Effectiveness of intravesical resiniferatoxin in treating detrusor hyper-reflexia and external sphincter dyssynergia in patients with chronic spinal cord lesions

Objective To investigate the therapeutic effect of resiniferatoxin in patients with chronic spinal cord lesions, as detrusor hyper-reflexia and external sphincter dyssynergia (DESD) are common phenomenon in such patients. Patients and Methods Twenty patients with chronic spinal cord lesions and DESD refractory to anticholinergic treatment were enrolled in a prospective study. They were treated with 30 mL of 10 mumol/L resiniferatoxin for 30 min. Four types of response were recorded during instillation: type 1, a sustained high-pressure detrusor contraction followed by complete acontractility; type 2, a high-pressure contraction followed by progressively lower contractions; type 3, intermittent high-pressure detrusor contractions throughout the instillation; type 4, intermittent low-pressure detrusor contractions. The changes in clinical symptoms and urodynamics at baseline, during resiniferatoxin instillation and 1 month after treatment were compared. Results All patients had DESD and 10 had autonomic dysreflexia; 18 had urinary incontinence and 13 had difficult urination. Continence and/or difficult urination improved in 12 patients, including all five with type 1, four with type 2, two with type 3 and only one with a type 4 response. Four patients became dry during the day and eight had less urgency and fewer incontinence episodes, and a significantly increased voided volume. Of the 13 patients who complained of difficult urination, eight had an improvement either by spontaneous voiding (five) or the Crede manoeuvre to voiding (three). The mean (SD) maximum cystometric capacity increased significantly after treatment, from 102.1 (31.5) to 236.6 (88.6) mL (P<0.001), but the detrusor pressure showed no significant change, at 55.9 (23.2) to 47.5 (28.1) cmH(2)O. The external urethral sphincter showed intermittent activity during reflexic detrusor contractions at baseline. Conclusion Resiniferatoxin at 10 μmol/L has a clinical effect on two-thirds of patients with a spinal cord lesion and detrusor hyper-reflexia, but not on the DESD. The initial response to resiniferatoxin instillation might predict a favourable therapeutic outcome.