Lignocaine test and detrusor instability.

Detrusor instability in infravesical obstruction is well recognised and often resolves after surgery. The aetiology is not clearly understood but is probably due to increased vesical sensory input. Since intravesical lignocaine has been proved to have an effect (although shortlived) on detrusor instability in some patients, we have used it in order to differentiate between idiopathic detrusor instability and detrusor instability caused by infravesical obstruction. Our study showed that in patients with a positive lignocaine test pre-operatively, the detrusor instability and micturition disorder disappeared after operation, and in patients with a negative lignocaine test, it persisted. The differences were statistically significant (P less than 0.5).