Possible mechanisms of action of transurethral needle ablation of the prostate on benign prostatic hyperplasia symptoms: a neurohistochemical study.J Urol. 1997 Mar; 157(3):894-9.JU
Transurethral needle ablation of benign prostatic hypertrophy (BPH) is a rapid, anesthesia-free outpatient procedure using low level radiofrequency energy that produces coagulative necrosis lesions at temperatures of approximately 100C. Clinically, significant improvement in objective and subjective parameters has been observed in BPH patients. Transurethral needle ablation has also been shown to be effective in relieving urinary retention. However, the precise mechanism of action of this procedure remains to be clarified. Ablation could produce its action on the dynamic component of the infravesical outlet obstruction. We analyzed the possible effects of transurethral needle ablation on the intraprostatic innervation.
MATERIALS AND METHODS
Histological sections from 10 open prostatectomy specimens (BPH) recovered 1 to 46 days after transurethral needle ablation were stained with hematoxylin and eosin and an immunohistochemical technique, using antibodies against S100 proteins and nonspecific enolase as specific nerve markers, and against anti-prostate specific antigen and anti-desmin for glandular and muscle cells, respectively. We used 5 BPH specimens as controls.
Microscopic examination of the treated areas showed necrotic lesions affecting epithelial and smooth muscle cells in the transition zone at a depth of 0.3 to 1.0 cm, from the preserved urethra. Nerve fibers in the control specimens and untreated prostatic areas were predominant in the urethral submucosal layer and in the stroma surrounding the epithelial nodules. No staining of any axon or isolated nerve cell was observed in any specimen treated by transurethral needle ablation, and there was a sharp and clear delineation between treated and untreated areas.
Our study demonstrated severe thermal damage to intraprostatic nerve fibers caused by transurethral needle ablation. A long-term denervation of alpha-receptors and/or sensory nerves could explain the clinical effects of transurethral needle ablation of the prostate. Theoretically, the best location to produce necrotic lesions should include submucosal and subcapsular nerve endings. Differences in the distribution of the adrenoreceptors and morphometry of the prostate transition zone could partly explain differences in clinical outcome observed after transurethral needle ablation of the prostate.