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Biomedical subjects

T R Larson

Publications and source records attributed to T R Larson.

34 records · Page 2Linked to original sources
PubMed1998

Interstitial cystitis in men.

OBJECTIVES: To determine the personal characteristics, the mode of presentation, the duration of the delay in diagnosis, the number of misdiagnoses, the means to achieve diagnosis, and previous treatment provided for a group of men with interstitial cystitis (IC). METHODS: A chart review of 29 men diagnosed with IC at our facility from 1988 to 1996 was performed. Basic demographic data, historical information, laboratory findings, and endoscopic and biopsy results were tabulated. RESULTS: IC in this series of men was diagnosed at a mean age of 67.3 years. There was approximately a 4-year diagnostic lag between presentation and diagnosis. The most common prior erroneous diagnoses were prostatitis in 48% and benign prostatic hypertrophy (BPH) in 38% of the men. Ulcers were encountered cystoscopically in about 70% and biopsy specimens uniformly showed nonspecific chronic cystitis at the time of diagnosis. CONCLUSIONS: IC should be considered in the differential diagnosis of voiding disorders accompanied by irritative symptoms and pelvic pain in older men. The diagnosis should be especially considered in men who are refractory to the usual treatments for BPH and prostatitis. Cystoscopy and bladder distention under anesthesia provided the most useful objective information in our hands. Biopsy is useful to rule out inflammatory cancer but adds little to the diagnosis of IC.

Adult↗
PubMed1998

Transurethral microwave thermotherapy: what role should it play versus medical management in the treatment of benign prostatic hyperplasia?

Both transurethral microwave thermotherapy (TUMT) and medical management by alpha-blockade or 5-alpha-reductase inhibition are increasingly being considered as alternatives to surgery for treatment of patients with benign prostatic hyperplasia (BPH). We review current evidence supporting the effectiveness and safety of TUMT and medical management. Factors for consideration in appropriately selecting patients for TUMT versus medical management are suggested. Available data indicate that TUMT confers greater long-term benefits than medical management as judged by symptom score and peak urinary flow rate improvements. TUMT-associated morbidity is comparatively low. Alpha-blockade affords more rapid relief than TUMT for patients with BPH; however, other strategies such as the use of temporary intraurethral endoprostheses during the acute post-TUMT recovery period may diminish or abolish the differences in time-course of symptom and flow rate improvement between TUMT and alpha-blockade. 5-Alpha-reductase inhibition with finasteride offers a favorable side-effect profile, although the magnitude of symptom and flow rate improvements is modest, and maximal effects of finasteride do not become manifest until after several months of treatment. As TUMT continues to evolve, increasing attention is being accorded the delivery of high thermal doses and precise targeting of the thermal energy delivered. The development of alpha-blockers with a more favorable side-effect profile continues to be a major focus of investigation. The potential clinical utility of combination therapy with TUMT and alpha-blockade is currently under investigation.

Clinical Trials as Topic↗
PubMed1998

Current status of transurethral thermotherapy at the Mayo Clinic.

With the ever-expanding elderly population in the United States, benign prostatic hyperplasia (BPH) has become a widespread condition. Although surgical intervention (open prostatectomy and transurethral resection of the prostate) was the typical management approach for BPH in the past, other options currently include drug therapy and transurethral thermotherapy, a minimally invasive procedure that involves the targeting of heat deep within the prostate transition zone while cooling the surrounding anatomic structures with circulating water. Two thermo-therapy-devices--the Prostatron and the T3 transurethral thermoablation therapy catheter--have been studied in randomized controlled clinical trials at the Mayo Clinic. Both devices were shown to be effective in a substantial subset of patients with BPH: symptom scores decreased, peak urinary flow rates increased, and total serum prostate-specific antigen levels increased, an indication of destruction of adenomatous tissue. All patients were able to complete the treatment without the need for general or regional anesthesia, and thermotherapy was associated with few postprocedural events. Although this therapeutic strategy is currently used selectively in patients with lateral lobe prostatic adenoma, improvements in technology and understanding of the thermoregulatory properties of the prostate should broaden the application of thermotherapy devices in the management of BPH.

Adult↗
PubMed1997

Leiomyoma of the female urethra and bladder: report of twenty-three patients and review of the literature.

OBJECTIVES: Our purpose was to review what may be the largest experience of bladder and urethral leiomyomas from a single institution. STUDY DESIGN: A retrospective review was done of 23 female patients with emphasis on presentation, symptoms, and operative approach for excision. RESULTS: The majority of bladder and urethral leiomyomas in this series were asymptomatic, nonobstructive, or incidental (discovered at surgery for another entity). Ten patients had a palpable mass on physical examination. Two patients had pain as a presenting complaint. The route of operative excision was transvaginal (10 patients), transurethral (6 patients), or abdominal (6 patients). One patient had the leiomyoma removed elsewhere with a resultant vesicovaginal fistula. CONCLUSIONS: Corollaries should be sought with the experience of uterine leiomyomas, which are histologically identical to bladder leiomyomas. Asymptomatic, nonobstructive, and nonproblematic leiomyomas should not serve as an indication for primary operation. Pedunculated endovesical lesions may be an exception because of the ease of transurethral removal and their tendency to cause future symptoms. Ultrasonographic imaging, cystoscopy, and biopsy should be considered to allow observation and follow-up of leiomyomas. Future investigative cytogenetic studies should be considered on these mesenchymal tumors.

Adult↗
PubMed1997

Comparison of the modified vest and the direct anastomosis for radical retropubic prostatectomy.

OBJECTIVES: This retrospective study was undertaken to compare the efficacy of the Vest and direct vesicourethral anastomosis for radical prostatectomy. METHODS: Five hundred six patients who underwent consecutive radical prostatectomies at our institution were analyzed. Two hundred fifty-nine patients underwent vesicourethral anastomosis using the Vest technique and 247 underwent a direct suture anastomosis. The groups were analyzed relative to time until healing, the occurrence of anastomotic strictures, and the continence rate 1 year after surgery. RESULTS: Approximately twice as many patients who underwent the Vest procedure experienced delayed healing and 8.5% developed anastomotic strictures compared with 1.2% of the direct anastomosis group. The Vest group experienced slightly better urinary continence 1 year postoperatively. CONCLUSIONS: The Vest procedure is a reasonable alternative to direct anastomosis for radical prostatectomy and provides similar results. We suggest specific circumstances when the Vest anastomosis may be particularly useful.

Aged↗
PubMed1996

The result of radical retropubic prostatectomy and adjuvant therapy for pathologic stage C prostate cancer.

PURPOSE: The results of therapy in 288 men with pathologic Stage C prostate cancer who underwent radical retropubic prostatectomy (RRP) were analyzed to determine the effects of adjuvant therapy. METHODS AND MATERIALS: Twenty-seven of the 288 patients received preoperative neoadjuvant hormonal therapy (leuprolide acetate). Postoperatively, 60 patients received adjuvant radiotherapy (RT) to the prostate bed. Follow-up ranged from 3 to 83 months (median = 32 months). Freedom from failure (FFF) was defined as maintaining a serum PSA level of < or = 0.3 ng/ml. RESULTS: The FFF was 61% at 3 years and 45% at 5 years for the entire group. The FFF following RRP plus RT was 75% at 3 years and 57% at 5 years as compared to 56% at 3 years and 40% at 5 years for RRP without RT (p=0.049). The FFF following RRP plus neoadjuvant hormonal therapy was 58% at 3 years and 40% at 5 years as compared to 60% at 3 years and 45% at 5 years following RRP without hormonal therapy (p=0.3). In patients without seminal vesicle (SV) invasion, the FFF was 81% at 3 years and 5 years for RRP plus RT as compared to 61% at 3 years and 50% at 5 years for RRP without RT (p=0.01). In patients with SV invasion, the FFF was 61% at 3 years and 36% at 5 years for RRP plus RT as compared to 44% at 3 years and 23% at 5 years for RRP without RT (p=0.23). The projected local control rate was 83% at 5 years for those with RRP alone as compared to 100% for RRP plus RT (p=0.02). Survival at 5 years was projected to be 92% and was not significantly altered by the administration of adjuvant therapies. CONCLUSIONS: Postoperative RT was associated with significantly improved local control and FFF rates, especially in patients with tumors which did not involve the seminal vesicles.

Aged↗
PubMed1996

Detailed prostatic interstitial thermal mapping during transurethral grooved rollerball electrovaporization and loop electrosurgery for benign prostatic hyperplasia.

OBJECTIVES: To determine the detailed pattern of prostatic interstitial temperature change during rollerball electrovaporization and loop electrosurgery in patients with benign prostatic hyperplasia (BPH). METHODS: Four patients with symptomatic BPH necessitating prostate surgery were subjected to rollerball electrovaporization on one side of their prostate glands, as well as contralateral loop electrosurgery. Continuous temperature readings were recorded from 20 to 24 interstitially implanted fiber-optic thermosensors using a novel stereotactic thermal mapping technique. Ultrasound and video endoscopic visualization were used to evaluate and quantify the spatial relationship between the thermosensors and the rollerball or loop. RESULTS: The patterns of temperature change during rollerbal electrovaporization and loop electrosurgery were substantially similar. Temperatures decreased steeply and significantly with increasing distance from both the rollerball (P < 0.001) and loop (P < 0.001). Marked mean temperature increases occurred at 1 to 2 mm from both the rollerball (30.8 degrees C, 95% confidence interval [CI] 27.8 to 33.8 degrees C) and loop (34.8 degrees C, 95% CI 24.0 to 45.6 degrees C), and temperatures at this distance were significantly higher than those at greater distances (P < 0.05). At 3 to 5 mm, the mean temperature increases declined by 58% for the rollerball and 68% for the loop. Further declines of 68% and 63%, respectively, were observed at 6 to 10 mm, and at distances exceeding 10 mm the temperature changes were minimal (0.5 degree C [95% CI 0.3 to 0.8 degree C] for the rollerball and 0.5 degree C [95% CI 0.1 to 0.8 degree C] for the loop). There was no change in temperature at any of the thermosensors near the neurovascular bundles and rectum. CONCLUSIONS: The patterns of temperature change with rollerball electrovaporization and loop electrosurgery are closely similar. Interstitial temperature changes during use of the rollerball and loop are transient and highly localized, posing minimal risk of unintended thermal damage to adjacent tissues, including the neurovascular bundles and rectum.

Aged↗
PubMed1996

Temperature-correlated histopathologic changes following microwave thermoablation of obstructive tissue in patients with benign prostatic hyperplasia.

OBJECTIVES: To determine the intraprostatic pathologic changes following accurately measured doses of transurethral microwave thermal energy in patients with benign prostatic hyperplasia. METHODS: Eight patients scheduled for prostate surgery were treated for approximately 1 hour without anesthesia using a newly designed microwave treatment catheter that allows a close impedance match to prostate tissue and concentrates thermal energy preferentially in the anterior and lateral prostate gland. Interstitial, urethral, and rectal temperatures were continuously measured using a novel stereotactic thermal mapping technique. Serial sections of prostate tissue harvested during subsequent surgery were evaluated pathologically with prostate mapping. RESULTS: Microwave treatment resulted in marked and continuous intraprostate temperature elevation, while urethral and rectal temperatures remained low. Peak intraprostate temperatures in individual patients reached as high as 80 degrees C. Mean temperature reached a maximum of 54 degrees C at a radial distance of approximately 0.5 cm from the urethra and remained 45 degrees C or higher up to a distance of 1.6 cm. The predominant pathologic findings were uniform hemorrhagic necrosis and tissue devitalization without significant inflammation. The mean distance from the urethra to the viable-necrotic tissue border was 1.6 +/- 0.2 cm (range, 0.5 to 2.5). At this border, no more than 1 mm in thickness, temperature averaged 45.7 +/- 0.6 degrees C, and there was a suggestion that pure stromal nodules were more resistant to thermal injury. CONCLUSIONS: Microwave treatment can destroy obstructive prostate tissue while maintaining innocuous urethral and rectal temperatures. Temperatures of 45 degrees C or higher for approximately 1 hour cause uniform thermoablation of prostate tissue.

Body Temperature↗
PubMed1995

Transurethral microwave thermal therapy: pathologic findings in the canine prostate.

Microwave irradiation administered by transurethral transducer to the prostate permits focused hyperthermia with resultant tissue ablation; a coding system within the catheter allows urethral preservation. We evaluated the effect of microwave hyperthermia in 13 dogs receiving 48-79 min of focused irradiation (16-45 watts, intraprostatic temperature > 45 degrees C) delivered by a specially-designed transducer with an operator-controlled directional antenna (T3, Urologix Inc., Minneapolis, MN); one other dog had transducer placement without irradiation (sham control). After treatment, the dogs were in good health, voiding well without complications, and were sacrificed after 5-38 days. The prostate and vasa deferentia were removed, fixed in 10% formalin, grossly inspected, cut at 5 mm intervals, and serially sectioned with whole mount sections; representative sections of the adjacent rectum and distal bladder were also obtained. All cases were histologically evaluated with prostatic mapping without knowledge of treatment or time of sacrifice. In the acute phase (5-13 days), the prostate showed sharply circumscribed periurethral coagulative necrosis with hemorrhage; necrosis was also seen in the mucosa and bladder wall of those with transducers placed at the bladder neck. In the subacute phase (17 days), the hemorrhagic necrosis was resolving, often with cystically dilated urethra due to sloughed necrotic tissue; the urothelium was intact. By 24-38 days, the necrosis was in the late stages of resolution, with residual patchy acute and chronic inflammation at the periphery, and frequent persistence of megalourethra. In all cases, the prostatic capsule was intact, the urethral mucosa was preserved, and the vasa deferentia and rectum were normal except for two cases with mild fat necrosis. Microwave irradiation allows precisely localized thermal ablation of prostatic tissue and enlargement of the urethral bore without clinical complications in dogs, offering promise as a therapeutic alternative to surgery in select patients with symptomatic prostatic nodular hyperplasia.

Animals↗
PubMed1995

Increased prostatic blood flow in response to microwave thermal treatment: preliminary findings in two patients with benign prostatic hyperplasia.

OBJECTIVES: To determine the effects on prostate blood flow of heat generated by microwave thermal treatment in patients with benign prostatic hyperplasia. METHODS: Prostate blood flow was evaluated by continuous transrectal color Doppler ultrasonography in 2 patients at baseline, after implantation of interstitial needles used for thermal mapping, and during microwave thermal treatment. Temperatures at 30 prostatic, periprostatic, urethral, and rectal sites were continuously monitored. In 1 patient, transrectal prostate compression was applied and the blood flow and temperature response to this maneuver noted. RESULTS: Microwave thermal treatment achieved maximum prostate temperatures of 59 degrees C at 5 mm radially from the urethra. Urethral and rectal temperatures remained low. Marked increases occurred in prostate blood flow in response to microwave thermal treatment. These increases were apparent throughout the prostate gland, with the greatest increase in perfusion occurring in the peripheral zone and the posterior half of the transitional zone. After 15 minutes of microwave treatment, peak systolic blood flow increased 99% and 70% in patients 1 and 2, respectively, while end-diastolic blood flow climbed 50% and 112%, respectively. Prostate compression resulted in a prompt quenching of blood flow and an increase in prostate temperature. CONCLUSIONS: Based on these preliminary findings in 2 patients, prostate blood flow increases markedly in response to microwave thermal treatment. This compensatory increase in blood flow is likely to be a significant treatment-limiting factor in achieving effective thermoablation.

Blood Flow Velocity↗
PubMed1995

An accurate technique for detailed prostatic interstitial temperature-mapping in patients receiving microwave thermal treatment.

A minimally invasive prostatic interstitial temperature-mapping technique is described that supplies accurate, detailed information on thermal doses delivered to precisely localized tissue sites. The technique employs a comparatively large numbers of thermosensors, highly accurate placement of those thermosensors at specified three-dimensional coordinates, fiberoptic technology that avoids significant interaction between the thermosensors and the applied microwave field, and continuous temperature readout. Biplane ultrasound imaging and fluoroscopy were used to ensure stereotactic accuracy of thermosensor placement. The technique was applied in 15 patients with benign prostatic hyperplasia (BPH) undergoing a 1-hour microwave thermal treatment session. The thermal mapping procedures and microwave treatment were generally well tolerated. The mean maximum temperature in the prostate and periprostatic tissue (57.9 +/- 1.9 degrees C) was significantly higher (P < 0.001) by more than 18 degrees C than that in either the urethra (39.6 +/- 0.9 degrees C) or the rectum (40.8 +/- 1.7 degrees C). In a representative patient, microwave treatment resulted in stable elevation of temperature 5 mm radially from the urethra that averaged 66.0 +/- 0.1 degrees C. At 10 mm from the urethra, the temperature averaged 50.5 +/- 0.1 degrees C. Urethral and rectal temperatures remained at innocuous levels. In conjunction with pathologic studies, this interstitial thermal mapping method should prove useful in defining the optimal thermal doses for microwave therapy. The method should also find uses in evaluating different microwave treatment systems, which can vary markedly in thermal performance, as well as other modalities that apply heat to prostatic tissue.

Aged↗
PubMed1995

Condom-related allergic contact dermatitis.

After 25 years of wearing a condom catheter, recurrent blisters and epidermal sloughing of the penile shaft developed in a patient. Patch testing revealed hypersensitivities to several allergenic components of the condom catheter (that is thiram and mercaptobenzothiazole). After immediate treatment with topically applied steroids, the condition improved and the patient successfully switched to a silicone condom without further irritation.

Condoms↗
PubMed1994

Simplified technique for improving exposure of the apical prostate during radical retropubic prostatectomy.

We describe a rapid and easily learned technique that greatly assists in exposure of the apical prostate during radical retropubic prostatectomy. The technique is a modification of the previously reported "bunching" maneuver. A curved Kocher clamp is used to compress the dorsal vein complex and surrounding fascia into a tight midline bundle. Once transected, dissection of the prostatomembranous urethra, neurovascular bundles, and apical prostate is markedly facilitated.

Constriction↗
PubMed1994

Assessment of bladder function after lumbar decompressive laminectomy for spinal stenosis: a prospective study.

Lumbar spinal stenosis is a common problem in elderly patients. In its more advanced forms, it typically causes intractable leg pain, but many patients also manifest varying degrees of bladder dysfunction. The goal of lumbar decompressive laminectomy is relief of leg pain and paresthesias, yet some patients also achieve improvement in bladder function. This study prospectively investigated patients with lumbar spinal stenosis to determine whether laminectomy had any effect on urological function. Of the 20 patients in the study, 10 were men and 10 women (average age 70.9 years). All patients had severe lumbar stenosis affecting between two and four spinal segments, and all reported some degree of bladder dysfunction. Cystoscopy and urodynamic testing were completed preoperatively. A standard decompressive laminectomy was performed over the appropriate number of spinal segments. Urodynamic studies were repeated at 2 and 6 months postoperatively. At the 6-month follow-up review, bladder function was subjectively improved in 12 patients (60%) and unchanged in eight (40%). Postvoiding residual urine volume was the urodynamic factor most likely to be improved by laminectomy. In nine patients (45%), baseline postvoiding residual urine volume was elevated and all nine had improvement postoperatively. In the remaining 11 patients (55%), this urine volume was normal before and after surgery. Maximum urine flow rates also improved, but the results of cytometrography and electromyography, urine flow pattern, and bladder capacity were unchanged postoperatively. Cystoscopy detected previously undiagnosed malignancy of the lower urinary tract in two patients (10%). It is concluded that lumbar decompressive laminectomy can have a beneficial effect on bladder function in a significant number of patients with advanced lumbar spinal stenosis.

Aged↗
PubMed1992

Clinical trials of the Northgate SD-3 dual-purpose lithotriptor for renal calculi.

The Northgate SD-3 is a bathless, portable shock wave lithotriptor made in the United States. It uses ultrasound localization and spark-gap, electrode-generated shock waves to fragment calculi in the upper urinary tract. Since October 1987, 312 treatments have been performed on 281 patients (286 kidneys) with stone burdens less than 2 cm. during clinical trials at 6 investigational sites in the United States. A fragmentation rate of 94% was achieved. Of the treatments 78% were judged successful (stone-free or fragments of less than 5 mm. remaining in an asymptomatic patient) and a 3-month stone-free rate of 58% was noted. The retreatment rate was 9% and the ancillary procedure rate was 5%. The complications (hematuria, ecchymosis, pain, obstruction) were mild and not unlike those seen in patients undergoing lithotripsy with other devices.

Adult↗