Functional coupling between the limbs during bimanual reach-to-grasp movements

While it is frequently advantageous to be able to use our hands independently, many actions demand that we use our hands co-operatively. In this paper we present two experiments that examine functional binding between the limbs during the execution of bimanual reach-to-grasp movements. The first experiment examines the effect of gaze direction on unimanual and bimanual reaches. Even when subjects' eye movements are restricted during bimanual reaches so that they may only foveate one target object, the limbs remain tightly synchronized to a common movement duration. In contrast, grip aperture is independently scaled to the size of the target for each hand. The second experiment demonstrates however, that the independent scaling of grip aperture is task dependent. If the two target objects are unified so that they appear to be part of a single object, grip apertures become more similar across the hands (i.e., grip aperture to the large target object is reduced in size while peak aperture to the small target item is increased in size). These results suggest that the coupling of the limbs can operate at a functional level.

The role of ureter in the creation of Mitrofanoff channels in children

PURPOSE

Since 1980 numerous variations of the Mitrofanoff principle have been described. We report on 22 children in whom a ureteral Mitrofanoff channel was created.

MATERIALS AND METHODS

Between 1986 and 1995 a ureteral Mitrofanoff channel was constructed as a catheterizable conduit in 22 children 2 to 15 years old (average age 6.5) with various abnormalities of the lower urinary tract, mainly exstrophy and neurogenic bladder. Indications included unavailability or unsuitability of the appendix, preference for appendix as a catheterizable colonic stoma for antegrade washouts or concomitant removal of a nonfunctioning kidney, leaving the ureter available for use. Surgical technique was based on the principles of appendicovesicostomy and in 9 cases the ureteral Mitrofanoff channel was reimplanted.

RESULTS

Followup ranged from 1 to 72 months (average 30.5). Complications included stenosis of the conduit that caused difficult catheterization in 3 patients, necessitating dilation or minor revision in 2 and complete replacement by appendix in 1. Urinary leakage from the Mitrofanoff channel in 5 patients was treated with polydimethylsiloxane injection or oxybutinin. In 1 patient the channel was reimplanted, since the catheter struck the bladder neck during catheterization and caused severe pain.

CONCLUSIONS

Results of the ureteral Mitrofanoff channel seem somewhat less satisfactory than those of appendicovesicostomy but they remain acceptable and even comparable, strongly supporting its use in certain circumstances.

A randomized cross-over study comparing the use of a catheter valve and a leg-bag in urethrally catheterized male patients

OBJECTIVES

To evaluate the use of a catheter valve (CV) and a leg-bag (LB) in men with urethral catheters and to determine the preferred modality.

PATIENTS AND METHODS

Eighteen men (mean age 71.4 years, SD 3.4, range 63-76) presenting in acute retention and catheterized urethrally were enrolled in a 6-week randomized cross-over study comparing the CV with the LB (3 weeks with each modality). The outcome was assessed using a questionnaire which quantified the incidence of bladder spasms, nocturnal frequency, the extent of any by-passing episodes and the degree of discomfort. At the end of the study, the patients were asked to express a preference (using a subjective scoring scale) for either the CV or the LB and to give the reasons why.

RESULTS

There was no difference in the reported incidence of bladder spasms or discomfort and no difference in positive urine cultures with each modality. However, with the CV, there was a slightly higher incidence in nocturnal frequency and by-passing episodes. Thirteen patients preferred the CV whilst five preferred the LB. With the subjective scoring scale (range 0-10), the CV scored significantly higher than the LB (7.2, SD 3.1 and 5.2, SD 2.8, P < 0.05: paired t-test).

CONCLUSIONS

Most patients preferred to use the CV, reporting that it felt more comfortable and discreet, and many patients did not like the sensation of urine 'sloshing about' when using the leg-bag. Some patients using the CV were troubled by nocturnal frequency. In these patients we suggest that a combination of a valve during the day and an overnight bag may be the ideal solution.

Comparison of relaxation responses of detrusor strips from neuropathic and control patients

OBJECTIVES

To confirm the existence of relaxation responses to electrical-field stimulation in strips of human detrusor, and to compare these responses in strips from control subjects with those in strips from a group of neuropathic patients exhibiting hyperreflexia.

PATIENTS AND METHODS

Detrusor specimens were obtained at operation from a group of control patients, and from a group of patients with neuropathy (mainly spina bifida) and a history of hyper-reflexia. Muscle strips were prepared from these, mounted in organ baths, and contracted by exposure to a modified Krebs' solution containing 26 mM KCl and atropine. Relaxation responses were induced by an electrical-field stimulation (50 V, 90 microsecond pulses at 2-16 Hz for 10 s).

RESULTS

Of 29 strips, 20 (69%) from control patients showed relaxations, compared with 17 of 28 strips (61%) from neuropathic patients (P > 0.1). The maximum relaxation response in the control strips was 49 +/- 5.6% (mean +/- SEM) of the maximum relaxation induced by isobutyl methylxanthine, compared with 43 +/- 4.8% in the strips from neuropathic patients (P > 0.1). The maximum response occurred at similar frequencies (4 or 8 Hz) in the two groups. The relaxations were reduced by the inhibitor of nitric oxide synthase, N-nitro L-arginine methyl ester (0.1 mM, P < 0.05), but were not affected by guanethidine (50 microM) or tetrodotoxin (0.5 microM).

CONCLUSION

These results confirm the existence of field stimulation-induced relaxation in human detrusor, but suggest that hyper-reflexia in the neuropathic bladder cannot be accounted for by any deficiency in this response.

Physiological and morphometric studies into the pathophysiology of detrusor hyperreflexia in neuropathic patients

The in vitro responses of isolated detrusor strips obtained from neuropathic patients with neuropathic bladder dysfunction were found to be supersensitive to both carbachol [ED50 1.2 x 10(-6) M. versus 2.5 x 10(-6) M. in control strips; p < 0.005] and potassium chloride [ED50 41.8 mM. versus 49.3 mM. in control strips, p < 0.05]. There were no significant differences in the frequency-response curves obtained with intramural nerve stimulation. However, expressed as a percentage of the maximal response with carbachol, the maximal responses to intramural nerve stimulation in neuropathic strips were reduced [58.3 +/- 21% versus 74.4 +/- 18% for control strips; p < 0.005, Student t test]. Morphometric studies revealed a lower density of 'presumptive' cholinergic nerves in neuropathic detrusor (1.0 +/- 1.4 x 10(-4) microns -2 compared with 3.2 +/- 1.3 x 10(-4) microns -2 in controls, p < 0.05, Mann Whitney U test). The combined physiological and morphometric results were in keeping with a state of postjunctional supersensitivity of neuropathic detrusor secondary to a partial parasympathetic denervation of the smooth muscle. This may be an important factor in the etiology of detrusor hyperreflexia. The contractility of neuropathic tissue in response to field stimulation was found to be much lower than normal (2.4 +/- 1.5 g./10 mg. versus 5.9 +/- 3.0 g./10 mg., p < 0.001; Mann Whitney U test). This reduced contractility to neuronal stimulation might be responsible for some of the characteristics of bladder dysfunction that are seen in patients with similar neurological conditions.

An assessment of the contribution of visco-elastic factors in the aetiology of poor compliance in the human neuropathic bladder

OBJECTIVE

To compare the mechanical properties of fullthickness bladder strips from poorly compliant neuropathic bladders with controls and to determine the overall contribution that mechanical factors might have in the aetiology of the poor compliance of medium-fill cystometry.

PATIENTS AND METHODS

The visco-elastic properties of full-thickness bladder strips from 11 neuropathic patients (with poorly compliant bladders during medium-fill cystometry) were compared with strips from 11 control bladders. A strip (measuring 2 cm long and 0.5 cm wide) was mounted in an organ bath and stretched by 1 cm at a slow and at a fast rate. The stretches were repeated in modified Krebs solution containing zero calcium and 12 mM magnesium. The final experiment involved stretching the strip by 1 cm in < 1 s (instantaneous stretch).

RESULTS

Only modest differences in the peak tensions of both tissues were uncovered by the slow and fast stretches (fast stretch: 14.6 +/- 5.5 in neuropaths vs 10.1 +/- 4.1 g in controls, P = NS; slow stretch: 9.6 +/- 3.5 in neuropaths vs 6.7 +/- 2.5 g in controls, P < 0.05). Stretches carried out in modified Krebs solution resulted in lower tensions. Fast, intermediate and slow components of viscous decay (derived from the rate of tension decay following the instantaneous stretch) were not significantly different in neuropaths compared to controls (P = NS).

CONCLUSION

The differences in the mechanical properties between neuropathic and control bladder strips were small and could not alone have accounted for the large differences in bladder compliance that was observed between neuropathic and normal patients during medium-fill cystometry. This implied that neurogenic rather than mechanical factors were more important in the aetiology of the observed poor compliance in these patients.

Carcinosarcoma in a bladder diverticulum

A 47-year-old man presented with hematuria and dysuria. He was found to have a carcinosarcoma originating from a bladder diverticulum. He underwent a partial cystectomy and received postoperative chemotherapy. One year later, he presented with a large local recurrence and died shortly afterward. We believe this to be the second case of a carcinosarcoma originating in a bladder diverticulum.

Same day diagnostic service for new cases of haematuria--a district general hospital experience

OBJECTIVE

To describe the running of a special haematuria diagnostic service which catered for a flexible cystoscopy on the same day as the first clinical visit. The impact of this service especially with regard to the timing of the intravenous urogram (IVU) is discussed. The service was designed to facilitate early diagnosis, particularly of bladder tumours, in new cases of haematuria. Potentially this would allow a more effective planning of operating lists and implementation of early definitive treatment.

PATIENTS AND METHODS

Within the setting of a District General Hospital, new cases of haematuria were studied (42 male, 29 female, mean age 60 +/- 13 years). Fifty-one had a pre-clinic IVU whereas 20 had this deferred until after their first visit. All patients underwent a flexible cystoscopy under local anaesthesia on their first visit. New cases of bladder cancer were placed on the next available list for definitive treatment whilst patients with normal cystoscopy were referred back to the clinic for further investigations.

RESULTS

Altering the timing of the IVU helped in reducing hospital delay from 33 +/- 19 days (range 9-92 days) to 22 +/- 9 days (range 8-52 days; P < 0.04); the number of diagnostic cystoscopies performed within 4 weeks increased from 65% to 95%.

CONCLUSION

The same day diagnostic service has not been difficult to administer. Patient acceptability was excellent and design objectives were achieved.

Cystodiathermy under local anaesthesia using the flexible cystoscope

The use of the flexible cytoscope in the follow-up of patients with bladder carcinoma is becoming more widespread. In a series of 17 patients, cystodiathermy of small recurrent tumours using the flexible cytoscope and topical urethral anaesthesia proved to be a safe, effective and well tolerated procedure.