Detrusor areflexia is observed most commonly in cauda equina lesions where the sacral reflex is disrupted. However, people with cauda equina lesions may also present atypically with autonomic detrusor contraction which causes a continuous increase of intravesical pressure during urination (Shin et al. 2002). Detrusor areflexia can also occur below the S2 spinal cord level and involve the conus medularis or peripheral nerves. Clinically, this means that the bladder cannot empty completely or at all, leading to overdistension and stasis. Additionally, there is frequently incontinence due to lack of external sphincter tone, most often due to increased abdominal pressure on the bladder (i.e. stress incontinence). This can be especially problematic in persons with paraplegia that may require high valsalva forces for activities such as transferring from wheelchairs.
Unfortunately, there is a great paucity of research examining the impact and treatment of detrusor areflexia. Although the goals remain the same as with overactive bladder in SCI, (i.e., avoiding incontinence, stasis, UTI, and upper urinary tract damage), these goals may be achieved differently. In general, the goal is either: 1) stopping leakage and improving storage with medications and intermittent catheterization, or 2) improving emptying, either voluntarily in the incomplete injury, and/or into condom drainage in males with more severe neurogenic bladder impairments. However, further discussion on detrusor areflexia will not occur in this chapter given the extremely sparse evidence base. It should be noted that in two other studies described in the sections pertaining to DESD therapy there were mixed samples with a few subjects with detrusor areflexia. In one instance, subjects with detrusor areflexia comprised all study participants providing level 4 evidence from a single case series (n=10) for the surgical anastomosis of the T11 ventral nerve root to the S2-S3 ventral nerve roots in improving bladder function (e.g., Table 20 for Other Miscellaneous Treatments).