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Biomedical subjects

D G Kline

Publications and source records attributed to D G Kline.

At least 19 recordsLinked to original sources
PubMed2002

Accumulation of PN1 and PN3 sodium channels in painful human neuroma-evidence from immunocytochemistry.

BACKGROUND: The axolemmal distribution and density of voltage-gated sodium channels largely determines the electrical excitability of sprouting neurites. Recent evidence suggests that accumulation of sodium channels at injured axonal tips may be responsible for ectopic axonal hyperexcitability and the resulting abnormal sensory phenomena of pain and paresthesias. For future improvement in pain management it is necessary to identify structurally significant generators of autorhythmicity. A first step in this regard will be to determine the predominant types of sodium channels in injured axons. The opportunity to test human specimens from painful and non-painful neuroma is of great value. METHODS: We employed immunocytochemical methods to investigate if two types of highly specific voltage-gated sodium channel subtypes could be detected in sections of human neuroma. FINDINGS: Both subtypes of sodium channels PN1 and PN3 accumulated abnormally in human neuromas. The immunoreactive pattern was more pronounced in painful neuromas. This is in contrast to previous reports that focused either on PN1 or PN3 as main generators of hyperexcitability induced pain. INTERPRETATION: Both, PN1 and PN3 seem to be involved in hyperexcitability induced pain. It can be expected that a variety of other highly specific voltage gated sodium channel subtypes will be detected in regenerating peripheral nerve in the near future, which contribute to the development of neuropathic pain states. Thus, in order to therapeutically control hyperexcitability induced neuropathic pain, it might be worthwhile to develop pharmaceuticals that can selectively block different sodium channel subtypes and subunits.A review of the role of sodium channels in neuropathic pain is implemented in the discussion.

Humans↗
PubMed2001

Failure of surgical decompression for a presumed case of piriformis syndrome. Case report.

Diagnosis of piriformis syndrome is difficult and its precise definition is highly controversial. In this article, the authors present the case of a patient who had clinical features suggestive of piriformis syndrome. During surgery the patient was found to have a rare variation in anatomical structures, in which the peroneal nerve was displaced by the piriformis muscle. Surgical decompression did not alleviate the patient's symptoms.

Adult↗
PubMed2001

Outcomes in a consecutive series of 111 surgically treated plexal tumors: a review of the experience at the Louisiana State University Health Sciences Center.

OBJECT: The authors conducted a retrospective study of 107 consecutive patients with 111 brachial plexus tumors surgically treated at the Louisiana State University Health Sciences Center (LSUHSC). METHODS: During a 12-year period, from 1986 to 1998, 371 patients with lesions of the brachial plexus underwent surgery at LSUHSC. Among this group, 107 patients harbored 111 tumors of the brachial plexus. Neural sheath tumors were the most commonly found and included 33 neurofibromas (20 of which were associated with von Recklinghausen disease), 36 schwannomas, and 12 malignant neural sheath tumors. Of the non-neural sheath tumors, 13 were benign and 17 were malignant. Presenting symptoms included pain (59%), palpable mass (52%), paresthesias (30%), and paresis (29%). Anterior supraclavicular (82%) or posterior subscapular (18%) approaches were used to achieve gross-total (79%) or subtotal (21%) resection of tumor. The average follow-up period was 38.3 months or 3.2 years. Seventy percent of patients with benign neural sheath tumors became free from pain postoperatively or reported improvement in their preoperative pain status. Function remained intact or improved in 50% and remained stable postoperatively in another 20% of cases. Preservation of function was more likely in patients who presented intact and in those who had not undergone a previous attempted biopsy procedure or resection than in those in whom such manipulation had occurred. CONCLUSIONS: Resection of most plexal tumors is technically feasible and associated with acceptable morbidity and mortality rates.

Adolescent↗
PubMed2001

Surgical management and outcome in patients with radial nerve lesions.

OBJECT: The goal of this paper was to review surgical management and outcomes in patients treated for radial nerve (RN) lesions at Louisiana State University Health Sciences over a period of 30 years. METHODS: Two hundred sixty patients with RN injuries were evaluated. The most common mechanisms of injuries involving the RN included fracture of the humerus, laceration, blunt contusions, and gunshot wounds. One hundred and eighty patients (69%) underwent surgery. Lesions not in continuity required primary or secondary end-to-end suture repairs or graft repairs. With the use of direct intraoperative nerve action potential recording, RN injuries in which the lesion was in continuity required external or internal neurolysis or resection of the lesion followed by end-to-end suture or graft repair. A minimum of 1.5 years follow-up review was available in 90% of the patients who underwent surgery. Motor function recovery to Grade 3 or better was observed in 10 (91%) of 11 patients who underwent primary suture repair, 25 (83%) of 30 who underwent secondary suture repair, 43 (80%) of 54 who received graft repair, and 63 (98%) of 64 in whom neurolysis was performed. Sixteen (71%) of 21 patients with superficial sensory RN injury achieved satisfactory pain relief after complete resection of a neuroma or neurolysis. CONCLUSIONS: This study clearly demonstrates that excellent functional recovery can be achieved with proper surgical management of RN injuries.

Adolescent↗
PubMed2001

Surgical management and outcomes in patients with median nerve lesions.

OBJECT: One hundred sixty-seven of 250 patients with median nerve (MN) lesions, excluding carpal tunnel syndrome and nerve sheath tumors, at the levels of the arm, elbow, forearm, and wrist, underwent surgical treatment at Louisiana State University Health Sciences over a 30-year period. The most common causes of MN injuries were laceration, fracture-associated stretch and contusion, gunshot wound, compression, and injection injuries. In this study, surgically treated patients were followed and evaluated retrospectively for favorable functional outcomes. METHODS: Lesions not in continuity required primary or secondary end-to-end suture or graft repairs. With the aid of direct intraoperative recording of nerve action potentials (NAPs), MN injuries in which the lesion was in continuity underwent external or internal neurolysis, or resection of the lesion, followed by end-to-end suture or graft repair. A minimum of 12 months follow-up review (mean 18 months) was available in 85% of the surgically treated patients. For lesions in continuity, a functional recovery of Grade 3 or better was seen in 72 (95%) of 76 patients who underwent neurolysis, 18 (86%) of 21 who received suture repair, and 21 (75%) of 28 who received graft repair. In lesions not in continuity, favorable results (Grade > or = 3) were seen in 10 (91%) of 11 patients who received primary suture repair, seven (78%) of nine who received secondary suture repair, and 15 (68%) of 22 who received graft repair. CONCLUSIONS: Surgical intervention for MN injuries with complete or severe deficits achieved favorable outcomes.

Adolescent↗
PubMed2000

Surgery for peripheral nerve and brachial plexus injuries or other nerve lesions.

The selection of patients who will benefit from peripheral nerve surgery continues to evolve. The evaluation of patients with peripheral nerve problems, and the indications and timing of surgery are reviewed. This includes patients with transections, lesions in continuity, entrapments, tumors, injection injuries, and birth palsies. The treatment outlined for patients with peripheral nerve and brachial plexus injuries is based on a comprehensive clinical and electrodiagnostic evaluation complemented by imaging studies. A systematic approach to the surgical management of these neural lesions has evolved at our institution, based in part on extensive experience with intraoperative recording of nerve action potentials (NAPs) and a resultant large number of referrals. Advanced microsurgical techniques including use of grafts have expanded the scope of peripheral nerve surgery. These advances coupled with intraoperative electrophysiologic measurements have improved outcomes.

Brachial Plexus↗
PubMed2000

Model for avulsion injury in the rat brachial plexus using passive acceleration.

We have developed an experimental model for brachial plexus injuries in the rat that closely simulates the characteristics of human injury. This model produces avulsion injuries in a noninvasive manner. A prototype apparatus was designed that allowed a force to be transmitted to a restrained limb by passive acceleration. Reproducible results were obtained in 32 rats. A significant correlation was found between the test weight and the number of roots avulsed (r = 0.92; P < 0.05). The amount of force also correlated to the pattern of avulsion injury: a 230-g weight produced either C6 (54%), C7 (15%), or C6 and C7 (31%) avulsions; a 330-g weight produced C6 (18%), C7 (9%), or C6 and C7 (73%) avulsions; a 530-g weight produced C5 through C8 (75%) or C6 through T1 (25%) avulsions. This model of brachial plexus injury may be useful to further our understanding of the cellular response to this incapacitating injury and to develop therapeutic strategies with behavioral correlates.

Acceleration↗
PubMed2000

Neurogenic tumors of the cervical vagus nerve: report of four cases and review of the literature.

OBJECTIVE AND IMPORTANCE: Nerve sheath tumors arising from the cervical vagus nerve are extremely rare. These tumors most often present as asymptomatic, slowly enlarging, lateral neck masses and therefore often come initially to the attention of otolaryngologists and general surgeons. Because they are nerve tumors, however, neurosurgeons must be able to recognize and treat these rare entities. We report three cases of schwannoma and one case of neurofibroma of the cervical vagus nerve that were encountered at our center (Louisiana State University Medical Center) during a 31-year period. CLINICAL PRESENTATION: The patients ranged from 31 to 61 years of age at the time of presentation to Louisiana State University Medical Center. Presenting complaints included hoarseness, Horner's syndrome, and palpation of an enlarging, asymptomatic, cervical mass. Reviews of systems revealed episodes of aspiration for one patient and frequent respiratory illnesses for two patients. These episodes were possibly related to their tumors. Imaging studies demonstrated well-circumscribed masses in the region of the carotid sheath. INTERVENTION: Using microsurgical techniques, gross total resection of all four tumors was accomplished. For one patient, the vagus nerve needed to be divided and an end-to-end anastomosis was performed. For the other three patients, resection of the tumor was achieved with the vagus nerve in continuity. CONCLUSION: Vagal nerve schwannomas and neurofibromas in the neck are rare neoplasms. We present four cases of these benign tumors. The pathological features, epidemiological characteristics, presentation, differential diagnosis, and management are discussed. Gross total resection with preservation of the vagus nerve remains the treatment of choice.

Adult↗
PubMed1999

Tethered cord syndrome in adults.

Adult onset of tethered cord syndrome is a rare pathologic entity. Its treatable nature makes early diagnosis and timely surgical intervention important goals. Because of present referral patterns, adult patients with tethered cord syndrome may present initially to their primary care physician. We present a recent representative case of adult-onset tethered cord syndrome, with emphasis on initial complaints and the symptom constellation relevant to the primary care physician. Thorough clinical history and physical examination should direct investigators to include tethered cord syndrome in the differential diagnosis of select patients.

Adult↗
PubMed1998

Abnormal distributions of potassium channels in human neuromas.

Twenty-seven human traumatic neuromas were examined immunocytochemically using highly specific antibodies directed against the voltage-gated delayed-rectifier potassium channel, Kv1.1. Normal sural nerves from six of the above-noted patients served as control specimens. Additionally, nine of the neuromas and two of the sural nerves were immunostained for voltage-gated calcium channels using an antibody that reacts with a wide spectrum of calcium channels. Normal myelinated fibers showed Kv1.1 specific immunoreactivity only at the juxtaparanodal regions. In contrast, within the neuromas approximately 30% of the myelinated fibers exhibited Kv1.1 specific immunoreactivity in dense patches along internodal axonal regions. The clustering of Kv1.1 channels along myelin-ensheathed internodal segments of axon was highly specific for the neuromas, and was never seen in normal nerve. Specific calcium channel immunoreactivity was not detectable in either the neuromas or sural nerves. Taken together with prior studies on sodium channels, these results suggest that selective and specific mechanisms control the distribution of ion channels within neuromas. Further investigation of ion channel changes within neuromas should provide a better understanding of the abnormal axonal hyperexcitability that frequently develops after nerve injury.

Axons↗
PubMed1998

Management of severe proximal vascular and neural injury of the upper extremity.

PURPOSE: Early amputation has been suggested to be the optimal treatment for severe combined vascular and neural injuries of the proximal upper extremity. This retrospective study was done to evaluate the long-term clinical outcome of our policy of limb salvage by revascularization and delayed treatment of neural injuries. METHODS: Forty-six patients with neural and vascular trauma to the upper extremity were treated at our institution. All of these patients had aggressive treatment directed at limb salvage with restoration of vascular supply and nerve function. Long-term vascular and neurologic outcomes were recorded. Neurologic deficits were validated by the American Medical Association's standardized disability impairment scale (0% to 100%). RESULTS: The rate of preoperative disability was 83%, which improved to 52% (p < 0.01) after treatment (mean follow-up, 43 months). Overall, 87% showed improvement. CONCLUSION: These results suggest that early amputation should not be performed unless there is massive tissue loss or an attempt at limb salvage might endanger life. Final outcomes cannot be predicted on the basis of initial clinical presentation. As a group, the majority of these patients improved with aggressive intervention.

Adolescent↗
PubMed1998

Expression of c-Fos protein in the spinal cord after brachial plexus injury: comparison of root avulsion and distal nerve transection.

OBJECTIVE: Clinical reports indicate poor outcomes for avulsion injuries, compared with more peripheral nerve damage. These two different injuries may both affect gene expression in spinal neurons, and the changes in gene expression may be related to the types of injuries. METHODS: The brachial plexus of 48 adult male rats was lesioned by either root avulsion close to the spinal cord or distal nerve transection. The rats were quickly revived and remained awake until death at 30, 60, or 120 min after surgery. In rats with avulsive injuries, traumatic sites on the dorsal and ventral horns of the spinal cord were microscopically detected. Immunocytochemical analysis of the c-fos product was performed for the two experimental groups and for sham-treated control animals at the same survival times. RESULTS: An increase in Fos-like immunoreactivity (FLI) in cells of the spinal cord, at levels C4-T1, was detected at 30 min after nerve transection or root avulsion. The number of FLI-positive cells continued to increase at 60 and 120 min after the nerve injury (P=0.001). FLI-positive cells were compared at the C7 level, in laminae 1 and 2, 3 and 4, and 5 to 10, after the two injuries and were found to be more abundant after the avulsive injury (P=0.0001); furthermore, the number of FLI-positive cells increased with time (P=0.001). In a comparison of all levels, both experimental groups demonstrated significantly greater numbers of FLI-positive cells than did controls, and the group with nerve root avulsion showed significantly (P=0.0001) more FLI-positive cells than did the group with distal nerve transection. CONCLUSION: These results suggest that nerve root avulsion from the spinal cord leads to increased and prolonged expression of c-fos and, potentially, greatly increased transcription of new messages for recovery, survival, or cell death.

Animals↗