Predictors Of Pain Relief Research Articles

Symptoms predicting pain relief with gabapentin in patients with neuropathic pain

Symptoms predicting pain relief with gabapentin in patients with neuropathic pain

Trigeminal Neuralgia: Outcomes after Gamma Knife Radiosurgery

Trigeminal neuralgia (TN) often remains difficult to treat despite multiple available medications, and can severely impact on the quality of life of affected patients. Gamma knife radiosurgery has recently emerged as a minimally-invasive alternative to surgery for patients suffering from drug-resistant TN. The goal of this study was to report the short-term efficacy of gamma knife radiosurgery for TN and assess its impact on the quality of life of patients treated in the first 18 months of our experience. Patients with medically-refractory TN or with unacceptable drug side effects were considered for radiosurgery. A maximum dose of 80 Gy was administered to the affected nerve using a single 4-mm isocenter. Follow-up assessments were made at 2,4 and 6 months, with evaluation of pain relief, drug reduction and quality of life. Factors impacting treatment response were assessed using Cox regression analysis. A total of 67 patients were treated. Significant pain relief was seen in 77.6% of patients, including 32.6% who became pain-free. Patients were able to discontinue all medications in 34.3% or reduce drug intake by more than 50% in an additional 28.4% of cases. No variable was found to predict pain relief although older age (>66 years) approached statistical significance. Sensory side effects were seen in 14.9% of patients. Quality of life improved in the majority of patients after radiosurgery. Gamma knife radiosurgery is a safe and effective management alternative for trigeminal neuralgia, providing good or excellent pain relief and improvement in quality of life in the majority of patients with few side effects.

Gallbladder dyskinesia

The most appropriate means to diagnose and manage patients with suspected gallbladder dyskinesia remain contentious. A major problem relates to difficulties in clearly identifying the features that characterize biliary-like pain. Conflicting reports in the literature regarding whether symptoms alone are reliable predictors of pain relief after cholecystectomy in patients with suspected gallbladder dysfunction underscore the perceived need by clinicians for a reliable test to help confirm a clinical suspicion of gallbladder dysfunction before cholecystectomy. Most studies report use of cholecystokinin-cholescintigraphy (CCK-CS) with calculation of gallbladder ejection fraction in predicting symptom outcome after cholecystectomy in patients with suspected gallbladder dyskinesia. However, quality evidence is lacking, thereby precluding a definitive recommendation regarding its use. Nevertheless, CCK-CS may be useful when performed using a slow infusion of CCK in a well-selected patient population. Based on our clinical experience and interpretation of the literature, we currently suggest consideration of cholecystectomy to our patients based on high clinical suspicion. This is performed after adequate follow-up with trials of pharmacologic therapies and exclusion of other disease entities and counseling the patient on postoperative expectations. Clearly, a large, prospective, controlled study is needed with patients meeting the Rome definition of gallbladder dyskinesia, randomized to surgery or no surgery, and using standardized CCK-CS methods and outcome measures with long-term follow-up. This study would help us better understand the pathophysiology and optimal management of this clinically challenging condition.

The role of bone scintigraphy in treatment planning, and predicting pain relief after kyphoplasty

The role of whole-body Tc-MDP bone scanning in the management of vertebral compression fractures with kyphoplasty has not been clearly established. To determine the accuracy of bone scanning in patient selection, planning treatment and predicting response to kyphoplasty. Retrospective chart reviews were undertaken of all kyphoplasties performed by the same orthopaedic surgeon between June 2000 and June 2004. All patients who underwent plain radiographs (X-ray) of the spine and bone scanning within 4 weeks of treatment were included. Response to treatment was assessed via a questionnaire administered to the patient 3 weeks after intervention and concomitant objective assessment. Response was graded as excellent, intermediate or poor. Each bone scan was reviewed by two nuclear physicians blinded to the initial scan results, level of treatment and therapeutic response. The readers were asked to indicate the level(s) to be treated according to the bone scan findings. Sites of chronic fractures were also recorded. Sixty-six procedures on 60 patients fulfilled the selection criteria. Fifty-three patients were managed by X-ray and bone scanning (A) and seven were managed by X-ray only (B). There was a significant difference in the rates of sub-optimal results between (A) and (B) (11/53 vs. 7/7, P=0.0001). There was also a significant difference in chronic fracture rates between patients with excellent outcome and those with sub-optimal results (3/42 vs. 7/11, P=0.0002). A high rate of incorrect level selection (3/7) was found in (B). In 12 patients (20%) X-ray showed multiple fractures but the bone scanning demonstrated only one level of acute disease. Bone scanning is an excellent predictor of response to kyphoplasty and decreases the number of vertebrae to be treated as suggested by X-ray. Preoperative bone scanning is recommended to avoid incorrect selection of treatment level. Even when the appropriate level has been selected an incomplete response can be expected if additional chronic fracture is seen on bone scanning. In the event of unexpected incomplete response, re-evaluation with bone scanning may demonstrate new disease amenable to therapy.

Predictors of Spinal Cord Injury Neuropathic Pain: The Role of QST

Neuropathic pain in spinal cord injury (SCI) presents itself as different constellations of spontaneous and evoked types of pain. Quantitative sensory testing (QST) is used to assess and quantify the sensory system by measuring altered perception or pain thresholds or stimulus—response relationships to standardized sensory stimuli. QST is used to address a variety of issues relevant to SCI neuropathic pain: pathophysiological mechanisms and predictors of SCI pain, modality-specific treatment effects and predictors of pain relief, and SCI pain phenotypes as part of a mechanism-based classification.

Safety and Efficacy of Implant Removal for Patients With Recurrent Back Pain After a Failed Degenerative Lumbar Spine Surgery

The etiology of failed degenerative lumbar spine surgery may include a wide array of conditions. There is a group of patients who have recurrence of back pain despite a solid fusion in the absence of any obvious pain generator. Implant removal in those patients is a controversial optional treatment. The purpose of this study was to evaluate the efficacy and safety of implant removal and to determine the possible predictors of its efficacy. Twenty-five patients (10 M, 15 F) with an average age of 44 (18 to 74) were retrospectively evaluated. All patients had prior titanium posterior pedicle screw instrumentation and fusion for lumbar degenerative disorders. Twenty patients with increase in pain during palpation of the operative side underwent a preoperative anesthetic injection at the site of their trigger points. Patients' clinical charts, operative notes, and preoperative x-rays were evaluated. Relief of pain was evaluated by the percent Visual Analog Scale (VAS) pain change due to implant removal. Functional improvement was rated on a five-point scale. Predictors of pain relief were analyzed by using bivariate analysis. A P value <0.05 was considered significant. Average follow-up period was 20 (12 to 37) months. The median time after the index operation and the recurrence of pain was 13.5 (1 to 119) months. VAS decrease after implant removal was 50% (P<0.001). Functional improvement was reported by 84% of patients. One patient developed a superficial infection managed successfully. Bivariate analysis showed that percent VAS change after injection, months free of pain after the index operation, and provocation of pain by palpation were significant predictors for pain relief (P<0.05). Removal of the implant may be an efficient and safe procedure for carefully selected patients and the most consistent predictor of its efficacy is the percent pain relief after the diagnostic injection of the painful operative side.

Pain of Intravenous Peripheral Sensation as an Objective Number and a Predictor of Pain Relief: POISON

Pain of Intravenous Peripheral Sensation as an Objective Number and a Predictor of Pain Relief: POISON

How high should total pain-relief score be to obviate the need for analgesic remedication in acute pain? Estimation using signal detection theory and individual-patient meta-analysis

A pain relief score 50% of the maximum is often used as a clinically meaningful outcome in meta-analyses of analgesic trials. This arbitrary value requires validation. To determine the optimum pain relief score for predicting pain relief sufficient to obviate the need for analgesic remedication in acute post-surgical pain. Individual-patient meta-analysis of randomized controlled trials and use of signal detection theory to identify the optimum cut-off point on the total pain relief score (TOTPAR). Analgesic remedication was used as the clinical outcome. Seven parallel-group, active and placebo-controlled trials of minor analgesics. The predictive value of the TOTPAR score [expressed as a percentage of the maximum score (%maxTOTPAR)] for remedication was excellent for all the trials. The pooled estimate of the area under the receiver operating curve, an index of discriminative power, was outstanding 0.96 (95% CI 0.95-0.97). The pooled estimate of the optimal %maxTOTPAR for predictive purposes was 44.11 (95% CI 44.00-44.23). The analysis suggests that the arbitrary 50% cut-off point TOTPAR score often used in meta-analyses of analgesic trials in dental pain is reasonably acceptable. This is different to the 33% cut-off point reported for analgesic trials of acute breakthrough cancer pain and some chronic pain states such as diabetic neuropathy and postherpetic neuralgia. These differences deserve careful consideration when reading reports of analgesic trials and meta-analyses. Remedication itself should be considered as the preferred outcome measure for analgesic trials.

Abstract 36 POISON: Pain of intravenous sensation as an objective number and a predictor of pain relief

Abstract 36 POISON: Pain of intravenous sensation as an objective number and a predictor of pain relief

Uncertainty Analysis in Pharmacokinetics and Pharmacodynamics: Application to Naratriptan

The aim of the study was to predict pain relief of migraine in patients following naratriptan oral (tablet) administration by using uncertainty analysis. The analysis was based on phase I pharmacokinetic naratriptan data, sumatriptan pharmacodynamic data, and naratriptan preclinical (animal) potency information, together with general knowledge as to how migraine affects oral absorption. A previously developed pharmacokinetic (PK)/pharmacodynamic (PD) model for naratriptan disposition and effect was used. The uncertain parameters in the model, which were associated with absorption and scaling between first-in-class compound sumatriptan and naratriptan, were modeled using fuzzy sets theory. Global sensitivity analysis was then used to investigate the impact of each PK/PD parameter on the responses. Acknowledging parametric uncertainty did not improve prediction of the probability of pain relief. Global sensitivity analysis demonstrated that predictions were heavily influenced by interindividual variability in pharmacodynamics, as the dose response relationship was relatively insensitive to the pharmacokinetics. To predict the probability of pain relief following oral (tablet) administration of naratriptan, a simple dose response, instead of the PK/PD model, would have yielded very similar predictions. The naratriptan PK/PD model may be improved by either refining the PD model or better still by specifying the interindividual error by additional data collecting with an improved design.

Opponent appetitive-aversive neural processes underlie predictive learning of pain relief

Termination of a painful or unpleasant event can be rewarding. However, whether the brain treats relief in a similar way as it treats natural reward is unclear, and the neural processes that underlie its representation as a motivational goal remain poorly understood. We used fMRI (functional magnetic resonance imaging) to investigate how humans learn to generate expectations of pain relief. Using a pavlovian conditioning procedure, we show that subjects experiencing prolonged experimentally induced pain can be conditioned to predict pain relief. This proceeds in a manner consistent with contemporary reward-learning theory (average reward/loss reinforcement learning), reflected by neural activity in the amygdala and midbrain. Furthermore, these reward-like learning signals are mirrored by opposite aversion-like signals in lateral orbitofrontal cortex and anterior cingulate cortex. This dual coding has parallels to 'opponent process' theories in psychology and promotes a formal account of prediction and expectation during pain.

Serum levels of tartrate-resistant acid phosphatase-5b in breast cancer patients treated with pamidronate.

A novel immunoassay specific for the osteoclast-produced TRAP isoform 5b has been developed recently. By means of this assay we studied the usefulness of serum TRAP-5b in monitoring the response to palliative treatment with pamidronate in breast cancer patients with bone metastases. We correlated serum TRAP-5b levels with pain intensity and intake of analgesics to assess the possible utility of the marker in identifying patients who could benefit from pamidronate treatment. Twenty-eight advanced breast cancer patients with bone metastases entered the study. Patients were treated according to the following schedule: two two-week cycles of 60 mg/week pamidronate IV, with a three-week interval in between (six infusions over seven weeks), followed by one infusion every three weeks for a total of 24 infusions over a treatment period of 61 weeks. Blood samples were taken before the start of treatment and before each infusion during two treatment cycles. To measure serum TRAP levels we employed the new immunoassay kit BoneTRAP produced by Suomen Bioanalytiikka Oy (SBA), Oulu, Finland. In order to assess the usefulness of this marker in evaluating the response to pamidronate treatment we divided patients into two groups (group A, worsened; group B, improved) with respect to pain trend and analgesic intake. Our results did not show any statistically significant difference in baseline serum TRAP levels in the two groups. However, one week after the first pamidronate infusion TRAP-5b serum levels decreased by 39% and 18% in groups A and B, respectively (p=0.01); these levels persisted throughout the treatment period. In conclusion, a decrease in TRAP-5b serum levels may reflect the pharmacological activity of pamidronate and seems to predict pain relief and a reduction in analgesic consumption.

Serum levels of tartrate-resistant acid phosphatase-5b in breast cancer patients treated with pamidronate

A novel immunoassay specific for the osteoclast-produced TRAP isoform 5b has been developed recently. By means of this assay we studied the usefulness of serum TRAP-5b in monitoring the response to palliative treatment with pamidronate in breast cancer patients with bone metastases. We correlated serum TRAP-5b levels with pain intensity and intake of analgesics to assess the possible utility of the marker in identifying patients who could benefit from pamidronate treatment. Twenty-eight advanced breast cancer patients with bone metastases entered the study. Patients were treated according to the following schedule: two two-week cycles of 60 mg/week pamidronate IV, with a three-week interval in between (six infusions over seven weeks), followed by one infusion every three weeks for a total of 24 infusions over a treatment period of 61 weeks. Blood samples were taken before the start of treatment and before each infusion during two treatment cycles. To measure serum TRAP levels we employed the new immunoassay kit BoneTRAP produced by Suomen Bioanalytiikka Oy (SBA), Oulu, Finland. In order to assess the usefulness of this marker in evaluating the response to pamidronate treatment we divided patients into two groups (group A, worsened; group B, improved) with respect to pain trend and analgesic intake. Our results did not show any statistically significant difference in baseline serum TRAP levels in the two groups. However, one week after the first pamidronate infusion TRAP-5b serum levels decreased by 39% and 18% in groups A and B, respectively (p=0.01); these levels persisted throughout the treatment period. In conclusion, a decrease in TRAP-5b serum levels may reflect the pharmacological activity of pamidronate and seems to predict pain relief and a reduction in analgesic consumption.

Failure of external spinal skeletal fixation to improve predictability of lumbar arthrodesis.

Whether lumbar arthrodesis can relieve isolated low-back pain in the absence of focal neurological findings or instability is unclear. The results of published studies are also inconsistent with regard to whether temporary back-pain relief with external spinal skeletal fixation can predict lasting back-pain relief after arthrodesis. This report presents the results, with regard to clinical benefit and complications, of more than 100 external spinal skeletal fixation procedures undertaken as a prelude to lumbar arthrodesis. The records of all patients who underwent external spinal skeletal fixation between 1989 and 1999 were reviewed with attention to perioperative complications, pain relief from the test procedure, the clinical benefit from a subsequent arthrodesis, and the functional status after the arthrodesis. Analyzed data included the frequency of neurological complications and infections and the benefit (Prolo score) after staged spinal arthrodesis in patients who underwent arthrodesis after temporarily experiencing pain relief with the test procedure. A total of 103 external spinal skeletal fixation procedures were undertaken. Neurological complications occurred in two procedures (2%); one resulted in permanent sciatica. Infections occurred in five patients (5%). Sixty patients experienced pain relief during the external fixation test, but only twenty-seven of forty-nine patients who went on to have an arthrodesis and had sufficient follow-up reported that they were doing well at a minimum of one year later. In no case did the external spinal skeletal fixation procedure cause a permanent increase in low-back pain. On the basis of this analysis, external spinal skeletal fixation should not be used as a predictor of pain relief after lumbar arthrodesis.

Cerebrospinal fluid nitric oxide metabolites are novel predictors of pain relief in degenerative lumbar diseases

This study was undertaken to determine whether or not nitric oxide metabolites (NO2− plus NO3−: NOx levels) in cerebrospinal fluid (CSF) would be predictors of treatment outcome in patients with degenerative lumbar diseases (DLD) including lumbar disc herniation (LDH) and lumbar spinal canal stenosis (LCS). The NOx levels in CSF were measured using an NO analyzer based on the Griess method. Six healthy volunteers and 18 patients with painless diseases were included in the control group. The pre- and postoperative NOx levels in 25 DLD patients, who underwent herniotomy for LDH (17 patients) or selective decompression for LCS (eight patients), were analyzed. The postoperative follow-up periods were approximately 8 months. Nineteen of 25 DLD patients, whose preoperative NOx levels were two standard deviations higher than the mean NOx levels of an age-matched control group, were included in an NO elevated (NOE) group. Among the 25 DLD patients, the preoperative NOx levels in six patients (young LDH group) were within the normal range. The pain-related Japanese Orthopaedic Association score and the Hirabayashi recovery rate were respectively used to evaluate the pain severity and the degree of pain relief. The preoperative and changes of postoperative NOx levels in the NOE group were negatively correlated with the Hirabayashi recovery rate. Normal postoperative NOx levels and excellent pain relief were achieved in young DLD patients. In conclusion, the preoperative and changes in postoperative NOx levels are quantitative predictors of postoperative pain relief in DLD patients.

Outcome of patients with chronic abdominal pain referred to chronic pain clinic

OBJECTIVE: We determined the outcome of patients with chronic abdominal pain of unknown etiology referred by gastroenterologists to a chronic pain clinic. METHODS: A retrospective chart review of 43 consecutive patients seen by a university-based gastroenterology group was referred to our Chronic Pain Clinic for evaluation and treatment. Pain character and location, the referring diagnosis, and initial Chronic Pain Clinic diagnosis was compared between responders and nonresponders. Early and long-term pain relief was scored by standard questionnaire. RESULTS: Of the 43 patients with chronic abdominal pain of undetermined etiology, 70% reported complete or substantial pain relief by the end of chronic pain management. Pain character and location and the referring diagnosis were not predictors of pain relief. Long-term pain relief was reported by 35% of patients. CONCLUSION: A substantial group of patients with chronic abdominal pain of unknown etiology benefited from Chronic Pain Clinic services.

Outcome of patients with chronic abdominal pain referred to chronic pain clinic.

We determined the outcome of patients with chronic abdominal pain of unknown etiology referred by gastroenterologists to a chronic pain clinic. A retrospective chart review of 43 consecutive patients seen by a university-based gastroenterology group was referred to our Chronic Pain Clinic for evaluation and treatment. Pain character and location, the referring diagnosis, and initial Chronic Pain Clinic diagnosis was compared between responders and nonresponders. Early and long-term pain relief was scored by standard questionnaire. Of the 43 patients with chronic abdominal pain of undetermined etiology, 70% reported complete or substantial pain relief by the end of chronic pain management. Pain character and location and the referring diagnosis were not predictors of pain relief. Long-term pain relief was reported by 35% of patients. A substantial group of patients with chronic abdominal pain of unknown etiology benefited from Chronic Pain Clinic services.

Chronic pancreatitis

In the past year, numerous important papers were published on chronic pancreatitis, its causes, and its diagnosis; the cause of fibrosis; and pain in pancreatic cancer. More than 750 mutations have been described in the cystic fibrosis transmembrane regulator (CFTR) gene. Some mutations cause relatively mild reductions in CFTR function and may lead to disease in one organ without clinical involvement of other organs. Two groups of investigators recently reported that "idiopathic" chronic pancreatitis may be the sole manifestation of some CFTR mutations. Some recent reports may enhance our understanding of pancreatic fibrogenesis and may lead to therapies for painful chronic pancreatitis. Pancreatic stellate cells are vitamin A-containing cells that resemble hepatic stellate cells and were recently isolated from rat and human pancreas. They respond to inflammatory cytokines by producing collagen. Two studies show that endoscopic ultrasonography (EUS) correlates well with endoscopic retrograde cholangiopancreatography in moderate to severe chronic pancreatitis. However, in patients who have a few nondiagnostic abnormalities on EUS, these results have poor correlation with the results of endoscopic retrograde cholangiopancreatography and the secretin test. The clinical significance of these abnormalities is unclear, and the diagnosis of chronic pancreatitis should not be based on EUS findings alone. Painful chronic pancreatitis is a complex and difficult management problem. A recent study of alcoholic chronic pancreatitis suggests that the best predictors of pain relief are an intermittent pattern of pain and the presence of surgically correctable complications (eg, pseudocysts or biliary obstruction). An American Gastroenterological Association technical review of painful chronic pancreatitis emphasized the lack of controlled studies supporting any form of therapy. Further evidence that longstanding chronic pancreatitis is a premalignant condition has been provided by recent epidemiologic, pathologic, and molecular biology studies.

Substance P level in cerebrospinal fluid (CSF) on lumber spinal disc herniation with severe pain may predict pain relief after herniotomy

Substance P level in cerebrospinal fluid (CSF) on lumber spinal disc herniation with severe pain may predict pain relief after herniotomy

Substance P level in synovial fluid may predict pain relief after knee replacement.

Substance P is readily detected in the synovial fluid of the knee in which it acts as a powerful inflammatory agent in response to injury and disease. It may be an objective predictor of pain after knee replacement surgery. The level of substance P was measured in the synovial fluid in both knees of 114 patients having unilateral and in 86 patients having bilateral total knee replacement for osteoarthritis. All had severe pain in the knee to be replaced and joint destruction. Substance P was elevated in 73% of replaced knees but not in normal or asymptomatic knees. Good or excellent pain relief was achieved in 97% of patients with an elevated preoperative level of substance P and in 61% of those with a normal preoperative level (p < 0.05 compared with preoperative values).