Fecal incontinence patients categorized based on anal pressure and electromyography: Anal sphincter damage and clinical symptoms

Background Disruption of external anal sphincter muscle (EAS) is an important factor in the multifactorial etiology of fecal incontinence (FI). Objectives We categorize FI patients into four groups based on the location of lesion in neuromuscular circuitry of EAS to determine if there are differences with regards to fecal incontinence symptoms severity (FISI) score, age, BMI, obstetrical history, and anal sphincter muscle damage. Methods Female patients (151) without any neurological symptoms, who had undergone high‐resolution manometry, anal sphincter EMG, and 3D ultrasound imaging of the anal sphincter were assessed. Patients were categorized into four groups: Group 1 (normal)—normal cough EMG (>10 μV), normal squeeze EMG (>10 μV), and normal anal squeeze pressure (>124 mmHg); Group 2 (cortical apraxia, i.e., poor cortical activation)—normal cough EMG, low squeeze EMG, and low anal squeeze pressure; Group 3 (muscle damage)—normal cough EMG, normal squeeze EMG, and low anal squeeze pressure; and Group 4 (pudendal nerve damage)—low cough EMG, low squeeze EMG, and low anal squeeze pressure. Results The four patient groups were not different with regards to the patient's age, BMI, parity, and FISI scores. 3D ultrasound images of the anal sphincter complex revealed significant damage to the internal anal sphincter, external anal sphincter, and puborectalis muscles in all four groups. Conclusion The FI patients are a heterogeneous group; majority of these patients have significant damage to the muscles of the anal sphincter complex. Whether biofeedback therapy response is different among different patient groups requires study. Group 1: Normal—typical function observed. Group 2: Cortical apraxia—impaired cortical neuron activation despite intact peripheral nerves and muscles. Group 3: Pudendal nerve damage—suspected pudendal nerve impairment evident in all measures. Group 4: Muscle damage—isolated damage to the external anal sphincter muscle evident.