Visceral pain.

Visceral pain, which originates from organ tissues of the thorax, abdomen or pelvis, is generally perceived as a deep, dull and vague sensation; in most cases it cannot even be clearly described, being a sense of discomfort, malaise or oppression rather than real pain. Crushing, cutting and burning generally have no algogenic effect in the viscera whereas mechanical stimulation, ischemia and chemical stimulation, separately or in combinations, may cause pain. With these characteristics, visceral pain differs from somatic pain. The characteristics of visceral pain, perception and transmission of painful visceral stimuli are explained, some common visceral pain syndromes are presented and sympathetic neurodestructive approaches as a treatment option are described in this review.

Spinal cord stimulation: a comparison of efficacy versus other novel treatments for refractory angina pectoris.

Recently much attention has been directed toward novel treatment alternatives for refractory angina pectoris. Refractory angina is persistent stable class III or IV angina despite maximally tolerated medical treatment in patients with end-stage coronary artery disease. Transmyocardial laser revascularization (TMLR), gene therapy, intermittent urokinase therapy, enhanced external balloon counterpulsation, and spinal cord stimulation have all been employed to treat refractory angina pectoris. TMLR and gene therapy are invasive open-chest procedures that have yielded controversial results. Intermittent urokinase and enhanced external balloon counterpulsation studies have limited follow-up times and require multiple clinic visits for treatment. Spinal cord stimulation has a proven short- and long-term efficacy and cost-effectiveness in the treatment of refractory angina. When compared to coronary artery bypass grafting (CABG), it has been shown to decrease the frequency of anginal attacks and consumption of short-acting nitrates to the same extent in refractory angina. Spinal cord stimulation's safety profile has also been well established and it can be used concurrently with cardiac pacemakers or MRI systems, provided the proper precautions are taken. Since spinal cord stimulation is a minimally invasive procedure with a favorable efficacy and safety profile, it should be considered as a valid treatment alternative after medical management has failed in refractory angina prior to implementing invasive modalities such as TMLR or gene therapy.

Painless electrodiagnostic current perception threshold and pain tolerance threshold values in CRPS subjects and healthy controls: a multicenter study.

The purpose of this study is to evaluate both painless and painful sensory transmission in patients with Complex Regional Pain Syndrome (CRPS) using the automated electrodiagnostic sensory Nerve Conduction Threshold (sNCT) test. This test generates reliable, painless Current Perception Threshold (CPT) and atraumatic Pain Tolerance Threshold (PTT) measures. Standardized CPT and PTT measures using constant alternating current sinusoid waveform stimulus at 3 different frequencies 5 Hz, 250 Hz, and 2 kHz (Neurometer CPT/C Neurotron, Inc. Baltimore, MD) were obtained from CRPS subjects at a distal phalange of the affected extremity and at an ipsilateral asymptomatic control site. Matched sites were tested on healthy subjects. Detection sensitivities for an abnormal PTT and CPT test were calculated based on specificity of 90% as determined from data obtained from healthy controls. A Spearman rank correlation was used to test for a significant association between presence of allodynia and an abnormal PTT or CPT at any frequency tested. Thirty-six CRPS subjects and 57 healthy controls were tested. The highest detection sensitivity of the PTT test from symptomatic test sites was 63% for the finger and 71% for the toe. PTT abnormalities were also detected, to a lesser degree, at the asymptomatic control site (41% finger control site, 16% toe control site). The highest CPT detection sensitivity at the symptomatic site was 37% for the finger site and 53% for the toe site. CPT abnormalities were also detected at the asymptomatic control site (29% finger control site, 37% toe control site). Eighty-six percent of the CRPS subjects had either a PTT or CPT abnormality at any frequency at the symptomatic site. There was a significant correlation between presence of allodynia and presence of an abnormal CPT and PTT, respectively (P < .01). The correlation coefficient was lower for CPT than for PTT, ie, 0.34 versus 0.6 for the finger and 0.48 versus 0.67 for the toe, respectively. In studied CRPS patients an abnormal PTT was detected with higher sensitivity than an abnormal CPT. Assessing PTT may become a useful electrodiagnostic quantitative sensory test for diagnosing and following the course of neuropathic pain conditions.

Comparison of the efficacy of epidural morphine given by intermittent injection or continuous infusion for the management of postoperative pain.

BACKGROUND AND OBJECTIVES: To compare the effectiveness and side effects of epidural morphine sulfate (MSO4), delivered by continual infusion or intermittent bolus. METHODS: Thirty patients undergoing upper abdominal surgery were randomized into two equal groups to receive MSO4 through a thoracic epidural catheter by one of two methods. Group 1 patients received an initial bolus of morphine (0.07 mg/kg) at the end of surgery, followed by injections of 2-5 mg morphine into the epidural catheter on demand. Patients in group 2 received an initial bolus of morphine (0.03 mg/kg) during surgical peritoneal closure and were immediately started on an infusion of 0.01% morphine at 5 mL/hour (0.5 mg/hour). The infusion dose was titrated from 0.2 to 1.0 mg/hour, dependent on side effects. Outcome measurements included pulmonary function studies, arterial blood gases, morphine plasma levels, pain relief scores, global evaluations, and side effects. RESULTS: No difference existed between groups in forced vital capacity, forced expiratory volume in 1 second, or in arterial blood gas measurements. Side effects were similar in both groups. Respiratory depression was not seen in either group. Group 2 reported significantly better analgesia than group 1 on postoperative days 1 and 2 (P < .01). Peak plasma morphine levels for group 1 were significantly higher than the steady state plasma morphine levels for group 2 (P < .05). CONCLUSIONS: Continuous epidural infusion provides better analgesia without increased side effects for postoperative pain when compared with an intermittent (or demand) bolus technique.

Continuous epidural methadone for the management of postoperative pain after lower abdominal surgery.

BACKGROUND AND OBJECTIVES: The efficacy of methadone administered by continuous epidural infusion for 24 hours for the management of postoperative pain has been reported. The pharmacokinetic characteristics of methadone predict that significant accumulation would occur if infusions were continued for longer than 24 hours and that this accumulation could result in serum concentrations above the threshold associated with systemic analgesia. METHODS: We tested this hypothesis by measuring serum methadone concentrations, pain scores, and side effects in 18 patients receiving continuous epidural infusions of methadone for the relief of postoperative pain after lower abdominal surgery over 3 days. RESULTS: Twelve of 18 patients completed the study. Persistent inadequate analgesia required a change in the infusion mixture in 5 of these patients by the second postoperative day. The sixth patient suffered a fatal pulmonary embolus (judged to be unrelated to the study) on the morning of the first postoperative day. Methadone concentrations increased significantly from 20 +/- 18 ng/ml (median +/- quartile) on postoperative Day 1 to 70 +/- 47 ng/ml on Day 3. Pain relief scores steadily increased from 50 +/- 5 at 2 hours postoperatively to 83 +/- 5 by Day 3. The only side effects noted in the present study were nausea and sedation. CONCLUSION: The accumulation of serum concentrations reported here argue that the risks of thoracic epidural placement may outweigh the potential benefits when methadone is administered alone by continuous infusion for longer than 24 hours.

Behavioral and histopathologic effects following intrathecal administration of butorphanol, sufentanil, and nalbuphine in sheep.

A large number of opioids and nonopioids have been administered epidurally and intrathecally in the hope of providing segmental analgesia without serious adverse effects. However, neurotoxicity data are generally unavailable for many of these drugs. The present study evaluated the behavioral, motor, electroencephalographic, and histopathologic changes following intrathecal injection of large and small doses of butorphanol, sufentanil, and nalbuphine in sheep. Thirty-two sheep (20-32 kg) were anesthetized and catheters placed intrathecally after hemilaminectomy. The large doses of butorphanol, sufentanil and nalbuphine were 0.375 mg/kg (4.4-5.2 ml), 7.5 micrograms/kg (3.6-4.8 ml) and 0.75 mg/kg (1.5-2.4 ml), and the small doses were 0.075 mg/kg (0.9-1.1 ml), 1.5 micrograms/kg (0.7-0.9 ml) and 0.15 mg/kg (0.38-0.5 ml), respectively. The opioids were administered intrathecally every 6 h for 3 days and the above-mentioned parameters studied. Five sheep received intrathecal saline (1.1 or 5.2 ml) and served as controls. Histopathologic changes were evaluated by a neuropathologist blinded to the study protocol. Irrespective of dose, intrathecal injection of butorphanol was associated with severe behavioral responses such as agitation, rigidity, vocalization, and restlessness, as well as prolonged or irreversible hindlimb paralysis. Electroencephalography showed increased cortical activity or seizure activity. One sheep died because of severe respiratory depression that did not respond to naloxone. Spinal cord histologic changes consisted of suppurative meningitis and myelitis as well as neuronal changes such as spongiosis and chromatolysis. Large doses of intrathecal sufentanil were associated with similar though somewhat less severe responses. The behavioral and motor changes following the small dose of intrathecal sufentanil were of mild to moderate nature. Following intrathecal nalbuphine, the above-mentioned changes were similar to those seen in control animals. We conclude that butorphanol in doses of 0.075 and 0.375 mg/kg intrathecally and sufentanil 7.5 micrograms/kg intrathecally are neurotoxic in sheep.

Anatomic spread of india ink in the human intercostal space with radiographic correlation.

In a study designed to determine the spread of anesthetic solutions in the intercostal space, the spread of india ink was studied in fresh cadavers. They were turned prone and had epidural catheters placed at ribs 4, 6, 8 and 10, 7-8 cm lateral to the midline, by two different techniques. Group 1 had epidural catheters directed laterally into the subcostal groove. Group 2 had catheters directed medially into the intercostal space. A window was dissected in the anterior chest wall to visualize the location of the catheters and the spread of india ink. Catheters in Group 1 were observed to be lateral to the medial border of the intercostalis intimus muscle and injection of india ink resulted in spread entirely within a single intercostal space. Catheters in Group 2 were observed to be 2-3 cm medial to the border of the intercostalis intimus muscle and injection of ink resulted in concentric spread over 3-5 intercostal spaces. Posteroanterior and lateral radiographs taken with contrast material in live patients confirmed these patterns of spread. The catheters in Groups 1 and 2 were within the same tissue plane. The results indicate that the pattern of spread obtained by injection of fluid in the intercostal space is dependent upon the site of injection in relation to the angle of the rib.

Subjective signs of efficacious inferior alveolar nerve block in children.

This study is designed to examine the clinical signs relating to profound anesthesia of the primary dentition using the inferior alveolar nerve block (IANB) injection. The IANB injection has been used for many years for both adults and children to anesthetize the mandibular teeth. Most dentists are quite familiar with the signs of profound intraoral anesthesia in the adult. Because of infrequent exposure, they might not be as aware of the signs of adequate anesthesia on the child patient. Additionally, the dentist may not be able to differentiate apprehensive behavior from behavior elicited with inadequate pulpal anesthesia. The study consisted of forty male and female children. The subjects who ranged in age from 3 years to 12 years, with a mean age of 7 years, were scheduled for routine restorative care of mandibular primary teeth. Each subject was injected with 1.8 ml of 2 percent xylocaine, 1:100,000 epinephrine using the mandibular-block technique. Anesthesia was evaluated using direct ice placement, lip reaction, tongue reaction and gingival reaction at intervals of 0, 1, 2, and 5 minutes. The results showed a correlation of lip and tongue anesthesia and pulpal anesthesia over time. A stronger correlation existed with gingival anesthesia and pulpal anesthesia over time. There was no statistical relationship between the subject response to ice and pulpal anesthesia.

Pharmacokinetics of continuous intravenous infusion of methadone in the early post-burn period.

The pharmacokinetics of methadone were studied in 14 patients with acute, severe burns and receiving an intravenous infusion of methadone to control their pain. Serum methadone concentrations were measured by gas chromatography on 5 mL arterial blood samples obtained at 0.5, 1.0, 1.5, 2.0, 3.0, 4.0, 5.0 and 24 hours after the start of infusion. Albumin and Alpha-1-Acid glycoprotein (AAG) were measured by radial immunodiffusion. Serum methadone concentration-time data were fit with the appropriate sum of exponentials equation using iterative nonlinear regression analysis. All serum methadone concentration-time data were best described by a monoexponential equation. Estimates of Vd (180 +/- 62 L) were not significantly different from those predicted for Vc from body weight using literature values (156 +/- 41). Estimates of Vd were, however, significantly lower than those predicted for Vz using literature values (282 +/- 74) (P less than 0.001). In addition, CL values (53.0 +/- 19.3 L/h) were significantly higher than those predicted from body weight using literature values (9.2 +/- 2.3 L/h) (P less than 0.001). These changes resulted in estimates of the elimination half-life for methadone of 2.6 +/- 1.1 h. Methadone protein binding was independent of both albumin and AAG concentration. Multiple regression demonstrated that the significant predictors of CL in the early post burn injury period were serum albumin, days post injury and age. The coefficient of determination (r2) for this model was 0.8190. In summary, methadone CL is markedly elevated while the Vc is essentially unchanged during the early post burn injury period.(ABSTRACT TRUNCATED AT 250 WORDS)

SRK II formula in the calculation of intraocular lens power.

We studied 400 eyes which underwent cataract extraction with posterior chamber intraocular lens (IOL) implantation to compare the predictive accuracy of various IOL power calculation formulae. The new Sanders-Retzlaff-Kraff (SRK) II formula was more accurate than the original SRK and Binkhorst II formulae. Modification of the A constants used in the SRK II formula to make it 'surgeon specific' improved its performance further; 80% of the eyes had less than 1 dioptre error and only one eye (0.3%) had an error of more than 3 dioptres.

Continuous intravenous infusion of methadone for control of burn pain.

Seventeen patients with acute, severe burns were treated with a two-stage continuous, intravenous infusion of methadone to control pain. An initial loading infusion was run for 2 hours at 0.1 mg/kg/hr of methadone; then a maintenance infusion was continued at 0.01 mg/kg/hr of methadone. Median visual analog scale scores were 70% pain relief after the 2-hour loading infusion and 80% after 24 hours. Cardiovascular parameters were stable. There was a significant decrease in the respiratory rate of the patients. It appears that continuous intravenous methadone is an effective analgesic agent for the patient with acute, severe burns. Administration of the drug should be on an individualized basis with conservative dosing in a well-monitored environment because somnolence and respiratory depression can occur.

Supplementary iron dose in pregnancy anemia prophylaxis.

This study was conducted to determine the optimum dose of supplemental iron for prophylaxis against pregnancy anemia. One hundred and ten pregnant women were randomly allocated to three groups: Group A receiving equivalent of 60 mg, group B 120 mg and Group C 240 mg, elemental iron as ferrous sulphate daily; the content of folic acid was constant in all the three groups (0.5 mg). These women had at least consumed 90 tablets in 100 +/- 10 days. Blood was drawn at the beginning and at the end of the treatment. Fifty percent were anemic (less than 11 g/100 ml). The hemoglobin levels rose similarly in all groups and the differences were statistically not significant. Fifty-six percent had depleted iron stores (serum ferritin value less than 12 micrograms/l) at the beginning of the study. Following therapy a statistically significant increase in iron stores was observed in group B and C as compared to group A. The difference between group B and C was not significant. The side effects increased with increasing doses of iron; 32.4%, 40.3% and 72% in group A, B and C respectively. Based on these findings, the authors advocate that optimum dose of iron should be 120 mg instead of 60 mg as is currently being used in the National Nutritional Anemia Prophylaxis Programme.

Influence of acetylator phenotype of the leprosy patient on the emergence of dapsone resistant leprosy.

The half time of disappearance of dapsone and monoacetyl dapsone and the acetylator phenotype of the leprosy patients who harboured dapsone sensitive and dapsone resistant M. leprae was assessed in 27 subjects. Sixteen patients were rapid acetylators, five were slow and six were intermediate acetylators. The mean T 1 1/2 lives of dapsone (30.26 +/- 11.0) and monoacetyl dapsone (31.11 +/- 12.0) were also studied in the above patients. The percentage of different acetylators in both resistant and sensitive groups were similar showing no correlation between the emergence of drug resistance and the phenotype of the patient. The mean time of disappearance of DDS and MAD in the different acetylators did not show significant difference. The ratios of MAD/DDS in an individual at 3, 6 or 24 hours after the dose were similar. The mean T 1 1/2 lives of DDS and MAD in resistant and sensitive patients also showed no difference. Neither T 1 1/2 lives of DDS or MAD nor the acetylator phenotype seem to influence the emergence of dapsone resistance.

Certain aspects of dapsone metabolism in leprosy patients as studied by high performance liquid chromatography (HPLC) and qualitative screening tests.

Dapsone (DDS) in urine of 250 leprosy patients collected on surprise visits were screened by simple paper spot, tile tests and sensitive Enzyme linked immunosorbent assay (ELISA) and Haemagglutination inhibition (HI) tests. The urinary DDS concentration as well as DDS/C ratios were also studied. Simultaneously, 50 microliter of blood was collected from each of these patients and its dapsone content was estimated by HPLC. Urine samples with means of 25 to 30 micrograms/ml DDS and 55-64 micrograms/mg DDS/C ratios were found to give positive tests by any of the above screening procedures, while their mean blood DDS concentration was found to be 0.91 microgram/ml. The corresponding values for those specimens giving negative tests were 3.8 to 5.7 micrograms DDS per ml and 9 to 13 micrograms/mg DDS/C ratio. The blood DDS concentration in this group was ranging from 0.16 to 0.18 micrograms/ml. The findings are discussed in relation to their metabolic significance and their application in a leprosy control programme.

Secondary and primary dapsone resistant leprosy: an analysis of 199 patients from St. Thomas Hospital and leprosy project, Chettupattu, South India.

The occurrence of secondary and primary dapsone resistance in 199 patients in our control area and the influence of certain variables such as age, initial bacteriological and morphological indices, duration of regular dapsone monotherapy, on the emergence of dapsone resistance was investigated. Ninety one of 122 patients and 29 out of 77 showed secondary (SDR) and primary (PDR) resistance to dapsone respectively. Very low BI (BI:2.5) group also showed both SDR (60%) and PDR (40%). Low or high MI group exhibited the same degree of resistance. Multiplication of M. leprae was obtained even when the MI of the inocula was zero. Even in the group who had 1 to 5 years duration of regular dapsone treatment, 85% patients showed SDR. Significance of such results are discussed in relation to chemotherapy. The overall minimum prevalence of SDR was found to be 5.6% and 21% in the case of PDR in our control area.