Interference pattern in perineal muscles. A quantitative electromyographic study in patients with faecal incontinence

Area of Science:

• Neurology
• Gastroenterology
• Physiology

Background:

• Faecal incontinence (FI) can stem from various causes, including neuromuscular dysfunction.
• Understanding the underlying mechanisms of FI is crucial for effective treatment.

Purpose of the Study:

• To investigate neuromuscular dysfunction in patients with faecal incontinence.
• To measure electromyographic interference patterns in the external anal sphincter and puborectalis muscles.

Main Methods:

• Open study involving 20 patients with faecal incontinence (14 idiopathic, 6 sphincter rupture).
• Quantitative electromyography (QEMG) measured interference patterns (turns/amplitude analysis) at rest and during maximum voluntary contraction.
• Single-fibre electromyography assessed fibre density (n=10), and anal manometry measured pressures (n=17).
• Results compared against a reference group of normal volunteers.

Main Results:

• Puborectalis muscle interference pattern density was significantly lower in idiopathic FI patients versus controls (137 vs. 241 turns/sec, p < 0.01).
• Anal sphincter muscle interference pattern density was significantly lower in patients with sphincter rupture versus controls (76 vs. 165 turns/sec, p < 0.05).
• Fibre density was higher in idiopathic FI patients (1.64 (0.2) vs. 1.33 (0.1), p < 0.01) and increased with age.

Conclusions:

• Central activation of perineal muscles plays a significant role in faecal incontinence.
• Neuromuscular dysfunction, particularly impaired muscle activation, contributes to faecal incontinence.
• While central control is important, other factors may also be involved in the pathophysiology of FI.