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Presented at EAU Congress. Paris, 1 st -4 th of September, 1996

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José Pereira da Silva M.D.,
Joäo C. Gençalves M.D.,
Lopes Santiago M.D.
Clinica Harmonia, Lisboa, Portugal

INTRODUCTION

Penile rigidity it is the axial resistance to a compressive force, related with the intracavernous pressure. During the rigid stage, high intracavernous pressures are attained due to the constrictory force of the intracavernous smooth muscle, of the tunica albuginea, and the superficial tissues of the penis. Penile rigidity only occurs after tumescence. In the physical point of view the erection process includes two interactive phenomena:

• Hemodynamic filling of the cavernous bodies
• Constrictive action

During the rigid stage, penile tissues are submitted to tension both in an axial and in a radial directions and, therefore this tension over the penis wall will offer resistance to deformation in two directions:

• Axial: measurable by axial rigidometer (mechanical or digital)
• Radial: measurable by radial rigidometer, becoming a means for indirect measurament of axial rigidity

METHODS

This evaluation is part of a protocol in use Clinica Harmonia, which also includes: clinical background, physical examination, psychological assessment, penile rigidometry during sleep or associated to sexual visual stimulation and manipulation (or pharmacological stimulation), penile ecodoppler, biochemical tests, hormone dosage. Different measurements were taken after an artificial erection was induced with a 20 mg PGE1 intracavernous injection and saline infusion with perfusion pump, such as:

• Development of tumescence and firmness of the sections at two different points of the penile shaft with Rigiscan
• Axial resistance of the penis, with mechanical and digital inflexion rigidometer (RID), by Dr. Roselló Barbará.

Measurement moments:

• Pharmacological and mechanically induced maximum rigidity during maintenance debitometry
• 1 minute after stopping the infusion pump
• 5 minutes after stopping the infusion pump In a rigid erection situation, were measured using the same technique axial and radial resistance for comparison purposes.

Rigiscan rigidometry parameters considered in this study were:

• variation of tumescence at the base > 3 cm
• variation of tumescence at the top > 2 cm
• sufficient rigidity at the top > 70%
• sufficient rigidity at the base > 70%

Normal tumescence > 3 cm at the base and > 2 cm at the top are mandatory in order to validate rigidity and was a rule in this study.

RESULTS

Seventy patients were randomly choosen out of the 691 which attended our clinic with erectile dysfunction complaints between June 1994 and June 1995. Radial / Axial Rigidometry Number of cases % Compatible measurements 43 61,4 Non-compatible measurements 27 38,6 Possibility of compatible diagnosis 45 64,3 Possibility of non-compatible diagnosis 25 35,7 Clear non compatible diagnosis 23 32,8 In 25 situations, the relationship between the result and the possible diagnosis were non-compatible in both method used: N r cases (%) Clearly contradictory possible diagnosis 4 (17,40) Penile curvature 1 (4,35) Curve with Peyronie 21 (91,3%) seemed compatible with clinical background 18 (78,20) In apparent anatomically normal situation 2 (8,70%) seemed non compatible with clinical background 2 (2,86) Through non compatible in possible diagnosis, the conclusion attained by both methods are leveraged For the cases of non compatibility in the possible diagnosis, and taken into conside ration the final diagnosis, in 20 of 23 (87,0%) 20 of 70 (28,6%) The results of the axial rigidometry were more consistent in 3 of 23 (13,0%) 3 of 70 (4,3%) The results of the radial rigidometry were more consistent.

The results of this study show that compatibility between both rigidometry methods is almost coincident in a majority of cases –43 (61.4%) in 70-.

CONCLUSIONS

1. In similar conditions, axial rigidometry showed more reliable results.
2. In some cases, the results attained by radial rigidometry may be more appropiate, because among the available equipment, Rigiscan with radial moni toring is the only one which assesses the necessary tumescence indicator.
3. As a rule, both methods –radial and axial rigidometry should be used
4. For clinical en medical legal reasons it is advisable to use methods which are not only reliable but also enable result registration. Therefore we advise the use of Digital Inflection Rigidometer in axial rigidometry.