Yoshiaki Banya

Two Circulatory Routes Within the Human Corpus Cavernosum Penis: A Scanning Electron Microscopic Study of Corrosion Casts

The microvascular architecture of the human corpus cavernosum penis was studied by scanning electron microscopy of vascular corrosion casts. The corpus cavernosum was supplied by the penile deep artery. It gave off branches to become either arteries distributed within the corpus cavernosum or those directly supplying the corpus spongiosum urethrae. The former arteries further divided into small arteries which fell into two categories: 1) arteries breaking up into capillaries, and 2) arteries draining directly into the cavernous sinuses. The capillaries were collected into venular networks just beneath the tunica albuginea (the subalbugineal venular plexus), while the cavernous sinuses were collected into venules at the periphery of the corpus cavernosum. These postcavernous venules also received venules from the subalbugineal venular plexus, and left the corpus cavernosum. Thus, two circulatory routes are evident within the corpus cavernosum. These findings suggested that the penile erectile cycle is controlled by hemodynamic changes between these two routes within the corpus cavernosum.

Hyperbaric Oxygen Therapy for Radiation Cystitis in Patients with Prostate Cancer: A Long-Term Follow-Up Study

Objective: To assess the safety and efficacy of hyperbaric oxygen (HBO) for treating radiation cystitis a long-term follow-up study was done in patients with prostate cancer, the second most common malignancy in Japan. Patients and Methods: A total of 38 patients at an age of 68 ± 8 years with radiation cystitis following irradiation of prostate cancer were treated with HBO at 2 absolute atmospheric pressures for 90 min daily. The average number of HBO treatment sessions in each patient was 62 ± 12. The follow-up period was 11.6 ± 3.7 years. We evaluated objective and subjective symptoms periodically with special reference to the initiation timing of HBO therapy. Results: High efficacy ratios of objective and subjective findings were obtained at 2 and 4 (79–95%) years, respectively. After 7 years’ follow-up, these ratios decreased slightly (72–83%) but still remained stable thereafter (75–88%) without any serious accident. Comparison of late morbidity scores before and 11.6 years after HBO therapy showed significant improvement (p < 0.0005). Twenty-eight patients (74%) obtained nonrecurrent outcome. They had received 18% lower (p < 0.001) radiation dosage than recurrent patients. The interval between the onset of hematuria and start of HBO treatment in nonrecurrent patients was 30% shorter (p < 0.001) than that of recurrent patients. Conclusions: We elucidated the long-term safety and beneficial effect of HBO therapy of radiation cystitis in patients with prostate cancer. Early application of HBO treatment after the onset of hematuria appears to produce favorable outcome.

Quantitative analysis of outflow pathway of corpora cavernosa by pressure flow technique.

Using a pressure flow technique, quantitative analysis of the physiological characteristics of the outflow pathway of the corpus cavernosum was carried out in 19 male dogs weighing 7.5 to 23.0 kg. Pressure flow curves were made on dogs whose pelvic nerve was stimulated electrically and on dogs left unstimulated. When a cyclical change in saline perfusion rate was applied without nerve stimulation, the variable of the intracorporeal pressure showed a large hysteretic loop, indicating that the resistance of the outflow canals to flow was altered by the distension of the sinusoidal space. In dogs whose pelvic nerve was stimulated, the pressure flow curves shifted to the left side in comparison with the outward phase of the pressure flow curve of animals without pelvic nerve stimulation, and this curve piled on the returning phase. No hysteretic relation was observed between the outward and returning phase of the pressure flow curve with pelvic nerve stimulation, but in the detailed analysis, in which the % flow rate was used instead of actual flow rate of saline perfusion, a small hysteretic loop based on the difference of the elasticity of the outlet canals was found. The distension of the corpora cavernosa and the pelvic nerve electrostimulation probably act as the triggers of the same occlusive mechanism in the outflow pathway. The percentage decrease in the blood flow in the outflow canal of the corpus cavernosum induced by the distension of the sinusoidal space or by the pelvic nerve electrostimulation was 69.6 +/- 14.4% (mean +/- SD).

Human Penile Hemodynamics Studied by a Polarographic Method

Observations of the tissue oxygen tension alteration were made using an open tip type oxygen electrode polarographic method as an index of blood flow change in the penile skin, corpus cavernosum and thigh skin of 16 males aged 20-26 years (average age: 20.5 years). In another five males aged 18-21 (average age: 19.8 years) the relationship between corpus cavernosum tissue oxygen tension alteration and penile circumference change in the erection process was observed. This relation was obtained in the penile circulation model, and penile hemodynamics were ascertained. In the flaccid penis the corpus cavernosum contains low-oxygen blood and there is a blockade at the vascular tree in the corpus cavernosum. In the tumescence phase the blood flow of the corpus cavernosum increased suddenly by the relief of cavernosum vascular blockade. During the penile tumescence phase the increased inflow and outflow persisted in corpus cavernosum, and in penile skin the blood also increased initially, but gradually decreased as penile circumference increased. After erection was attained it is thought that resistance to inflow occurred by outflow pathway contraction. In the detumescence phase, a decrease of inflow and a concomitant increase of outflow occurred and the reopening of outflow is thought to be necessary for prompt penile detumescence.