Does perineal descent correlate with pudendal neuropathy?

A prospective study was undertaken to assess the potential correlation between increased perineal descent (IPD) and pudendal neuropathy (PN) in 213 consecutive patients. These 165 females and 48 males of a mean age of 62 (range, 18-87) years had constipation (n = 115), idiopathic fecal incontinence (n = 58), or chronic intractable rectal pain (n = 40). All 213 patients underwent cinedefecography (CD) and bilateral pudendal nerve terminal motor latency (PNTML) assessment. Perineal descent (PD) of more than the upper limit of normal of 3.0 cm during evacuation was considered increased. Pudendal neuropathy was diagnosed when PNTML exceeded the upper limit of normal of 2.2 milliseconds. Although 65 patients (31 percent) had PD, only 16 (25 percent) of these 65 patients had neuropathy. Moreover, PN was also found in 42 (28 percent) of 148 patients without IPD. Conversely, only 16 (28 percent) of the 58 patients who had PN also had IPD, and IPD was present in 49 (32 percent) of 155 patients without PN. The frequency of PN according to the degree of IPD was: 3.0 to 4.0 cm, 6 of 27 patients (22 percent); 4.1 to 5.0 cm, 4 of 15 (27 percent); 5.1 to 6.0 cm, 4 of 12 (25 percent); 6.1 to 7.0 cm, 2 of 8 (25 percent); and > 7.0 cm, 0 of 3 (0 percent). Linear regression analysis was undertaken to compare the relationships between measurements of PD at rest (R), push (P), and change (C = P-R) and values of PNTML. These values for all 213 patients were: R, r = 0.048; P, r = 0.031; and C, r = -0.050. The correlation coefficients were equally poor for all the individual subgroups analyzed, including the patient's sex or diagnosis. In summary, no correlation was found between PD and PNTML. The lack of a relationship was seen for the entire group as well as for those patients with either neuropathy or increased perineal descent. Therefore, the often espoused relationship between increased PD and PN was not supported by this prospective evaluation. Although increased PD and prolonged PNTML are frequently observed in patients with disordered defecation, they may represent independent findings.