Relationship between manometric anal waves and fecal incontinence

PURPOSE: The significance of manometric anal waves is uncertain, and their fate and diagnostic importance are unknown. It is conceivable that in neurogenic fecal incontinence (NFI) the frequency and amplitude of these waves may be altered into specific, recognizable patterns. Evaluation of this unexplored relationship between fecal incontinence and anal manometric waves has potential diagnostic use. METHODS: Anal motility was studied in 20 patients, each with NFI and traumatic fecal incontinence (TFI), and results were compared with findings in 20 control subjects to determine changes in frequency and amplitude of anal waves in fecal incontinence. RESULTS: Frequency of slow waves when present (NFI=9.5/minute; TFI=9.5/minute; control subjects=9.1/minute) was identical in the three groups (P>0.05). Amplitude of slow waves (NFI=mean, 4.3 mmHg; TFI=mean, 3.9 mmHg; control subjects =mean, 6.6 mmHg) was reduced in patients who were incontinent compared with control subjects but failed to reach statistical significance (P>0.05). Frequency of ultraslow waves when present (NFI=mean, 0.75/minute; TFI =mean, 0.6/minute; control subjects=mean, 1.2/minute) was not statistically different between the three groups (P>0.05). Amplitude of ultraslow waves (NFI=mean, 10.5 mmHg; TFI=mean, 23.4 mmHg; control subjects=mean, 29.6 mmHg) was significantly reduced in NFI vs.control subjects (P<0.01) and between TFI vs.control subjects (P<0.05). CONCLUSIONS: Manometric slow and ultraslow waves, when present, retain their frequency characteristics, irrespective of underlying disease. Amplitude of slow waves was not statistically different from control subjects, but the amplitude of ultraslow waves was significantly decreased in patients who were incontinent.