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TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY: A TOOL FOR RECORDING THE ELECTROMYOGRAPHIC ACTIVITY OF THE CORPORA CAVERNOSA
0022-5347/05/1742-0629/0 THE JOURNAL OF UROLOGY® Copyright © 2005 by AMERICAN UROLOGICAL ASSOCIATION
Vol. 174, 629 – 631, August 2005 Printed in U.S.A.
DOI: 10.1097/01.ju.0000165571.70300.2e
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY: A TOOL FOR RECORDING THE ELECTROMYOGRAPHIC ACTIVITY OF THE CORPORA CAVERNOSA AHMED SHAFIK,* OLFAT EL SIBAI, ISMAIL SHAFIK
AND
ALI A. SHAFIK
From the Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo (AS, IS, AAS), and the Department of Surgery, Faculty of Medicine, Menoufia University, Shebin El-Kom (OES), Egypt
ABSTRACT
Purpose: The electric activity of the corpora cavernosa (CC) is recorded by needle electrodes introduced into the CC. We investigated the hypothesis that transcutaneous electrocavernosography (ECG) would register electric waves similar to those recorded by the needle ECG but noninvasively. Materials and Methods: The ECG was recorded transcutaneously in 35 healthy volunteers (mean age 37.6 ⫾ 4.8 SD years). Two silver-silver chloride electrodes were applied on the dorsum of the penis over 1 of the CC. A reference electrode was applied to the thigh. Intracavernosal ECG using 2 needle electrodes introduced into the CC was performed in the same subjects. At least two 20 minutes sessions were recorded for each subject. Results: Slow waves (SWs) were registered transcutaneously. The waves from the 2 electrodes in each individual had the same frequency, amplitude and conduction velocity. They had a regular rhythm and were reproducible. The SWs were followed or superimposed by action potentials which occurred randomly. The transcutaneously recorded SWs were confirmed by the intracavernous route. Both routes had similar ECG recordings. Conclusions: The study demonstrated that the transcutaneous ECG recorded electric waves similar to those registered by the intracavernosal route. The transcutaneous ECG is simple, easy, non-invasive, and may be included as an investigative tool in the diagnosis of erectile dysfunction. KEY WORDS: impotence, penis, action potentials; muscle, smooth
Penile erection and detumescence depend on cavernous smooth muscle relaxation and contraction.1⫺5 During erection, the arterial blood fills the sinusoids of the corpus cavernosum (CC). The male erectile response is a neurovascular event depending on the complex interaction between neurological and vascular responses.6⫺8 Erectile dysfunction (ED) is usually multifactorial and has been classified as vasculogenic, neurogenic, endocrinologic and psychogenic. Impaired blood flow to the penis is the most common cause of ED.1⫺6 Altered neural function is generally regarded as the second common cause of ED, although its contribution is commonly underestimated as it is difficult to assess.6 Smooth muscle relaxation of the CC is considered as the key mechanism of erection. The recording of electric activity, or electrocavernosography (ECG), was first introduced by Wagner et al9 and later studied by other investigators.10⫺14 Electrocavernosography provides information on the smooth musculature and autonomic innervations of the penis. It has been adopted for diagnostic evaluation of ED.10⫺14 Stief et al suggested that single potential analysis of cavernous electric activity may be useful in the diagnosis of cavernous autonomic neuropathy and cavernous smooth muscle myopathy.12, 15 The important parameters in the study of motor unit action potentials are amplitude, frequency and velocity of conduction. Parameters vary according to the electrode position within the territory of individual motor units.16 With concen-
tric needle electrode, groups of motor unit action potentials are recorded. Single muscle fiber action potentials can be recorded extracellularly by using an electrode with a small leading-off surface. Electrocavernosography is performed by means of a concentric electromyographic needle electrode inserted in the CC.9⫺14 As the use of a needle electrode represents an invasive method, albeit it minimal, for the recording of the CC electromyogram (EMG), we hypothesized that the transcutaneous ECG would register electric waves similar to those recorded by the needle electrode, but in a noninvasive manner. The current communication investigated this hypothesis. SUBJECTS AND METHODS
Subjects. The study comprised 35 healthy volunteers with a mean age of 37.6 ⫾ 4.8 SD years (range 32 to 44). They had normal erection and a normal sexual life. The results of physical examination, including neurologic assessment, were unremarkable. The laboratory work which comprised blood count, renal and hepatic function tests and electrocardiogram recorded normal findings. All subjects gave an informed written consent after having been fully informed about the nature of the study and the tests to be done. The study was approved by the Review Board and Ethics Committee of the Cairo University Faculty of Medicine. Transcutaneous ECG. All recordings were performed while the penis was in the flaccid state. In each subject, the CC EMG was recorded twice: transcutaneously and by needle electrode. The subject lay supine, uncovered from the umbilicus to the mid thigh. For the transcutaneous approach, we used Beckman’s silver-silver chloride surface electrodes
Submitted for publication November 13, 2004. Study received Cairo University Faculty of Medicine Review Board and Ethics Committee approval. * Correspondence: 2 Talaat Harb St., Cairo 11121, Egypt (telephone/FAX: ⫹20 –2-749 – 8851; e-mail: [email protected] or [email protected]; Internet: www.ahmed-shafik.org). 629
630
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY
methods, a 20 minutes recording was performed for the individual subject at each of minimally 2 recording sessions. The results were analyzed statistically using Student’s t test and values were given as mean ⫾ SD. Differences assumed significance at p ⬍0.05. RESULTS
FIG. 1. Transcutaneous device
(Smith Kline-Beckman, Los Angeles, California) (fig. 1). To define the optimal electrode position, several leads were used at different sites on the penis. The most marked, regular and reproducible signals were selected for further analysis with respect to contamination by a respiratory component or artifacts. A strain gauge respiration transducer was applied to the thoracic wall. The optimal positions of the electrodes were found to be as follows: one electrode applied to the dorsum of the penis over one of the CCs and 1 to1.5 cm distal to the symphysis pubis, and the 2nd electrode 2 cm distal to the first electrode. A reference electrode was applied to the thigh. The signals were recorded on paper (van Gogh EP-8b) and stored on magnetic tape (Recall Store 14). High and low pass filters (6 dB/0) were used for all recordings and were set at 0.01 and 0.5 Hz, respectively. Intracavernosal electromyography. Later on the same day and in the same subjects, we recorded the CC EMG using an electromyographic needle electrode (Type 13L49, Disa, Copenhagen, Denmark) of 40 mm in length and 0.65 mm in diameter. Two needle electrodes were introduced into the CC from the positions as had been determined for the surface electrodes. The respiratory transducer and ground electrode were placed as aforementioned. A standard EMG apparatus (Type MES, Medelec, Woking, United Kingdom) was used to amplify and display the recorded potentials. Films of these potentials were taken on a light sensitive paper (Linagraph type 1895, Kodak, London, United Kingdom) from which measurements of the duration of the motor unit action potentials were obtained. The EMG signals were in addition stored on an FM tape recorder (type 7758A, HewlettPackard, Waltham, Massachusetts) for further analysis as required. After electrode application, a 20-minute period was allowed before the start of recording so that the CC would have adapted to the applied electrodes and the subjects anxiety diminished. For the transcutaneous and needle electrode
The recordings of all the subjects were successful with no adverse side effects and were evaluated. Slow waves (SWs) were recorded from the two electrodes applied transcutaneously in each individual. The wave was negatively deflected and had a constant shape in all the recordings from the same site. The SWs in each individual exhibited the same frequency (mean 4.6 ⫾ 1.2 cycle per minute), amplitude (mean 0.48 ⫾ 0.07 mV) and conduction velocity (mean 5.2 ⫾ 0.8 cm per second) from the 2 electrodes (fig. 2, table). These variables were constant, reproducible and identical from both CCs of each subject. Bursts of fast activity spikes or action potentials followed or were superimposed over the SWs (fig. 2). They occurred randomly and did not accompany each SW, yet had similar pattern and distribution from the 2 electrodes of the individual subject. The ECG parameters registered by both the surface and needle electrodes in the same subject showed no significant difference between the 2 recordings (p ⬎0.05, fig. 3, table). The electric waves recorded transcutaneously had a similar frequency, amplitude and conduction velocity, and also regularity, as those registered by the needle electrodes (see table). There was no significant difference in the results of CC EMG recordings between the studied age groups. We do not know if the results would be similar in an older group age. These recordings were reproducible with no significant difference when the registration was repeated in the same subject. DISCUSSION
The CCs, consisting of smooth muscle fibers, discharge electric waves like other smooth muscles in the body.9⫺14 These waves proved recordable by electromyography. The corpus cavernosum EMG has been introduced as an investigative tool in the diagnosis of ED9⫺14 and has been demonstrated as valuable in the evaluation of the integrity of the autonomic innervation and smooth musculature of the CC.12, 15 The ECG was performed by inserting needle electrodes into the CC. Albeit that this technique is minimally invasive, yet it may be accompanied, though rarely, by the known complications of cavernous tissue injection. To simplify the routine clinical procedure, a transcutaneous recording technique has been developed that showed no complications, was well tolerated, non-invasive, evaluable in all the subjects and provided high quality recordings. This transcutaneous ECG produced EMG variables similar to those recorded by the needle electrodes. Likewise, the wave morphology was similar for both recording methods. The transcutaneously recorded waves could be confirmed by the intracavernosal route. The potential argument that the transcutaneously recorded cavernosal waves are respiratory, cardiac or intesti-
FIG. 2. Transcutaneous electrocavernosography showing regular slow waves followed by random action potentials.
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY Frequency, amplitude and conduction velocity recorded transcutaneously and by needle electrodes in the same subject EMG Parameters
Mean ⫾ SD Transcutaneous (range)
Mean ⫾ SD Needle Electrodes (range)
Frequency (cycle/min) 4.6 ⫾ 1.2 (3.2–5.8) 4.4 ⫾ 1.2* (3.1–5.6) Amplitude (mV) 0.48 ⫾ 0.07 (0.4–0.6) 0.49 ⫾ 0.07* (0.4–0.6) Conduction velocity (cm/sec) 5.2 ⫾ 0.8 (4.1–6.2) 5.3 ⫾ 0.8* (4.3–6.4) * Needle electrode recordings compared to transcutaneous recordings p ⬎0.05.
631
regular. The patients had ED, and erection occurred not with sildenafil but with intracavernosal injection of papaverine which caused the SW variables to decline. CONCLUSIONS
The current study demonstrated that recording the CC myoelectric activity by the transcutaneous route is a simple, easy and noninvasive procedure. This route records electrocavernosographic activity similar to that registered by the intracavernosal route, with consistency and reproducibility. It may be included as an investigative tool in the diagnosis of ED. However, further studies are needed to assess both transcutaneous and intracavernous ECG in the healthy volunteers during erection and in patients with neurogenic ED. Margot Yehia assisted in preparing the manuscript. REFERENCES
FIG. 3. Needle electrocavernosography of same subject in figure 1 showing similar electrocavernosographic pattern.
nal artifacts would be refuted. Respiratory artifacts were excluded by the application of the respiratory transducer to the chest wall, while cardiac waves would be identifiable by their characteristic shape. Moreover, intestinal waves are inconsistent due to the peristaltic activity of the gut. The origin of the cavernosal waves from the abdominal wall musculature can further be ruled out by the fact that the striated muscles of the abdominal wall, unlike the smooth muscles, exhibit no resting electric activity. These data, as well as the similarity between the waves recorded transcutaneously and those recorded by needle electrodes, and in addition the reproducibility of the waves during the two 20-minute recording sessions seem to indicate that the cavernosal waves originate from the CC and do not constitute artifacts. It may be argued that we did not record both transcutaneous and intracavernosal ECG simultaneously. One ECG was recorded after the other because the transcutaneous and needle electrodes had to be applied at the same site so that recording by the 2 procedures would be similar, thus adding to the accuracy of recording by the 2 methods. Electric waves’ parameters vary according to the position of the electrode within the territory of individual motor units.16 The transcutaneous ECG may prove to be of diagnostic significance in the evaluation of ED as it purportedly provides information on the integrity of the CC smooth musculature. The CC smooth muscle fibers are primarily or secondarily involved in the various pathologic conditions of ED. A recent study has demonstrated a silent ECG pattern in neurogenic, a bradyarrhythmic in arteriogenic and a normal one in venogenic ED.13 Furthermore, in the syndrome of overactive CC, the SW variables showed significant increase compared with the healthy volunteers, and the rhythm was ir-
1. Meuleman, E. J. and Diemont, W. L.: Investigation of erectile dysfunction. Diagnostic testing for vascular factors in erectile dysfunction. Urol Clin North Am, 22: 803, 1995 2. Mills, T. M., Lewis, R. W. and Stopper, V. S.: Androgenic maintenance of inflow and veno-occlusion during erection in the rat. Biol Reprod, 59: 1413, 1998 3. Lue, T. F.: Erectile dysfunction. N Engl J Med, 342: 1802, 2000 4. Wagner, G. and Saenz de Tejada, I.: Update on male erectile dysfunction. BMJ, 316: 678, 1998 5. Melman, A. and Gingell, J. C.: The epidemiology and pathophysiology of erectile dysfunction. J Urol, 161: 5, 1999 6. Bluestein, C. B., Arezzo, J. C., Eckholdt, H. and Melman, A.: The neuropathy of erectile dysfunction. Int J Impot Res, 14: 433, 2002 7. Giuliano, F. and Rampin, O.: Central neural regulation of penile erection. Neurosci Biobehav Rev, 24: 517, 2000 8. Nehra, A. and Moreland, R. B.: Neurologic erectile dysfunction. Urol Clin North Am, 28: 289, 2001 9. Wagner, G., Gerstenberg T. and Levin, R. J.: Electrical activity of corpus cavernosum during flaccidity and erection of the human penis: a new diagnostic method? J Urol, 142: 723, 1989 10. Kellner, B., Stief, C. G., Hinrichs, H. and Hartung, C.: Computerized classification of corpus cavernosum electromyogram signals by the use of discriminant analysis and artificial neural networks to support diagnosis of erectile dysfunction. Urol Res, 28: 6, 2000 11. Machtens, S. A., Stief, C. G., Gorek, M., Becker, A. J., Truss, M. C. and Jonas, U.: Corpus cavernosum electromyography: technique and clinical implications. Tech Urol, 3: 147, 1997 12. Stief, C. G., Ho¨ppner, C., Sauerwein, D. and Jonas, U.: Single potential analysis of cavernous electrical activity in spinal cord injury patients. J Urol, 151: 367, 1994 13. Shafik, A., Shafik, A. A., El-Sibai, O. and Ahmed, I.: Electrocavernosogram in erectile dysfunction: a diagnostic tool. Arch Androl, 50: 317, 2004 14. Shafik, A., Shafik, I., El-Sibai, O. and Shafik, A. A.: Overactive corpus cavernosum: a novel cause of erectile dysfunction. Andrologia, 36: 378, 2004 15. Stief, C. G., Kellner, B., Gorek, M. and Jonas, U.: Smooth muscle electromyography. Urol Clin North Am, 28: 259, 2001 16. Rosenfalck, P.: Intra- and extracellular potential fields of active nerve and muscle fibers. A physico-mathematical analysis of different models. Thromb Diath Haemorrh Suppl, 321: 1, 1969
Vol. 174, 629 – 631, August 2005 Printed in U.S.A.
DOI: 10.1097/01.ju.0000165571.70300.2e
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY: A TOOL FOR RECORDING THE ELECTROMYOGRAPHIC ACTIVITY OF THE CORPORA CAVERNOSA AHMED SHAFIK,* OLFAT EL SIBAI, ISMAIL SHAFIK
AND
ALI A. SHAFIK
From the Department of Surgery and Experimental Research, Faculty of Medicine, Cairo University, Cairo (AS, IS, AAS), and the Department of Surgery, Faculty of Medicine, Menoufia University, Shebin El-Kom (OES), Egypt
ABSTRACT
Purpose: The electric activity of the corpora cavernosa (CC) is recorded by needle electrodes introduced into the CC. We investigated the hypothesis that transcutaneous electrocavernosography (ECG) would register electric waves similar to those recorded by the needle ECG but noninvasively. Materials and Methods: The ECG was recorded transcutaneously in 35 healthy volunteers (mean age 37.6 ⫾ 4.8 SD years). Two silver-silver chloride electrodes were applied on the dorsum of the penis over 1 of the CC. A reference electrode was applied to the thigh. Intracavernosal ECG using 2 needle electrodes introduced into the CC was performed in the same subjects. At least two 20 minutes sessions were recorded for each subject. Results: Slow waves (SWs) were registered transcutaneously. The waves from the 2 electrodes in each individual had the same frequency, amplitude and conduction velocity. They had a regular rhythm and were reproducible. The SWs were followed or superimposed by action potentials which occurred randomly. The transcutaneously recorded SWs were confirmed by the intracavernous route. Both routes had similar ECG recordings. Conclusions: The study demonstrated that the transcutaneous ECG recorded electric waves similar to those registered by the intracavernosal route. The transcutaneous ECG is simple, easy, non-invasive, and may be included as an investigative tool in the diagnosis of erectile dysfunction. KEY WORDS: impotence, penis, action potentials; muscle, smooth
Penile erection and detumescence depend on cavernous smooth muscle relaxation and contraction.1⫺5 During erection, the arterial blood fills the sinusoids of the corpus cavernosum (CC). The male erectile response is a neurovascular event depending on the complex interaction between neurological and vascular responses.6⫺8 Erectile dysfunction (ED) is usually multifactorial and has been classified as vasculogenic, neurogenic, endocrinologic and psychogenic. Impaired blood flow to the penis is the most common cause of ED.1⫺6 Altered neural function is generally regarded as the second common cause of ED, although its contribution is commonly underestimated as it is difficult to assess.6 Smooth muscle relaxation of the CC is considered as the key mechanism of erection. The recording of electric activity, or electrocavernosography (ECG), was first introduced by Wagner et al9 and later studied by other investigators.10⫺14 Electrocavernosography provides information on the smooth musculature and autonomic innervations of the penis. It has been adopted for diagnostic evaluation of ED.10⫺14 Stief et al suggested that single potential analysis of cavernous electric activity may be useful in the diagnosis of cavernous autonomic neuropathy and cavernous smooth muscle myopathy.12, 15 The important parameters in the study of motor unit action potentials are amplitude, frequency and velocity of conduction. Parameters vary according to the electrode position within the territory of individual motor units.16 With concen-
tric needle electrode, groups of motor unit action potentials are recorded. Single muscle fiber action potentials can be recorded extracellularly by using an electrode with a small leading-off surface. Electrocavernosography is performed by means of a concentric electromyographic needle electrode inserted in the CC.9⫺14 As the use of a needle electrode represents an invasive method, albeit it minimal, for the recording of the CC electromyogram (EMG), we hypothesized that the transcutaneous ECG would register electric waves similar to those recorded by the needle electrode, but in a noninvasive manner. The current communication investigated this hypothesis. SUBJECTS AND METHODS
Subjects. The study comprised 35 healthy volunteers with a mean age of 37.6 ⫾ 4.8 SD years (range 32 to 44). They had normal erection and a normal sexual life. The results of physical examination, including neurologic assessment, were unremarkable. The laboratory work which comprised blood count, renal and hepatic function tests and electrocardiogram recorded normal findings. All subjects gave an informed written consent after having been fully informed about the nature of the study and the tests to be done. The study was approved by the Review Board and Ethics Committee of the Cairo University Faculty of Medicine. Transcutaneous ECG. All recordings were performed while the penis was in the flaccid state. In each subject, the CC EMG was recorded twice: transcutaneously and by needle electrode. The subject lay supine, uncovered from the umbilicus to the mid thigh. For the transcutaneous approach, we used Beckman’s silver-silver chloride surface electrodes
Submitted for publication November 13, 2004. Study received Cairo University Faculty of Medicine Review Board and Ethics Committee approval. * Correspondence: 2 Talaat Harb St., Cairo 11121, Egypt (telephone/FAX: ⫹20 –2-749 – 8851; e-mail: [email protected] or [email protected]; Internet: www.ahmed-shafik.org). 629
630
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY
methods, a 20 minutes recording was performed for the individual subject at each of minimally 2 recording sessions. The results were analyzed statistically using Student’s t test and values were given as mean ⫾ SD. Differences assumed significance at p ⬍0.05. RESULTS
FIG. 1. Transcutaneous device
(Smith Kline-Beckman, Los Angeles, California) (fig. 1). To define the optimal electrode position, several leads were used at different sites on the penis. The most marked, regular and reproducible signals were selected for further analysis with respect to contamination by a respiratory component or artifacts. A strain gauge respiration transducer was applied to the thoracic wall. The optimal positions of the electrodes were found to be as follows: one electrode applied to the dorsum of the penis over one of the CCs and 1 to1.5 cm distal to the symphysis pubis, and the 2nd electrode 2 cm distal to the first electrode. A reference electrode was applied to the thigh. The signals were recorded on paper (van Gogh EP-8b) and stored on magnetic tape (Recall Store 14). High and low pass filters (6 dB/0) were used for all recordings and were set at 0.01 and 0.5 Hz, respectively. Intracavernosal electromyography. Later on the same day and in the same subjects, we recorded the CC EMG using an electromyographic needle electrode (Type 13L49, Disa, Copenhagen, Denmark) of 40 mm in length and 0.65 mm in diameter. Two needle electrodes were introduced into the CC from the positions as had been determined for the surface electrodes. The respiratory transducer and ground electrode were placed as aforementioned. A standard EMG apparatus (Type MES, Medelec, Woking, United Kingdom) was used to amplify and display the recorded potentials. Films of these potentials were taken on a light sensitive paper (Linagraph type 1895, Kodak, London, United Kingdom) from which measurements of the duration of the motor unit action potentials were obtained. The EMG signals were in addition stored on an FM tape recorder (type 7758A, HewlettPackard, Waltham, Massachusetts) for further analysis as required. After electrode application, a 20-minute period was allowed before the start of recording so that the CC would have adapted to the applied electrodes and the subjects anxiety diminished. For the transcutaneous and needle electrode
The recordings of all the subjects were successful with no adverse side effects and were evaluated. Slow waves (SWs) were recorded from the two electrodes applied transcutaneously in each individual. The wave was negatively deflected and had a constant shape in all the recordings from the same site. The SWs in each individual exhibited the same frequency (mean 4.6 ⫾ 1.2 cycle per minute), amplitude (mean 0.48 ⫾ 0.07 mV) and conduction velocity (mean 5.2 ⫾ 0.8 cm per second) from the 2 electrodes (fig. 2, table). These variables were constant, reproducible and identical from both CCs of each subject. Bursts of fast activity spikes or action potentials followed or were superimposed over the SWs (fig. 2). They occurred randomly and did not accompany each SW, yet had similar pattern and distribution from the 2 electrodes of the individual subject. The ECG parameters registered by both the surface and needle electrodes in the same subject showed no significant difference between the 2 recordings (p ⬎0.05, fig. 3, table). The electric waves recorded transcutaneously had a similar frequency, amplitude and conduction velocity, and also regularity, as those registered by the needle electrodes (see table). There was no significant difference in the results of CC EMG recordings between the studied age groups. We do not know if the results would be similar in an older group age. These recordings were reproducible with no significant difference when the registration was repeated in the same subject. DISCUSSION
The CCs, consisting of smooth muscle fibers, discharge electric waves like other smooth muscles in the body.9⫺14 These waves proved recordable by electromyography. The corpus cavernosum EMG has been introduced as an investigative tool in the diagnosis of ED9⫺14 and has been demonstrated as valuable in the evaluation of the integrity of the autonomic innervation and smooth musculature of the CC.12, 15 The ECG was performed by inserting needle electrodes into the CC. Albeit that this technique is minimally invasive, yet it may be accompanied, though rarely, by the known complications of cavernous tissue injection. To simplify the routine clinical procedure, a transcutaneous recording technique has been developed that showed no complications, was well tolerated, non-invasive, evaluable in all the subjects and provided high quality recordings. This transcutaneous ECG produced EMG variables similar to those recorded by the needle electrodes. Likewise, the wave morphology was similar for both recording methods. The transcutaneously recorded waves could be confirmed by the intracavernosal route. The potential argument that the transcutaneously recorded cavernosal waves are respiratory, cardiac or intesti-
FIG. 2. Transcutaneous electrocavernosography showing regular slow waves followed by random action potentials.
TRANSCUTANEOUS ELECTROCAVERNOSOGRAPHY Frequency, amplitude and conduction velocity recorded transcutaneously and by needle electrodes in the same subject EMG Parameters
Mean ⫾ SD Transcutaneous (range)
Mean ⫾ SD Needle Electrodes (range)
Frequency (cycle/min) 4.6 ⫾ 1.2 (3.2–5.8) 4.4 ⫾ 1.2* (3.1–5.6) Amplitude (mV) 0.48 ⫾ 0.07 (0.4–0.6) 0.49 ⫾ 0.07* (0.4–0.6) Conduction velocity (cm/sec) 5.2 ⫾ 0.8 (4.1–6.2) 5.3 ⫾ 0.8* (4.3–6.4) * Needle electrode recordings compared to transcutaneous recordings p ⬎0.05.
631
regular. The patients had ED, and erection occurred not with sildenafil but with intracavernosal injection of papaverine which caused the SW variables to decline. CONCLUSIONS
The current study demonstrated that recording the CC myoelectric activity by the transcutaneous route is a simple, easy and noninvasive procedure. This route records electrocavernosographic activity similar to that registered by the intracavernosal route, with consistency and reproducibility. It may be included as an investigative tool in the diagnosis of ED. However, further studies are needed to assess both transcutaneous and intracavernous ECG in the healthy volunteers during erection and in patients with neurogenic ED. Margot Yehia assisted in preparing the manuscript. REFERENCES
FIG. 3. Needle electrocavernosography of same subject in figure 1 showing similar electrocavernosographic pattern.
nal artifacts would be refuted. Respiratory artifacts were excluded by the application of the respiratory transducer to the chest wall, while cardiac waves would be identifiable by their characteristic shape. Moreover, intestinal waves are inconsistent due to the peristaltic activity of the gut. The origin of the cavernosal waves from the abdominal wall musculature can further be ruled out by the fact that the striated muscles of the abdominal wall, unlike the smooth muscles, exhibit no resting electric activity. These data, as well as the similarity between the waves recorded transcutaneously and those recorded by needle electrodes, and in addition the reproducibility of the waves during the two 20-minute recording sessions seem to indicate that the cavernosal waves originate from the CC and do not constitute artifacts. It may be argued that we did not record both transcutaneous and intracavernosal ECG simultaneously. One ECG was recorded after the other because the transcutaneous and needle electrodes had to be applied at the same site so that recording by the 2 procedures would be similar, thus adding to the accuracy of recording by the 2 methods. Electric waves’ parameters vary according to the position of the electrode within the territory of individual motor units.16 The transcutaneous ECG may prove to be of diagnostic significance in the evaluation of ED as it purportedly provides information on the integrity of the CC smooth musculature. The CC smooth muscle fibers are primarily or secondarily involved in the various pathologic conditions of ED. A recent study has demonstrated a silent ECG pattern in neurogenic, a bradyarrhythmic in arteriogenic and a normal one in venogenic ED.13 Furthermore, in the syndrome of overactive CC, the SW variables showed significant increase compared with the healthy volunteers, and the rhythm was ir-
1. Meuleman, E. J. and Diemont, W. L.: Investigation of erectile dysfunction. Diagnostic testing for vascular factors in erectile dysfunction. Urol Clin North Am, 22: 803, 1995 2. Mills, T. M., Lewis, R. W. and Stopper, V. S.: Androgenic maintenance of inflow and veno-occlusion during erection in the rat. Biol Reprod, 59: 1413, 1998 3. Lue, T. F.: Erectile dysfunction. N Engl J Med, 342: 1802, 2000 4. Wagner, G. and Saenz de Tejada, I.: Update on male erectile dysfunction. BMJ, 316: 678, 1998 5. Melman, A. and Gingell, J. C.: The epidemiology and pathophysiology of erectile dysfunction. J Urol, 161: 5, 1999 6. Bluestein, C. B., Arezzo, J. C., Eckholdt, H. and Melman, A.: The neuropathy of erectile dysfunction. Int J Impot Res, 14: 433, 2002 7. Giuliano, F. and Rampin, O.: Central neural regulation of penile erection. Neurosci Biobehav Rev, 24: 517, 2000 8. Nehra, A. and Moreland, R. B.: Neurologic erectile dysfunction. Urol Clin North Am, 28: 289, 2001 9. Wagner, G., Gerstenberg T. and Levin, R. J.: Electrical activity of corpus cavernosum during flaccidity and erection of the human penis: a new diagnostic method? J Urol, 142: 723, 1989 10. Kellner, B., Stief, C. G., Hinrichs, H. and Hartung, C.: Computerized classification of corpus cavernosum electromyogram signals by the use of discriminant analysis and artificial neural networks to support diagnosis of erectile dysfunction. Urol Res, 28: 6, 2000 11. Machtens, S. A., Stief, C. G., Gorek, M., Becker, A. J., Truss, M. C. and Jonas, U.: Corpus cavernosum electromyography: technique and clinical implications. Tech Urol, 3: 147, 1997 12. Stief, C. G., Ho¨ppner, C., Sauerwein, D. and Jonas, U.: Single potential analysis of cavernous electrical activity in spinal cord injury patients. J Urol, 151: 367, 1994 13. Shafik, A., Shafik, A. A., El-Sibai, O. and Ahmed, I.: Electrocavernosogram in erectile dysfunction: a diagnostic tool. Arch Androl, 50: 317, 2004 14. Shafik, A., Shafik, I., El-Sibai, O. and Shafik, A. A.: Overactive corpus cavernosum: a novel cause of erectile dysfunction. Andrologia, 36: 378, 2004 15. Stief, C. G., Kellner, B., Gorek, M. and Jonas, U.: Smooth muscle electromyography. Urol Clin North Am, 28: 259, 2001 16. Rosenfalck, P.: Intra- and extracellular potential fields of active nerve and muscle fibers. A physico-mathematical analysis of different models. Thromb Diath Haemorrh Suppl, 321: 1, 1969