Advantages and limitations of sleep-related erection and rigidity monitoring: a review


Over the past decades, sleep-related erection and rigidity monitoring has been used to differentiate psychogenic from organic erectile dysfunction (ED), due to the involuntary nature of erections in sleep. This study retrospectively reviewed all available literature focusing on sleep-related erection and rigidity monitoring through a systematic PubMed search. To date, there are mainly seven methods and their modifications, including: sleep laboratory testing, the mercury strain gauge, the stamp test, the erectometer, the Snap gauge, the RigiScan, and nocturnal electrobioimpedance volumetric assessment. This study analyzes and summarizes the advantages and limitations of seven monitoring methods. This study indicates that both of the above methods possess the capacity to assess erectile quality and provide guidance to the diagnosis, etiology, and differential diagnosis of ED. However, some limitations still exist for the application. New devices which can continuously monitor kinds of variables, including sleep-related erection, axial and radial rigidity, and oxygen saturation are needed.

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  1. 1.

    Lue TF. Erectile dysfunction. N Engl J Med. 2000;342:1802–13.

  2. 2.

    Hatzimouratidis K, Amar E, Eardley I, Giuliano F, Hatzichristou D, Montorsi F, et al. Guidelines on male sexual dysfunction: erectile dysfunction and premature ejaculation. Eur Urol. 2010;57:804–14.

  3. 3.

    Ponholzer A, Temml C, Mock K, Marszalek M, Obermayr R, Madersbacher S. Prevalence and risk factors for erectile dysfunction in 2869 men using a validated questionnaire. Eur Urol. 2005;47:80–85.

  4. 4.

    Gupta BP, Murad MH, Clifton MM, Prokop L, Nehra A, Kopecky SL. The effect of lifestyle modification and cardiovascular risk factor reduction on erectile dysfunction: a systematic review and meta-analysis. Arch Intern Med. 2011;171:1797–803.

  5. 5.

    Laumann EO, Nicolosi A, Glasser DB, Paik A, Gingell C, Moreira E, et al. Sexual problems among women and men aged 40-80 y: prevalence and correlates identified in the Global Study of Sexual Attitudes and Behaviors. Int J Impot Res. 2005;17:39–57.

  6. 6.

    Cheng JY, Ng EM, Chen RY, Ko JS. Prevalence of erectile dysfunction in Asian populations: a meta-analysis. Int J Impot Res. 2007;19:229–44.

  7. 7.

    Burnett AL, Aus G, Canby-Hagino ED, Cookson MS, D’Amico AV, Dmochowski RR, et al. Erectile function outcome reporting after clinically localized prostate cancer treatment. J Urol. 2007;178:597–601.

  8. 8.

    Whelan P, Ekbal S, Nehra A. Erectile dysfunction in robotic radical prostatectomy: outcomes and management. Indian J Urol. 2014;30:434–42.

  9. 9.

    Montorsi F, Adaikan G, Becher E, Giuliano F, Khoury S, Lue TF, et al. Summary of the recommendations on sexual dysfunctions in men. J Sex Med. 2010;7:3572–88.

  10. 10.

    Caskurlu T, Tasci AI, Resim S, Sahinkanat T, Ergenekon E. The etiology of erectile dysfunction and contributing factors in different age groups in Turkey. Int J Urol. 2004;11:525–9.

  11. 11.

    Tang Z, Li D, Zhang X, Yi L, Zhu X, Zeng X, et al. Comparison of the simplified International Index of Erectile Function (IIEF-5) in patients of erectile dysfunction with different pathophysiologies. BMC Urol. 2014;14:52.

  12. 12.

    Cera N, Di Pierro ED, Ferretti A, Tartaro A, Romani GL, Perrucci MG. Brain networks during free viewing of complex erotic movie: new insights on psychogenic erectile dysfunction. PLoS ONE. 2014;9:e105336.

  13. 13.

    Shamloul R, Ghanem H. Erectile dysfunction. Lancet. 2013;381:153–65.

  14. 14.

    van Driel MF. Sleep-related erections throughout the ages. J Sex Med. 2014;11:1867–75.

  15. 15.

    Halverson HM. Genital and sphincter behavior of the male infant. Pedagog Semin J Genet Psychol. 1940;56:95–136.

  16. 16.

    Ohlmeyer P, Brilmayer H, Hüllstrung H. Periodische Vorgänge im schlaf [German]. Pflüg Arch. 1944;248:559–60.

  17. 17.

    Aserinsky E, Kleitman N. Regularly occurring periods of eye motility, and concomitant phenomena, during sleep. Science. 1953;118:273–4.

  18. 18.

    Karacan I, Goodenough D, Shapiro A, Starker S. Erection cycle during sleep in relation to dream anxiety. Arch Gen Psychiatry. 1966;15:183–9.

  19. 19.

    Guay AT, Heatley GJ, Murray FT. Comparison of results of nocturnal penile tumescence and rigidity in a sleep laboratory versus a portable home monitor. Urology. 1996;48:912–6.

  20. 20.

    Jannini EA, Granata AM, Hatzimouratidis K, Goldstein I. Use and abuse of Rigiscan in the diagnosis of erectile dysfunction. J Sex Med. 2009;6:1820–9.

  21. 21.

    Fisher C, Schiavi P, Lear H, Edwards A, Davis DM, Witkin AP. The assessment of nocturnal REM erection in the differential diagnosis of sexual impotence. J Sex Marital Ther. 1975;1:277–89.

  22. 22.

    Levine LA, Lenting EL. Use of nocturnal penile tumescence and rigidity in the evaluation of male erectile dysfunction. Urol Clin North Am. 1995;22:775–88.

  23. 23.

    Karacan I, Salis PJ, Ware JC, Dervent B, Williams RL, Scott FB, et al. Nocturnal penile tumescence and diagnosis in diabetic impotence. Am J Psychiatry. 1978;135:191–7.

  24. 24.

    Wasserman MD, Pollak CP, Spielman AJ, Weitzman ED. Theoretical and technical problems in the measurement of nocturnal penile tumescence for the differential diagnosis of impotence. Psychosom Med. 1980;42:575–85.

  25. 25.

    Karacan I, Salis P, Williams R. The role of the sleep laboratory in diagnosis and treatment of impotence. Sleep disorders: diagnosis and treatment. New York, NY: John Wiley & Sons; 1978. p. 353–82.

  26. 26.

    Licht MR, Lewis RW, Wollan PC, Harris CD. Comparison of RigiScan and sleep laboratory nocturnal penile tumescence in the diagnosis of organic impotence. J Urol. 1995;154:1740–3.

  27. 27.

    Jankowski JT, Seftel AD, Strohl KP. Erectile dysfunction and sleep related disorders. J Urol. 2008;179:837–41.

  28. 28.

    Fisher C, Gorss J, Zuch J. Cycle of penile erections synchronous with dreaming (REM) sleep: preliminary report. Arch Gen Psychiatry. 1965;12:29–45.

  29. 29.

    Schiavi RC, Davis DM, Fogel M, White D, Edwards A, Igel G, et al. Luteinizing hormone and testosterone during nocturnal sleep: relation to penile tumescent cycles. Arch Sex Behav. 1977;6:97–104.

  30. 30.

    Lal S, Laryea E, Thavundayil JX, Nair NP, Negrete J, Ackman D, et al. Apomorphine-induced penile tumescencein impotent patients—preliminary findings. Prog Neuropsychopharmacol Biol Psychiatry. 1987;11:235–42.

  31. 31.

    Kiely ME, Thavundayil JX, Lal S. Effect of blood sampling on apomorphine-induced penile tumescence in erectile impotence: a case report. J Psychiatry Neurosci. 1995;20:233–5.

  32. 32.

    Axelson HW, Johansson E, Bill-Axelson A. Intraoperative cavernous nerve stimulation and Laser-Doppler flowmetry during radical prostatectomy. J Sex Med. 2013;10:2842–8.

  33. 33.

    Ek A, Bradley WE, Krane RJ. Nocturnal penile rigidity measured by the snap-gauge band. J Urol. 1983;129:964–6.

  34. 34.

    Leliefeld HH, Muhr S. Erectile impotence--clinical experience with the phalloplethysmography. Urol Int. 1982;37:257–66.

  35. 35.

    Barry JM, Blank B, Boileau M. Nocturnal penile tumescence monitoring with stamps. Urology. 1980;15:171–2.

  36. 36.

    Glina S, Barry JM, Hackett GI, Sadeghi-Nejad H. Nocturnal penile tumescence monitoring with stamps–Barry JM, Blank B, and Boileau M. J Sex Med. 2011;8:1296–8.

  37. 37.

    Takahashi Y, Hirata Y. Nocturnal penile tumescence monitoring with stamps in impotent diabetics. Diabetes Res Clin Pract. 1988;4:197–201.

  38. 38.

    Bertini J, Boileau MA. Evaluation of nocturnal penile tumescence with PotenTest. Urology. 1986;27:492–4.

  39. 39.

    Segraves KA, Segraves RT, Schoenberg HW. Use of sexual history to differentiate organic from psychogenic impotence. Arch Sex Behav. 1987;16:125–37.

  40. 40.

    Morales A, Marshall PG, Surridge DH, Fenemore J. A new device for diagnostic screening of nocturnal penile tumescence. J Urol. 1983;129:288–90.

  41. 41.

    Suzuki K, Sato Y, Horita H, Adachi H, Kato R, Hisasue S, et al. The correlation between penile tumescence measured by the erectometer and penile rigidity by the RigiScan. Int J Urol. 2001;8:594–8.

  42. 42.

    Matsuda Y, Hisasue S, Kumamoto Y, Kobayashi K, Hashimoto K, Sato Y, et al. Correlation between erection hardness score and nocturnal penile tumescence measurement. J Sex Med. 2014;11:2272–6.

  43. 43.

    Ek A, Bradley WE, Krane RL. Snap-gauge band: new concept in measuring penile rigidity. Urology. 1983;21:63.

  44. 44.

    Condra M, Fenemore J, Reid K, Phillips P, Morales A, Owen J, et al. Screening assessment of penile tumescence and rigidity. Clinical test of Snap-Gauge. Urology. 1987;29:254–7.

  45. 45.

    Ellis DJ, Doghramji K, Bagley DH. Snap-Gauge band versus penile rigidity in impotence assessment. J Urol. 1988;140:61–63.

  46. 46.

    Allen J, Ellis DJ, Carroll JL, Baltish MR, Bagley DH. Snap-Gauge band vs multidisciplinary evaluation in impotence assessment. Urology. 1989;34:197–9.

  47. 47.

    Mizuno I, Fuse H, Fujiuchi Y. Snap-Gauge band compared to RigiScan Plus in a nocturnal penile tumescence study for evaluation of erectile dysfunction. Urol Int. 2003;71:96–99.

  48. 48.

    Chen J, Greenstein A, Sofer M, Matzkin H. Rigiscan versus snap gauge band measurements: is the extra cost justifiable? Int J Impot Res. 1999;11:315–8.

  49. 49.

    Plante TG, Kerns RD, Yellig W, Haythornthwaite J. Using the biopsychosocial model to predict nocturnal penile rigidity in men with erectile dysfunction. J Sex Marital Ther. 1989;15:247–54.

  50. 50.

    Tscholl R, Largo M, Poppinghaus E, Recker F, Subotic B. Incidence of erectile impotence secondary to transurethral resection of benign prostatic hyperplasia, assessed by preoperative and postoperative Snap Gauge tests. J Urol. 1995;153:1491–3.

  51. 51.

    Kihara K, Kageyama Y, Kitahara S, Tsujii T, Ishizaka K, Nagamatsu H, et al. En bloc cystourethrectomy with preservation of potency. Nihon Hinyokika Gakkai zasshi. 1996;87:676–81.

  52. 52.

    Allen R, Brendler CB. Snap-gauge compared to a full nocturnal penile tumescence study for evaluation of patients with erectile impotence. J Urol. 1990;143:51–54.

  53. 53.

    Diedrich GK, Stock W, LoPiccolo J. A study on the mechanical reliability of the Dacomed snap gauge: implications for the differentiation between organic and psychogenic impotence. Arch Sex Behav. 1992;21:509–23.

  54. 54.

    Bradley WE, Timm GW, Gallagher JM, Johnson BK. New method for continuous measurement of nocturnal penile tumescence and rigidity. Urology. 1985;26:4–9.

  55. 55.

    Granata AR, Rochira V, Lerchl A, Marrama P, Carani C. Relationship between sleep-related erections and testosterone levels in men. J Androl. 1997;18:522–7.

  56. 56.

    Hatzichristou DG, Hatzimouratidis K, Ioannides E, Yannakoyorgos K, Dimitriadis G, Kalinderis A. Nocturnal penile tumescence and rigidity monitoring in young potent volunteers: reproducibility, evaluation criteria and the effect of sexual intercourse. J Urol. 1998;159:1921–6.

  57. 57.

    Munoz MM, Bancroft J, Marshall I. The performance of the Rigiscan in the measurement of penile tumescence and rigidity. Int J Impot Res. 1993;5:69–76.

  58. 58.

    Levine LA, Carroll RA. Nocturnal penile tumescence and rigidity in men without complaints of erectile dysfunction using a new quantitative analysis software. J Urol. 1994;152:1103–7.

  59. 59.

    Benet AE, Rehman J, Holcomb RG, Melman A. The correlation between the new RigiScan plus software and the final diagnosis in the evaluation of erectile dysfunction. J Urol. 1996;156:1947–50.

  60. 60.

    Mizuno I, Fuse H, Fujiuchi Y, Nakagawa O, Akashi T. Comparative study between audiovisualsexual stimulation test and nocturnal penile tumescence test using RigiScan Plus in the evaluation of erectile dysfunction. Urol Int. 2004;72:221–4.

  61. 61.

    Taniguchi H, Kawa G, Kinoshita H, Matsuda T. Recovery of erectile function after nerve-sparing laparoscopic radical prostatectomy in Japanese patients undergoing both subjective and objective assessments. J Sex Med. 2012;9:1931–6.

  62. 62.

    Kropman RF, Lycklama a Nijeholt AA, Zwartendijk J, Experiences with the Surgitek Art-1000 penile tumescence and rigidity monitor, and comparison with the RigiScan. J Urol. 1991;146:43–45.

  63. 63.

    Bahouth Z, Zreik R, Graif A, Nativ O, Halachmi S, Pillar G. Endothelial function assessment in patients with erectile dysfunction. Isr Med Assoc J. 2015;17:682–6.

  64. 64.

    Guan Y, Wendong S, Zhao S, Liu T, Liu Y, Zhang X, et al. The vascular and neurogenic factors associated with erectile dysfunction in patients after pelvic fractures. Int Braz J Urol. 2015;41:959–66.

  65. 65.

    Kim DJ, Hawksworth DJ, Hurwitz LM, Cullen J, Rosner IL, Lue TF, et al. A prospective, randomized, placebo-controlled trial of on-Demand vs. nightly sildenafil citrate as assessed by Rigiscan and the international index of erectile function. Andrology. 2016;4:27–32.

  66. 66.

    Peng J, Zhang Z, Gao B, Yuan Y, Cui W, Tang Y, et al. Effect of daily sildenafil on patients with absent nocturnal erections due to pelvic fracture urethral disruption: a single-centre experience. Andrologia. 2016;48:1120–4.

  67. 67.

    Zhu GY, Shen Y, Liu HG. Forensic medical assessment for neurologic erectile dysfunction: 58 case reports. Fa Yi Xue Za Zhi. 2015;31:369–72.

  68. 68.

    Cai L, Jiang M, Wen Y, Peng C, Zhang B. Forensic identification for erectile dysfunction: experience of a single center. Urology. 2015;86:68–71.

  69. 69.

    Bradley WE. New techniques in evaluation of impotence. Urology. 1987;29:383–8.

  70. 70.

    Weinberg JJ, Badlani GH. Utility of Rigiscan and papaverine in diagnosis of erectile impotence. Urology. 1988;31:526–9.

  71. 71.

    Karadeniz T, Topsakal M, Aydogmus A, Beksan M. Role of RigiScan in the etiologic differential diagnosis of erectile dysfunction. Urol Int. 1997;59:41–45.

  72. 72.

    Elhanbly S, Elkholy A, Elbayomy Y, Elsaid M, Abdel-gaber S. Nocturnal penile erections: the diagnostic value of tumescence and rigidity activity units. Int J Impot Res. 2009;21:376–81.

  73. 73.

    Goldstein I, Udelson D. Axial penile rigidity: determinants and relation to hemodynamic parameters. Int J Impot Res. 1998;10(Suppl 2):S28–S33.

  74. 74.

    Udelson D, Park K, Sadeghi-Nejad H, Salimpour P, Krane RJ, Goldstein I. Axial penile buckling forces vs Rigiscan radial rigidity as a function of intracavernosal pressure: why Rigiscan does not predict functional erections in individual patients. Int J Impot Res. 1999;11:327–37.

  75. 75.

    Ku JH, Song YS, Kim ME, Lee NK, Park YH. Is there a role of radial rigidity in the evaluation of erectile dysfunction? Int J Impot Res. 2001;13:200–4.

  76. 76.

    Allen RP, Smolev JK, Engel RM, Brendler CB. Comparison of RigiScan and formal nocturnal penile tumescence testing in the evaluation of erectile rigidity. J Urol. 1993;149:1265–8.

  77. 77.

    Mizuno I, Komiya A, Watanabe A, Fuse H. Importance of axial penile rigidity in objective evaluation of erection quality in patients with erectile dysfunction--comparison with radial rigidity. Urol Int. 2010;84:194–7.

  78. 78.

    Rossello Barbara M. Digital inflection rigidometry in the study of erectile dysfunction. A new technique. Arch Esp Urol. 1996;49:221–7.

  79. 79.

    El-Sakka AI. Association between International Index of Erectile Function and axial penile rigidity in patients with erectile dysfunction. Int J Impot Res. 2003;15:426–9.

  80. 80.

    Gutierrez P, Langan P, Bancroft J. Comparison of home and laboratory based monitoring of NPT using the Rigiscan; a preliminary report. Int J Impot Res. 1995;7:137–46.

  81. 81.

    Knoll LD, Abrams JH. Application of nocturnal electrobioimpedance volumetric assessment: a feasibility study in men without erectile dysfunction. J Urol. 1999;161:1137–40.

  82. 82.

    Knoll LD, Abrams JH. Nocturnal electrobioimpedance volumetric assessment of patients with erectile dysfunction. Urology. 1999;53:1200–4.

  83. 83.

    Salama N. Nocturnal electrobioimpedance volumetric assessment in diabetic men with erectile dysfunction before and after tadalafil intake. Int J Impot Res. 2004;16:441–7.

  84. 84.

    Li JB, Huang DZ, Rao K, Zhang QP, Zhao S, Li YZ. Comparison study on the diagnosis of erectile dysfunction with color Doppler ultrasonography and nocturnal electrobioimpedance volumetric assessment. Zhonghua Nan Ke Xue. 2006;12:243–6.

  85. 85.

    Wang XL, Feng F. Penile erectile function in renal transplant recipients and uremic men undergoing hemodialysis: a clinical control study. Zhonghua Nan Ke Xue. 2012;18:819–22.

  86. 86.

    Kuo YC, Liu SP, Chen JH, Chang HC, Tsai VF, Hsieh JT. Feasability of a novel audio-video sexual stimulation system: an adjunct to the use of penile duplex Doppler ultrasonography for the investigation of erectile dysfunction. J Sex Med. 2010;7:3979–83.

  87. 87.

    Tang J, Tang Y, Dai Y, Lu L, Jiang X. The use of intracavernous injection and audiovisual sexual stimulation during real-time pharmacopenile doppler ultrasonography in vasculogenic erectile dysfunction. Urol Int. 2013;90:460–4.

  88. 88.

    Hackett G, Kirby M, Wylie K, Heald A, Ossei-Gerning N, Edwards D, et al. British Society for Sexual Medicine Guidelines on the management of erectile dysfunction in Men-2017. J Sex Med. 2018;15:430–57.

  89. 89.

    Thase ME, Reynolds CF 3rd, Jennings JR, Frank E, Garamoni GL, Nofzinger EA, et al. Diminished nocturnal penile tumescence in depression: a replication study. Biol Psychiatry. 1992;31:1136–42.

  90. 90.

    Yang CC, Bowen JD, Kraft GH, Uchio EM, Kromm BG. Physiologic studies of male sexual dysfunction in multiple sclerosis. Mult Scler. 2001;7:249–54.

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This paper was supported by the Natural Science Foundation of China (No. 81671453, 81270691, and 81170565) and Thousand Talent Plan of Sichuan Province.

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Qin, F., Gao, L., Qian, S. et al. Advantages and limitations of sleep-related erection and rigidity monitoring: a review. Int J Impot Res 30, 192–201 (2018).

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