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Biomedical subjects

S E Mackinnon

Publications and source records attributed to S E Mackinnon.

At least 235 records · Page 13Linked to original sources
PubMed1986

Treatment of the painful neuroma by neuroma resection and muscle implantation.

The successful treatment of the painful neuroma remains an elusive surgical goal. This report evaluates one approach to the management of this problem which entails neuroma excision and placement of the proximal end of the nerve away from denervated skin, away from tension, and into a well-vascularized environment: muscle. Seventy-eight neuromas in 60 patients with a mean follow-up of 31 months (range 18 to 43 months) were evaluated. Sixty-seven percent of these patients involved Workmen's Compensation and 57 percent had had at least one previous operation to treat their pain. The results demonstrated good to excellent results in 82 percent of the treated nerves in the entire group. Factors that were predictive of a poorer outcome were (1) digital neuroma (p less than 0.0005), (2) Workmen's Compensation (p less than 0.01), and (3) three or more previous operations for pain (p less than 0.01). Transposition of nerves into small superficial muscles or muscles with significant excursion resulted in treatment failures. The etiology and histopathology of treatment failures are reviewed. Treatment of radial sensory neuromas by transposition of the radial sensory nerve into the brachioradialis muscle when any associated injury to the lateral antebrachial cutaneous nerve was also treated, gave good to excellent relief of pain, and improved hand function in 88 percent of the patients.

Adult↗
PubMed1986

Complex maxillary fractures: role of buttress reconstruction and immediate bone grafts.

Between 1978 and 1984, 558 patients with complex facial fractures have been treated. One hundred and seventy-one of these patients have had complex Le Fort fractures of the maxilla. In this group of patients, the importance of direct anatomic reconstruction of the anterior maxillary buttresses has been assessed. Complete exposure of the injured buttresses will facilitate assessment of the exact fracture pattern. Direct fixation of the medial and lateral maxillary buttresses on each side, in combination with immediate bone-graft reinforcement or replacement of comminuted or missing buttresses, will facilitate the reconstruction of even the most severely injured maxilla in one stage. This approach is combined with similar reconstructive techniques in other areas of the craniofacial skeleton. Associated mandibular fractures are managed with rigid internal fixation utilizing A-O techniques. The use of these techniques dramatically facilitates airway management and simplifies the treatment of the edentulous patient, the patient with bilateral condylar neck fractures, and those patients with sagittal splitting of the maxilla and palate. The use of both internal craniofacial suspension wires and external craniofacial suspension devices has become largely unnecessary, and reconstruction of even the most complex injuries in one stage with minimal complications and secondary deformities is made possible.

Bone Transplantation↗
PubMed1986

Experimental study of chronic nerve compression. Clinical implications.

The connective tissue and nerve fiber changes associated with chronic nerve compression in an experimental animal model are described. Similar findings in specimens from patients with chronic nerve compression are outlined. The clinical implications associated with these histologic findings are discussed.

Animals↗
PubMed1985

Neural activity originating from a neuroma in the baboon.

Single nerve fiber recordings were obtained from traumatically induced neuromas of the superficial radial nerve in baboons 1-7 months after injury. Eight to 18% of the fibers had spontaneous activity, and 67% of these were unmyelinated. Myelinated as well as unmyelinated fibers responded to mechanical stimulation of the neuroma whereas no fibers responded to similar stimulation of the normal nerve. Apparent crosstalk of action potential activity between fibers at the neuroma was observed which could be due to electrical coupling, though retrograde sprouting is another possible explanation. These abnormalities in neural activity originating from a neuroma in the primate are qualitatively similar to those noted in other species and may provide an explanation for certain abnormal sensory phenomena associated with peripheral nerve injury.

Action Potentials↗
PubMed1985

The overlap pattern of the lateral antebrachial cutaneous nerve and the superficial branch of the radial nerve.

The anatomic relationship between the lateral antebrachial cutaneous nerve (LABC) and the superficial branch of the radial nerve (SBR) is outlined in 53 cadaver and 41 clinical dissections. Either partial or complete overlap of the LABC with the SBR occurred in 75% of the cases. The LABC and the SBR innervated separate territories in only 25% of the dissections. We suggest that injury to the LABC may be a concomitant finding in patients with injury to the SBR and that this associated injury to the LABC may be one of the reasons why neuromas of the SBR have been thought to be more resistant to therapy than neuromas elsewhere.

Humans↗
PubMed1985

Soft tissue expanders in upper limb surgery.

Five cases in which soft tissue expanders have been used as an aid to reconstruction in the upper limb are reported. The cases involved the reconstruction of the shoulder mound after forequarter amputation, excision of a large tattoo of the forearm, excision of a malignant melanoma of the elbow, excision of a giant hairy nevus of the forearm, and the creation of large advancement flaps to release an axillary burn scar contracture. No complications were noted with the use of these expanders. Patient tolerance was excellent, and the final result was significantly enhanced by the use of this technique.

Adult↗
PubMed1985

A primate model for chronic nerve compression.

Peripheral compression neuropathy is a common clinical entity but little human nerve material has been available for study. It has been difficult to develop an experimental model of chronic nerve compression which is reliable and reproducible, making it difficult to assess the various treatment modalities currently in use to manage this problem. In a recent study using a rat model, connective tissue and nerve fiber changes associated with chronic nerve compression were described by the authors. The present study expands this same model of chronic nerve compression to the multifascicular median nerve of the cynomolgus monkey, using this model to test whether or not current surgical treatment modalities for nerve entrapment will alter the course of chronic nerve compression. Using histologic and morphometric parameters, there did not appear to be a difference between nerves treated by decompression alone or by decompression and internal neurolysis. Total number of nerve fibers remained constant, as did axon size, but a demyelinating process was demonstrated which is a significant component of chronic nerve compression. Although the small number of experimental animals (7) makes precise evaluation of the clinical modalities impossible, the authors expect that further study of the multifascicular median nerve of the cynomolgus monkey will prove to be a useful source of future experimental evidence and will help to interpret the diverse therapeutic and operative techniques currently in use.

Animals↗
PubMed1985

The nerve allograft response--an experimental model in the rat.

The nerve allograft response in a rat model is presented. The Lewis rat (RTI1) served as the recipient animal while Fischer rats (RTI1) and ACI rats (RTIa) provided the donor nerve allografts. A Lewis/Lewis autograft group was used as the control group. Histological and electrophysiological measurements of nerve regeneration were assessed at five months. While good regeneration was noted in the autograft and matched allograft groups, regeneration across the unmatched allograft was poor. The degree of nerve regeneration (as measured with histological and electrophysiological values) correlated well with previous immunological studies and would support the use of this model for future investigation of the nerve allograft response in the rat.

Animals↗
PubMed1985

Peripheral nerve injection injury with purified bovine collagen--an experimental model in the rat.

This study investigated the effect of purified bovine collagen (Zyderm collagen implant) on peripheral nerve tissue in rats. Zyderm was injected extrafascicularly and intrafascicularly into the sciatic nerve of adult Wistar rats. The nerves were examined by light and electron microscopy and the integrity of the blood-nerve barrier assessed by protein tracer technique. With light microscopy the precise anatomical location of the injected material could be identified. The purified bovine collagen did not appear to be neurotoxic. After extrafascicular injection, only minimal nerve fiber damage was seen. Intrafascicular injection produced a histological picture compatible with compression neuropathy and was associated with a breakdown in the blood-nerve barrier.

Animals↗
PubMed1985

Medial antebrachial cutaneous-lateral femoral cutaneous neurotization to provide sensation to pressure-bearing areas in the paraplegic patient.

Although rotation of musculocutaneous flaps can achieve closure of pressure sores, these insensitive flaps in the paraplegic or quadriplegic contribute to recurrent ulceration. This report suggests a method of reinnervating the territory of the lateral femoral cutaneous nerve (the tensor fascia lata musculocutaneous flap) using the medial antebrachial cutaneous nerve of the forearm. This neurotization procedure has restored sensibility to the area of the healed pressure sore.

Adult↗
PubMed1985

The role of primary bone grafting in complex craniomaxillofacial trauma.

The role of craniofacial surgical techniques and immediate bone grafting in the management of complex craniofacial trauma has been reviewed. Four hundred and one patients with complex facial injuries have been treated. Two hundred and forty-one primary bone and cartilage grafts have been performed in 66 patients. Complex facial injuries should be managed by direct exposure, reduction, and fixation of all fractures utilizing interfragmentary wiring. Very comminuted or absent bone is replaced by immediate bone grafting, producing a stable skeleton without the need for external fixation devices. Associated mandibular fractures are managed with rigid internal fixation utilizing A-O technique. Results of immediate bone grafting have been excellent, and complications are rare. All deformities should be corrected, whenever possible, during the initial operation. This one-stage reconstruction of even the most complex facial injuries will prevent severe postoperative traumatic deformity and disability that may be extremely difficult or impossible to correct secondarily.

Adult↗
PubMed1985

Histologic assessment of nerve regeneration in the rat.

This study reports the degree of spontaneous regeneration that will occur in the sciatic nerve of a rat 5 months after complete resection of the nerve. In 30 animals, the sciatic nerve was excised. Histological assessment at 5 months revealed evidence of regeneration for a variable distance (mean 23.7 mm +/- 6.4 mm). Histological sections were studied at 1-cm intervals along the length of the nerve. Evidence of compartmentation with "minifascicle" formation was noted. The orientation of the nerve fibers was parallel to the long axis of the nerve. This study assessing spontaneous regeneration is meant to serve as a control for other studies evaluating the effect of factors that may influence nerve regeneration in the rat model.

Animals↗
PubMed1985

Nerve regeneration through a pseudosynovial sheath in a primate model.

This study investigated nerve regeneration through a pseudosynovial sheath in a primate. After resecting a 3-cm segment of the ulnar nerve at the elbow, the two ends of the divided nerve were placed at either end of the pseudosynovial tube, positioning the nerve ends such that they were separated by a 3-cm gap. Histologic evaluation at 3, 5, 7, and 9 months demonstrated evidence of nerve regeneration across this gap. Nerve fiber diameter and density assessment demonstrated a maturation of the fiber pattern with time. The overall morphologic pattern of the regenerating nerve within the pseudosheath was that of multiple small fascicles, each within its own perineurial compartment. This pattern resembled neither the proximal nor distal nerve fascicular pattern.

Animals↗
PubMed1985

Alteration of neuroma formation by manipulation of its microenvironment.

In a primate model a histologic assessment of neuroma formation is reported. Three experimental groups were defined. Transected sensory nerves left adjacent to the incisional wound in an area of movement (wrist) were considered the control group. In the "proximally cut" group the same sensory nerves were positioned well proximal to the incisional wound. In the "muscle-implantation" group these nerves were placed in adjacent muscles. At 6 months a histologic assessment of the neuroma formation in the three experimental groups was carried out. Implantation of the sensory nerve into muscle significantly altered the regenerative potential of that nerve. The muscle completely surrounded the sensory nerve. The minimal neuroma that formed had significantly less scar tissue and contained nerve fibers that were of a smaller diameter and decreased density than either the control or the proximally cut group. There were no histologic differences between these latter two groups. However, regeneration into the overlying skin that was noted in the control neuromas was not seen in those nerves which had been proximally cut.

Animals↗
PubMed1984

Tibial nerve branching in the tarsal tunnel.

To provide an anatomical basis for diagnosis and treatment of the tarsal tunnel syndrome, the relationship of the tibial nerve to the tarsal tunnel was investigated in 31 feet of 20 cadavers. The bifurcation into medial and lateral plantar nerves occurred within 1 cm of the malleolar-calcaneal axis in 90% of the feet. Seven of 11 bilateral specimens were bilaterally symmetrical in the bifurcation location; three varied within 1 cm between sides; and in the fourth cadaver, one side bifurcated at 3 cm and the other at 5 cm proximal to the axis. The calcaneal nerve showed great variability; in seven cadavers, it arose within, in eight cadavers proximal to, and in five cadavers there were multiple branches arising both proximal to and within the tarsal tunnel.

Foot↗
PubMed1984

Susceptibility of the superficial sensory branch of the radial nerve to form painful neuromas.

The superficial sensory branch of the radial nerve appears prone to develop painful neuromas out of proportion to its likelihood for injury. Based on cadaver dissections and intraoperative observations, an anatomical mechanism for this "predisposition" is suggested. Exit of this nerve beneath dense fascia and the tendons of brachioradialis and extensor carpi radialis longus provide a proximal tethering against which tension develops as the distal fixation point (neuroma) is pulled through the long excursion of wrist arc of motion. This long excursion and proximal tethering are not present anatomically for the dorsal cutaneous branch of the ulnar nerve nor the palmar cutaneous branch of the median nerve.

Disease Susceptibility↗