Influence of Pain Sensitivity on Surgical Outcomes of Arthroscopic Rotator Cuff Repair: A Prospective Cohort Study

BACKGROUND

The Pain Sensitivity Questionnaire (PSQ) has been found to be a valid tool, and PSQ scores have been shown to be predictive of outcomes after surgery for lumbar stenosis. The effect of pain sensitivity on outcomes of rotator cuff repair (RCR) surgery has not been examined.

HYPOTHESIS

PSQ scores would be associated with surgical outcomes after arthroscopic RCR surgery.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Patients 18 to 80 years old scheduled for RCR were consecutively enrolled. Patients with glenohumeral arthritis grade ≥2 or RCR revision surgery were excluded. PSQ was completed preoperatively. The Disabilities of the Arm, Shoulder and Hand score and American Shoulder and Elbow Surgeons score were used as patient-reported outcome measurements (PROMs), and visual analog scale pain score was documented as well. Active shoulder external rotation (ER), internal rotation, and anterior forward elevation range of motion (ROM) were recorded. PROMs and ROM measurements were recorded preoperatively and at 3 months, 6 months, and 1 year after surgery. Rotator cuff tear size, type of repair, and concomitant procedures were documented. Patients were classified as having high or normal pain sensitivity based on PSQ scores.

RESULTS

Of 100 enrolled patients, 38 patients were classified as having high pain sensitivity. Patients with high pain sensitivity had worse American Shoulder and Elbow Surgeons and Disabilities of the Arm, Shoulder and Hand scores preoperatively, 6 months postoperatively, and 1 year postoperatively (P < .01). From the preoperative assessment to 3 months postoperatively, PROMs improved more in patients with high versus normal pain sensitivity. However, for patients with high pain sensitivity, PROMs plateaued after 3 months but continued to improve for patients with normal pain sensitivity (P < .01). Visual analog scale pain scores were higher at all time points for patients with high pain sensitivity (P < .05). Preoperatively, patients with high pain sensitivity had restricted active ROM compared with patients who had normal pain sensitivity for anterior forward elevation, ER, and internal rotation (P = .009, P = .012, and P = .006, respectively). By 1 year after surgery, ER ROM was still restricted in patients with high pain sensitivity.

CONCLUSION

Pain sensitivity is an important factor influencing RCR outcomes. Patients with high pain sensitivity undergoing RCR showed less improvement in active ROM and worse PROMs after surgery compared with patients who had normal pain sensitivity. Preoperative PSQ may predict postoperative improvements.

Incidence of concussions and helmet use in equestrians

OBJECTIVES

Equestrians have a high risk of concussions per hospital records. However, most concussions occur in private settings where concussions are not tracked. We determined concussion incidence by self-report, expressed per 1000 h of exposure, and determined helmet usage and concussion knowledge.

DESIGN

Descriptive epidemiological study.

METHODS

Equestrians were recruited using a snowball method of sampling in which enrolled participants recruited more equestrians. Participants completed a survey of equestrian experience and history of concussion, symptoms and provided estimates of hours spent in various equestrian activities. From these data, incidences of concussions were calculated. In addition, they answered questions regarding helmet usage and willingness to take risks when concussed.

RESULTS

210 participants (203 women) reported 27 ± 14 years of equine experience and 728 concussions, 3.47 ± 5.34 per person (0-55). Incidence while riding was 0.19/1000 h which was greater than the incidence while driving (0.02/1000 h) or handling horses (0.03/1000 h). Riders were helmeted at the time of injury 85% of the time. While concussion knowledge was high, most reported willingness to risk permanent injury by continuing to work with horses while injured.

CONCLUSIONS

To our knowledge this is the first study to document incidence of concussions in equestrians: incidence is higher while riding than during football or rugby training. Helmets were far more commonly worn at the time of concussion than reported in hospital data, suggesting that helmets effectively reduce concussions severe enough to warrant urgent medical care.

Endo-hepatology: An emerging field

Gastroenterologists have long been spearheading the care of patients with various forms of liver disease. The diagnosis and management of liver disease has traditionally been a combination of clinical, laboratory, and imaging findings coupled with percutaneous and intravascular procedures with endoscopy largely limited to screening for and therapy of esophageal and gastric varices. As the applications of diagnostic and therapeutic endoscopic ultrasound (EUS) have evolved, it has found a particular niche within hepatology now coined endo-hepatology. Here we discuss several EUS-guided procedures such as liver biopsy, shear wave elastography, direct portal pressure measurement, paracentesis, as well as EUS-guided therapies for variceal hemorrhage.

Effect of Intraoperative Platelet-Rich Plasma Treatment on Postoperative Donor Site Knee Pain in Patellar Tendon Autograft Anterior Cruciate Ligament Reconstruction: A Double-Blind Randomized Controlled Trial

BACKGROUND

Donor site morbidity in the form of anterior knee pain is a frequent complication after bone-patellar tendon-bone (BPTB) autograft anterior cruciate ligament (ACL) reconstruction. Hypothesis/Purpose: The purpose was to examine the effect of the intraoperative administration of platelet-rich plasma (PRP) on postoperative kneeling pain. It was hypothesized that PRP treatment would reduce knee pain.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 2.

METHODS

Fifty patients (mean ± SD age, 30 ± 12 years) undergoing BPTB ACL autograft reconstruction were randomized to the PRP (n = 27) or sham (n = 23) treatment. In either case, 10 mL of venous blood was drawn before the induction of anesthesia and either discarded (sham) or processed (PRP) for preparation of a PRP gel to be later mixed with donor site bone chips and inserted into the patellar defect. At 12 weeks, 6 months, 1 year, and 2 years after surgery, patients completed International Knee Documentation Committee (IKDC) forms and visual analog scale pain scores for activities of daily living and kneeling. Healing indices at the donor site were assessed by routine noncontrast magnetic resonance imaging (MRI) at 6 months. Mixed-model analysis of variance was used to assess the effect of PRP on patient symptoms and MRI indices of donor site healing, as measured by the width of the donor site defect.

RESULTS

Kneeling pain, pain with activities of daily living, and IKDC scores were not different between treatment groups at any of the time intervals ( P = .08-.83). Kneeling pain improved from 12 weeks to 6 months and from 1 to 2 years ( P < .05). IKDC scores improved substantially from 12 weeks to 6 months ( P < .001) and continued to improve to 2 years (PRP, 86 ± 19; sham, 89 ± 10). MRI indices of donor site healing were not different between treatment groups ( P = .53-.90).

CONCLUSION

Whether randomized to receive PRP in their patellar defect or not, patients continued to have similar levels of kneeling pain and patellar defect sizes after autograft BPTB ACL reconstruction. Registration: NCT01765712 ( ClinicalTrials.gov identifier).

Clinical outcomes of the addition of eccentrics for rehabilitation of previously failed treatments of golfers elbow

INTRODUCTION AND PURPOSE

Eccentric training of the wrist extensors has been shown to be effective in treating chronic lateral epicondylosis. However, its efficacy in the treatment of medial epicondylosis has yet to be demonstrated. The objective of this study was to assess the effectiveness of a novel eccentric wrist flexor exercise added to standard treatment for chronic medial epicondylosis in patients who did not respond to previous therapeutic interventions for this disorder.

NUMBER OF SUBJECTS

20.

MATERIALS/METHODS

Patients (13 men, 7 women; age 49±12 yr) with chronic medial epicondylosis who had failed previous treatment for this disorder (physical therapy 7, cortisone injection 7, PRP 1, NSAIDS 15) were prescribed isolated eccentrics in addition to wrist stretching, ultrasound, cross-friction massage, heat and ice. The specific isolated eccentric wrist flexor strengthening exercise performed by the patients involved twisting a rubber bar (Flexbar, Hygenic Corportation, Akron OH) with concentric wrist flexion of the noninvolved arm and releasing the twist by eccentrically contracting the wrist flexors of the involved arm (3 × 15 twice daily). A DASH questionnaire was recorded at baseline and again after the treatment period. Treating clinicians were blinded to baseline DASH scores. Treatment effect was assessed using paired t-test. Based on previous work it was estimated that with a sample of 20 patients there would be 80% power to detect a 13 point improvement in DASH scores (p<.05).

RESULTS

The pathology was in the dominant arm of 18 patients and recurrent in 10. Primary symptomatic activities were golf (14), tennis (2), basketball (1), weight lifting (1), and general activities of daily living (2). There was a significant improvement in outcomes following the addition of isolated eccentrics (Pre DASH 34.7±16.2 vs. Post DASH 7.9±11.1, p<.001). For the 18 patients involved in sports, the sports module of the DASH score improved from 73.9±28.9 to 13.2±25.0, p<.001). Physical therapy visits ranged from 1-22 with an average of 12±6 and, average treatment duration of 6.1±2.5 wks (range 1-10). Home exercise program compliance was recorded for each subject (15 full, 3 mostly, 1 occasionally, 1 none).

CONCLUSIONS

The outcome measure for chronic medial epicondylosis was markedly improved with the addition of an eccentric wrist flexor exercise to standard physical therapy. Given the inconsistent outcomes for patients previously treated with chronic medial epicondylosis the addition of isolated eccentrics seems warranted based on the results of this study.

CLINICAL RELEVANCE

This novel exercise, using an inexpensive rubber bar, provides a practical means of adding isolated eccentric training to the treatment of chronic medial epicondylosis.

LEVEL OF EVIDENCE

2b.

Vascular development during distraction osteogenesis proceeds by sequential intramuscular arteriogenesis followed by intraosteal angiogenesis

Vascular formation is intimately associated with bone formation during distraction osteogenesis (DO). While prior studies on this association have focused on vascular formation locally within the regenerate, we hypothesized that this vascular formation, as well as the resulting osteogenesis, relies heavily on the response of the vascular network in surrounding muscular compartments. To test this hypothesis, the spatiotemporal sequence of vascular formation was assessed in both muscular and osseous compartments in a murine model of DO and was compared to the progression of osteogenesis. Micro-computed tomography (μCT) scans were performed sequentially, before and after demineralization, on specimens containing contrast-enhanced vascular casts. Image registration and subtraction procedures were developed to examine the co-related, spatiotemporal patterns of vascular and osseous tissue formation. Immunohistochemistry was used to assess the contributory roles of arteriogenesis (formation of large vessels) and angiogenesis (formation of small vessels) to overall vessel formation. Mean vessel thickness showed an increasing trend during the period of active distraction (p=0.068), whereas vessel volume showed maximal increases during the consolidation period (p=0.009). The volume of mineralized tissue in the regenerate increased over time (p<0.039), was correlated with vessel volume (r=0.59; p=0.025), and occurred primarily during consolidation. Immunohistological data suggested that: 1) the period of active distraction was characterized primarily by arteriogenesis in the surrounding muscle; 2) during consolidation, angiogenesis predominated in the intraosteal region; and 3) vessel formation proceeded from the surrounding muscle into the regenerate. These data show that formation of vascular tissue occurs in both muscular and osseous compartments during DO and that periods of intense osteogenesis are concurrent with those of angiogenesis. The results further suggest the presence of morphogenetic factors that coordinate the development of vascular tissues from the intramuscular compartment into the regions of osseous regeneration.

Vascular tissues are a primary source of BMP2 expression during bone formation induced by distraction osteogenesis

Prior studies showed that bone regeneration during distraction osteogenesis (DO) was dependent on vascular tissue development and that inhibition of VEGFR signaling diminished the expression of BMP2. A combination of micro-computed tomography (μCT) analysis of vascular and skeletal tissues, immunohistological and histological analysis of transgenic mice containing a BAC transgene in which β-galactosidase had been inserted into the coding region of BMP2 and qRT-PCR analysis, was used to examine how the spatial temporal expression of the morphogenetic signals that drive skeletal and vascular tissue development is coordinated during DO. These results showed that BMP2 expression was induced in smooth muscle and vascular endothelial cells of arteries and veins, capillary endothelial cells, hypertrophic chondrocytes and osteocytes. BMP2 was not expressed by lymphatic vessels or macrophages. Separate peaks of BMP2 mRNA expression were induced in the surrounding muscular tissues and the distraction gap and corresponded first with large vessel collateralization and arteriole remodeling followed by periods of angiogenesis in the gap region. Immunohistological and qRT-PCR analysis of VEGF receptors and ligands showed that mesenchymal cells, lining cells and chondrocytes, expressed VEGFA, although PlGF expression was only seen in mesenchymal cells within the gap region. On the other hand VEGFR2 appeared to be predominantly expressed by vascular endothelial and hematopoietic cells. These results suggest that bone and vascular tissue formation is coordinated via a mutually supporting set of paracrine loops in which blood vessels primarily synthesize the morphogens that promote bone formation while mesenchymal cells primarily synthesize the morphogens that promote vascular tissue formation.

Key pecking in pigeons produced by pairing keylight with inaccessible grain

In Experiment I, keylight was paired with inaccessible grain delivery (under two conditions of keylight intensity) to determine if autoshaping would occur in the absence of primary reinforcement. In Experiment II, the procedure was repeated with accessible grain, for comparison. In Experiment III, the procedures were repeated with explicitly unpaired presentations of keylight and either inaccessible or accessible grain. The results indicated that key pecking occurred as quickly in the presence of keylight pairings with inaccessible grain as with accessible grain, though (except for one bird) key pecking was not maintained with inaccessible grain. Furthermore, compared to the dim keylight, the bright keylight greatly suppressed key pecking when paired with inaccessible grain, and reduced the rate of key pecking when paired with accessible grain. Little key pecking occurred in groups exposed to explicitly unpaired presentations of keylight (whether bright or dim) and grain (whether accessible or inaccessible). When the birds in Experiment III were retested with explicitly paired presentations of keylight and grain, little key pecking was observed, suggesting suppressive effects of prior explicitly unpaired presentations. It is suggested that the effects of key-brightness manipulation were produced by the association of grain with cues other than the response key, or by distraction produced by partial illumination of the grain hopper.

Transcatheter closure of an atrial septal defect in a dog

Atrial septal defect, while rare in dogs, can result in severe clinical signs. Surgical correction of atrial septal defect requires open-heart surgery. Transcatheter closure techniques provide minimally invasive surgical alternatives.

Effect of knee flexion angle on active joint stiffness

AIM

The purpose of this study was to determine if active joint stiffness measured during maximum voluntary knee extension contractions was affected by knee flexion angle.

METHODS

Eighteen subjects volunteered (11 male, seven female). A stretch was imposed on isometric knee contractions performed at 30 degrees, 50 degrees, 70 degrees, 90 degrees, and 110 degrees of knee flexion. Active joint stiffness was computed from the increase in torque relative to the change in knee flexion angle for the first 50 ms of the stretch (approximately 1.5 degrees ) and corrected for effects of gravitational component due to leg mass and passive tension.

RESULTS

There was a plateau in knee extension torque between 70 degrees and 90 degrees with lower values at all other angles (P < 0.05). Peak active joint stiffness occurred at 70 degrees with lower values (P < 0.05) at all other angles except 50 degrees. Stiffness at 70 degrees (441.1 +/- 189.9 Nm rad-1) was 49% higher than at 30 degrees and 45% higher than at 110 degrees.

CONCLUSION

Active joint stiffness was dependent on knee flexion angle. Peak joint stiffness during maximal contractions occurred at, or prior to, the optimal angle for torque production for all subjects.

Emergency department impact of the Oklahoma City terrorist bombing

STUDY OBJECTIVE

To collect descriptive epidemiologic injury data on patients who suffered acute injuries after the April 19, 1995, Oklahoma City bombing and to describe the effect on metropolitan emergency departments.

METHODS

A retrospective review of the medical records of victims seen for injury or illness related to the bombing at 1 of the 13 study hospitals from 9:02 AM to midnight April 19, 1995. Rescue workers and nontransported fatalities were excluded.

RESULTS

Three hundred eighty-eight patients met inclusion criteria; 72 (18.6%) were admitted, 312 (80.4%) were treated and released, 3 (.7%) were dead on arrival, and 1 had undocumented disposition. Patients requiring admission took longer to arrive to EDs than patients treated and released (P =.0065). The EDs geographically closest to the blast site (1.5 radial miles) received significantly more victims than more distant EDs (P <.0001). Among the 90 patients with documented prehospital care, the most common interventions were spinal immobilization (964/90, 71.1%), field dressings (40/90, 44.4%), and intravenous fluids (32/90, 35.5%). No patients requiring prehospital CPR survived. Patients transported by EMS had higher admission rates than those arriving by any other mode (P <.0001). The most common procedures performed were wound care and intravenous infusion lines. The most common diagnoses were lacerations/contusion, fractures, strains, head injury, abrasions, and soft tissue foreign bodies. Tetanus toxoid, antibiotics, and analgesics were the most common pharmaceutical agents used. Plain radiology, computed tomographic radiology, and the hospital laboratory were the most significantly utilized ancillary services.

CONCLUSION

EMS providers tended to transport the more seriously injured patients, who tended to arrive in a second wave at EDs. The closest hospitals received the greatest number of victims by all transport methods. The effects on pharmaceutical use and ancillary service were consistent with the care of penetrating and blunt trauma. The diagnoses in the ED support previous reports of the complex but often nonlethal nature of bombing injuries.

The medical impact of tornadoes in North America

North America suffers some of the most severe tornado disasters of any location on the planet. Significant injury and economic impact may result from these storms, particularly in rural areas. Tornadic storms present unique problems for prehospital and Emergency Department personnel. Soft tissue injuries seen after tornadoes are contaminated with polymicrobial flora and may require delayed primary closure. Fractures are a frequent cause of hospital admission and head injury is a frequent cause of death. Advanced warning and proper sheltering actions by a population are the most significant factors in reducing morbidity and mortality. This article reviews the pertinent literature on the medical impact of tornadoes and details the mechanisms of injury, nature of injuries, pre-hospital and ED planning points associated with tornadic storms.

The emergency department approach to diarrhea

Enteric disease represents a significant medical problem on a worldwide basis. The evaluation of patients with diarrhea in the emergency department should follow a stepwise methodology to identify potentially serious disorders. The evaluation of the stool for fecal leukocytes is an important differentiation point in the evaluation of the moderately to seriously ill diarrhea patient. Oral rehydration alone can treat the vast majority of diarrhea patients. Oral rehydration solution takes advantage of the sodium glucose coupled active absorption mechanism, which is largely unaffected by enteric toxins. Antimicrobial or antidiarrheal agents are rarely indicated in the treatment of diarrhea.

When a snake bites

Primary care physicians may be required to treat snake-bitten patients and must differentiate between venomous and nonvenomous snakes. The chief distinguishing characteristics of venomous snakes are fangs and a single row of subcaudal anal plates. The physiologic effects of snake venom are on the cardiovascular, hematologic, and neurovascular systems. The snake-bitten patient first needs supportive treatment and stabilization. Then, the physician must establish whether envenomation has occurred, grade it, and monitor edema around the bite. Local treatment, broad-spectrum antibiotics, and tetanus prophylaxis should be used for all envenomation grades. The decision to administer antivenin therapy should be made on clinical grounds and the envenomation grade. Its use, however, can lead to anaphylaxis and anticomplement reactions.

A prospective evaluation of risk factors for infections from dog-bite wounds

OBJECTIVE

To define risk factors for infections from dog- bite wounds and to model the probability of wound infection in patients presenting without infection who are treated as outpatients.

METHODS

A prospective survey of 769 consecutive dog-bite victims presenting over a two-year period to a community hospital emergency department (ED) with an emergency medicine residency program. A standardized wound-cleaning protocol was used, which included debridement and wound closure when indicated. Wounds were examined for infection at follow-up. Variables analyzed included demographic data (patient age, gender, race); wound information (wound age, type, number, location, depth); and treatment (prior to hospital, ED debridement, suturing, tetanus or rabies shots, antibiotics).

RESULTS

There were 734 patients with complete records. These patients had a mean age of 13.4 +/- 13.2 years (range, 4 months to 71 years). Infection was evident in 2.5% of the wounds upon presentation. There were 704 patients (765 wounds) managed as outpatients and without wound infection upon presentation. Wounds were distributed as follows: 26.7% head/neck, 20.4% hand, 15.7% arm, 10.1% trunk, 9.5% thigh, 15.9% leg, and 1.7% foot. There were 32.9% puncture, 39.9% full-thickness, and 60.1% partial-thickness wounds. Wound infections were diagnosed in 2.1% Of these wounds at follow-up. Wounds requiring surgical debridement had a sevenfold higher infection rate (p = 0.01). Patients more than 50 years of age had a sixfold higher infection rate than younger patients (p = 0.05). Stepwise logistic regression found the following variables to be the best predictors for wound infection: full-thickness [p = 0.006, odds ratio (OR) = 6.23], female gender (p = 0.048, OR = 2.88), and wound debridement (p = 0.024, OR = 5.01). Combinations of these three variables predict infection rates from 0.35% to 23.9%.

CONCLUSION

A low wound infection rate was seen in this cohort of dog-bite victims who were treated on an outpatient basis. Wound depth, patient gender, and wound debridement were the clinical variables that best predicted the likelihood of developing infection. Future interventional studies should concentrate on wounds with high probabilities of infection.

Double-blinded comparison of diphenhydramine versus lidocaine as a local anesthetic

STUDY OBJECTIVE

To evaluate the efficacy, onset of action, duration of action, and side effects of 1% diphenhydramine compared with 1% lidocaine when used as a local anesthetic agent.

DESIGN

Prospective, double-blinded, cross-over study.

SETTING

Emergency medicine residency program, research section.

PARTICIPANTS

Ten healthy male volunteers, aged 26 to 38 years old.

INTERVENTIONS

Baseline levels of sensation to pinprick (18-gauge needle) within a 2.4-cm-diameter midvolar forearm area and levels of sedation were recorded on 10.2-cm visual analog scales. Subjects then underwent subcutaneous infiltration of 20 mg (2 mL) of the study agent using a 27-gauge needle. Visual analog scale sensation and sedation scores were recorded at five, ten, and 15 minutes and then every 15 minutes until return to baseline. Subjects were studied one week later with the alternate agent. Nonparametric data were analyzed using the Mann-Whitney U test with significance at P < .05.

RESULTS

No significant differences in mean pinprick sensation were seen from baseline to 30 minutes. Significant differences were seen at 45 (P = .036) and 60 minutes (P = .036). The mean duration of effective anesthesia was significantly longer for lidocaine than diphenhydramine (81 versus 42 minutes, P = .028). No significant differences were seen in the sedation scores or in the frequencies of local reactions. One subject developed skin necrosis at the injection site with diphenhydramine.

CONCLUSION

The duration of local anesthesia for 1% lidocaine was significantly longer and the depth of anesthesia after 30 minutes was significantly higher than that of 1% diphenhydramine. Diphenhydramine resulted in skin necrosis in one test subject.

Prophylactic oral antibiotics for low-risk dog bite wounds

The use of prophylactic antibiotics in the initial treatment of noninfected dog bite wounds is controversial. All patients with noninfected dog bite wounds who presented to our emergency department (ED) over a two-year period were considered for entry into a randomized prospective study. Patients were excluded from the study if they had any high-risk criteria for infection: puncture wounds, hand or foot wounds, wounds greater than 12 hours old, a history of immunocompromising disorders, or the use of immunosuppressive drugs. Patients in the antibiotic group (n = 89) were treated with local wound care and given either dicloxacillin, cephalexin, or erythromycin orally for seven days. Patients in the control group (n = 96) received local wound care only. All patients had their wounds irrigated with a 1% povidone-iodine solution and debrided and sutured if clinically indicated. All patients were subsequently reevaluated for clinical signs of wound infection. The groups were similar in age, sex, time of delay in seeking treatment, anatomic sites of wounds, depths and types of wounds, and number of wounds requiring suturing. The wound infection rates for the antibiotic and control groups were 1.1 and 5.1%, respectively. This difference was not significant (P = 0.212). There were 36 wounds in the antibiotic group and 37 wounds in the control group that were full thickness. The infection rates for these wounds were 2.8 and 13.5%, respectively. This was not statistically significant (P = 0.132). This study suggests that prophylactic oral antibiotics in low-risk dog bite wounds are not indicated.

Venomous snakes of southwest Asia

This report provides a brief description of the venomous snakes encountered in Southwest Asia, as well as a brief review of the clinical implications of envenomation from each animal. Specific therapy for snake envenomation in the United States is somewhat controversial, and it is no less controversial with animals from this region. The most logical approach probably combines medical management with antivenom when available, and surgical intervention when clearly indicated due to elevated compartment pressure or massive tissue necrosis. Antivenom is available for all species except W aegyptia (in vitro only) and Atractaspis species. Antivenom for V palaestinae may be used for Atractaspis envenomation (Tables 2 and 3).

Imaging after head trauma. Who needs what?

Decisions about the optimal imaging strategy in patients after acute head trauma can be based on clinical observations. Low-risk patients do not require radiographic imaging. CT is the procedure of choice for imaging moderate- and high-risk patients after head trauma. Because of its limited ability to guide therapy, plain skull radiography should be used sparingly; it may be useful in equivocal cases of bony injury not detected by CT or in selected moderate-risk patients (especially children under the age of 2 years). MR imaging rivals CT in the detection of intracranial injuries but is more expensive and cumbersome in seriously ill subjects and does not image bony structures. MR imaging is recommended after initial CT if subtle acute nonhemorrhagic and subacute hemorrhagic lesions are suspected, especially in the evaluation of child abuse. Otherwise, MR imaging is rarely needed in the emergency department management of acute head injury patients.

Anaphylactic shock secondary to rattlesnake bite

Anaphylactic reactions to Crotalidae envenomation are extremely rare. The presentation of anaphylaxis after envenomation can be a confusing variable in the timely diagnosis of both problems. The therapy of this dual disorder involves combining treatment of the obvious shock from the allergic reaction with a standard approach to Crotalidae envenomation. We present the case of a 22-year-old man who presented to the emergency department with urticaria, hypotension, and bronchospasm that developed immediately after his second envenomation from a rattlesnake. His symptoms resolved after administration of 0.8 mg SQ epinephrine, 100 mg IV diphenhydramine, 2,000 mL normal saline IV, and 250 mg IV methylprednisolone. Only one previous case report of anaphylactic shock from a rattlesnake bite could be found in the medical literature.

Oddity learning in the pigeon as a function of the number of incorrect alternatives

Pigeons' rate of learning a two-color oddity task increased as a function of the number of incorrect alternatives from 2 to 24 in Experiments 1, 2, and 3. In general, pigeons that were transferred from many-incorrect-alternative to two-incorrect-alternative oddity performed better than controls, but considerably below baseline (Experiments 2 and 3). In Experiment 4, pigeons showed no unconditioned tendency to peck the odd stimulus among 24 incorect alternatives, when pecks were nondifferentially reinforced, and in Experiment 5, when this procedure was preceded by oddity training, a progressive drop in odd-stimulus pecking was found. In Experiment 6, pigeons exposed to a nine-stimulus array in which the odd stimulus appeared (a) in the center or (b) separate from the array learned faster than when the odd stimulus was at the edge. This outcome suggests ththe figure-ground relation between the odd stimulus and the incorrect alternatives plays a role in the facilitation produced by increasing the number of incorrect alternatives but that poor performance on the standard, three-alternative oddity task appears to be due to center-odd trials which provide a difficult size or number discrimination.