Renal deterioration after spinal cord injury is associated with length of detrusor contractions during cystometry-A study with a median of 41 years follow-up.

AIMS: To investigate which urodynamic parameters are associated with renal deterioration over a median of 41 years follow-up after traumatic spinal cord injury.

METHODS: Medical records of patients with a traumatic spinal cord injury sustained 1944-1975 were reviewed from time of injury until 2012. Patients who attended regular renography and/or renal clearance examinations and had minimum one cystometry and pressure-flow study were included. Renal deterioration was diagnosed as split renal function ≤30% in one kidney or relative glomerular filtration rate ≤51% of expected according to age and gender. Detrusor function, presence of detrusor sphincter dyssynergia, maximum detrusor pressure, post-void residual volume, and cystometric bladder capacity were obtained. In patients with detrusor overactivity, a detrusor overactivity/cystometry ratio was calculated using duration of detrusor contraction(s) during filling cystometry divided by total duration of filling cystometry.

RESULTS: A total of 73 patients were included in the study, and the median follow-up time was 41 years after injury (range 24-56). Sixty-four patients (88%) used reflex triggering or bladder expression as bladder emptying method for the longest period after injury. During follow-up 60% changed to clean intermittent catheterization. The majority of the patients (68%) had neurogenic detrusor overactivity. In 35 patients, a detrusor-overactivity/cystometry ratio could be calculated and a detrusor overactivity/cystometry ratio > 0.33 was significantly associated with renal deterioration (P < 0.02). No significant association was found between maximum detrusor pressure or other urodynamic parameters and renal deterioration.

CONCLUSIONS: Duration of detrusor overactivity longer than one third of the duration of cystometry is associated with renal deterioration after spinal cord injury.