Bulbocavernosus reflex latency in the investigation of diabetic impotence

Bladder outlet obstruction triggers neural plasticity in sensory pathways and contributes to impaired sensitivity in erectile dysfunction

Lower urinary tract symptoms (LUTS) and erectile dysfunction (ED) are common problems in aging males worldwide. The objective of this work was to evaluate the effects of bladder neck nerve damage induced by partial bladder outlet obstruction (PBOO) on sensory innervation of the corpus cavernosum (CC) and CC smooth muscle (CCSM) using a rat model of PBOO induced by a partial ligation of the bladder neck. Retrograde labeling technique was used to label dorsal root ganglion (DRG) neurons that innervate the urinary bladder and CC. Contractility and relaxation of the CCSM was studied in vitro, and expression of nitric oxide synthase (NOS) was evaluated by Western blotting. Concentration of the sensory neuropeptides substance P (SP) and calcitonin gene-related peptide was measured by ELISA. Partial obstruction of the bladder neck caused a significant hypertrophy of the urinary bladders (2.5-fold increase at 2 wk). Analysis of L6-S2 DRG sections determined that sensory ganglia received input from both the urinary bladder and CC with 5-7% of all neurons double labeled from both organs. The contractile responses of CC muscle strips to KCl and phenylephrine were decreased after PBOO, followed by a reduced relaxation response to nitroprusside. A significant decrease in neuronal NOS expression, but not in endothelial NOS or protein kinase G (PKG-1), was detected in the CCSM of the obstructed animals. Additionally, PBOO caused some impairment to sensory nerves as evidenced by a fivefold downregulation of SP in the CC (P ≤ 0.001). Our results provide evidence that PBOO leads to the impairment of bladder neck afferent innervation followed by a decrease in CCSM relaxation, downregulation of nNOS expression, and reduced content of sensory neuropeptides in the CC smooth muscle. These results suggest that nerve damage in PBOO may contribute to LUTS-ED comorbidity and trigger secondary changes in the contraction/relaxation mechanisms of CCSM.

Pudendal nerve conduction to evaluate organic erectile dysfunction

OBJECTIVE

This study aimed to evaluate the value of testing pudendal nerve conduction in men with erectile dysfunction.

DESIGN

This open prospective study was conducted on 150 men with documented erectile dysfunction of at least 6 mo of duration, all of whom underwent pudendal nerve conduction by the same investigator.

RESULTS

Only patients with erectile dysfunction and low back pain (n = 9) showed statistically significant prolonged pathologic pudendal nerve conduction latency of 43.1 msec/div (SD +/- 11.3 msec/div, P < 0.05). There were no correlations between the pudendal nerve conduction latency in patients suffering from erectile dysfunction associated with diabetes mellitus, local trauma, pelvic surgery, or antihypertensive drugs.

CONCLUSIONS

Pudendal nerve conduction may contribute valuable information to the evaluation of patients with erectile dysfunction caused by neurologic deficits as manifested by low back pain.

Quantitative sensory and autonomic testing in male diabetic patients with erectile dysfunction

OBJECTIVE

To correlate abnormalities of nerve fibres in the lower limbs with erectile dysfunction in male diabetic patients, using a range of quantitative sensory and autonomic function tests.

PATIENTS AND METHODS

The study included 68 male diabetic patients with symptomatic erectile dysfunction and 11 matched diabetics without erectile dysfunction; none had clinical evidence of peripheral vascular disease or psychological disorder. Patients were evaluated with a symptom questionnaire based on the Michigan Neuropathy Screening Instrument questionnaire and examined clinically. Sural and peroneal nerve-conduction studies, and quantitative sensory and autonomic tests (vibration, thermal, light-touch thresholds, sensory and autonomic cutaneous axon-reflexes) were used to detect nerve abnormalities in the lower limbs, which were correlated with erectile dysfunction.

RESULTS

Symptoms of neuropathy were more common in the group with male erectile dysfunction (MED), but statistically significant only for neuropathic pain (53% MED, 18% nonMED, P<0.05, chi-square test) and gastroparesis (44% MED, 0% nonMED, P<0.05). Tests of unmyelinated afferents (warming perception and capsaicin-induced sensory axon-reflex vasodilatation) were most often abnormal, sometimes with no other abnormalities on tests or neurological examination. However, abnormality of warm perception was not significantly different between groups (81% MED, 70% nonMED), suggesting that it is a poorer discriminant than abnormal sensory axon-reflex vasodilatation (89% MED, 22% nonMED, P<0.001). The only other significant test difference was decreased sural nerve action potential (70% MED, 22% non-MED, P<0.01).

CONCLUSIONS

There appeared to be preferential involvement of unmyelinated sensory fibres that mediate axon-reflex vasodilatation in the limbs of diabetic patients with erectile dysfunction. This test appears to be a helpful indicator of neurological involvement in erectile dysfunction, and may be used to monitor the effect of new treatments.

[Penile neuropathy: clinical and electrophysiologic study. Report of 186 cases]

Penile neuropathy is a common disease due to lesion of the sensory branch of the pudendal nerve, ie, the dorsal nerve of the penis. Sexual disorders (deterioration of erection) and sensory signs (hypoesthesia or paresthesia of the penis) are noted in patients with penile neuropathy. Electrophysiological recordings help guide the diagnosis (reduction of the sensory velocity of the dorsal nerve of the penis). Many etiologies can be found (traumatic, toxic, compressive), but the most common lesion is neuropathy related to diabetes.

The clinical application of dorsal penile nerve cerebral-evoked response recording in the investigation of impotence

OBJECTIVE

To determine whether recording of penile cerebral-evoked response (CER) is useful in the assessment of men with impotence.

PATIENTS AND METHODS

A total of 280 impotent men underwent CER recording as part of an assessment for a complaint of impotence. They were categorized from findings in the history and examination as having non-neurogenic impotence (n = 106), impotence related to existing neurological disturbance (n = 67), type I diabetes (n = 49) or type II diabetes (n = 58). Increased period of latency or absence of first positive peak (P1) on CER were used as the criteria for an abnormal response with reference to an age-matched control group of potent men (n = 34).

RESULTS

Overall, impotent men with diabetes or a history of neurological disturbance had significantly longer P1 latencies and lower response amplitudes compared with the control group. In contrast the CER recorded from men with non-neurogenic impotence was similar to the control group. Individual results showed an increased period of latency or absence of P1 in 100 (36%) impotent men, 72 (72%) of whom were diabetic or had a history of neurological dysfunction. CER abnormalities were associated with neurological signs on physical or cystometrographic examination in 40 (40%) individuals.

CONCLUSION

Although technically satisfactory, the clinical usefulness of CER recording is limited by the poor discriminatory value of response latencies. Most abnormal results could be predicted by the presence of diabetes or pre-existing neurological dysfunction, or by evidence of neurological deficit on physical examination. The test is not therefore suitable for routine clinical assessment of impotence but may be worthwhile if objective evidence of penile sensory dysfunction is required.

Microsurgical arteriovenous revascularization in the treatment of vasculogenic impotence

We studied 35 patients with vasculogenic impotence who underwent an operation since 1986 and who were followed postoperatively for a minimum of 1.5 years. In all patients a microsurgical anastomosis was performed between the inferior epigastric artery and the arteriovenous shunt of the dorsal penile vessels. Potency was restored or improved in 77% of the patients during the long-term observation. Doppler or duplex sonography confirmed the same percentage of patent anastomoses. Through microsurgical modifications of the Hauri procedure and the interposition of free venous grafts, it was possible to operate further in 3 patients with short epigastric arteries and to treat intraoperative complications effectively in 1.

The effects of simple hysterectomy on vesicourethral function

Many women who present with symptoms of bladder dysfunction relate the onset to the operation of simple hysterectomy. A group of 42 women undergoing simple hysterectomy was studied prospectively. Urinary symptoms, urodynamic findings and sacral reflex latencies (SRLs) were assessed pre- and post-operatively. After hysterectomy the incidence of urinary symptoms increased from 58.3 to 75.0%. Vesicourethral dysfunction was altered in 30.6% of patients, 72.7% of whom had evidence of pelvic neuropathy as detected by SRLs. The results show that simple hysterectomy is associated with a significant incidence of post-operative vesicourethral dysfunction and that there is an identifiable neurological abnormality incurred at operation which is pertinent to the subsequent disordered voiding.

Dose-dependent effect and side-effect of prostaglandin E1 in erectile dysfunction

1. Recent work has demonstrated artificial penile erection after intracavernous injection of prostaglandin E1 (PGE1). A possible dose-response relationship between PGE1 and its erectile action was examined in a double-blind, cross-over designed, placebo-controlled study. 2. Twenty patients aged (mean +/- s.d.) 45 +/- 10.5 years suffering from psychogenic erectile dysfunction were tested on four occasions. Subjects received four intracavernous injections of saline containing either no other substance, preservative, 5 micrograms or 10 micrograms PGE1. 3. Investigations revealed clear dose-dependency of PGE1 in the grade and duration of erection achieved as well as in the latency between injection and achievement of erection (P less than 0.001). Saline and preservative did not induce erection. 4. Some local pain of varying grades did occur in 11/20 patients after 5 micrograms PGE1 and in 14/20 patients after 10 micrograms PGE1 injected intracavernously. This side-effect was caused by PGE1 itself and also showed a clear dose-relation (P = 0.0035). 5. Prostaglandin E1 appears to be a promising substance for diagnostic and therapeutic purposes in erectile dysfunction. Despite the discomfort observed in some patients, PGE1 is very effective even in low doses. PGE1 10 micrograms is suggested as the appropriate initial diagnostic dose for intracavernous injection to differentiate between the normal and pathological cavernous-vascular system.

Primary erectile dysfunction

We evaluated 67 patients 18 to 60 years old (mean age 28.5 years) with primary erectile dysfunction (absence of full sustained erections since early childhood or puberty) using a multidisciplinary approach. Organic causes of the erectile dysfunction were found in 57 of the 67 patients (85 per cent): 12 (18 per cent) had neurological, 35 (52 per cent) arteriogenic and 35 (52 per cent) venogenic abnormalities. Psychogenic factors were diagnosed in 11 patients (16 per cent), while in 4 (6 per cent) a classification was not possible. Concomitant psychogenic abnormalities were found in 39 of the 57 patients (68 per cent) with organic primary erectile dysfunction. Our results suggest that primary erectile dysfunction is caused mainly by organic factors. However, for successful therapy the frequent secondary psychogenic abnormalities must be considered.

Chronic urinary retention--a sensory problem?

Factors which predispose some men with benign prostatic hyperplasia to chronic urinary retention whilst others develop acute retention are not understood. In order to assess whether there is an occult neuropathy associated with chronic retention, neurophysiological measurements were used to test the integrity of the lower urinary tract nerve supply. A series of 22 male patients with chronic urinary retention secondary to prostatic hyperplasia underwent sacral reflex latency measurement; 73% demonstrated a sensory suprasacral abnormality with intact spinal reflex arcs. These results suggest that although the sacral reflex pathways are intact, there is a sensory/proprioceptive abnormality in the higher neurological centres which may be an adaptive mechanism to the presence of bladder outflow obstruction.