Botulinum toxin A modulates afferent fibers in neurogenic detrusor overactivity.
BACKGROUND
Although botulinum toxin (BoNT/A) injected into the detrusor muscle improves overactive bladder symptoms in patients with neurogenic detrusor overactivity, how it does so remains unclear. In this study, we investigated whether BoNT/A improves detrusor overactivity by modulating bladder afferent activity.


METHODS
To do so, during urodynamic assessment, we tested the soleus muscle Hoffmann (H) reflex during bladder filling before and after intradetrusor BoNT/A in patients with Parkinson's disease (PD) and in patients with complete chronic spinal cord lesion (SCI) and detrusor overactivity refractory to conventional therapy. Healthy subjects underwent H reflex studies during urodynamic assessment and acted as controls.


RESULTS
Our findings show that BoNT/A injected into the detrusor muscle effectively reduces clinical overactive bladder symptoms in patients with PD and SCI. In healthy subjects and patients with PD, bladder filling [at maximum cystometric capacity, (MCC)] significantly decreased the H reflex size, whereas in patients with SCI, it slightly facilitated the H reflex size. At MCC, in patients with PD, BoNT/A significantly reduced the expected H reflex inhibition, whereas in those with SCI, BoNT/A turned the H reflex facilitation at maximum bladder filling into a slight inhibition.


CONCLUSIONS
These findings show that BoNT/A injected into the detrusor muscle in patients with PD and SCI modulates bladder afferent activity. Modulation of bladder afferents possibly explains why BoNT/A improves detrusor overactivity.
Department of Neurology and Psychiatry, University of Rome, Rome, Italy.
A
A
Conte
A
A
Giannantoni
S
S
Proietti
S
S
Giovannozzi
G
G
Fabbrini
A
A
Rossi
M
M
Porena
A
A
Berardelli
D000328:Adult; D000344:Afferent Pathways / Q000187:drug effects*; D000368:Aged; D000704:Analysis of Variance; D019274:Botulinum Toxins, Type A / Q000627:therapeutic use*; D004576:Electromyography; D005260:Female; D005500:Follow-Up Studies; D006181:H-Reflex / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D010147:Pain Measurement; D010300:Parkinson Disease / Q000150:complications / Q000188:drug therapy; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy; D013223:Statistics as Topic; D018608:Ultrasonography, Doppler / Q000379:methods; D053201:Urinary Bladder, Overactive / Q000188:drug therapy* / Q000209:etiology / Q000473:pathology*; D014563:Urodynamics / Q000187:drug effects
D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A