[Simultaneous urethrocystometry and hyperactive bladders: differential diagnosis and types of dyssynergia].

The authors reviewed the simultaneous urethrocystometry (SUCM) of 96 hyperactive bladders subclassified into 4 groups (pure detrusor instability, mixed instability, suprasacral spinal lesion, and CNS lesion) and compared the frequency of various urethral parameters. The absence of urethral relaxation before or during the augmentation of the detrusor pressure is the most specific sign of suprasacral spinal lesions. It constitutes what we call passive or tonic dyssynergia. When, in the beginning of SUCM, the maximal closure pressure is greater than or equal to 30 cm H20, or when a sphincteric contraction is associated with, either before ("kick") or during (active or clonic dyssynergia) the detrusor contraction, this urethral non relaxation is pathognomonic of such a spinal lesion. A "kick" is also specific of hyperreflexia but is less constant. On the contrary, in this series and with this technic, an active dyssynergia has no etiological significance; it' only reflects the degree of the vesicosphincteric imbalance.