Periprostatic nerve block gives better analgesia for prostatic biopsy

Authors


Abstract

Objective  To prospectively compare two local anaesthetic techniques for prostatic biopsies, which are usually taken with no anaesthesia; because multiple biopsy techniques are becoming more common and there is an increasing need for analgesia/anaesthesia during the procedure.

Patients and methods  The study group comprised 86 consecutive men (median age 67.7 years) undergoing prostatic biopsy because of either an abnormality of prostate specific antigen level or digital rectal examination. They were randomized into four groups; men in group 1 received 10 mL of 1% lignocaine infiltrated into the periprostatic nerve plexus bilaterally; men in group 2 received 11 mL of 2% lignocaine gel rectally; men in groups 3 and 4 were recruited as controls, and given either plain gel rectally or an injection with saline into the periprostatic nerve plexus. Sextant prostate biopsies were taken in all cases using a standardized protocol. Immediately after the procedure patients were asked to indicate the degree of pain on a 10-cm visual analogue scale.

Results  Men in group 1 had significantly less pain than the others ( P  < 0.001). There was no statistically significant difference in pain between men who received plain gel rectally or saline injection ( P   =  0.35). The rectal instillation of 2% lignocaine gel did not reduce pain significantly ( P   =  0.186) compared with the controls.

Conclusion  A periprostatic nerve block with 1% lignocaine was associated with significantly less pain during prostatic biopsy than was rectal lignocaine gel or placebo.

Introduction

TRUS and biopsy of the prostate are the standard investigations for detecting prostate cancer, undertaken with no analgesia and as an outpatient procedure in the UK. The degree of pain and discomfort felt by these patients is variable. Investigators who used a 10-cm visual analogue scale (VAS) reported that the mean pain score during sextant biopsy was 3 for these patients; 19% would refuse to undergo a similar procedure again with no analgesia [1]. Various investigators have reported different methods of anaesthesia during prostatic biopsy. We report a prospective randomized placebo-controlled study comparing rectal lignocaine gel application and periprostatic nerve block.

Patients and methods

The study comprised a series of 86 consecutive men (median age 67.7 years, range 48–88) with an abnormal PSA level (> 4 ng/mL) and/or an abnormal DRE, who underwent TRUS and prostatic biopsy for the first time. Approval was obtained from the hospital ethics committee. After obtaining informed consent from each man, they were randomized into four groups using envelopes (block randomization). Men in group 1 (30) received a periprostatic nerve block with 1% lignocaine; 10 mL of 1% lignocaine was injected into the periprostatic nerve plexus with an 18 cm spinal needle (Becton Dickinson Co., New Jersey, USA) under TRUS guidance [2]. The accuracy of the block was determined by detecting a collection of local anaesthetic fluid on TRUS. The block was applied 5 min before prostatic biopsy. Men in group 2 (27) had 2% lignocaine gel instilled rectally 30 min before biopsy. Groups 3 and 4 were recruited as controls and received either plain gel rectally (14) or an injection with normal saline into the periprostatic nerve plexus (15), respectively. Only the patients were unaware of the nature of the anaesthetic, although they were aware of whether they received an injection or an instillation of gel. The patients were given 500 mg of ciprofloxacin 30 min before the procedure and were asked to take two further doses of 500 mg 12-hourly afterward. TRUS was undertaken using a 7.5 MHz transducer (Leopard 2001, Bruel & Kjaer, Denmark) with the patient in the left lateral position. After initial scanning to detect abnormalities, the prostatic volume was measured, after which sextant biopsies were taken in all men using an 18 G Tru-cut needle (Bard UK, Milton Keynes) using a standardized protocol. Immediately after biopsy each patient was asked to express the degree of pain on a 10-cm VAS. The Kruskal–Wallis test was used to determine differences among the groups and the Wilcoxon signed-ranks test to compare two groups.

Results

The overall median (range) score on the VAS was 1.9 (0–9.7); the pain scores for each group are shown in Table 1. Men in group 1 had significantly less pain than the others (P < 0.001). There was no statistically significant difference in pain between men who received plain gel rectally or a saline injection (P = 0.35). Rectal instillation of 2% lignocaine gel reduced the pain but the difference was not statistically significant (P = 0.186) from that of the controls.

Table 1.  Descriptive statistics showing median (95% CI) values for individual groups
VariableGroup
1234
No30271415
Age,67.568.068.568.0
years(63.9–69.4)(65.3–71.5)(62.2–73.9)(63.4–71.8)
PSA,15.722.320.814.2
ng/mL  (3.1–18.0)  (2.5–25.0)  (4.5–25.0)  (3.8–18.0)
VAS pain   0.5  2.7   4.8   4.3
score  (0.4–1.1)  (2.4–4.4)  (3.5–6.1)  (2.7–4.8)

Discussion

In the UK, prostatic biopsies are usually taken with no analgesia, but a study in the UK reported that 24% of the patients had moderate to severe pain during the procedure [3]. Of patients studied by Irani et al.[1], 16% had VAS pain scores of > 5 (from a maximum of 10) and 19% would refuse to undergo a repeat prostatic biopsy with no analgesia. Therefore, a substantial portion of patients have pain during prostate biopsy and some form of analgesia would be helpful to them.

The sensory innervation of the prostate is not well-studied; McVary et al.[4] showed in rat prostate that not only is there sensory innervation of the prostate but also that afferent feedback or its absence might be a pathway regulating the autonomic control of growth. In their study, dorsal root neurectomy of L5–S1 removed the sensory supply from the prostate. From the retrograde transport of Fast Blue from the prostatic injection site, Danuser et al.[5] reported that more areas of mid-lumbar neurones might carry nociception from the prostate. Issa et al.[6] recommended that the prostatic block should be directed to the prostatic nerves originating from the inferior hypogastric nerve plexus; they identified these nerves within the envelope of endopelvic fascia lateral to the prostate.

Wallner et al.[7] reported that it is possible to apply prostate brachytherapy by infiltrating the apex of the prostate and the pelvic floor with lignocaine. Interstitial laser thermal therapy of the prostate could also be conducted under local prostatic block alone using 1% lignocaine with noradrenaline [8]. Using a 10-cm VAS they reported a mean pain score of 2.2 (median 2.0) during the procedure. Similarly, other studies show that a periprostatic nerve block reduced pain during prostatic biopsy [9–12], although Fredman et al.[13] reported that a periprostatic nerve block did not reduce analgesic use after transvesical prostatectomy. Pain after transvesical prostatectomy is probably multifactorial, with most of the pain arising from the abdominal wall and bladder rather than the prostate.

Soloway and Obek [2] described a modified version of the periprostatic nerve block, involving instilling local anaesthetic agent into the periprostatic nerve under TRUS guidance. In addition to bilateral injections at the junction of the base of the prostate and seminal vesicles, as described by Nash et al.[11], they recommended two more injections on each side (one beside the apex and one in between the apex and the base). Before the present trial we tried both these techniques and found that patients had pain when an apical biopsy was taken with local anaesthetic infiltration only at the base. However, Schostak et al.[14] reported a randomized controlled trial comparing these techniques, finding that infiltration at the apex gave the lowest pain score.

Other local anaesthetic techniques include the rectal instillation of lignocaine gel [15] and intraprostatic injection of lignocaine [16]. The present study was mainly intended to compare the efficacy of periprostatic nerve block and rectal lignocaine gel instillation in prostate biopsy. The anaesthetic was injected 5 min before biopsy, which can be time-consuming in a busy TRUS clinic, thus we routinely apply the nerve block before imaging the prostate and measuring prostate volume, which saves time while waiting for the anaesthetic to work. As a single-blinded study there was the potential for investigator bias, and to reduce this we only used a pain score expressed by the patients.

The periprostatic nerve block gave better analgesia than rectal lignocaine instillation or placebo. Although rectal lignocaine reduced the pain score (Table 1) the difference was not significantly different from that with placebo. However, it is likely that with a larger study population there could be a statistically significant reduction in pain with rectal lignocaine gel instillation.

N.N.K Lynn, 91 Pype Hayes Road, Birmingham, B24 0LU, UK
e-mail: nlynn@btinternet.com

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