Damage to the innervation of the voluntary anal and periurethral sphincter musculature in incontinence: an electrophysiological study.

Abstract

SUMMARY In 40 women with idiopathic (neurogenic) faecal incontinence, 20 of whom also had stress urinary incontinence, single fibre EMG studies showed an increased fibre density in the external anal sphincter muscle. All these patients showed excessive descent of the pelvic floor on straining. The mean terminal motor latencies in the pudendal and perineal nerves, measured by a digitally-directed intrarectal stimulating technique, were increased when compared with 20 control subjects (p < 0.01). The perineal nerve terminal motor latency was more markedly increased in the 20 patients with double incontinence than in those with faecal incontinence alone (p < 0.01). These results provide direct electrophysiological evidence of damage to the innervation of the pelvic floor musculature in idiopathic faecal and double incontinence, and imply that idiopathic stress urinary incontinence may have a similar cause.Histological and electrophysiological studies have revealed denervation of the pelvic floor musculature in 75% of patients with idiopathic (neurogenic) faecal incontinence.'-3 Kiff and Swash have provided direct evidence of damage to the innervation of the perianal musculature, consisting of an increase in the terminal motor latency in the pudendal nerves measured by recording the compound muscle action potential in the external anal sphincter muscle after stimulating the pudendal nerves at the level of the ischial spines.4 In addition to supplying the external anal sphincter muscle, the pudendal nerves via their perineal branches also innervate the periurethral striated sphincter musculature.5 About 12% of our patients with neurogenic faecal incontinence also suffer from urinary incontinence of stress type.' These observations have therefore suggested to us that denervation of the periurethral striated musculature may be a factor in some patients with urinary incontinence, perhaps particularly in women in whom urinary incontinence of gradual onset in middle life is associated with perineal descent, and in those who have experienced a difficult labour. This suggestion is consistent with the clinical finding

Neurophysiological testing in anorectal disorders

“…This approach owes its popularity to a number of studies reporting prolonged TMLs in various anorectal disorders, 101,121 such as fecal incontinence, 18,48,58,62,94,120,129,130,142,150,162,166 obstetrical lesions, 141,144,146,152,153,155 perineal descent, 6,51,53,62,77,143 or even constipation. 162,163 Evidence of pudendal/ anal neuropathy, as shown by a prolonged TML, was proposed as a predictive factor for the clinical outcome of biofeedback therapy 67 or surgical repair 13,39,145 of pelvic floor disturbances, even in case of unilateral neuropathy.…”

“…The normal fiber density for the external anal sphincter is below 2.0 and its increase is a sensitive indicator of collateral reinnervation after partial muscle denervation, for example, in patients with fecal incontinence. 33,88,89,94,126,128,130,142,143,171 However, single-fiber EMG remains less widely practiced than con- centric needle EMG. Another application of singlefiber EMG is for the measurement of the jitter, that is, the variability of consecutive muscle fiber discharges, which correlates with the stability of terminal motor axons and neuromuscular transmission.…”

Chiropractic care of interstitial cystitis/painful bladder syndrome associated with pelvic lumbar spine dysfunction: a case series

“…Snooks et al 33 describe how traction neuropathy of the pelvic nerves has caused urethral incompetence; and Torrens in his review of "Disorders of Micturition" goes as far as to state, "There is a neuropathic element in almost every form of urinary dysfunction." 34 One form of urinary dysfunction is contractile overactivity of the bladder, which causes spontaneous contractions during filling, which the patient cannot inhibit.…”

Clinical Neurophysiology of the Pelvic Floor

“…Using a technique called single-fiber EMG, patients with anal incontinence had evidence of denervation and reinnervation when compared with patients without incontinence [17].…”