P19. Risk factors for postoperative bladder dysfunction in lumbar spinal canal stenosis surgery

Background Context

The occurrence of postoperative bladder dysfunction is one of the most confusing complications for both patients and surgeons after lumbar spinal canal stenosis surgery.

Purpose

To investigate the risk factors for newly-onset postoperative bladder dysfunction.

Study Design/Setting

Retrospective study.

Patient Sample

The study enrolled 738 cases among the patients who underwent lumbar spinal canal stenosis surgery between 2005 and 2020. Patients with severe preoperative bladder dysfunction (incontinence and urinary retention) or perioperative complications (intraoperative dural injury and long-term urinary catheter placement) were excluded. Patients who had urinary retention for at least 1 week after postoperative urinary catheter removal or who needed intermittent urinary drainage were included in the study.

Outcome Measures

The study items included patient background (age, sex, and duration), preoperative JOA score, and surgical factors (surgical procedures and number of decompressed segments). Propensity score-matching was performed at a ratio of 1:2 (postoperative bladder dysfunction group: subject group), and patient background (BMI, smoking history, comorbidities (hypertension, diabetes)), laboratory data (Cre, Chol, TG), imaging findings (lumbar spine alignment, dural canal area at each vertebra, type of cauda equina redundancy), and surgical factors (operation time, blood loss, and history of lumbar surgery) were investigated.

Methods

Univariate and multivariate analyses were performed to identify the risk factors for postoperative bladder dysfunction.

Results

Postoperative bladder dysfunction occurred in 23 (3.1 %) patients. At 1 year postoperatively, three patients required continued intermittent voiding, and four patients required continued medical treatment. Although the median recovery time in the improvement group was 41 days, only 12 patients (52.2%) showed improvement 3 months after surgery. Patients with postoperative bladder dysfunction were significantly older in all patient data. There were no significant differences in sex, duration, surgical procedures, or the number of decompressed segments. Univariate analysis performed after propensity score matching showed significant differences in imaging findings of curve type of cauda equina, ventral or dorsal deviation of the compressed dura mater, and the lumbar Cobb angle. There were no significant differences in laboratory data, history of lumbar surgery, or dural tube area at the most compressed segment. Multivariate analysis of all three factors was an independent factor.

Conclusions

Regardless of the preoperative patient background, surgical procedures, or number of decompressed segments, older patients and those with curve-type cauda equina were at a higher risk of developing postoperative bladder dysfunction. In such cases, the impact on the dural canal and cauda equina during decompression may be stronger, with increased susceptibility to heat injury and neuropathy. It is also possible that the cauda equina is more susceptible to significant downward traction after decompression than straight-type compression of the cauda equina, necessitating more careful informed consent and wider decompression during surgery for these patients.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.