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Biomedical subjects

D G Kline

Publications and source records attributed to D G Kline.

At least 73 records · Page 4Linked to original sources
PubMed1989

Localized hypertrophic neuropathy: possible focal perineurial barrier defect.

Localized hypertrophic neuropathy (hypertrophic mononeuropathy) is a rare benign condition that generally occurs in people under 40 years of age. Our immunocytochemical (S-100 protein) study of four new cases confirms previous observations that the cells forming the hypertrophic onion bulb are composed of perineurial cells. These observations and previously published illustrations, reveal a curious hyalinization of the outer perineurium of affected fascicles which suggests the absence of a perineurial barrier. Compartmentation (compartmentalization) of the endoneurium in hypertrophic mononeuropathy closely mimics the transient compartmentation which occurs in the distal nerve stumps of axotomized nerves, particularly in nerves in which re-innervation is prevented. Compartmentalization also can be produced by resection of the perineurial sheath. These findings suggest that hypertrophic mononeuropathy may be a reactive condition due to focal damage to the perineurial barrier.

Adult↗
PubMed1989

Civilian gunshot wounds to the brachial plexus.

Many gunshot wounds (GSW's) to the brachial plexus do not improve spontaneously with time and are therefore candidates for surgery. Over an 18-year period, 141 patients with GSW's were evaluated, 90 of whom were operated on; 75 of the surgical cases were followed for 2 years or more. Thirty operative patients had initial vascular repair, while eight required thoracotomies. Total plexus palsy was present in 19 of those selected for operation. The average interval between injury and operation was 17 weeks. Six patients required early operation for an expanding aneurysm with progressive neural loss. Persistent complete loss of function in the distribution of one or more elements and/or noncausalgic pain not managed by medications provided the major operative indications. Four patients required sympathectomies for causalgia. Of 166 lesions in continuity believed to be complete, based on clinical examination and electromyography, 48 with preserved intraoperative nerve action potentials (NAP's) were spared resection or were treated with a split repair with excellent eventual results on a weighted grading system. By comparison, only seven of 55 elements believed to have incomplete loss or to be recovering did not have NAP's and required repair. Fifty-three of 98 lesions repaired by grafts and 18 of 26 wounds with suture repair recovered to a Grade 3 level or better. Most elements were in continuity but 14 were found "blown apart" and required repair, usually by grafting. The best outcome was achieved with upper trunk and lateral and posterior cord lesions, but recovery occurred with some C-7 to middle trunk and medial cord to median repairs. Results with lower trunk and most medial cord lesions were poor unless early regeneration was proved by operative NAP's, in which case either neurolysis or split repair could be performed. Surgery is warranted for selected GSW's to the plexus.

Action Potentials↗
PubMed1989

Laser-assisted nerve repair in primates.

Studies on the peripheral nerves in rats and other species have helped in the development of laser-assisted nerve anastomosis (LANA), but offer little in evaluating the efficacy of this technique in primates. The authors present a study of LANA in the peripheral nerves of rhesus monkeys. Twelve adult rhesus monkeys underwent bilateral resection of a portion of the peroneal nerve followed by placement of autogenous sural nerve interposition fascicular grafts. The grafts were completed with conventional microsurgical suture technique on one side and with LANA on the other. At 5, 8, 10, and 12 months, the grafted nerves were evaluated for continuity, nerve conduction, and histology (both light and electron microscopy). No significant difference in continuity, conduction velocity, nerve degeneration, nerve regeneration, axon fiber number, or axon fiber density was found in any animal between grafts performed by conventional microsuture and LANA grafts. There was no difference in distal or proximal myelinated fiber density between the LANA grafts and the conventional microsuture grafts. It was concluded that LANA is as effective as microsurgical suture nerve anastomosis in a primate model of nerve repair and grafting.

Animals↗
PubMed1988

Occult carotid artery injury related to automobile seat belts.

A 24-year-old woman had a clinically occult injury of the carotid artery from the shoulder seat belt restraint in a motor vehicle accident. Acute thromboembolism and hemiplegia occurred two hours after her admission to the emergency department. There were contusions of the neck and chest (seat belt sign) but no associated injuries of the cervical spine, mandible, larynx, or brachial plexus. The diagnosis was made by carotid arteriography after the occurrence of thromboembolism. Early clinical suspicion, diagnosis, and surgical repair of the artery are necessary to prevent delayed or recurrent thromboembolism and stroke. Carotid artery and duodenal injuries in this patient were related to improperly fitting seat belts. The current useful preventive measures are adjustment of seat belts to individual body habitus and the regular use of snugly adjusted belts.

Adult↗
PubMed1987

Tumors of the brachial plexus.

Over a 17-year period, 56 patients with 57 tumors involving the brachial plexus were operated upon. The 40 neural sheath tumors included 26 neurofibromas, 8 schwannomas, 4 malignant neural sheath tumors, 1 fibrosarcoma, and 1 meningioma. Nine of the neurofibromas were associated with von Recklinghausen's disease (VRD), and 2 others were what was termed regionalized neurofibromatosis characterized by involvement of one limb with extension along the course of one or more plexus elements. Seventeen tumors were not of neural sheath origin; 7 were benign and 10 were metastatic malignant tumors compressing or invading the plexus. Benign neurofibromas and malignant sheath tumors almost always presented with pain or functional neural deficit, whereas schwannomas often presented with a palpable mass as their only initial symptom. Patients with solitary neurofibromas were significantly older, often female, and more likely to have tumor on the right side than patients with schwannomas, malignant neural sheath tumors, or neurofibromas associated with VRD. Solitary neurofibromas could often be totally resected without added deficit by sacrificing fascicles entering and leaving tumor that were determined to be "nonfunctional" by intraoperative nerve action potential recordings. Resection of neurofibromas associated with VRD sometimes but not always resulted in significant loss. Operation is nonetheless recommended, especially when malignancy is suspected because of rapidly increasing size, when severe pain or neural deficit is present, or when compression of adjacent plexus elements is a concern. Schwannomas and benign non-neural sheath tumors can usually be extirpated without damage to plexus elements. Forequarter amputation is advised for malignant intrinsic tumors involving distal plexus elements even though gross total resection seems feasible.

Adult↗
PubMed1986

Surgery for lesions of the brachial plexus.

Current diagnostic workup and surgical management of stretch injuries, gunshot wounds, lacerations, iatrogenic injuries, tumors, and thoracic outlet syndromes involving the brachial plexus are reviewed. Use of appropriate radiologic and electrodiagnostic studies to work up such patients is summarized as is selected literature concerning the more controversial aspects of their management. Some of the arguments both for and against operation on stretch injuries are presented and it is concluded that surgery can be of value for well-selected patients. Although a number of patients with gunshot wounds involving the plexus recover spontaneously, many still require an operation. Experience with tumors arising from the plexus suggests the need for early and relatively aggressive removal. Use of magnification and intraoperative recording permits removal of some but not all neurofibromas without further deficit. Timing for repair of lacerating injuries to the plexus, as well as iatrogenic injuries, selection of the few patients with thoracic outlet syndrome who require operation, and a brief review of plexus neuropathy are also presented. Importance of evaluating individual plexus injuries in terms of how complete or incomplete loss is in the distribution of each individual element is stressed. Development of intraoperative stimulation and recording methods to help sort out lesions, use of magnification for repair, and improved grafting techniques where gaps result from resection have helped to restimulate interest in managing these patients.

Action Potentials↗
PubMed1986

Recognition of special qualifications in neurological surgery.

In recent years, one-half of the 23 recognized specialty boards in medicine have begun formally to recognize subspecialization with some type of certification process. One such board, the American Board of Internal Medicine, examines and certifies in 11 subspecialty areas while the American Board of Pathology does so in nine, the American Board of Pediatrics in eight, the American Board of Obstetrics and Gynecology in four, and the American Board of General Surgery in three. Arguments for and against similar recognition of subspecialization within neurosurgery are reviewed. The present position of other specialties and their boards regarding this sensitive issue is summarized, as well as their certification structure. The various pathways available to certifying boards for recognition of subspecialization are also presented. The American Board of Neurological Surgery (ABNS) has approved a subspecialty certificate called a "certificate of Special Qualification in Critical Care Medicine." This is a subspecialty that is longitudinally oriented, touching on a number of other specialties in addition to neurosurgery, and thus differs from a vertical subspecialty such as Pediatric Neurosurgery or Cerebrovascular Neurosurgery. The background for development of such a certificate and the current requirements for obtaining it are reviewed. At the present time, the ABNS opposes the possible fragmentation of neurosurgery by offering certification in multiple subspecialty areas. Nonetheless, the current trend in medicine as a whole is in the direction of such subspecialization and its formal recognition. Increasing numbers of neurosurgeons tend to concentrate all or a good deal of their professional efforts in a specific area. Thus, organized neurosurgery must continue to consider methods for subspecialty recognition.

Certification↗
PubMed1985

Selected recent advances in peripheral nerve injury research.

Interactions between Schwann cells and growing neurites are reviewed as are the implications of axonal transport studies in shaping the regenerative process. Increased investigative attention will be required to study biochemical changes occurring in the local environment of the injury site even though continued study of the neuronal metabolic process remains critical. Important studies concerning the connective tissue structure of nerve and probable "blood-nerve barrier" sites are reviewed. Factors responsible for connective tissue proliferation and fibroblast alignment after injury are not well understood. Recent experimental studies relating to surgical repair of nerve are reviewed as are a few selected papers reflecting changes in clinical management of the patient with nerve injury.

Axonal Transport↗
PubMed1984

Peripheral nerve injury by chymopapain injection.

Chymopapain injected into the intervertebral disc space (chemonucleolysis) has been used clinically in patients with disc disease with success. Neurosurgical complications secondary to the procedure have, however, been reported. In this study, the authors have investigated the possible neurotoxic effect of chymopapain on the peripheral nerve in rat and primate models. While the extrafascicular injection caused no nerve fiber damage, the intrafascicular injection caused dose-related nerve fiber damage in both species.

Animals↗
PubMed1983

Operative management of selected brachial plexus lesions.

A 12-year operative experience with 171 consecutive patients with severe brachial plexus lesions who had at least 1 1/2 years of follow-up review is analyzed. Selection for and timing of operation was helped by categorization of each individual plexus element as "completely" or "incompletely" injured and as "in continuity" or "not in continuity." Results for each element could be given a single grade by a system which defined that element's proximal and distal input. For most lesions in continuity, an operative delay of several months is advocated so that intraoperative electrical evaluation can be used. Thus, in 282 gunshot wounded and stretch-injured elements of which 210 were thought to be clinically complete, 63 were spared resection because of nerve action potentials (NAP's) found at intraoperative testing, and 57 recovered function with only neurolysis. Elements resected (120) were confirmed as neurotmetic both by intraoperative electrical and subsequent histological studies. Acceptable results were achieved in 16 of 24 sutures, in 43 of 89 grafts, and in each of seven split repairs. Upper trunk and lateral and posterior cord elements fared better than lower trunk and medial cord lesions unless the latter were shown, with evidence of NAP's, to be regenerating and could be spared resection. Some stretched elements could, however, not be repaired, even though an attempt was made to exclude such cases from operation. Lacerations to the brachial plexus where continuity is lost are best repaired primarily if the injury is sharp; in this series, 14 of 18 elements having such repair recovered, whereas in 37 elements with secondary repair, grafts were often necessary and only 50% recovered function. Although associated with skin lacerations, 17 elements with complete loss were in continuity, and six of these were shown to be regenerating and were not resected. Despite intraneural location, large size, and prior operation, many benign tumors (including neurofibromas) can be removed without significant loss by use of the surgical loupes or microscope and repetitive NAP recording. Surgery for selected brachial plexus lesions is worthwhile.

Action Potentials↗
PubMed1982

Peripheral nerve injection injury with steroid agents.

The possible neurotoxic effects of five commonly used steroid agents were examined. Using histologic studies and studies of the microneural circulation, it was found the steroids can indeed cause neurotoxicity. The injection site was critical in effecting injury. Only intrafascicular injection caused damage. The damage produced varied with the agent used. Dexamethasone (Decadron) caused minimal damage, while hydrocortisone (Solu-Cortef) and triamcinolone hexacetonide (Aristospan) caused widespread axonal and myelin degeneration. Disturbance in the blood-nerve barrier correlated with the changes noted on light and electron microscopy, but is thought to be coincidentally and not causally related. In conclusion, it was shown that the intrafascicular injection of commonly used steroid agents had a direct toxic effect on peripheral nerve-fibers and caused a disruption of the blood-nerve barrier. Use of the more toxic agents in the vicinity of peripheral nerves should probably be avoided.

Animals↗
PubMed1982

Timing for exploration of nerve lesions and evaluation of the neuroma-in-continuity.

Despite complete distal neurologic deficit, not all sharp injuries to an extremity transect or even partially divide nerve. These injuries may require delayed intraoperative electrophysiologic evaluation to determine whether neurolysis or resection and repair is necessary. On the other hand, where nerve is sharply and completely divided, there are many advantages to acute or primary repair, especially with brachial, plexus, and sciatic nerve transections. Where nerves are bluntly divided, stumps should be tacked down to adjacent fascial or muscular planes and repair delayed for two to three weeks carved out so that the stumps can be sectioned back to healthy neural tissue. A partially lacerated nerve, if explored in a delayed fashion, may require suture or more likely a nerve graft repair of some fasicular groups, and neurolysis of others or what can be referred to as a split procedure. Urgent or very acute indications for operative intervention are few but are important ot keep in mind. Blunt injuries are responsible for the majority of lesions-in-continuity. These injuries can be followed clinically and electrically for two to three months. If there is no clinical or electrical reversal of the proximal portion of the distal loss, then exploration is in order. A decision whether or not to resect a lesion-in-continuity, based on gross or even operating microscopic appearance, has been difficult to make. For this reason, stimulation and stimulation and recording techniques were used to measure early regeneration in 600 cases with acceptable results.

Diagnosis, Differential↗