USE OF KINESIOLOGICAL EMG AND CN EMG IN PARTICULAR PATIENT GROUPS

Kinesiological EMG recordings of sphincter and PFM are used in research, and diagnostically in selected patients with voiding dysfunction to ascertain striated muscle behaviour during bladder filing and voiding, and in selected patients with anorectal dysfunction. The method is not standardized. The demonstration of voluntary and reflex activation of PFM is indirect proof of the integrity of respective (central and peripheral) neural pathways. The demonstration of a normal PFM behaviour pattern (i.e. striated sphincter non-activity during voiding) is indirect proof of integrity of the relevant central nervous system centres for lower urinary tract neural control. Kinesiological EMG as a tool (if a sound technique is used) is not controversial, but here is little knowledge on behavioural patterns of PFM in health and disease. Therefore, short intervals of EMG in a particular patient may be misinterpreted as indicating significant pathology, whereas it only may represent normal variability of muscle behaviour or some non-specific muscle response to the experimental setting. Kinesiological EMG is also used as a therapeutic tool in biofeedback. CN EMG is performed particularly in neurological, neurosurgical and orthopaedic patients with (suspected) lesions to the conus, cauda equina, the sacral plexus or Kinesiological EMG recordings of sphincter and PFM are used in research, and diagnostically in selected patients with voiding dysfunction to ascertain striated muscle behaviour during bladder fi lling and voiding, and in selected patients with anorectal dysfunction. The method is not standardized. The demonstration of voluntary and reflex activation of PFM is indirect proof of the integrity of respective (central and peripheral) neural pathways. The demonstration of a normal PFM behaviour pattern (i.e. striated sphincter non-activity during voiding) is indirect proof of integrity of the relevant central nervous system centres for lower urinary tract neural control.

Kinesiological EMG as a tool (if a sound technique is used) is not controversial, but there is little knowledge on behavioural patterns of PFM in health and disease. Therefore, short intervals of EMG in a particular patient may be misinterpreted as indicating significant pathology, whereas it only may represent normal variability of muscle behaviour or some non-specific muscle response to the experimental setting. Nesiological EMG is also used as a therapeutic tool in biofeedback. CN EMG is performed particularly in neurological, neurosurgical and orthopaedic patients with (suspected) lesions to the conus, cauda equina, the sacral plexus or the pudendal nerve, and only rarely in urological, urogynecological and proctological patients with suspected ‘neurogenic’ uro-ano-genital dysfunction.

Pelvic floor muscle denervation has been implicated in the pathophysiology of genuine stress incontinence and genitourinary prolapse; different EMG techniques have been used in research to identify sphincter injury after childbirth. The usefulness of CN EMG in routine investigation of women after vaginal delivery and/or with urinary incontinence is, however, minimal and seems to be restricted in practice to the rare cases of severe sacral plexus involvement.

Isolated urinary retention in young women was traditionally thought to be due either to multiple sclerosis or psychogenic factors. Profuse complex repetitive discharges and ‘decelerating burst activity’ in the urethral sphincter muscle have been, however, described by CN EMG in such patients. It was proposed that this pathological spontaneous activity leads to sphincter contraction, which endures during micturition and causes obstruction to flow. The syndrome was associated with polycystic ovaries and is now referred to as Fowler’s syndrome. Because CN EMG will detect both changes of denervation and reinnervation that occur with a cauda equina lesion, as well as abnormal spontaneous activity, it has been argued that this test is mandatory in women with urinary retention (Fowler et al 1988). The specificity of CN EMG pathological changes in women in retention has, however, been questioned. The CN EMG electrode can be employed at the same diagnostic session for recording motor evoked responses and/or reflex responses for a more comprehensive evaluation of the nervous system.

In conclusion, both ‘kinesiological’ and ‘motor unit’ EMG have contributed significantly to our understanding of pelvic floor, lower urinary tract, anorectal and sexual function in health and disease, but there is still much research to be done. EMG is helpful in diagnosing selected patients with suspected neurogenic PFM dysfunction, either to demonstrate dysfunction of detrusor–sphincter coordination (kinesiological EMG) or to prove denervation/reinnervation in striated PFM and sphincters. In the case of mild to moderate partial denervation EMG is very limited in providing data on muscle strength (which is logically impaired due to denervation).