[The characteristics of anorectal manometry in Parkinson's disease with constipation and functional constipation]

To investigate the discrepancy of anorectal function in patients of Parkinson's disease (PD) with constipation and functional constipation (FC).

Fifteen consecutive male PD patients with constipation and 45 male FC patients were recruited for the study. All subjects underwent colonoscopy or barium enema in order to exclude organic colon diseases. Every patient underwent anorectal manometry and was categorized into subgroups of either dyssynergia defecation (F3a) or inadequate defecatory propulsion (F3b).

The ages of PD with constipation and FC patients were (70 ± 11) and (68 ± 11) years old respectively. The rectal resting pressure in PD with constipation was higher than that in FC group without statistical significance [9.0(4.0, 15.0) mm Hg vs 6.0(3.0, 9.5) mm Hg, P = 0.082, 1 mm Hg = 0.133 kPa]. The anal resting pressure in PD group was not different from FC group [(51.2 ± 17.2) mm Hg vs (59.7 ± 20.4) mm Hg, P = 0.152]. During anal squeezing, the maximal contraction pressure and area under the squeeze curve in PD with constipation group were both significantly lower than FC patients [maximal contraction pressure: (136.9 ± 43.8) mm Hg vs (183.0 ± 62.1) mm Hg, P = 0.010; area under the squeeze curve: (823.5 ± 635.7) mm Hg·s vs (1392.4 ± 939.9) mm Hg·s, P = 0.033]. During forced defecation, both of the defecation rectal pressure and defecation anal pressure in PD with constipation group were significantly lower than that of FC patients [22.0(15.0, 30.0) vs 42.0(31.0, 55.0) mm Hg, P = 0.000; and (46.3 ± 23.3) vs (77.9 ± 35.1) mm Hg, P = 0.002]. The proportions of F3a subtype were 10/15 and 46.7% (21/45) in PD with constipation and FC patients respectively. There was no significant difference in the constituent ratio (P = 0.120). Initial rectal sensory volumes were (91.3 ± 56.9) ml and (67.2 ± 38.9) ml in PD with constipation and FC patients respectively. Even both volumes were higher than the normal controls, there was no significant difference between the two groups (P = 0.074).

Both PD with constipation and FC patients have abnormal anorectal motility and sensation comparing to the FC group, the parameters of anal contraction and defecation are significantly lower, F3b is dominant, and rectal sensory threshold is higher in PD with constipation patients. These parameters could possibly characterize the anorectal manometry for PD with constipation patients, which is helpful to understand the pathogenesis of PD and differentiate from other diseases.