Jaleh Winter

Intrathecal baclofen as adjuvant therapy to enhance the effect of spinal cord stimulation in neuropathic pain: a pilot study.

Only about 60–70% of well selected patients with neuropathic pain syndromes of peripheral origin enjoy sufficient pain relief with spinal cord stimulation (SCS). Since recent animal experiments have demonstrated that the GABA‐B receptor is pivotal in the effect of SCS on certain neuropathic symptoms, the use of baclofen as an adjunct to stimulation emerged as an option in patients not responding satisfactorily to SCS. Forty‐eight patients with neuropathic pain of peripheral origin responding poorly to SCS were enrolled in a study with intrathecal baclofen; in a few cases adenosine was also tried. Twenty patients reported significant pain reduction at bolus trials and were offered implantation of a drug pump. Seven patients subsequently had pumps implanted together with SCS and four had pumps alone. Three patients had only peroral baclofen therapy as an adjunct to SCS. The 14 patients continuing with baclofen therapy as an adjunct to SCS, or alone, were followed for an average of 35 months after pump implant. The group with SCS + pump (n=5; 2 explanted) reported an average decrease of pain ratings from VAS 82 to 33. The group with i.t. baclofen only had a pain decrease from VAS 63 to 33, while the three patients with peroral baclofen + SCS had less benefit from drug therapy. Adjunctive drug therapy for patients with unsatisfactory pain relief by SCS may offer a possibility to enhance pain alleviation.

Baclofen-enhanced spinal cord stimulation and intrathecal baclofen alone for neuropathic pain: Long-term outcome of a pilot study.

In a previously published pilot study, we addressed the possibility to increase the effectiveness of spinal cord stimulation (SCS) applied for neuropathic pain by using adjunct pharmacological therapy. This combined treatment approach was a direct spin‐off from animal experiments aiming at the exploration of transmitter and receptor mechanisms involved in the pain relieving effect of SCS. Out of 48 patients with neuropathic pain of peripheral origin responding poorly to SCS, seven received pumps for intrathecal baclofen (GABA‐B receptor agonist) delivery together with SCS, and four had pumps alone. In order to assess the long‐term effect a follow‐up has been performed, with an average, total treatment time of 67 months. At the follow‐up the remaining nine patients still enjoy about the same pain relief as initially, but with a mean, further dose increase of about 30%. This study demonstrates that a deficient SCS effect in neuropathic pain may be considerably improved by intrathecal baclofen administration, and that this enhanced effect persists for a long‐time. On‐going and future animal studies may provide new and even more efficient pharmaceutical candidates for such combined therapy.

Implantation of laminotomy electrodes for spinal cord stimulation in spinal anesthesia with intraoperative dorsal column activation.

OBJECTIVETo optimize the technique of implanting laminotomy plate electrodes for spinal cord stimulation and to minimize the discomfort of the patients during surgery. This operation is often performed while the patient is under local anesthesia, which is very stressful for the patient, or under general anesthesia, which precludes the use of test stimulation. An alternative approach is to perform the implantation with a spinal anesthetic and to examine whether stimulation-induced paresthesiae can still be evoked to guide the positioning of the electrode. METHODSSpinal anesthesia was induced by bupivacaine (12.5–20 mg), which produced complete motor block and anesthesia up to a midthoracic level. After a single-level laminotomy (thoracic vertebrae 9–11) a four-pole plate electrode was inserted into the epidural space. Stimulation was applied with commonly used parameters, and the electrode was positioned so that the paresthesiae covered the painful region. RESULTSIn 19 patients (20 procedures) with different forms of neuropathic pain, implantation of laminotomy plate electrodes could be performed under spinal anesthesia without problems. In all patients, it was possible to evoke paresthesiae, the distribution of which could be reproduced postoperatively. The paresthesia thresholds during surgery were only moderately higher than those recorded after implantation (mean, 3.1 versus 2.1 V, respectively). During an interview after the intervention, no patient reported that he or she had experienced surgery as painful or uncomfortable. CONCLUSIONImplantation of laminotomy electrodes can be performed conveniently with spinal anesthesia because it minimizes discomfort for the patient and enables the use of intraoperative test stimulation to guide the positioning of the electrode. In spite of the total motor block and anesthesia, paresthesiae representing the activation of the dorsal columns can be evoked and are well perceived, and the thresholds are not abnormally high. This observation supports the notion that the subarachnoidal anesthetic agent acts predominantly on the spinal rootlets rather than on the spinal afferent pathways.

Intrathecal clonidine and baclofen enhance the pain-relieving effect of spinal cord stimulation: a comparative placebo-controlled, randomized trial.

OBJECTIVESpinal cord stimulation (SCS) is a well-established treatment for neuropathic pain; nevertheless, 40% of patients fail to obtain satisfactory pain relief and in many patients, the effect tends to diminish with time. Based on animal experiments, intrathecal baclofen was previously introduced clinically to enhance suboptimal SCS effects. Later animal experiments demonstrated similar data for clonidine. The aim of this study was to elucidate whether intrathecal clonidine or baclofen enhances the effect of SCS in neuropathic pain patients in whom the pain relieving-effect of SCS is inadequate. METHODSA randomized, double-blind, placebo-controlled clinical trial was conducted with 10 patients experiencing neuropathic pain with insufficient pain relief with SCS alone. Clonidine, baclofen, and saline (control) were intrathecally administered by bolus injections in combination with SCS. RESULTSSeven of 10 patients reported significant pain reduction when SCS was combined with active drugs. The mean visual analog scale ratings were reduced by more than 50% with either drug combined with SCS. Four patients previously treated with SCS alone later underwent implantation of a pump for long-term administration of clonidine or baclofen. In the 2 patients with clonidine pumps with a mean follow-up of 15 months, the combined therapy produced pain reduction of 55% and 45%, respectively. The corresponding effect with baclofen was 32% and 82%, respectively, at 7 months follow-up. CONCLUSIONA trial with clonidine and baclofen combined with SCS may be warranted in patients who do not obtain satisfactory pain relief with SCS alone or experienced a decreasing therapeutic effect.

Factors That Influence Outcome of Percutaneous Balloon Compression in the Treatment of Trigeminal Neuralgia

BACKGROUND:Percutaneous balloon compression is an effective, low-cost, simple therapeutic modality with the special advantage of being the only percutaneous technique that can be simply performed with the patient under general anesthesia for the treatment of trigeminal neuralgia. OBJECTIVE:To identify surgical and individual parameters that could influence outcome in patients with trigeminal neuralgia treated with percutaneous balloon compression. METHODS:Within a 5-year period, 66 consecutive percutaneous balloon compressions were performed in 47 patients. The medical and surgical records of all patients were retrospectively reviewed and analyzed for a possible correlation between the following parameters and outcome: balloon shape, balloon volume, compression time, age, sex, type of pain, duration of disease, previous procedures, and trigeminal division affected. Univariate and multivariate analyses were used to test for statistical significance. RESULTS:The initial success rate was 85%, and 36% of the responders are still pain free with a mean follow-up of approximately 20 months, whereas in 33 patients, trigeminal pain recurred after a mean of approximately 17 months. Of the investigated parameters, significant correlations were obtained between balloon shape and all aspects of outcome, previous operations and complication rate, pain type and complication rate, and compression time and postoperative numbness. CONCLUSION:The balloon shape is a parameter with a very strong impact on outcome, and balloon volume should be adjusted to this parameter. Persistent elliptical balloon shapes should raise consideration of aborting the procedure. There were no differences in outcomes between 60 seconds and longer compression times. The number of previous operations did not correlate with pain relief, but seemed to increase the risk of complications. Patients with multiple sclerosis seemed to obtain similar benefit from the procedure as do patients with classic trigeminal neuralgia.

Subthalamic Stimulation for Essential Tremor

Background/Aims/Methods: In order to explore the usefulness and long-term result of subthalamic nucleus (STN) stimulation for the treatment of essential tremor (ET), we evaluated 3 groups of patients undergoing deep brain stimulation (DBS) for ET. Results: Group 1 consisted of 3 patients who 9 years ago at intra-operative testing had good tremor reduction from STN stimulation. The second group consisted of 10 patients treated with DBS in the ventral intermediate (Vim) nucleus of the thalamus. The third group comprised 9 patients subjected to STN stimulation for ET with 1–3 years of follow-up. The 3 ET patients with STN stimulation in group 1 have continued to have excellent tremor reduction for up to 9 years. The second group, with Vim stimulation, showed less favourable long-term results. All of the recent STN stimulation group experienced good tremor reduction, but some of the patients above 70 years of age reported troublesome side effects. Conclusion: Provided that intra-operative test stimulation produces satisfactory tremor control, STN is a good target for long-term treatment of ET. For patients above the age of 70 years, however, the Vim is a preferable target.

Drug-enhanced spinal stimulation for pain: a new strategy

Neuropathic pain is notoriously difficult to manage and only a few classes of drugs may provide adequate benefits. Thus, in many cases spinal cord stimulation (SCS) is considered; however, in this group of patients, between 30-50% of the cases offered a percutaneous SCS trial may fail to obtain a satisfactory effect. Additionally, a certain number of patients with a good initial effect, report that after a period the benefits are reduced necessitating additional peroral drug therapy. Based on animal studies of transmitters and receptors involved in the effects of SCS in neuropathic pain, the GABA-B receptor seems to play a pivotal role for the effect and, moreover, the agonist baclofen injected intrathecally in rats potentiated the SCS effect in animals not responsive to SCS per se. Based on these and further studies, 48 patients with neuropathic pain and inadequate response to SCS were given intrathecal (i.t.) baclofen (ITB) in bolus doses as an adjuvant. In this group 7 patients enjoyed such a good effect that they were implanted with both SCS and drug delivery systems for ITB. Four additional cases received baclofen pumps alone. Some other patients were given intrathecal (i.t.) adenosine in combination with SCS and initially preferred this to baclofen. The chronic use of this drug in a pump however proved to be technically problematic and all the adenosine cases were eventually terminated. At follow-ups, in average 32 and 67 months after start of SCS + baclofen therapy, more than 50% still enjoy a very good effect. The daily dose of baclofen needed to maintain the effects was approximately doubled during the observation period. There were few and mild side-effects. However, in a group of three patients with peroral baclofen therapy and SCS, complaints of side-effects were common and this therapy was terminated. Informal reports from collegues support the negative experience with additional peroral baclofen. In conclusion, in patients with neuropathic pain demonstrating inadequate response to SCS (small VAS reduction; short duration) a trial of intrathecal baclofen in combination with SCS may be warranted.

Therapeutic value of spinal cord stimulation in irritable bowel syndrome: a randomized crossover pilot study.

Irritable bowel syndrome (IBS) is characterized by abdominal pain and changed bowel habits. Spinal cord stimulation (SCS) has been used for treatment of chronic pain syndromes. Animal studies have shown SCS to reduce the reaction to colonic balloon distension, known to be increased in IBS patients. To elucidate the potential for SCS as treatment for IBS, a pilot study was performed. Ten IBS patients (age 26-56 yr) were recruited. A SCS system with a four-polar electrode was implanted at the T5-T8 level. After a 2-wk run-in, a randomized, crossover design SCS during 6 wk was compared with no stimulation, with an ensuing stimulation period for 12 wk; total study period 28 wk. Patients recorded pain level, pain attacks, diarrheas, and global quality of life in a diary. At end of the study patients could choose to retain their SCS system or have it removed. Nine patients completed the whole trial. During stimulation periods the median pain scores were significantly reduced from visual analogue scale (VAS) 7 (4-8) to 3 (2.5-7) and to 4 (2-6) during early and late stimulation periods, respectively (P < 0.03-0.04). Pain attacks were numerically reduced. A few patients reported reduced number of diarrheas. After study termination, six patients chose to retain their SCS system. To conclude, SCS is a minimally invasive treatment option for pain in IBS. With SCS the pain level was reduced though with merely a trend for number of attacks and diarrheas. The efficacy of SCS in IBS pain indicates a possible usefulness in other painful bowel disorders.

596 PERCUTANEOUS BALLOON COMPRESSION FOR THE TREATMENT OF REFRACTORY TRIGEMINAL NEURALGIA

dose of 2.1 joule was used. The control group was exposed with an indifferent dose. The maximal range of painless mouth opening was measured pre and post laser exposure. Using a VAS, patients reported their pain felt at the end of that range. The maximal mouth opening (MMO) was measured at the end of each session. Results: In the experimental group, the maximal range of painless opening increased significantly (p = 0.019 and p=0.005) after the first and second session but not after the 3 and 4 session (p =0.160 and p=0.228) (paired t-test ANOVA). Less pain was reported on a VAS in the first and second session (p =0.041 and p=0.023), but not in the 3 and 4 session (p =0.408 and p=0.414) (Wilcoxon). However, the MMO did not increase significantly (Friedman’s test). Conclusion: Low power laser exposure could increase the range of painless mouth opening in patients with arthrogenous TMJ disorder but not the MMO.