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Biomedical subjects

I Perkash

Publications and source records attributed to I Perkash.

At least 37 records · Page 2Linked to original sources
PubMed1998

Surgical challenge of massive bilateral staghorn renal calculi in a spinal cord injury patient.

We report a rare case of massive bilateral staghorn calculi in a spinal cord injury patient with significant renal compromise. The patient was successfully treated with percutaneous nephrolithotomy to achieve a stone-free status. The various options of treatment are discussed with special attention to the technical aspects necessary to achieve complete eradication of the stone burden during percutaneous nephrolithotomy. Furthermore, the importance of treating bladder dysfunction and urinary metabolic abnormalities is emphasized.

Follow-Up Studies↗
PubMed1997

Micturition by functional magnetic stimulation in dogs: a preliminary report.

The effectiveness of functional magnetic stimulation (FMS) technology on bladder contraction and bladder emptying was evaluated in ten normal neurologically intact male dogs. In seven animals, FMS of the bladder was performed by using a commercially available magnetic coil (non-water-cooled) for stimulating the sacral nerves or over the suprapubic region. With sacral stimulation, the mean change in bladder pressure (Pves) was 68.0 +/- 12.96 cm H2O; with suprapubic stimulation, the mean change in Pves was 40.7 +/- 8.08 cm H2O. This change in Pves by sacral stimulation was higher than suprapubic stimulation (P < 0.01). In three additional animals, voiding was demonstrated by using a specialized water-cooled magnetic coil and by stimulating the sacral nerves with an intermittent stimulation sequence. Voiding occurred in all three animals and was reproducible. In summary, FMS of the bladder has the potential to be a useful non-invasive technology for bladder emptying and bladder training in patients with neurogenic bladder.

Animals↗
PubMed1997

Micturition by functional magnetic stimulation.

Effectiveness of functional magnetic stimulation (FMS) technology on bladder contraction and bladder emptying was evaluated in twenty-two spinal cord injured subjects. FMS of the bladder was performed by stimulating the sacral nerves or the suprapubic region using a commercially available magnetic stimulator with a round coli. With sacral stimulation, the mean change in bladder pressure (Pves) was 24.4 +/- 4.88 cm H2O; with suprapubic stimulation, the mean change in Pves was 16.5 +/- 4.44 cm H2O. The change in Pves with sacral stimulation was higher than with suprapubic stimulation (p < .01). Seventeen subjects demonstrated voiding, either with sacral or suprapubic stimulation. Using a water-cooled coli, one subject demonstrated complete bladder emptying. FMS of the bladder has the potential to be a useful non-invasive technology for bladder emptying and bladder training in patients with neurogenic bladders.

Adult↗
PubMed1997

Ablation of urethral strictures using contact chisel crystal firing neodymium:YAG laser.

PURPOSE: The technique for ablation of urethral strictures using the contact crystal tip firing neodymium:YAG laser was evaluated for adequacy and long-term durability of the ablation. MATERIALS AND METHODS: A total of 42 male spinal cord injured patients with suspected urethral strictures approximately 1 to 4 cm. long was evaluated. The strictures were localized and the men underwent endoscopic laser ablation using a contact laser chisel probe (2.5 or 3.5 mm.) screwed onto the end of a semirigid fiber. The usual power setting was 25 to 35 watts. Circumferential vaporization of fibrous tissue was done to achieve complete ablation. For pinpoint strictures with dense fibrosis, subsurface buttonholes were also made to vaporize and ablate expediently all fibrous tissue. A catheter was usually left indwelling overnight only. Estimated blood loss was 25 to 50 ml. RESULTS: All patients were followed for a mean of 28.2 months (range 12 to 46). Of the patients 39 (93%) have adequate voiding and have maintained durability of the stricture ablation. Laser ablation was successfully repeated in 1 patient with initial failure and in 2 with partial failure. Both patients were well for 7 to 18 months. No patient required bougie dilation. CONCLUSIONS: For strictures of the urethra the success rate following ablation was greater than that after other reported techniques. Contact laser ablation is simple to perform, with the least morbidity following the procedure, and it can be easily repeated for lasting results.

Adult↗
PubMed1997

Modulation of detrusor contraction strength and micturition characteristics by intrathecal baclofen in anesthetized rats.

PURPOSE: The effect of intrathecal (i.t.) baclofen in modulating the micturition reflexes, detrusor contraction strength, and micturition efficiency was evaluated in anesthetized rats. MATERIAL AND METHODS: Female Wistar rats (n = 14, 337 +/- 8 gm.) were anesthetized with urethane (1.2 gm./kg. s.c.). Cystometrograms were done through a lower midline incision made to expose the bladder and a catheter was inserted through the bladder dome to record pressure during filling with saline at the rate of 0.038 ml./min. During the micturition phase of cystometrogram, the measurement of voided volume was made synchronously with the intravesical pressure. Baclofen was given intrathecally at the increasing doses of 0.05, 0.10, 0.5 microgram. and pressure/flow parameters were measured. RESULTS: The measured urodynamic parameters show that baclofen produced a significant dose dependent increase in bladder capacity and a decreases in voiding efficiency, detrusor pressure and maximum and average flow rate. Baclofen (0.1 microgram.) significantly decreased detrusor contractility reducing both Wmax from 3.7 +/- 0.1 (control) to 2.0 +/- 0.1 W/m2 and Wisv,max from 5.9 +/- 0.3 to 5.5 +/- 0.4 W/m2 respectively. Baclofen altered the characteristic pattern of the micturition reflex by suppressing high frequency pressure oscillations during voiding which was completely abolished after 0.1 microgram. in 75% of the rats. Furthermore, urinary dribbling incontinence was evident at a dose of 0.5 microgram. in 58% of all rats. CONCLUSIONS: These results demonstrate that i.t. baclofen has a significant inhibitory effect on the micturition reflex, depressing detrusor contraction strength and micturition efficiency, while increasing bladder capacity.

Anesthesia↗
PubMed1997

Autonomic dysreflexia and detrusor-sphincter dyssynergia in spinal cord injury patients.

This study reevaluates the significance of our previously reported blood pressure monitoring during cystometrographic studies in spinal cord injury patients who had detrusor-sphincter dyssynergia. We have now evaluated 26 spinal cord injury patients (21 tetraplegics and five high paraplegics) with complex urodynamic studies both before and after transurethral modified sphincterotomy (TURS). In these patients, mean systolic rise prior to TURS was 32.4 mm Hg (S.D. +/- 16.3) and diastolic rise was 14.3 mm Hg (S.D. +/- 9.3). Following TURS, mean systolic rise was 15.5 +/- 0.1 and diastolic rise was 7.3 +/- 8.6. This is a statistically significant difference (p value .001). Following TURS, blood pressure rises were transitory and not associated with significant symptoms of autonomic dysreflexia. The present study confirms our previous findings that a high correlation exists between the magnitude of blood pressure response, level of injury and severity of detrusor-sphincter dyssynergia. These results indicate that following the modified external sphincterotomy, there was a significant reduction in the dysreflexic response during cystomanometry of the bladder (CMG). The potential of a significant rise in blood pressure during CMG makes it necessary to monitor blood pressure during these studies and be prepared to expediently deflate the bladder to prevent an inordinate rise in blood pressure, preventing cerebral vascular complications. Patients with a significant rise in blood pressure during CMG are at risk for severe dysreflexia when their bladder is full and require management strategies to optimize control of blood pressure response with medication and/or transurethral surgery.

Adult↗
PubMed1996

Contact laser sphincterotomy: further experience and longer follow-up.

I report here the use of a crystal chisel contact tip firing Nd:YAG laser for transurethral sphincterotomy in 76 consecutive spinal cord injury patients. Their mean age was 53 years (range 26 to 77 years). Fifty-four (72%) were complete motor (Frankel A and B) and 21(28%) were incomplete lesions (Frankel C and D) They were evaluated with multichannel urodynamic equipment and 89% of the patients showed detrusor sphincter dyssynergia and 11% showed detrusor areflexia. Forty-three patients (56%) had previous electrocautery sphincterotomy and were not voiding well. A cystoscopic examination showed that 32% had an associated enlarged prostate and/or bladder-neck stenosis and 32% had associated wide-body strictures in the bulbous urethra. The crystal chisel contact tip firing Nd:YAG laser almost mimicked a hot diathermy knife to create an intraurethral incision as well as vaporizing the tissues. For sphincterotomy, a 12 o'clock incision was used from the verumontanum to the bulbous urethra. In patients with an associated enlarged prostate or bulging lateral lobes, 3 and 9 o'clock incisions were also made from the bladder-neck to the verumontanum and also vaporized the bulging prostate tissue. We used 25 to 40 watts for cutting, and vaporization of tissue and 15-25 watts to stop bleeding. The blood loss was less than 50 ml at surgery in 97.4% patients. None of the patients were transfused. An indwelling Foley catheter was usually left in situ for about 24 h and the majority of the patients were discharged the next day. All patients have been followed up at least every 6 months for a mean period of 27 months (range 16 to 41 months). The durability of surgery has been checked with linear array transrectal sonography and by urodynamic evaluation. Sixty-nine patients (92%) had adequate voiding, minimal to absent autonomic dysreflexia and no significant symptomatic urinary tract infection. There were seven patients who required repeat laser surgery within 2 to 5 months. All subsequent patients are voiding well with wide open bladder-neck and posterior urethra as shown on a voiding cystourethrogram.

Adult↗
PubMed1995

Modeling and simulation of paraplegic ambulation in a reciprocating gait orthosis.

We developed a three dimensional, four segment, eight-degree-of-freedom model for the analysis of paraplegic ambulation in a reciprocating gait orthosis (RGO). Model development was guided by experimental analysis of a spinal cord injured individual walking in an RGO with the additional assistance of arm crutches. Body forces and torques required to produce a dynamic simulation of the RGO gait swing phase were found by solving an optimal control problem to track the recorded kinematics and ground reaction forces. We found that high upper body forces are required, not only during swing but probably also during double support to compensate for the deceleration of the body during swing, which is due to the pelvic thrust necessary to swing the leg forward. Other stimulations showed that upper body forces and body deceleration during swing can be reduced substantially by producing a ballistic swing. Functional neuromuscular stimulation of the hip musculature during double support would then be required, however, to establish the initial conditions needed in a ballistic swing.

Biomechanical Phenomena↗
PubMed1995

Registration error quantification of a surface-based multimodality image fusion system.

This paper presents a new reference data set and associated quantification methodology to assess the accuracy of registration of computerized tomography (CT) and magnetic-resonance (MR) images. Also described is a new semiautomatic surface-based system for registering and visualizing CT and MR images. The registration error of the system was determined using a reference data set that was obtained from a cadaver in which rigid fiducial tubes were inserted prior to imaging. Registration error was measured as the distance between an analytic expression for each fiducial tube in one image set and transformed samples of the corresponding tube obtained from the other. Registration was accomplished by first identifying surfaces of similar anatomic structures in each image set. A transformation that best registered these structures was determined using a nonlinear optimization procedure. Even though the root-mean-square (rms) distance at the registered surfaces was similar to that reported by other groups, it was found that rms distances for the tubes were significantly larger than the final rms distances between the registered surfaces. It was also found that minimizing rms distance at the surface did not minimize rms distance for the tubes.

Biophysical Phenomena↗
PubMed1995

Efficacy and safety of terazosin to improve voiding in spinal cord injury patients.

A total of 28 male spinal cord injury (SCI) patients were enrolled in an open label study to evaluate the efficacy and safety of terazosin to improve voiding. All patients were started on 1 mg daily dose at bedtime. The dosage was gradually increased to 1-2 mg twice daily, depending upon patient tolerance and a minimum acceptable systolic blood pressure of 90 mm Hg. Urodynamic evaluation was done in 24 patients prior to and one week after a maximum tolerated dose was established for at least 48 hours. The maximum dose varied from 1 to 5 mg daily. Subjective improvement in voiding was noticed in 50 percent of patients. Objective assessment with urodynamics showed a mean drop in maximum voiding pressure of 35 cm H2O (range 9-65 cm H2O) in only 42 percent of patients. Subjective improvement in voiding occurred in 14 of 17 patients with absent detrusor sphincter dyssynergia. The drug was discontinued in three patients with side effects of syncope in one patient, lethargy in another and body rash in the third. Because the tolerance dose of terazosin is variable and the therapeutic response is unpredictable, urodynamic monitoring is recommended to accomplish a useful outcome.

Administration, Oral↗
PubMed1994

Hemorrhoidal bleeding in chronic spinal cord injury: results of multiple banding.

Most patients with chronic spinal cord injury (SCI) have hemorrhoidal bleeding. 87 banding procedures were performed for bleeding on 62 men with chronic SCI. Multiple bands per session were routinely necessary. Bleeding sites at or distal to the dentate line were also banded. There were no major complications. An outcome questionnaire was completed by 60 subjects (97%). Mean follow-up was one year, minimum one-half year. 73% of patients reported significant reduction in bleeding post-banding, and 20% reported some reduction. A majority of patients felt the procedure was useful or worthwhile overall. Absent sensation allows banding of external hemorrhoids, although symptoms of autonomic hyper-reflexia may occur in patients with lesions at T6 or above. Multiple banding is a safe and effective treatment for hemorrhoidal bleeding in SCI.

Adult↗
PubMed1994

Laser sphincterotomy and ablation of the prostate using a sapphire chisel contact tip firing neodymium:YAG laser.

I report a modified technique for use of a contact laser for urological endoscopic surgery in spinal cord injury patients. Instead of the usual technique of passing the laser probe for surface vaporization, subsurface buttonholes were drilled with subsequent incision of the overlying tissue. As a result, creation of an adequate channel was expedited with excellent hemostasis. A total of 40 spinal cord injury patients (mean age 50.1 years, range 28 to 76) underwent transurethral surgery for bladder outlet obstruction using a sapphire contact laser tip. Of the patients 50% had undergone previous transurethral surgery and were not voiding well. Urodynamic studies demonstrated detrusor-sphincter dyssynergia in 37 patients (92.5%). A voiding cystourethrogram was done in 83% of the patients and showed vesicoureteral reflux in 17%. On cystoscopic examination 32.5% of the patients had an associated enlarged prostate, 32% stricture of the bulbous urethra and 20% bladder neck stenosis. Apart from transurethral sphincterotomy in these patients, ablation of the prostate, stricture and eradication of bladder neck stenosis, as indicated, were also done with the contact laser. Blood loss was approximately 25 to 50 ml. per procedure except for 2 initial patients with a blood loss of 100 to 150 ml. Approximately 3,500 to 8,900 joules accumulated energy were used for transurethral sphincterotomy and 11,000 to 37,000 joules for transurethral resection of the prostate. An indwelling Foley catheter was placed postoperatively for a mean of 3 days (range 1 to 8). All patients were followed for 6 to 23 months (mean 13.1). Four patients failed laser transurethral sphincterotomy: 1 due to inadequate initial incision and 3 who initially underwent laser transurethral incisions of the prostate and had persistent detrusor-sphincter dyssynergia (all had relief following laser transurethral sphincterotomy). All subsequent patients are voiding well with a wide open bladder neck and posterior urethra as shown on a voiding cystourethrogram.

Adult↗
PubMed1993

Hinged anoscope.

A hinged anoscope for insertion of rectal catheters is presented. Catheters attached to or integrally part of an external monitoring device or collecting system can be inserted through this endoscope. The endoscope can be removed without disconnecting the catheter from the external device.

Equipment Design↗
PubMed1993

Single-operator hemorrhoid ligator.

A new device for elastic band ligation of hemorrhoids is presented. The three instruments used for this procedure, the anoscope, clamp, and ligator, are combined to allow performance of the procedure by a single operator.

Equipment Design↗