A morphological study of Schwann cells and axonal regeneration in chronically transected human peripheral nerves.

Relatively little is known about the effects of chronic transection on human peripheral nerves. In this study intraoperative biopsies were obtained from proximal and distal nerve stumps and intervening neuromas resected before peripheral nerve reconstruction. Biopsies were collected from ten patients following differing types of nerve injury, with delays to repair ranging from 8 to 53 months. Nerves were examined by light and electron microscopy. In general, reinnervation was poor, although even following the most severe injuries, all of the distal stumps contained some regrowing axons, which were always associated with Schwann cells. Denervated Schwann cells, arranged in typical bands of Büngner were consistently present in each distal stump. Our findings confirm that the morphology of chronically denervated human peripheral nerves is essentially similar to that described in experimental models.

Evidence for immune system involvement in reflex sympathetic dystrophy.

Skin biopsies from patients with reflex sympathetic dystrophy were immunostained using a variety of antisera. An incidental finding with S100 staining was the presence of numerous Langerhans cells in the epidermis. All patients had significant pain at the time of biopsy, and all had symptoms refractory to treatment. The potential implications of this finding are discussed.

The epidemiology and management of upper limb peripheral nerve injuries in modern practice.

This paper reports an epidemiological and clinical study of 813 patients with 1,111 peripheral nerve injuries who were treated for upper limb trauma, which included nerve injury, at two plastic surgery units in south-east England, predominantly between the years 1982 and 1991. The frequency distributions of the levels of nerve injury, and the causes of nerve injury in the sample, are presented, together with the surgical management and timing of nerve repair in these patients. 1,018 clinically suspected nerve injuries in 730 patients (91.6% of nerves, 89.8% of patients) were treated by primary nerve repair, elective delayed nerve repair or primary surgical exploration alone. Divisions of 93 nerves in 83 patients (8.3% of nerves, 10.2% of patients) were treated other than by primary repair or elective delayed repair, due to delayed referral from accident and emergency departments, resulting from missed or uncertain diagnosis at presentation or otherwise unaccounted delay in the initial referral.

Paradoxical clinical consequences of peripheral nerve injury: conduction of nerve impulses does not occur across the site of injury immediately following nerve division and repair.

The occasional apparent clinical phenomenon of the immediate although transient return of peripheral nerve function after nerve division and primary repair has been previously reported. Electrophysiological findings from the sciatic nerve of the rabbit have been previously presented in support of the concept of the transmission of nerve impulses across a freshly divided and repaired peripheral nerve for a short period until the onset of Wallerian degeneration. This paper presents experimental evidence to show that these findings were misinterpreted and that a compound action potential cannot be transmitted across a surgically repaired division in a peripheral nerve. Observations from previous experimental research in neurophysiology are discussed which confirm these conclusions. The claim that failure to diagnose a peripheral nerve injury at presentation can be explained in some circumstances by "jump transmission" is not based on sound evidence and the concept of "jump transmission" cannot be accepted as a defence for clinicians who fail to diagnose a peripheral nerve injury.

Paradoxical clinical consequences of peripheral nerve injury: a review of anatomical, neurophysiological and psychological mechanisms.

This paper reviews some of the possible explanations and mechanisms that may be responsible for variation from expected clinical findings soon after nerve injury in certain patients, and for subjective sensations and objective sensibility which can appear to arise from within the autonomous zone of the cutaneous distribution of a divided nerve. A number of features of peripheral innervation, central nervous system physiology and sensory psychology are discussed. These include: (1) the normal extent of overlap- or cross-innervation between the territories of adjacent peripheral nerves; (2) anomalous innervation due to normal anatomical variation; (3) ectopic impulse generation and cross-excitation between neurons in the peripheral nervous system after nerve injury; (4) neurophysiological responses and mechanisms of re-innervation other than axon regeneration across the site of nerve repair; (5) cortical somatotopic reorganisation in response to nerve injury; and (6) phantom sensory phenomena including the psychology of sensory perception.

Nerve-muscle sandwich grafts: the importance of Schwann cells in peripheral nerve regeneration through muscle basal lamina conduits.

An interposed segment of nerve was used to enhance the distance over which freeze-thawed muscle autografts will support effective peripheral nerve regeneration. Gaps were created in the sciatic nerves of adult Lewis rats. Regeneration through 1 and 1.5 cm freeze-thawed muscle grafts was compared to regeneration through nerve-muscle sandwich grafts in which muscle grafts of equivalent length were divided and a 2 mm segment of the distal nerve sutured between the two halves of the muscle, providing an intermediate depot of Schwann cells. Electrophysiological and morphological evaluation was carried out 40 weeks after operation. Despite lengthening the graft, and having four anastomoses instead of two, this manoeuvre enhanced nerve regeneration over each gap studied and for the 1.5 cm gaps compared favourably with perfect match nerve autografts. In addition, a number of grafts were examined at 7 and 14 days by S100 immunohistochemistry. Schwann cell migration was seen to proceed both proximally and distally from the intermediate segment at a rate similar to that from the distal stump. It is concluded that sandwich grafts may prove to be effective alternatives to cutaneous nerve grafts for peripheral nerve reconstruction.

Digital nerve compression by hyperplastic Pacinian corpuscles. A case report and immunohistochemical study.

A 68-year-old lady developed digital pain within days of the excision of a palmar ganglion. This was found to be due to a mass of hyperplastic Pacinian corpuscles compressing the digital nerve. Immunohistochemistry was carried out on the resected corpuscles using antisera to a range of neuropeptides. Possible mechanisms of hyperplasia are discussed.

Interpreting the results of unilateral digital nerve repair.

We report the results of examination of patients before primary and secondary unilateral digital nerve repair. Two-point discrimination was uniformly recorded. The results show that significant overlap of adjacent digital nerves is common and this has important implications for interpretation of results after repair. Recommendations are made regarding the evaluation of outcome following surgery.

Repair of mixed peripheral nerves using muscle autografts: a preliminary communication.

Twelve patients were reviewed following the reconstruction of mixed motor/sensory nerves using freeze-thawed skeletal muscle autografts. A total of 13 nerves were reconstructed-6 median and 7 ulnar. All the repairs were secondary procedures, with a mean time from injury to grafting of 17 months. Sensory and motor evaluation was carried out and the patients asked to complete a pain questionnaire. Five patients achieved an S3+ level of sensory recovery. Two underwent revision of their muscle grafts to nerve grafts. Motor recovery was universally poor.

Glycosylated haemoglobin levels in patients with diabetes mellitus.

Glycosylated haemoglobin A1 levels were measured in 186 patients with diabetes mellitus and 108 non-diabetic controls. Forty-nine diabetics were considered well controlled with at least three blood glucose levels below 10 mmol/L, while 50 diabetic patients were poorly controlled with at least three blood glucose levels above 15 mmol/L. Mean glycosylated haemoglobin A1 levels for the 108 normal controls was 7.45% +/- 0.73%, for the well controlled diabetics, 10.7% +/- 2%, and for poorly controlled diabetics, 15.0% +/- 2.5% of total haemoglobin. In patients with the onset of diabetes after the age of 40 years, there was a significant difference between the haemoglobin A1 levels in those with diabetic retinopathy and those without complications. There was a significant association between haemoglobin A1 levels and the duration of the disease in diabetics controlled with insulin.

Serum pyridoxal and folate concentrations in diabetics.

Serum pyridoxal and folate concentrations were measured in 518 diabetics. There were 185 males and 333 females. The level of pyridoxal was significantly lower in the diabetics when compared with 371 'healthy' controls and 25% had levels below the lower limit of the normal range. No significant difference was observed between diabetics being treated by diet alone, oral hypoglycaemics or insulin. Only 20 patients had a reduced serum folate level and in 6 this was accompanied by a low pyridoxal concentration. The results suggest that diabetics may have an increased demand for pyridoxal.