Spinal stenosis is a major orthopedic disease which causes overactivity and underactivity. As urinary symptoms of spinal injury vary depending on whether the affected lesion is above the sacral cord, we hypothesized that spinal stenosis may correspond to spinal injury in clinical features. However, there has been little evidence which compared by affected lesions. The aims of this study were to compare urinary symptoms and urodynamic findings between cervical myelopathy (CM) and lumbar canal stenosis (LCS) patients and to evaluate the effectiveness of decompression surgery.

Of 667 patients (CM 286, LCS 381) who underwent decompression surgery for CM and LCS during 2006-2009 in our institution, we reviewed database of 357(53.5%) patients (CM 149(52.1%), LCS 208(54.6%)) referred to a urologic consult with any urinary symptoms on preoperative screening. We included patients who completed International Prostate Scoring System (IPSS) and uroflowmetry prior to decompression surgery. Data were compared between CM and LCS using unpaired t-test, and also compared on preoperative and postoperative periods using paired t-test. Subsequently, multivariate regression analysis was performed for >30% improvement of total IPSS scores after the decompression surgery on preoperative factors; age, sex, location of lesion (cervical or lumbar), length of lesion (number of affected vertebrae), preoperative IPSS, average urine flow rate<10ml/second (AUFR<10) on uroflowmetry, post-voiding residue (PVR) and decreased bulbocavaernous reflex (BCR).

We identified total 335 patients (CM 138, LCS 197) who met the inclusion criteria. Among excluded 22, 4 patients (2 each) were unable to examine uroflowmetry due to urinary catheterizations. Except the older age in LCS, there is no statistical difference between CM and LCS in characteristics; sex, prevalence of benign prostatic hyperplasia (>30ml), prevalence of urgent incontinence, decreased BCR, or any IPSS subscores (Fig 1). On uroflowmetry, voiding time (VT) was longer among CM patients, whereas other parameters were similar between CM and LCS. A total of 87 patients (CM 37, LCS 50) were followed up with postoperative IPSS, QOL score and uroflowmetry. Out of 87, 63 patients (CM 28(76%), LCS 35(70%)) improved with >30% reduction in total IPSS scores. There were significant improvements in subscores of incomplete emptying, frequency, weak stream in both CM and LCS (Fig 2). On uroflowmetry, VT shortened significantly in CM and LCS. When limited to patients with preoperative AUFR<10, AUFR and PVR significantly improved after the surgery. On multivariate analysis, improvement of IPSS was independent from compressed lesion, preoperative IPSS, physical findings, or urodynamic parameters.

Spinal injury above the sacral cord induces detrusor overactivity and detrusor-sphincter dyssynergia, whereas patients with cauda equina injury present with decreased sensation and underactivity. On the other hand, CM and LCS had remarkably similar features of both overactivity and underactivity in symptoms and urodynamic findings. The neuronal ischemia and edema due to mechanical compression are considered as the pathological condition in spinal stenosis. The damage to spinal cord or cauda equina may be reversible in mild-moderate cases, however, untreated stenosis may develop irreversible condition and symptoms may correspond to cervical spinal injury in CM and cauda equina injury in LCS even after decompression surgery. As a limitation, the presence of urinary symptoms in spinal stenosis is an important indicator for decompression surgery in our institution, therefore, this database is considered to have a potential selection bias toward mild-moderate cases before advancing irreversible status.

This study demonstrated limited difference of symptoms and urodynamic findings between CM and LCS. Furthermore, both storage and voiding symptoms improved significantly regardless of compressed lesion or preoperative status. These results will encourage active orthopedic consults when suspected of spinal stenosis in the future practice.

HG Deen Jr, RS Zimmerman, SK Swanson, et al.: Assessment of bladder function after lumbar decompressive laminectomy for spinal stenosis: a prospective study. J Neurosurg. 80 (6):971-974 1994
TL Tammela, MJ Heiskari, OA Lukkarinen: Voiding dysfunction and urodynamic findings in patients with cervical spondylotic spinal stenosis compared with severity of the disease. Br J Urol. 70 (2):144-148 1992