Prediction of response to treatment in chronic pain patients.

A seven-item rating scale reported by researchers from the Mayo Clinic to have high validity in identifying chronic pain patients who would benefit from inpatient treatment was administered to an outpatient sample. Initial results did not replicate the previous findings; inclusion of four additional variables (disruption of a close relationship, altered body image, history of childhood illness, and history of abuse in childhood) produced results comparable to the Mayo study. This expanded screening test appears to be a useful method for selecting patients in a pain-management program and warrants further investigation.

Unrecognized thrombocytopenia and regional anesthesia in parturients: a retrospective review.

Charts from 2929 consecutive parturients were reviewed. Twenty-four had platelet counts less than 100,000/microL in the peripartum period. Seventeen of the 24 had predisposing causes for thrombocytopenia, including preeclampsia (nine), immune thrombocytopenia purpura (two), infection (three), placenta accreta (one), abruption (one), and excessive surgical bleeding (one). Seven had asymptomatic thrombocytopenia of unknown origin. Fourteen of the 24 thrombocytopenic patients received regional anesthesia, and none had permanent sequelae. Based upon this retrospective review, peripartal thrombocytopenia (15,000-99,000/microL) did not increase the risk of neurologic complications after a regional anesthetic. There have been no reports in the literature of spinal or epidural hematomas in parturients after regional anesthesia, except for one patient with a spinal ependymoma.

Verapamil increases the toxicity of local anesthetics.

The calcium channel blocker verapamil has, in addition to its other properties, been shown to be a local anesthetic. Its concurrent use in a patient undergoing regional anesthesia may, therefore, increase the potential risk for local anesthetic toxicity. To evaluate this possibility, the effect of verapamil on the median lethal dose (LD50) of lidocaine and bupivacaine in mice was determined. Immediate pretreatment with verapamil increased the mortality of mice given the LD50 dose of lidocaine to 74%, and in mice given the LD50 doses of bupivacaine, to 82%. In animals pretreated with verapamil and calcium chloride, the mortality associated with the administration of LD50 doses of lidocaine and bupivacaine decreased to 43% and 48%, respectively, thus returning the mortality rate back to the LD50 of the local anesthetics when administered alone. It seems that the combined administration of local anesthetic and verapamil results in a significant drug interaction: the resulting blockade of sodium and calcium channels apparently impairs membrane function to a greater degree than with either drug alone. Additional investigation is warranted, and caution should be exercised in giving verapamil to patients during regional anesthesia. Should an adverse drug interaction ensue, the administration of calcium may be beneficial.

Cardiopulmonary arrest after retrobular block.

A 61-year-old woman experienced a cardiopulmonary arrest immediately after the retrobulbar injection of a mixture of 2 ml of 0.5% bupivacaine HCl, 2% mepivacaine HCl, and hyaluronidase. The patient was immediately resuscitated but remained unconscious for a total of 20 minutes. All neurologic deficits resolved completely over the two hours following the cardiopulmonary arrest and no adverse sequelae were noted. We assumed that this cardiopulmonary arrest was precipitated by the local anesthetic being transported via retrograde flow through the ophthalmic artery and then by antegrade flow through the internal carotid artery to the thalamus and other midbrain structures.

Failure of transcutaneous electrical stimulation to alleviate experimental tourniquet pain.

It has been proposed that transcutaneous electrical nerve stimulation (TENS) acts by stimulation of large nerve fibers which inhibits further propagation of nociceptive input conducted along smaller C-nerve fibers. We evaluated the effectiveness of TENS in alleviation of ischemic pain (C-fiber mediated) experimentally produced by the submaximal-effort tourniquet test. Cutaneous electrodes were placed proximal to the tourniquet and TENS was begun prior to exsanguination of the arm. Time from inflation of the tourniquet to onset of intolerable pain was noted together with a visual analog-derived intensity of pain for 10 subjects studied on three separate occasions. The results showed no statistically significant prolongation in the duration of ischemia tolerated nor reduction in the subjective intensity of pain during either single- or dual-channel stimulation in comparison to control levels.

Transdermal scopolamine decreases nausea and vomiting following cesarean section in patients receiving epidural morphine.

The authors evaluated the antiemetic properties of transdermal scopolamine (TDS) in healthy patients undergoing elective cesarean section and receiving epidural morphine for postoperative analgesia. Prior to administration of anesthesia, 203 patients had either TDS or a placebo study patch applied behind one ear. All patients were hydrated with lactated Ringer's solution iv and given 2.0% lidocaine with 1:200,000 epinephrine epidurally for surgical anesthesia. Following delivery of the infant, 4 mg of morphine sulphate was injected through the epidural catheter. After the operation patients were evaluated by "blinded" observers at 2, 4, 6, 8, 10, 24, and 48 h for nausea, vomiting, retching, pain relief, itching, and adverse effects. In addition, medications received were noted. No differences were found between the groups in terms of severity or incidence of pain, or requests for analgesic or antipruritic medication. Although there was no difference between the groups in the first 2 h, patients with TDS had significantly less nausea, vomiting, and retching than patients in the placebo group in each time interval between 2 and 10 h. Additionally, the TDS group required less antiemetic medication. There was no difference in the frequency of retching or vomiting between groups. Side effects were minimal and equal in both groups. The authors conclude that TDS results in a decreased incidence of nausea and vomiting in patients who have delivered by cesarean section and received epidural morphine. TDS appears safe for continuous antiemetic administration.

Costello syndrome: phenotype, natural history, differential diagnosis, and possible cause.

We describe 8 patients affected with Costello syndrome including an affected sib pair and review the literature on 29 previously reported cases. We emphasize an association with advanced parental age, which is consistent with autosomal dominant inheritance with germline mosaicism. The pathogenesis appears to involve metabolic dysfunction, with growth disturbance, storage disorder appearance, acanthosis nigricans, hypertrophic cardiomyopathy, and occasional abnormalities of glucose metabolism. Although the cause is currently unknown, Costello syndrome is interesting because of a potential genetic-metabolic etiology.