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Biomedical subjects

S E Mackinnon

Publications and source records attributed to S E Mackinnon.

At least 217 records · Page 12Linked to original sources
PubMed1988

Tissue expansion in head and neck reconstruction.

The present study reviews our clinical experience with tissue expansion in head and neck reconstruction. The clinical series consists of 33 expansions performed in 29 patients between 1983 and 1986. The results of tissue expansion in the head and neck were distinguished by a high complication rate, necessitating some revision in the original treatment plan in 48 percent of patients. Despite this high incidence of complications, sufficient tissue was generated to successfully complete the planned reconstruction in 79 percent of patients. Specific complications were observed with particularly high frequency within distinct anatomic sites. The highest incidence of complications occurred in the cheek and neck (69 percent) and forehead (50 percent) regions. Complications in the eyelid region (33 percent) and scalp (17 percent) were less common. Implant exposure was the most frequently observed complication. Other sequelae noted in this series included intractable pain, infection, and bone resorption.

Adolescent↗
PubMed1987

Soft tissue expanders in hand reconstruction.

Eight cases in which soft tissue expanders have been used as an adjunct to reconstruction in the hand are reported. Cases involved reconstruction after skin grafting for burns and crush injuries as well as skin resurfacing in the management of the painful hand. Patient tolerance was excellent and the final result was significantly aided by the use of this technique. The technical details of expansion as well as complications are discussed.

Adolescent↗
PubMed1987

Musculoaponeurotic variations along the course of the median nerve in the proximal forearm.

31 cadaver arms have been dissected to study the variations in the anatomy of the muscles and fibrous arches which might cause compression of the median nerve in the forearm. Pronator teres always had a superficial head and usually a deep head. Flexor digitorum superficialis varied greatly in its site of origin. The median nerve might be crossed by two, one or no fibro-aponeurotic arches. Gantzer's muscle, an accessory head of flexor pollicis longus, was present in 45% of cadavers. No ligament of Struthers was found. Possible sites and causes of nerve compression are discussed.

Forearm↗
PubMed1987

Reliability of two-point discrimination measurements.

Both moving and static two-point discrimination are valid measurements of functional sensibility in the hand. The present study investigated the interobserver variability of these measurements when two observers used the same testing instrument and the same definition of the testing procedure's end point. In testing 30 nerve-injured patients, interobserver variability was found to vary within 1 mm, or less, for moving two-point discrimination in 93.3% of the measurements and for static two-point discrimination in 86.8% of the measurements. In only two of the 30 measurements of moving two-point discrimination and in four of the measurements for static two-point discrimination were interobserver differences equal to 2 mm. Measurements for both moving and static two-point discrimination were analyzed statistically by linear regression and correlation co-efficient techniques. The measurements for two-point discrimination obtained with the protocol employed in this study were found to have an interobserver reliability at the p less than 0.00001 level.

Hand↗
PubMed1987

Validity of nerve conduction velocity studies after anterior transposition of the ulnar nerve.

To determine which anatomic position and marking techniques are valid for postoperative electrodiagnostic testing, ten patients were studied during anterior transposition of the ulnar nerve. Variables included skin and ulnar nerve distances measured anterior and posterior to the medial humeral epicondyle, and ulnar nerve conduction velocities over these distances, with the elbow flexed and extended, and with the ulnar nerve in the pretransposition and posttransposition location. The results of the study confirm that ulnar nerve conduction velocity is recorded as faster with elbow flexion preoperatively and elbow extension postoperatively when the skin measurement used for the distance is kept constant. Postoperatively, the most valid measurement of ulnar nerve conduction velocity was a skin distance that was posterior to the medial humeral epicondyle with the elbow extended.

Humans↗
PubMed1987

Results of treatment of recurrent dorsoradial wrist neuromas.

Dorsoradial wrist neuromas diagnosed and treated by traditional techniques remain the most difficult for which to achieve satisfactory pain relief. Between 1981 and 1985, 52 patients with dorsoradial wrist neuromas were treated by neuroma resection and implantation of the nerves innervating the neuroma into the brachioradialis muscle. Critical to this treatment schema was preoperative use of nerve blocks to diagnose overlapping patterns of the cutaneous nerves in this region. Of patients for whom this technique was the first surgical treatment of their neuroma (primary group), 100% achieved good to excellent pain relief. Among patients in whom the neuroma had been operated on once previously (first recurrence group), 88% achieved good to excellent pain relief with the technique described in this article. Of patients treated who had had 3 or more previous "neuroma" operations (multiple recurrence group), this technique resulted in excellent pain relief in 56%. Factors contributing to a poorer result in the multiple recurrence group included duration of pain longer than 24 months and the patient's unemployment. The diagnostic and surgical approach detailed in this article has yielded clinical results that recommend this approach not only as the primary treatment of choice but also as the treatment to help patients with pain from recurrent dorsoradial neuromas. The apparent susceptibility of the superficial branch of the radial nerve (SBRN) to form painful neuromas has been well documented. Once established, the neuroma appears particularly resistant to treatment. Based on experimental and cadaveric studies, we have formulated a treatment plan for patients with dorsoradial wrist neuromas.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

A model of chronic nerve compression in the rat.

This article describes a model of chronic nerve compression in the rat. The sciatic nerve of adult male Sprague Dawley rats was banded with a 1-cm Silastic tube for varying periods of time. Morphometric analysis, electrodiagnostic studies, and histological evaluation were carried out 3, 5, 8, and 12 months after banding. Histological evaluation at 3 months was normal. At 5 months perineurial thickening was demonstrated. In the periphery of the fascicles, segmental demyelination was noted; central fibers appeared normal. At 8 months there was further epineurial and perineurial thickening. Marked thinning of the myelin was noted in all fibers and evidence of Wallerian degeneration was apparent. Progressive connective tissue and nerve fiber changes were noted at 12 months. Nerve conduction studies after 3 months of compression demonstrated an increase in conduction velocity compared to the normal unbanded control nerves. Progressive slowing of conduction velocity was noted from 5 through 12 months.

Animals↗
PubMed1987

Medial antebrachial cutaneous--lateral femoral cutaneous neurotization in restoration of sensation to pressure-bearing areas in a paraplegic: a four-year follow-up.

Loss of cutaneous sensation predisposes paraplegics to ulceration in pressure-bearing areas. We have previously described a method of restoring sensation to anesthetic trochanteric or ischial areas by neurotizing the cutaneous territory of the lateral femoral cutaneous nerve with the medial antebrachial cutaneous nerve of the forearm. After reinnervation of the anterior skin, a musculocutaneous flap is rotated to the desired anesthetic area. A four-year follow-up evaluation has shown good recovery of the quickly and slowly adapting fiber receptor system, mediated through innervated hair follicles and resulting in excellent protective sensation.

Adult↗
PubMed1987

Vibratory sensory testing in acute compartment syndromes: a clinical and experimental study.

Invasive and noninvasive diagnostic testing was correlated in 11 patients with acute compartmental syndromes of the forearm. The excellent correlation between diminished perception of vibration and increasing compartmental pressure suggested that 256 cycle per second (cps) vibratory stimuli may be useful clinically in determining the appropriate time for surgical intervention in the acute compartmental syndrome. In 12 adult male volunteers, elevated compartment pressures were created in the anterior tibial compartment of the leg. A decrease in perception to 256 cycle per second (cps) vibratory stimulus was the earliest sensory abnormality to occur with elevated tissue compartment pressures. Analysis of variance showed significantly that 256-cps vibration was the most reliable and earliest sensory modality to change at pressures of 35 to 40 mmHg. These clinical and experimental findings support the use of the 256-cps tuning fork as a noninvasive diagnostic test in the evaluation of the patient with suspected acute compartment syndrome.

Adult↗
PubMed1987

The incidence and degree of scleral show in the normal population.

The degree and incidence of scleral show in a normal population was studied in 100 Caucasian patients. Subjects were fitted with a headband goniometer. The goniometer was related to a standard anatomic landmark (the Frankfort plane), and the subject's head was inclined through angles of 0 to -35 degrees. With the subject fixing on a constant point, the degree of white showing between the lower eyelid and the limbus was measured. The results demonstrated that scleral show was a normal finding, the degree of which increases with increasing inclination of the head from the Frankfort plane. No sex variation or increase with age was noted.

Adult↗
PubMed1987

The peripheral nerve allograft: an assessment of regeneration in the immunosuppressed host.

Regeneration across the nerve allograft in the immunosuppressed host was assessed using electrical and histologic parameters. The Lewis rat (RTIl) served as the recipient animal, and ACI rats (RTIa) provided the donor nerve allografts. Hydrocortisone and azathioprine were used in various dose schedules as the immunosuppressive agents. Animals were immunosuppressed for either 30 or 100 days. Histologic and electrophysiologic measurements of nerve regeneration were assessed at 30, 100, and 180 days. The degree of nerve regeneration was similar in all experimental groups. Short-term, low-dose immunosuppression was as successful as longer-term, higher-dose immunosuppression therapy. The degree of nerve regeneration in all experimental groups was significantly better than that in the fresh, untreated nerve allograft control group (Lewis/ACI) but was not as good as that seen in the autograft control group (Lewis/Lewis).

Animals↗
PubMed1986

Radial sensory nerve entrapment.

Fifty-one patients with entrapment of the radial sensory nerve were examined. The entrapment was usually due to a crush or twisting injury to the wrist or forearm or to repetitive pronation/supination movements at work. Presenting symptoms were usually pain or burning over the dorsoradial aspect of the wrist, aggravated by pinching or gripping activities. Results of physical examination demonstrated a positive Tinel's sign over the radial sensory nerve as it exits the deep fascia, a false-positive Finkelstein test, and a positive hyperpronation provocative test. The results of nonoperative and surgical management are presented.

Adult↗
PubMed1986

Pain after radial sensory nerve grafting.

Four cases are described in which a nerve graft to the radial sensory nerve was successful in restoring sensibility to the dorsum of the hand but failed in controlling pain. All of these patients subsequently were successfully treated with excision of the nerve graft and proximal implantation of the radial sensory nerve into the brachioradialis muscle.

Adult↗
PubMed1986

Radial sensory nerve entrapment in the forearm.

A group of 51 patients with complaints related to entrapment of the superficial sensory branch of the radial nerve is described. Symptoms included altered sensibility over the dorsoradial aspect of the hand and dorsoradial cutaneous pain with ulnar flexion of the wrist or with gripping and pinching. Pertinent history included compressive or crushing forearm injuries, work activities requiring frequent pronation and wrist hyperextension, and associated illnesses, such as diabetes. Physical examination included abnormal touch perception, abnormal moving two-point discrimination over the dorsoradial area of the hand, a positive Tinel sign in the forearm, and aggravation of the patient's symptoms with forced forearm pronation and wrist ulnar flexion. Seven (37%) of 19 patients treated with nonoperative modalities after a mean of 28 months from the onset of symptoms or their injury were improved. Of the 32 patients treated with surgery with a mean follow-up of 10 months (range of 6 to 29 months), there has been excellent subjective improvement in 37%, good subjective improvement in 49%, and fair subjective improvement in 6%, and 8% were not improved. Of this group of surgically treated patients, 43% have returned to their regular jobs, and 22% are in either vocational rehabilitation or working at a different job.

Adult↗
PubMed1986

Histopathology of compression of the superficial radial nerve in the forearm.

A histologic assessment of the radial sensory nerve from a patient with nerve compression is reported. Histologic changes were confined to the region of the nerve compression. Connective tissue changes consisted of an increased thickness of the epineurium and perineurium. Nerve fiber changes consisted of Schwann cell pathology with marked thinning of the myelin noted in the myelinated fibers and evidence of degeneration and regeneration noted in the unmyelinated fiber population. Nerve fiber pathology was not uniform but varied from fascicle to fascicle in the compressed area.

Forearm↗
PubMed1986

Exercise-induced chronic compartment syndrome of the first dorsal interosseous muscle of the hand: a case report.

A 21-year-old welder experienced chronic pain in the region of the first dorsal interosseous muscle after strenuous activity involving his hand. Direct measurement of the tissue pressures within the first dorsal interosseous muscle revealed an elevation of compartment pressure after lateral key pinch activity. After surgical release of the compartment, the pressures returned to normal, and the patient's symptoms improved. Exercise-induced chronic compartment syndrome of the small muscles of the hand should be considered in patients who describe aching pain in the hand after strenuous activity.

Adult↗
PubMed1986

A study of neurotrophism in a primate model.

This study investigated the existence of neurotrophism in a primate model. In eight adult cynomolgus monkeys the sensory component of the femoral nerve was sectioned and introduced into the proximal channel of a silicone Y chamber. The proximal stump was given distal choices of various tissues inserted into the remaining arms of the silicone Y chamber. The targets presented were combinations of tendon, muscle, intact distal nerve, distal nerve graft, or an empty silicone channel. After 6 weeks, ultrastructural analysis confirmed axonal growth toward distal nerve tissue, while minimal or no nerve regeneration was directed toward tendon, muscle, or the empty silicone channel. The results showed that either a distal nerve stump or a nerve graft will act as a specific target to the regenerating primate proximal nerve stump.

Animals↗