Neurourology and Urodynamics 27:99 (2008) LETTER TO THE EDITOR Re: Smith MD, Coppieters MW, Hodges PW. 2007. Postural Response of the Pelvic Floor and Abdominal Muscles in Women With and Without Incontinence. Neurourol Urodynam 26:377–85 To the Editor: In this excellent and well conducted study, the authors demonstrated that incontinent women have increased pelvic floor activity when compared to normal women. The findings are contrary to their hypothesis that women with incon- tinence would have less pelvic floor activity. Nevertheless, the findings are entirely consistent with another hypothesis: that connective tissue damage in the suspensory ligaments may be the major cause of inconti- nence. 1 All incontinence surgery using plastic midurethral slings is based on this concept. The plastic sling creates an artificial neoligament to reinforce the damaged pubourethral ligaments, and these in turn act as anchoring points for the three directional muscle forces which act to close the urethra and bladder neck. 2 The finding of increased pelvic floor activity in incontinent women may be explained by reference to the findings of spindle cells in the anterior portion of pubococcygeus muscles (PCM). 3 Using a feedback loop, these create a precise tensioning of the suburethral vagina into which the PCM inserts. Perception by the spindle cell of a lax vaginal membrane would act as a stimulus for increased pelvic floor contraction. That is, the muscles of incontinent women have to ‘‘work harder.’’ Such increased EMG con- traction was demonstrated in patients with prolonged emptying time. 4 Peter Petros* Urogynaecologist and Reconstructive Pelvic Floor Surgeon South Perth, Western Australia, Australia REFERENCES 1. Petros PE, Ulmsten U. An integral theory and its method for diagnosis and management of female urinary incontinence. Scand J Urol Nephrol 1993; 27:1–93. 2. Petros PE, Von Konsky B. Anchoring the midurethra restores bladder neck anatomy and continence. Lancet 1999;354:997–8. 3. Petros PE. The anatomy and dynamics of pelvic floor function and dysfunction, Ch 2. In: The Female Pelvic Floor—Function, dysfunction and management according to the integral theory, 2nd edition. Heidelberg: Springer; 2007. 4. Petros PE. Mapping the dynamics of connective tissue dysfunction, Ch 6. In: The Female Pelvic Floor—Function, dysfunction and management according to the integral theory, 2nd edition. Heidelberg: Springer; 2007. Reply: We thank Dr Petros for his interesting comments on our manuscript. We agree that there are a range of mechanical factors that could be associated with stress urinary inconti- nence in women. As suggested by Dr Petros, connective tissue damage may contribute to symptoms of incontinence in some women. As effective contraction of the pelvic floor muscles is dependent on the integrity of the passive structures, con- nective tissue damage may lead to ineffective function of the pelvic floor muscles. In this situation, increased activity of the pelvic floor muscle may fail to moderate symptoms of incontinence due to inefficient force transmission. However, we believe that our data also provides new insight into the mechanical complexities of continence mechanisms. In particular our data provide evidence of an unexpected increase in activity of the abdominal muscle, obliquus externus abdominis. Regardless of possible changes in the connective tissue of the pelvic floor, this change in activity will place greater demand on both the active and passive pelvic floor structures. Increased abdominal muscle activity is likely to induce greater pressure on the bladder, resulting in a greater demand to maintain urethral pressure via the complex mechanisms of the bladder neck and distal urethra. A major outcome of this finding is that in addition to techniques to change the active and passive support for the urethra, either through exercises for the pelvic floor muscles or surgery, training of coordination of the abdominal muscles is likely to be worthy of consideration. We are happy that our new data has stimulated further discussion of the potential complex mix of mechanical factors associated with stress urinary incontinence and encourage practitioners in the field to look beyond the pelvic floor; to consider the potential role of all of the trunk muscles in continence and incontinence. Michelle Smith Division of Physiotheraphy School of Health and Rehabilitation Science The University of Queensland St. Lucia, Australia DOI 10.1002/nau.20499 Published online 16 July 2007 in Wiley InterScience No conflict of interest reported by the author(s). *Correspondence to: Peter Petros, Urogynaecologist and Reconstructive Pelvic Floor Surgeon, 14A/38 Meadowvale Ave., South Perth, WA 6151, Australia. E-mail: kvinno@highway1.com.au Received 26 May 2007; Accepted 30 May 2007 Published online 16 July 2007 in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/nau.20478 ß 2007 Wiley-Liss, Inc.