Plateau pattern of detrusor contraction: A surrogate indicator of presence of external sphincter dysfunction during micturitional phase of urodynamic study

INTRODUCTION: Dysfunctional voiding results from a disturbance in the coordination between sphincter relaxation and detrusor contraction. Video urodynamic studies with electromyography (EMG) are used for diagnosis but have limitations of availability and interpretation. We identified a plateau type voiding detrusor pressure tracing pattern in these patients with a potential of helping diagnosis. MATERIALS AND METHODS: Urodynamic data and tracings of adult patients having been diagnosed with external urethral sphincter dysfunction (EUSD) were retrospectively analyzed. The urodynamic studies comprised of pressure flow studies, micturitional urethral pressure profilometry, and voiding cystourethrogram (VCUG). Diagnosis of EUSD was based on the presence of intermittent or continuous narrowing in the region of EUS on VCUG along with a urethral-vesical pressure gradient of >20 cm H2O in males and >5 cm H2O in females. RESULTS: A total of 25 patients (14 men and 11 women) with a mean age 36.6 ± 16.5 years, presented with lower urinary tract symptoms (international prostate symptom score 18 ± 5) and were diagnosed with EUSD on urodynamics/cystourethrography. The cause of EUSD was neurogenic DESD in four, dysfunctional voiding in 20 and voluntary pelvic floor squeeze in one. Resting maximum urethral closure pressure at EUS was 142.2 ± 38.3 cmH2O in both sexes. Three patients had detrusor overactivity. EMG activity during voiding was high in 10 patients, low in three, inconclusive in seven, and not performed in three. A plateau type pattern of detrusor contraction was observed in all the patients. This was qualitatively different from the roughly bell-shaped curve of detrusor contraction in men with prostatic obstruction (n = 14) and women with stress urinary incontinence (n = 11). CONCLUSIONS: Patients with EUSD have a characteristic plateau pattern of detrusor contraction on urodynamics which can be used as a surrogate for urodynamic diagnosis of nonrelaxing EUSD.