Diagnostic discordance of electromyography (EMG) versus voiding cystourethrogram (VCUG) for detrusor-external sphincter dyssynergy (DESD)

Aims: Detrusor sphincter dyssynergia (DSD) is defined as: "a detrusor contraction concurrent with an involuntary contraction of the urethral and/or periurethral striated muscle." In neurogenic etiology, this usually refers to involuntary contraction of the external striated sphincter and has classically been termed detrusor-external sphincter dyssynergia (DESD). There is currently no consensus regarding diagnosis [specifics of electromyographic (EMG) or voiding cystourethrographic (VCUG) determination], and little data on how well these modalities correlate. We explore the diagnostic congruence for DESD between needle EMG and VCUG in the neurogenic population. Methods: Consecutive studies performed by a single urodynamicist at a major neurologic center were reviewed. Presence of DESD was determined by increased wire needle EMG activity and/or by dilated bladder neck and proximal urethra during detrusor contraction, in the absence of valsalva or attempt to inhibit voiding. Minimal acceptable criterion for agreement between the two tests was set at 70%. Results: Fourty nine patients were diagnosed with DESD, had a videourodynamic study available, and had no history of sphincterotomy or stem. Binomial testing demonstrated significant disagreement (P < 0.000) in observed proportions. There was 60% agreement (28 patients) and 40% disagreement (21 patients) between EMG and VCUG for diagnosis of DESD. Conclusions: We found significant disagreement between needle EMG and VCUG for a positive diagnosis of DESD. A combination of EMG and VCUG may identify more cases of DESD than either modality alone and underscores the need for more strict criteria when defining this entity from a urodynamic standpoint.