated that the experimental piroxicam dose is inadequate to produce effective plasma blood levels in the rabbit. Therefore, any potential benefit from using piroxicam, as opposed to other nonsteroidal antiinflammatory drugs regarding fracture healing and bone remodeling, cannot be applied for the prophylactic treatment of heterotopic bone formation.

Electrical stimulation of nerve regeneration in the rat: functional evaluation by a twitch tension method.

The effect of D.C. electrical fields on in vivo nerve regeneration following rat sciatic nerve transection was assessed by a toe-twitch tension method for motor recovery. Two groups for baseline comparisons received either a nerve transection and a neutral battery implant or a nerve crush and no implant. Two treatment groups each received a nerve transection and an implant delivering either cathodal (-10 µA) or anodal (+10 µA) current via electrodes positioned on either side of the transection site. The contralateral nerve was exposed but not given a lesion. The functional recovery was assessed at weekly intervals by comparing the amplitude and area of the twitch tension curves on both sides, expressed as a ratio (index of motor recovery = IMR). By 28-35 days postoperative (dpo) the crushed/untreated group had mean IMR values not significantly different than the preoperative values. The transected/neutral group appeared to have the worst recovery throughout the study. Compared to these two groups, both the cathodal and anodal treatment groups with a transected nerve showed intermediate IMR values, but by 63 dpo the group differences were less. These results indicate that following a nerve transection lesion steady D.C. electrical fields may temporarily enhance the early functional recovery of motor nerve regeneration compared to conventional nerve repair alone.

Concurrent compartment syndromes of the foot and leg.

We reviewed the case summaries of eight patients who developed concurrent compartment syndromes of the foot and leg after trauma. Patients with multiple fractures of the lower extremities, particularly the tibia, femur, and foot, may develop this disorder. The obvious causes of the concurrent syndromes, concurrent fractures and generalized limb ischemia, were seen only in two patients. The communication between the compartments of the foot and leg may be an additional causative factor. Delayed fasciotomy resulted in muscle necrosis and/or tibial nerve dysfunction. Suspected cases should have the diagnosis established by catheterization of the involved compartments. Prompt fasciotomies of the foot and leg should be performed if the pressures are significantly elevated.

Acute foot compartment syndromes.

Twelve cases of compartment syndrome of the foot in 10 patients were retrospectively reviewed. All were high-energy injuries sustained in a fall from a height (six), crush (three), or motor vehicle accident (three). Bone injuries of the foot included five calcaneal fractures, three multiple metatarsal and/or phalangeal fractures, and two Lisfranc fracture-dislocations with multiple metatarsal neck fractures. The most consistent physical finding was tense swelling of the foot. The diagnosis was confirmed with compartmental pressure measurements in all cases. Decompressive fasciotomies were adequately performed by the medial approach of Henry or a combined approach with medial and dorsal incisions. An additional lateral incision was used in two instances.

Electrical stimulation of nerve regeneration in the rat: the early effects evaluated by a vibrating probe and electron microscopy.

This study examines the effect of applied d.c. electric fields on nerve regeneration following injury to the rat sciatic nerve using the circularly vibrating probe and electron microscopy. The transected and treated nerve which received a d.c. electrical stimulator (0.6 mu A) was compared with untreated transected and crushed nerves. At one week postoperative, the probe was used to measure in vivo the current density along the nerve length. All nerves studied had a proximal peak at the lesion site and a second peak at varying distal locations: crushed/untreated (13.3 mm), transected/untreated (9.7 mm) and transected/treated (16.3 mm). A significant difference (69%) between the distal peak distances in the two transection groups suggests that the electrical treatment enhanced the progress of nerve regeneration. There were no significant differences between the mean peak amplitudes (1.6-2.2 mu A/cm2). Applied verapamil reduced the peaks, suggesting they are associated in part with a calcium-dependent current. Electron microscopy at selected nerve regions indicated that the peaks correspond to regenerating axonal growth cones. The results suggest the potential clinical application of d.c. electric fields in the treatment of nerve injuries.

Compartment syndrome after low-velocity gunshot wounds to the forearm.

Between 1980 and 1988, 127 patients with 131 low-velocity gunshot wounds to the forearm were treated. In 71 extremities there was no bony injury; 60 extremities sustained fractures. The diagnosis of a compartment syndrome was based on tissue pressure measurements and/or clinical examination. A univariate analysis followed by a multivariate stepwise logistic regression was used to evaluate potential risk factors including fracture location, displacement, comminution, and the quantity of radiographically determined metallic foreign bodies in the wound. A compartment syndrome was diagnosed in 13 of the extremities (10%). Fracture location was the only significant risk factor for the development of a compartment syndrome. Low-velocity gunshot injuries to the forearm are at definite risk for the occurrence of a compartment syndrome. A high index of suspicion is necessary to prevent untoward sequelae. Patients with this injury, especially those with a proximal one-third fracture who constitute an extremely high-risk group, should be monitored closely.

A twitch tension method to assess motor nerve function in rat.

A simple and quantitative method is described which assesses the motor function of the rat tibial nerve by recording the twitch tension developed by the digital flexors. Stimulating electrodes are placed at the proximal end of the sciatic nerve of anesthetized rats, and the associated foot is immobilized on a sliding stage. The middle digit is connected via a thread to a force-displacement transducer and the sciatic nerve is stimulated supramaximally. The resulting twitch tension curve is recorded on an oscilloscope and/or signal averager. Measurement of the area and amplitude of the twitch tension curve provides an estimate of the recovery of motor function. The method is illustrated by examining the return of motor function following either sciatic nerve crush, or sciatic transection and repair. The results obtained are compared with other assessments of sciatic nerve function, such as the toe-spreading reflex and the analysis of walking tracks. The results from the twitch tension method are more sensitive, unaffected by changes in sensory function, and less prone to variation than the other assessments.

An experimental implant for applying a DC electrical field to peripheral nerve.

Several studies have shown that nerve fibers grow preferentially toward the cathode when placed in an electrical field. To study the effects of electrical stimulation on in vivo nerve regeneration, an inexpensive implantable current source has been developed which is able to reliably deliver a minute DC current (0.57 microA) via wick electrodes. The current density was measured directly with a vibrating probe and compared to the delivered current. The mean current density along the normal unoperated rat sciatic nerve was 0.19 microA/cm2, while the value along the nerve near the wick electrodes positioned 15 mm apart with an active in vivo implant was 23.39 microA/cm2. This application promises to provide a potentially useful means of enhancing nerve regeneration clinically.