Background: Persistent postsurgical pain (PPSP) affects between 10% and 50% of surgical patients, the development of which is a complex and poorly understood process. To date, most studies on PPSP have focused on specific surgical procedures where individuals do not suffer from chronic pain before the surgical intervention. Individuals who have a chronic nerve injury are likely to have established peripheral and central sensitization which may increase the risk of developing PPSP. Concurrent analyses of the possible factors contributing to the development of PPSP following lumbar discectomy have not been examined. Objective: The aim of this study is to identify risk and protective factors that predict the course of recovery following lumbar discectomy and to develop an easily applicable preoperative multivariate prognostic model for the occurrence of PPSP in this patient cohort. Study Design: A prospective study of elective lumbar discectomy with a 3 month follow-up. Setting: University setting in Ireland Methods: All ASA I-II patients, (n = 53, 18-65 years old), undergoing elective lumbar discectomy at a single institute were included and followed for a 3 month period postsurgery. Preoperative potential predictors were collected: age, gender, pain intensity (McGill score, visual analog scale [VAS], Present Pain Intensity), degree of dysfunction (Roland-Morris Function score), psychological status (pain catastrophizing, anxiety, and depression scores), health-related quality of life (SF36), quantitative sensory testing (QST), inflammatory biomarkers, and a genetic pain profile. The proposed primary outcome was significant pain reduction (VAS > 70%) 3 months following surgery compared to the preoperative pain intensity. Results: A final prediction model was obtained using a multivariate logistic regression in combination with bootstrapping techniques for internal validation. Twenty (37.7%) patients developed PPSP. Independent predictor factors included age (odds ratio [OR] = 1.0 per year), present pain intensity (OR = 0.6), and degree of dysfunction (OR = 1.2). The concordance index C (.658) supports a good monotonic association (where perfect prediction is 1) and the Akaike’s information criteria indicated a good fit of the model. Inclusion of additional measured parameters (QST, biomarker, or genotyping) did not improve the model. Limitations: Before this internally validated model can be integrated into clinical practice, and used for patient counselling and quality assurance purposes, external validation studies are necessary. Conclusions: We demonstrated that the occurrence of PPSP can be predicted using a small set of variables easily obtained at the preoperative visit. This a prediction rule that could further optimize perioperative pain treatment and reduce attendant complications by allowing the preoperative classification of surgical patients according to their risk of developing PPSP. Key words: Persistent post surgical pain, predictive modeling, prognostic, lumbar discectomy

The use of neuromodulation for pain relief is among the fastest-growing areas of medicine, involving many diverse specialties and impacting on hundreds of thousands of patients with numerous disorders worldwide. As the evidence of efficacy improves, the interest in spinal cord stimulation (SCS) will increase because it is minimally invasive, safe, and a reversible treatment modality with limited side effect profile. While the mechanism of action evades complete understanding, the technological improvements have been considerable and current neuromodulation developments have been coupled with the rapid growth of the neuromodulation device industry resulting in the development of the next-generation neuromodulation systems. The development, the newest technicaliti and the future for the clinical application of spinal cord stimulation (SCS) are reviewed here.

BackgroundPregabalin has been shown to have analgesic effect in acute pain models. The primary objective was to examine the efficacy a single dose of pregabalin, would have on morphine consumption following lumbar discectomy.MethodsWith ethical approval a randomized, placebo-controlled prospective trial was undertaken in 32 patients (ASA I-II, 18-65 years) with radicular low back pain for > 3 months undergoing elective lumbar discectomy. Patients received either oral pregabalin 300 mg (PG Group) or placebo (C Group) one hour before surgery. Pain intensity, the accumulative morphine consumption and adverse effects were recorded for 24 hours following surgery. Functional, psychological and quantitative sensory testing were also assessed.ResultsFourteen patients out of the 32 recruited were randomized to receive pregabalin. Morphine consumption was reduced (absolute difference of 42.3%) between groups with medium effect size. (Mann-Whitney; U = 52.5, z-score= 2.84, P = 0.004, r = 0.14). This was not associated with a significant difference in the incidence of adverse effects between the two groups. The median pain intensity (VAS) on movement was not significantly different between groups.ConclusionsA single pre-operative dose of pregabalin (300 mg) did not result in a reduction in pain intensity compared to placebo in this patient cohort but the significant reduction in morphine consumption suggests that a fixed peri-operative dosing regime warrants investigation.

Interstitial cystitis is a chronic inflammatory bladder syndrome with limited treatment options. Pudendal nerve stimulation is in vogue as treatment, yet its use has inherent drawbacks including availability and cost.Although pudendal nerve blocks are common practice [1], there has been no report of the specific use of ultrasound to treat interstitial cystitis. We describe bilateral ultrasound-guided pudendal nerve blocks in two patients with interstitial cystitis with excellent analgesic outcome.A 66-year-old man with a 7-year history of severe bladder pain and frequency/nocturia was diagnosed with interstitial cystitis. He had undergone transurethral resection of prostate and multiple therapeutic cystoscopies to alleviate his symptoms with no success. Despite long-term amitriptyline and analgesia, his pain continued to interfere with daily activities, and he was referred for further pain management.After skin preparation, a 2-5 MHz curved array ultrasound probe within a transparent sheath was used to visualize landmarks with the patient prone. The sacroiliac joint was identified, then the probe was moved inferolaterally where the sacrospinous ligament attaches to the ischial spine, as the pudendal nerve exits the greater sciatic foramen. Real-time imaging with color Doppler confirmation was used to direct a 22 G spinal needle in proximity to the pudendal nerve. Bilateral injections were performed sequentially by an experienced operator; using 4 ml 0.25% levobupivicaine and 40 mg methylprednisolone.His pain improved immediately after the intervention. At the 3-month follow-up, there was excellent sustained pain relief, mild improvement in his urinary symptoms, and no sensory loss in the pudendal nerve distribution.A 70-year-old woman diagnosed with refractory interstitial cystitis presented to our pain service. Her symptoms included pelvic and perineal pain and nocturia for 6 years. Her management included gabapentin, multiple cystoscopies, intravesical botulinum toxin injections, and intravesical instillation of dimethylsulfoxide, all with no relief.Bilateral pudendal nerve injections were performed in the same manner by the same operator. Injection dose was similar.There was relief of pain and urinary symptoms at her 3-month follow-up. Sustained pain and symptom relief was reported 9 months following the procedure, with no reported sensory loss. This is the first report of clinical outcomes following the use of ultrasound-guided pudendal nerve block for interstitial cystitis. It confirms that the pudendal nerve plays a role in interstitial cystitis [2], and that it can be thought of as a peripheral neuropathy based on neurogenic inflammation and sensitization [3]. In fact, interstitial cystitis as a manifestation of pudendal neuropathy is a current popular