Ventilatory response to intractable pain.

Fifty-two patients, admitted to a pain relief unit, had a cannula placed in the radial artery to measure the paO2, paCO2 and pH of arterial blood every 2 h, for periods ranging from 12 to 24 h. The patients were divided into 3 groups: 14 had low back pain, 21 patients had pain from cancer, and 17 had pain from other causes. Twenty were male and 32 were female with a mean age of 53 years (range 16-82 years). The mean paO2 of these groups was within normal limits. The mean paCO2 and pH for the 3 groups were, low back pain paCO2 4.1 kpa, pH 7.42, others, paCO2 4.2 kpa, pH 7.42. The finding of a normal pH associated with a low paCO2 suggests that patients were "reset" to a low paCO2. Treatment, which was most commonly nerve blocks, resulted in marked pain relief in 30 patients. Ten of these patients were available for follow-up at least 1 week later (4 from the low back pain group, 6 from the cancer group), and in every patient, after pain relief, there was a rise in paCO2 which was statistically significant (P less than 0.001) and was not accompanied by a fall in pH. This suggests that intractable pain is accompanied by chronic hyperventilation and that the relief of pain is accompanied by a decrease in ventilation.

Trigeminal neuralgia: what are the important factors for good operative outcomes with microvascular decompression.

BACKGROUND: Microvascular decompression has been widely used as the first choice in treating trigeminal neuralgia, but in a few patients, facial pain cannot be effectively controlled by microvascular decompression. We sought to clarify the important factors for good operative outcomes. METHODS: We reviewed 62 patients with trigeminal neuralgia treated by microvascular decompression during the period 2000 through 2002, including clinical presentation, operative findings, techniques, and outcomes. Neurovascular conflicts were divided into single contact, contact and indentation, single adhesion, adhesion and indentation, and trigeminal nerve atrophy. Operative outcomes were graded into immediate postoperative complete pain relief (excellent), delayed postoperative complete pain relief (better), significant pain relief (good), and no response to microvascular decompression (poor). RESULTS: All patients' presentations were typical at the time of pain onset, but the symptom in 17 patients changed to atypical before surgery. During operation, single contact and single adhesion was found in 14 patients and 15 patients, respectively; contact or adhesion in combination with indentation was found in 7 patients and 18 patients, respectively; atrophy occurred in 8 patients. Postoperatively, immediate and delayed complete pain relief was achieved in 32 (51.6%) patients and 17 (27.4%) patients, respectively; 11(17.7%) patients got significant pain relief; and 2 patients showed no response. The overall rate of complete pain relief in patients with shorter duration, typical presentation, artery compression and complete decompression was higher than that in patients with longer duration, atypical presentation, venous compression, and incomplete decompression. CONCLUSIONS: Shorter duration, typical presentation, single artery compression, and complete decompression are the positive factors for better operative outcomes with microvascular decompression. Worse outcomes are usually related to venous compression, longer duration, and atypical presentation.

Repeat radiosurgery for refractory trigeminal neuralgia.

OBJECTIVE: Stereotactic radiosurgery has become an important and minimally invasive alternative for patients with refractory trigeminal neuralgia. When a second procedure is necessary, the outcomes are unknown. The degree of pain relief and morbidity after repeat radiosurgery were studied. METHODS: Thirty-one patients underwent a second gamma knife radiosurgery procedure because of unsatisfactory or unsustained relief of pain after the first procedure. Twenty-seven patients were assessable at median follow-up periods of 42.7 and 20.4 months after the first and second procedures, respectively. Most patients had undergone multiple previous operations of other types (microvascular decompression, radiofrequency rhizotomy, glycerol rhizotomy, balloon compression). The median target doses of the first and second radiosurgeries were 75 and 64 Gy, respectively. All patients were evaluated by a physician who did not participate in patient treatment. RESULTS: After the first radiosurgical procedure, 13 patients had an excellent response initially (complete relief without any medication), 3 had a good response (complete relief with some medication), 7 had a fair response (>50% relief), and 4 had a poor response (<50% pain relief or treatment failure). Repeat radiosurgery was performed in patients with recurrent or residual pain. After the second radiosurgical procedure, 5 patients had an excellent response, 8 had a good response, 10 had a fair response, and 4 had a poor response. Thirteen patients (48%) achieved complete pain relief (with or without medication). Two patients (7.4%) experienced new sensory symptoms after the first radiosurgical procedure, and three (12.7%, actuarial) experienced new sensory symptoms after the second procedure. CONCLUSION: Repeat radiosurgery provided a similar rate of pain relief as the first procedure, despite a modest dose reduction. The risk of new sensory symptoms was increased, but no other morbidity was identified. For patients who experience recurrent pain and choose to undergo a second procedure, our current procedure is to deliver a maximum dose of 50 to 60 Gy to a trigeminal target anterior to the root entry zone near the entrance of the nerve beneath the petrous dura.

The effectiveness of 100 and 200 mg etodolac (Ultradol), aspirin, and placebo in patients with pain following oral surgery.

The analgesic efficacy of etodolac (Ultradol) was evaluated in 168 patients experiencing moderate to severe pain following oral surgery. The patients were given either etodolac 100 mg, etodolac 200 mg, aspirin 650 mg, or placebo. There was a minimum of forty patients in each drug group. Patients recorded pain intensity and pain relief at 1/2 hour and then hourly for up to 12 hours after medication. The efficacy variables analyzed were the sum of pain-intensity differences, total pain relief, onset of analgesia, and the patient's opinion of the study drug. Time-effect curves were made from the pain-relief and pain-intensity difference scores. The analgesic potency of both 100 and 200 mg of etodolac was comparable to 650 mg of aspirin and superior to placebo. Like aspirin, both doses of etodolac showed significant analgesia within one hour and a significantly longer duration of action than placebo.

Effects and pharmacokinetics of high dose metoprolol on chest pain in patients with suspected or definite acute myocardial infarction.

OBJECTIVE: Pain intensity and the plasma concentrations of metoprolol and its major metabolite alpha-hydroxymetoprolol as well as noradrenaline (NA), adrenaline (A) and neuropeptide Y (NPY) were determined in patients with pain due to definite or suspected acute myocardial infarction (AMI) after graded metoprolol infusion. Pain intensity and metoprolol kinetics were assessed over 8 h. METHODS: Twenty-seven patients of either sex, aged 48-84 years with ongoing chest pain upon arrival to the Coronary Care Unit (CCU) were subdivided into two groups: (1) patients with ECG signs of threatening transmural myocardial damage (n = 15); and (2) patients without such ECG signs (n = 12). Pain intensity was assessed by a numerical rating scale (NRS) and venous blood was obtained for determination of plasma catecholamine and NPY concentrations. A continuous infusion of metoprolol (3 mg.min-1 i.v) was started and serial blood samples for plasma catecholamines, NPY as well as metoprolol and its major metabolite alpha-hydroxymetoprolol were obtained from the contralateral arm. RESULTS: Initial pain intensity was 5.9 (arbitrary units) and 5.4 in the groups with and without signs of transmural myocardial damage, respectively. One third of the patients with ST changes reported full pain relief (NRS = 0) within 70 min after starting metoprolol infusion (accumulated dose, 15-180 mg). Among the patients without ST changes upon arrival, full pain relief was obtained in 70% (accumulated dose, 30-120 mg). There was a dose-dependent relation between accumulated metoprolol dose and pain relief. The diagnosis of acute myocardial infarction (AMI) was confirmed in all 15 patients with ECG signs on arrival of transmural myocardial damage. The mean metoprolol dose in this group was 91(12) mg. The mean metoprolol dose in the 12 patients without ST changes was 64(8) mg. In all, seven of these patients developed definite AMI. The terminal half-life of unchanged metoprolol ranged from 2.5 to 8.5 h in group 1 and from 2.2 to 5.2 h in group 2. In group 1, metoprolol half-life was 4.5 h and total plasma clearance (CL) 54.1 1.h-1. In group 2, the metoprolol half-life was 3.7 h and total plasma clearance 75.4 1.h-1. There was a significant difference in clearance between the groups. After the intravenous metoprolol infusion, alpha-hydroxymetoprolol concentrations increased gradually. In groups 1 and 2, maximal concentrations in plasma (Cmax) were 143 and 135 nmol.1(-1) for alpha-hydroxymetoprolol and 2830 and 1653 nmol.1(-1) for metoprolol, respectively. Plasma NA or NPY did not differ between the groups. In contrast, plasma A was significantly higher during the initial 90 min of observation in patients with ECG signs of transmural myocardial damage. CONCLUSION: High-dose intravenous metoprolol was well tolerated in patients with suspected AMI. There was a more rapid and almost complete pain relief in patients without signs of transmural ischaemia compared with the patients with ECG signs of transmural AMI at arrival. In the later group of patients, plasma clearance of metoprolol was significantly reduced.

Dose-dependent epidural leakage of polymethylmethacrylate after percutaneous vertebroplasty in patients with osteoporotic vertebral compression fractures.

OBJECT: The use of polymethylmethacrylate (PMMA) cement by percutaneous injection in cases requiring vertebroplasty provides pain relief in the treatment of osteoporotic vertebral compression fractures. A retrospective study was performed to assess what caused PMMA cement to leak into the epidural space and to determine if this leakage caused any changes in its therapeutic benefits. METHODS: Polymethylmethacrylate was injected into 347 vertebral compression fractures in 159 patients. The cement leaked into the epidural space in 92 (26.5%) of 347 treated vertebrae in 64 (40.3%) of the 159 patients, as demonstrated on postoperative computerized tomography scanning. Epidural leakage of PMMA cement occurred more often when injected above the level of T-7 (p = 0.001) than below. The larger the volume of PMMA injected the higher the incidence of epidural leakage (p = 0.03). Using an injector also increased epidural leakage (p = 0.045). The position of the needle tip within the vertebral body and the pattern of venous drainage did not affect epidural leakage of the cement. Leakage of PMMA into the epidural space reduced the pain relief expected after vertebroplasty. The immediate postoperative visual analog scale scores were higher (and therefore reflective of less pain relief) in patients in whom epidural PMMA leakage occurred (p = 0.009). Three months postoperatively, the authors found the highest number of patients presenting with pain relief, including those in the group with epidural leakage, and at this follow-up stage there were no significant differences between the two groups. CONCLUSIONS: The authors found that epidural leakage of PMMA after percutaneous vertebroplasty was dose dependent. The larger amount of injected PMMA, the higher the incidence of leakage. Injecting vertebral levels above T-7 also increased the incidence of epidural leakage. Epidural leakage of PMMA may attenuate only the immediate therapeutic effects of vertebroplasty.

Naloxone does not affect pain relief induced by electrical stimulation in man.

We wished to determine if pain relief that resulted from transcutaneous (TNS) or spinal cord electrical stimulation in patients with chronic pain was due to activation of an endogenous opiate-related pain control system. Naloxone (0.4-10 mg) or saline was injected in double-blind fashion intravenously into opiate-naive subjects with chronic pain who achieved 30% or greater pain relief with spinal cord stimulation (4 patients) or TNS (9 patients). Subjects rated their pain during stimulation and 2, 5, 10 and 15 min after the injection. Two days or more later the procedure was repeated using the alternate agent (naloxone or saline). Naloxone did not decrease the pain relief induced by stimulation, and therefore the effects of stimulation are probably not mediated by the endogenous opiates.

pain relief in labor by transcutaneous electrical nerve stimulation. A prospective matched study.

The study evaluated transcutaneous electrical nerve stimulation (TNS) for pain relief in labor, used in parallel with conventional methods. The investigation comprised 566 vaginally delivered women, 283 of whom were given TNS. pain relief was evaluated with a questionnaire which the women answered shortly after delivery. With a statistical multivariate technique, it was concluded that TNS has a specific effect on pain localized to the back. Few women in either the TNS or the control group reported good relief of pain localized to the suprapubic region. Nitrous oxide-oxygen mixture was used less often in the TNS group than in the controls. Duration of labor and maternal blood loss were comparable in the two groups. The babies borne by primiparae in the TNS group tended to have better Apgar scores. Fewer babies of primiparae in the TNS group required observation for two days or more on the neonatal ward than was the case with the controls. However, the electrical stimulation could not be used optimally as it interfered with monitoring the fetal heart rate in half the cases. It is concluded that although TNS has a good effect on low-back pain and seems to have no negative effects on the mother or child, it is only a complement to conventional methods.

Pitfalls of distal pancreatectomy for relief of pain in chronic pancreatitis.

PURPOSE: To examine whether preoperative computed tomography (CT) scans and pancreatograms can: (1) identify patients with chronic pancreatitis localized to the tail of the pancreas; and (2) select those patients who can obtain pain relief from a distal pancreatectomy. PATIENTS AND METHODS: Twenty patients were identified on whom the authors had performed distal pancreatectomy for relief of pain between January 1, 1991 and August 1, 1994. The results of surgery were classified as good, fair, or poor based on return to work and need for narcotics or rehospitalization. RESULTS: Eleven patients had good, 3 fair, and 6 poor results. All 7 patients with pseudocysts of the tail of the pancreas had good results, while 9 of 13 patients without pseudocysts had poor results. No other finding on CT scan, pancreatography, or laparotomy predicted successful pain relief by distal pancreatectomy. Furthermore, 3 patients had unexpected carcinoma found at the time of surgery. CONCLUSIONS: Even when anatomic evidence suggests that chronic pancreatitis primarily involves the tail of the pancreas and there is a stricture of the midpancreatic duct that is believed to cause the symptoms, distal pancreatectomy seldom provides sustained pain relief. Unsuspected carcinoma of the body and tail of the pancreas occurs frequently in this subset of patients with chronic pancreatitis.

A prospective analysis of predictive factors on the results of laparoscopic adhesiolysis in patients with chronic abdominal pain.

Laparoscopic adhesiolysis for chronic abdominal pain is subject for criticism. In this prospective study, we analyze factors that encourage or discourage the indication for therapeutic laparoscopic adhesiolysis. Two hundred twenty-four consecutive patients with chronic abdominal pain underwent diagnostic laparoscopy, and in case of adhesions, they underwent adhesiolysis. pain relief was assessed, and the individual impact of variables on pain relief was determined. Laparoscopy was performed in 224 patients. Two hundred patients had only adhesions and underwent primary laparoscopic adhesiolysis. Three months after adhesiolysis, 74% of patients were pain-free or had less pain. The remaining 26% of the patients felt no change (22%) or had more pain (4%). Gender, age, and bowel perforation leading to a laparotomy appear to be individual factors significantly influencing pain relief. Laparoscopic adhesiolysis can be done (almost) completely in 92% of patients with adhesions. After laparoscopic adhesiolysis, 74% of patients had good results and 4% had more pain. The complication rate is high.