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R K Nath

Publications and source records attributed to R K Nath.

At least 19 recordsLinked to original sources
PubMed2006

Formation of complex films with water-soluble CTAB molecules.

This communication reports the formation of complex Langmuir monolayer at the air-water interface with the water-soluble N-cetyl N,N,N-trimethyl ammonium bromide (CTAB) molecules when interacted with the stearic acid (SA) molecules. The reaction kinetics of the formation of the CTAB-SA complex was monitored by observing the surface pressure versus time graph. Multilayered LB films of this complex doped with Congo red was successfully formed onto a quartz substrate. UV-Vis absorption and steady-state fluorescence spectroscopic characteristics of this doped LB films confirms the successful incorporation of Congo red molecules in to the CTAB-SA complex films.

Absorption↗
PubMed2001

Cavermap-assisted sural nerve interposition graft during radical prostatectomy.

Wide excision of the neurovascular bundle and interposition nerve grafting of the cavernous nerves when there is suspected extracapsular extension at the posterolateral prostatic margin are logical applications of improved understanding of pelvic neuroanatomy. Although the indications for neurovascular bundle excision will remain controversial for the foreseeable future, evidence suggests that neurovascular bundle excision improves cancer control in some patients. The ability to predict extracapsular extension reliably at the neurovascular bundle would be a powerful addition to the urologist's armamentarium. The authors have shown, as proof of principle in bilaterally resected neurovascular bundle at the time of RRP, that sural nerve grafting can restore erectile function. The authors' data also support a role for sural nerve grafting in unilateral neurovascular bundle excision. Although the side effects of sural nerve harvest are minor, the ability to predict preoperatively which patients will benefit from such grafts would reduce the number of failures. The success of the authors' interposition nerve-grafting project has resulted, in part, from the use of a multidisciplinary team approach that includes experienced oncologic surgeons and a plastic surgeon with extensive microsurgical and nerve-grafting experience. The technique for sural nerve grafting described herein gives urologists an additional tool to improve patients' quality of life without compromising the chances of success in treating prostate cancer.

Erectile Dysfunction↗
PubMed2000

Nerve transfers in the upper extremity.

Restoration of extremity function following nerve injury is often unpredictable. Nerve transfers in the upper extremity are important techniques in the management of many types of peripheral nerve injury. The physiologic principles of nerve transfer lead to the indications for use. The elements of planning and execution of common nerve transfers are presented in this article.

Arm↗
PubMed1999

Transfer of flexor carpi ulnaris branch of the ulnar nerve to the pronator teres nerve: histomorphometric analysis.

Partial median-nerve injury high in the upper extremity, resulting from brachial plexus neuritis or trauma, can affect the pronator teres muscle and result in the inability to pronate the forearm. A nerve transfer from an ulnar nerve-innervated branch to the flexor carpi ulnaris (FCU) muscle to the branch to the pronator teres (PT) is an attractive option in this clinical scenario. This study, a histomorphometric analysis of nine cadaver specimens harvested at the proposed FCU branch to PT branch transfer site, demonstrates sufficient similarities between the two branches in total number of nerve fibers (371.6 with SEM 35.1, and 361.9 with SEM 47.1; p = 0.87) and nerve cross-sectional area (122,181 microm2 with SEM 14,546 microm2, and 142,492 microm2 with SEM 19,633 microm2; p = 0.42), to predict a functional transfer result. In addition, clinical application of this transfer resulted in functional pronation strength of M4+.

Aged↗
PubMed1999

Interposition of sural nerve restores function of cavernous nerves resected during radical prostatectomy.

PURPOSE: The permanent loss of erectile function when both neurovascular bundles are widely resected at radical prostatectomy as well as the successful use of autologous nerve grafts in reconstructive surgery led us to perform bilateral nerve grafts in an effort to restore erectile function in potent patients treated for prostate cancer who underwent radical retropubic prostatectomy and resection of both neurovascular bundles. MATERIALS AND METHODS: Radical retropubic prostatectomy with deliberate resection of both neurovascular bundles was recommended for high grade, locally extensive prostate cancer in 9 select, sexually active men who reported normal erectile function. After the prostate was removed but before vesicourethral anastomosis an autologous sural nerve graft was interposed between the divided ends of the cavernous nerves bilaterally. Erectile function was monitored by patient interview, questionnaire and nocturnal penile tumescence testing after the operation. RESULTS: Four to 5 months postoperatively patients noticed slowly improving spontaneous erections, as manifested by mild tumescence regularly every several hours. Nocturnal penile tumescence testing with the RigiScan device at 4 to 6 months in 2 cases revealed erections that approached minimal criteria for normalcy. Approximately 14 months after surgery a rigid erection sufficient for penetration and intercourse developed in 1 patient. He described this event as "an erection of substance-hard, not just fluffy." CONCLUSIONS: We have developed a technique using sural nerve grafts to restore continuity of the cavernous nerves, which are resected during radical prostatectomy. The early return of spontaneous partial erections in our patients suggests that interposition nerve grafts may enhance the recovery of erectile function when the neurovascular bundles are resected.

Adenocarcinoma↗
PubMed1998

Complete ear replantation without venous anastomosis.

Traumatic amputation of the entire auricle is a rare occurrence. Management ideally consists of microvascular reconstruction of auricular arterial, venous, and nerve continuity. However, appropriately sized veins are often not available and venous drainage must be accomplished with leech therapy. In occasional cases where leeches are unavailable or cannot be made to attach, mechanical drainage and anticoagulation can give satisfactory drainage. The authors present a case of mechanical wick venous drainage of a complete ear replantation, resulting in virtually normal appearance and function of the ear. In addition, the ear regained normal touch and two-point sensibility, although the great auricular nerve had not been repaired.

Adult↗
PubMed1998

Epidural spinal cord stimulation for treatment of chronic pain--some predictors of success. A 15-year experience.

BACKGROUND: We have used epidural spinal cord stimulation (SCS) for pain control for the past 15 years. An analysis of our series of 235 patients has clarified the value of specific prognostic parameters in the prediction of successful SCS. METHODS: Patients were followed up for periods ranging from 6 months to 15 years with a mean follow-up of 66 months. The mean age of the 150 men and 85 women in the study was 51.4 years. Indications for SCS included failed back syndrome (114 patients), peripheral vascular disease (39 patients), peripheral neuropathy (30 patients), multiple sclerosis (13 patients), reflex sympathetic dystrophy (13 patients), and other etiologies of chronic intractable pain (26 patients). RESULTS: One hundred and eighty-nine patients received permanent devices; 111 (59%) of these patients continue to receive satisfactory pain relief. Pain attributable to failed back syndrome, reflex sympathetic dystrophy, peripheral vascular disease of lower limbs, multiple sclerosis, and peripheral neuropathy responded favorably to spinal cord stimulation. In contrast, paraplegic pain, cauda equina syndrome, stump pain, phantom limb pain, and primary bone and joint disease pain did not respond as well. Cases of cauda equina injury had promising initial pain relief, but gradually declined after a few years. After long-term follow-up, 47 of the 111 successfully implanted patients were gainfully employed, compared with 22 patients before implantation. The successful patients reported improvements in daily living as well as a decrease in analgesic usage. Multipolar stimulation systems were significantly more reliable (p < 0.001) than unipolar systems. Complications included hardware malfunction, electrode displacement, infection, and tolerance. CONCLUSION: Aside from etiologies of pain syndromes as a prognostic factor, we have identified other parameters of success. In patients who have undergone previous surgical procedures, the shorter the duration of time to implantation, the greater the rate of success (p < 0.001). The diagnosis of failed back syndrome must be considered a confounding factor in our analysis. Those patients whose pain did not follow a surgical procedure had better responses to SCS than patients who had multiple surgical procedures prior to their first implant. The advent of multipolar systems has significantly improved clinical reliability over unipolar systems. Age, sex, and laterality of pain did not prove to be of significance.

Adult↗
PubMed1998

Antibody to transforming growth factor beta reduces collagen production in injured peripheral nerve.

Epineurial scarring in peripheral nerve after injury inhibits normal axonal regeneration primarily due to fibroblast deposition of type I collagen. The transforming growth factor beta (TGF-beta) family is an important class of signaling molecules that has been shown to stimulate fibroblasts to produce collagen. The aim of this study was to design a prototypic therapeutic system in which the neutralization of TGF-beta in crushed rat sciatic nerve would decrease collagen formation. A total of 45 experimental Lewis rats were used. Group 1 animals (20 rats) sustained a unilateral crush injury to the sciatic nerve with injection of phosphate buffer solution. Group 2 animals (20 rats) sustained a unilateral crush injury to the sciatic nerve with injection of phosphate-buffered saline and goat, anti-rat, panspecific TGF-beta antibody. Group 3 control animals (five rats) underwent only exposure of sciatic nerve with injection of antibody. All animals were killed at 14 days and sciatic nerve specimens were harvested at that time. Slides of experimental tissue were processed using a 35S-labeled oligomer for procollagen alpha-1 mRNA, then dipped in photographic emulsion and examined by darkfield autoradiography. Morphometric analysis of pixel counts was then performed. A significant reduction in total pixel count per high-power field and in total number of fibroblasts per high-power field was found in crushed rat sciatic nerve treated with anti-TGF-beta antibody when compared with those treated only with phosphate-buffered saline. These findings are consistent with successful reduction in procollagen induction after a crush injury by topical administration of blocking antibody against transforming growth factor beta. The concept of growth factor blockade for therapeutic collagen reduction is attractive in the context of nerve injury, and the current article provides a model for future clinical application.

Animals↗
PubMed1997

Spinal cord stimulation is effective in the management of reflex sympathetic dystrophy.

OBJECTIVE: The purpose of this study was to determine the efficacy of spinal cord stimulation (SCS) in patients with symptoms of reflex sympathetic dystrophy (RSD), a disabling clinical condition with significant consequences of morbidity and loss of productivity. METHODS: We have used epidural SCS for pain control during the past 15 years. An analysis of our records revealed 12 consecutive patients diagnosed as having RSD before undergoing SCS. Eight of the 12 patients had undergone previous ablative sympathectomy. The mean age of the nine men and three women was 38.2 years. All suffered extremity injuries from a variety of causes. RESULTS: All 12 patients experienced relief of pain after trial stimulation and had their systems permanently implanted. At an average of 41 months follow-up, all patients were using their stimulators regularly and only two were receiving adjunctive minor pain medication. The level of pain present pre- and postoperatively was determined by administering a modified McGill Pain Questionnaire and a visual analog scale to each patient. Eight patients reported excellent pain relief, and four patients described good results. Five minor complications occurred. CONCLUSION: SCS is an effective treatment for the pain of RSD, including recurrent pain after ablative sympathectomy. The low morbidity of this procedure and its efficacy in patients with refractory pain related to RSD suggest that SCS is superior to ablative sympathectomy in the management of RSD.

Adult↗
PubMed1997

Deep brain stimulation for intractable pain: a 15-year experience.

OBJECTIVE: During the past 15 years, we prospectively followed 68 patients with chronic pain syndromes who underwent deep brain stimulation (DBS). The objective of our study was to analyze the long-term outcomes to clarify patient selection criteria for DBS. METHODS: Patients were referred from a multidisciplinary pain clinic after conservative treatment failed. Electrodes for DBS were implanted within the periventricular gray matter, specific sensory thalamic nuclei, or the internal capsule. Each patient was followed on a 6-monthly follow-up basis and evaluated with a modified visual analog scale. RESULTS: Follow-up periods ranged from 6 months to 15 years, with an average follow-up period of 78 months. The mean age of the 54 men and 14 women in the study was 51.3 years. Indications for DBS included 43 patients with failed back syndrome, 6 with peripheral neuropathy or radiculopathy, 5 with thalamic pain, 4 with trigeminal neuropathy, 3 with traumatic spinal cord lesions, 2 with causalgic pain, 1 with phantom limb pain, and 1 with carcinoma pain. After initial screening, 53 of 68 patients (77%) elected internalization of their devices; 42 of the 53 (79%) continue to receive adequate relief of pain. Therefore, effective pain control was achieved in 42 of 68 of our initially referred patients (62%). Patients with failed back syndrome, trigeminal neuropathy, and peripheral neuropathy fared well with DBS, whereas those with thalamic pain, spinal cord injury, and postherpetic neuralgia did poorly. CONCLUSION: DBS in selected patients provides long-term effective pain control with few side effects or complications.

Adult↗
PubMed1997

Improvement of limb circulation in peripheral vascular disease using epidural spinal cord stimulation: a prospective study.

Spinal cord stimulation was used in 46 patients for pain associated with lower extremity ischemic vascular disease that was considered to be nonreconstructable. Thirty-nine patients who had a follow-up examination between 2 and 36 months after the procedure form the basis of this report. Thirty (77%) of 39 cases were considered successful. Clinical endpoints indicating failure included amputation, vascular reconstruction, poor pain relief, or hardware malfunction. The transcutaneous partial pressure of oxygen (TcPO2) increased in both target and control feet. In patients with good outcome with a preimplantation TcPO2 of less than 30 mm Hg, TcPO2 increased significantly (p < 0.05). Pulse volume recording improved significantly (p < 0.05) at the thigh, metatarsal, and great toe levels in successfully treated patients. Peak blood flow velocity also showed a significant increase in patients with good outcome (p < 0.05). Patients with a TcPO2 of less than 10 mm Hg following stimulation tended to undergo amputation within the first 3 months. Improvement in pain control, combined with an increase in TcPO2 values that was greater than 10 mm Hg, were significant early predictors of long-term success. An initial increase in peak blood flow velocities (measured in Doppler studies) of greater than 10 mm also signified a good long-term outcome. Spinal cord stimulation appears to be a useful therapeutic modality for controlling pain and improving perfusion in a select group of patients with end-stage ischemic vascular disease considered nonreconstructable. The best results were seen in patients with severe claudication and rest pain without trophic changes in the foot. The mechanism of this beneficial effect is not yet completely understood.

Aged↗
PubMed1997

Spatial pattern of type I collagen expression in injured peripheral nerve.

The authors studied the spatial expression and regulation of messenger RNA for the alpha subunit of collagen type I in crushed rat sciatic nerve to provide a basis for future therapeutic manipulation. Sciatic nerves in 20 male or female adult Lewis rats were crushed for 60 seconds; the unharmed contralateral sciatic nerves served as controls. Twenty-one days after injury the experimental animals were killed and their tissue was harvested. The spatial expression of collagen type I was determined by using in situ hybridization techniques. Quantification of fibroblast number and total signal was performed through computerized morphometry. Collagen upregulation was evident in epineurial and perineurial layers, with the epineurium displaying higher activity. The cells responsible for procollagen type I production were fibroblasts. No activity was seen in the endoneurium. Morphometric findings indicated that collagen upregulation in the epineurium and perineurium occurred at both pretranscriptional and posttranslational levels when compared to controls; a paired t-test analysis confirmed statistical significance for all comparisons between injured and control tissues. Epineurial fibroblasts are responsible for the collagen production associated with crushed peripheral nerve injury in the rat. Regulation occurs pretranscriptionally as well as posttranslationally. It is interesting to speculate that the delivery of agents directed against collagen production (such as neutralizing antibodies to growth factors) into epineurial tissues proximate to the time and location of clinical nerve injury might mitigate later deleterious effects of excess collagen production in axonal regeneration.

Animals↗
PubMed1996

Spinal cord stimulation for chronic pain in peripheral neuropathy.

BACKGROUND: Spinal cord stimulation (SCS) has been used for the relief of chronic, intractable pain for over 2 decades. Recent technologic improvements in hardware have resulted in improved clinical outcome. We report our experience with epidural spinal cord stimulation for pain control of peripheral neuropathy for the past 15 years. METHODS: An analysis of our series of 276 patients revealed 30 patients diagnosed with peripheral neuropathy. The mean age of the 16 men and 14 women in the study was 62.4 years. The anatomic sources of pain included thorax, as well as upper and lower limbs. Causes of intractable pain included postherpetic neuralgia, intercostal neuralgia, causalgic pain, diabetic neuropathy, and idiopathic neuropathy. RESULTS: Nineteen patients reported relief of pain on trial stimulation and had their systems permanently implanted. At an average of 87 months' follow-up, 14 of these patients achieved long-term success in control of chronic pain (47% of all patients included in this study). Six patients reported excellent pain relief (> 75% pain relief), eight described good results (> 50% pain relief), and six had poor pain relief (< 50% pain relief). CONCLUSION: SCS is an effective therapy for pain syndromes associated with peripheral neuropathy. Causalgic and diabetic neuropathic pain seem to respond relatively well. whereas postherpetic pain and intercostal neuralgia syndromes seem to respond less favorably to the long-term beneficial effects of SCS. This information will be useful in the selection of patients with peripheral neuropathic pain who could be helped by SCS.

Adult↗
PubMed1996

Symptomatic epidural lipomatosis secondary to obesity. Case report.

The authors present a case of thoracic spinal cord compression secondary to epidural lipomatosis in an obese patient. This patient represents the 10th case of epidural lipomatosis secondary to simple obesity reported in the literature. The diagnosis is based on three criteria: 1) medical history and physical examination consistent with segmental spinal cord compression; 2) epidural fat thickness greater than 7 mm in the region of compression, based on magnetic resonance imaging (preferred) or computerized tomographic imaging; and 3) a height-to-weight ratio greater than 27.5 kg/m2. This specific correlation between epidural fat thickness measurement and calculation of height-to-weight ratio has not previously been reported. Surgical decompression through a posterior laminectomy and excision of excess epidural fat resulted in immediate reversal of the patient's symptoms. Knowledge of the association of epidural lipomatosis with obesity in the absence of glucocorticoid imbalance is important in discerning what may be an underrecognized syndrome.

Aged↗
PubMed1996

Reflex sympathetic dystrophy. The controversy continues.

The chronic pain syndrome encompassed by the term RSD is poorly understood. The confusion is caused in large part by frequent misdiagnosis and excessive use of sympatholytic procedures in inappropriate circumstances. Recently, pain specialists have redefined the specific criteria for regional pain syndromes having sympathetic maintaining factors, emphasizing application of placebo testing in diagnosis and attention to anatomic principles in pharmacologic and surgical treatment. The authors believe that three-phase bone scanning is a valuable adjunct to clinical judgment in making the proper diagnosis. Current thinking suggests that sympathetic maintained pain exists but that it may comprise only approximately 10% of regional pain cases. Once the appropriate diagnosis is made, classically described sympatholytic procedures are reasonably used. Alternative techniques, such as spinal cord stimulation, may have an important role in refractory cases of sympathetically maintained pain.

Hand↗
PubMed1996

Management of neuromas in the hand.

Injury to a peripheral nerve in the hand can result in loss of motor and sensory function. In addition, incomplete or abnormal regeneration can cause painful sequelae. The approach to neuromas in the hand requires familiarity with the basic aspects of nerve regeneration as well as the neurophysiology of pain mechanisms.

Hand↗
PubMed1994

The regulation of collagen in fetal skin wounds: mRNA localization and analysis.

The deposition of collagen in fetal skin wounds has been shown in several animal models. The authors used a radiolabeled RNA antisense probe, complementary to the mRNA for the alpha-1 chain of human procollagen type I, to assess regulation of this collagen species in fetal and adult rabbit wounds. Dorsal skin wounds were placed on fetal and maternal animals at the beginning of the third trimester, and were harvested 3, 5, and 7 days later. In situ RNA/RNA hybridization was performed on suitable specimens, and morphometric analysis was carried out with a computerized LECO image analyzer. Fetal wounds exhibited an inflow of mesenchymal cells that produced collagen type I at levels higher than the surrounding tissue; this activity was highest on days 3 and 5 after wounding. Adult wounds had increased fibroblast presence by day 7, producing collagen type I at levels higher than those of adjacent unwounded tissue. Morphometric analysis of the signal produced by in situ hybridization and of the number of cells producing the signal in a given field showed that fetal wounds appear to produce collagen type I by an increase in the number of cells in the area of the wound--not by induction of the gene for procollagen type I. In contrast, adult wounds had both fibroblast migration and induction of procollagen type I mRNA synthesis. These findings imply multilevel regulation of collagen production in the adult and posttranslational regulation in the fetus.

Animals↗