Acute aortic occlusion: A narrative review for emergency clinicians.

INTRODUCTION: Acute aortic occlusion (AAO) is a rare but serious condition associated with significant morbidity and mortality. OBJECTIVE: This review provides an emergency medicine focused evaluation of AAO, including presentation, assessment, and emergency department (ED) management based on current evidence. DISCUSSION: AAO refers to obstruction of blood flow through the aorta due to either thrombosis or embolism. This condition primarily affects older adults ages 60-70 with cardiovascular comorbidities and most commonly presents with signs and symptoms of acute limb ischemia, though the gastrointestinal tract, kidneys, and spinal cord may be affected. The first line imaging modality includes computed tomography angiography of the chest, abdomen, and pelvis. ED resuscitative management consists of avoiding extremes of blood pressure or heart rate, maintaining normal oxygen saturation and euvolemic status, anticoagulation with heparin, and pain control. Emergent consultation with the vascular surgery specialist is recommended to establish a plan for restoration of perfusion to ischemic tissues via endovascular or open techniques. High rates of baseline comorbidities present in the affected population as well as ischemic and reperfusion injuries place AAO patients at high risk for complications in an immediate and delayed fashion after surgical management. CONCLUSIONS: An understanding of AAO can assist emergency clinicians in diagnosing and managing this rare but devastating disease.

High risk and low incidence diseases: Pediatric digestive volvulus.

INTRODUCTION: Pediatric digestive volvulus is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of pediatric digestive volvulus, including the presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Pediatric digestive volvulus is a deadly condition most commonly associated with malrotation. It occurs when the stomach or small intestine twists on itself, resulting in ischemia and potentially strangulation with necrosis and perforation. Presentation differs based on the gastrointestinal (GI) segment affected, degree of twisting, and acuity of the volvulus. Gastric volvulus most commonly presents with retching with or without nonbilious emesis and epigastric distension with pain, while midgut volvulus typically presents with bilious emesis in infants. Patients with GI necrosis and perforation may present with hemodynamic compromise and peritonitis. If suspected, emergent consultation with the pediatric surgery specialist is necessary, and if this is not available, transfer to a center with a pediatric surgeon is recommended. Imaging includes plain radiography, ultrasound, or upper GI series, while treatment includes resuscitation, administration of antibiotics, and emergent surgical decompression and detorsion of the involved segments. CONCLUSION: An understanding of pediatric digestive volvulus and its many potential mimics can assist emergency clinicians in diagnosing and managing this deadly disease.

Updates in emergency medicine: Ectopic pregnancy.

INTRODUCTION: Ectopic pregnancy is a serious condition that can have significant morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of ectopic pregnancy, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Ectopic pregnancy is a pregnancy that implants outside the normal uterine cavity. It most commonly presents with vaginal bleeding, abdominal or pelvic pain, and amenorrhea. Risk factors for ectopic pregnancy include abnormalities of the fallopian tube, prior ectopic pregnancy, and age over 35 years, but a significant number of patients with confirmed ectopic pregnancy will not have an identifiable risk factor. In patients with suspected ectopic pregnancy, evaluation includes quantitative serum hCG, blood type, and ultrasound. Ultrasound is necessary regardless of the hCG level. If the patient is hemodynamically unstable, resuscitation with blood products and early consultation of obstetrics/gynecology is necessary. Patients with confirmed ectopic pregnancy but who are otherwise stable may be managed medically or surgically. If a yolk sac or fetal pole is not seen in the uterus on ultrasound, this is considered a pregnancy of unknown location (PUL), which may represent an early, failed, or ectopic pregnancy. Stable patients with a PUL who can reliably follow up are managed with close specialist follow up and repeat 48 h HCG level. These patients need to have an hCG level repeated every 48 h until diagnosed with a viable pregnancy, failed pregnancy, or ectopic pregnancy. CONCLUSIONS: Knowledge of the latest advances in managing ectopic pregnancy will help clinicians more quickly and accurately diagnose patients presenting with this potentially fatal condition.

High risk and low prevalence diseases: Spontaneous cervical artery dissection.

INTRODUCTION: Spontaneous cervical artery dissection (sCAD) is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of sCAD, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: sCAD is a condition affecting the carotid or vertebral arteries and occurs as a result of injury and compromise to the arterial wall layers. The dissection most commonly affects the extracranial vessels but may extend intracranially, resulting in subarachnoid hemorrhage. Patients typically present with symptoms due to compression of local structures, and the presentation depends on the vessel affected. The most common symptom is headache and/or neck pain. Signs and symptoms of ischemia may occur, including transient ischemic attack and stroke. There are a variety of risk factors for sCAD, including underlying connective tissue or vascular disorders, and there may be an inciting event involving minimal trauma to the head or neck. Diagnosis includes imaging, most commonly computed tomography angiography of the head and neck. Ultrasound can diagnose sCAD but should not be used to exclude the condition. Treatment includes specialist consultation (neurology and vascular specialist), consideration of thrombolysis in appropriate patients, symptomatic management, and administration of antithrombotic medications. CONCLUSIONS: An understanding of sCAD can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Acute mastoiditis.

INTRODUCTION: Acute mastoiditis is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of mastoiditis, including the presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Acute mastoiditis most commonly affects pediatric patients and is a suppurative infection of the mastoid air cells. It is often associated with otitis media, and common bacteria include Streptococcus and Staphylococcus. History and examination may reveal tympanic membrane erythema, pinna protrusion, postauricular erythema, mastoid tenderness with palpation, external canal swelling, otorrhea, fever, and malaise. The disease should be suspected in those who fail treatment for otitis media and those who demonstrate the aforementioned abnormalities on examination and systemic symptoms. Laboratory analysis may reveal evidence of systemic inflammation, but a normal white blood cell count and other inflammatory markers should not be used to exclude the diagnosis. Computed tomography (CT) of the temporal bones with intravenous contrast is the recommended imaging modality if the clinician is unsure of the diagnosis. CT may also demonstrate complications. Treatment includes antibiotics such as ampicillin-sulbactam or ceftriaxone as well as otolaryngology consultation. Complications may include subperiosteal and intracranial abscess, deep neck abscess, facial nerve palsy, meningitis/encephalitis, venous sinus thrombosis, and seizures. CONCLUSIONS: An understanding of acute mastoiditis can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Guillain-Barré syndrome.

INTRODUCTION: Guillain-Barré syndrome (GBS) is a rare but serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of GBS, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: GBS is a rare immune-mediated neurologic disorder with peripheral nerve injury. It most commonly presents weeks after a bacterial or viral infection, though there are a variety of associated inciting events. The diagnosis is challenging and often subtle, as only 25-30% of patients are diagnosed on their initial healthcare visit. Clinicians should consider GBS in patients with progressive ascending weakness involving the lower extremities associated with hyporeflexia, but the cranial nerves, respiratory system, and autonomic system may be involved. While the ED diagnosis should be based on clinical assessment, further evaluation includes laboratory testing, cerebrospinal fluid (CSF) analysis, and potentially neuroimaging. Not all patients demonstrate albumino-cytological dissociation on CSF testing. Several criteria exist to assist with diagnosis, including the National Institute of Neurological Disorders and Stroke criteria and the Brighton criteria. Management focuses first on assessment of the patient's hemodynamic and respiratory status, which may require emergent intervention. Significant fluctuations in heart rate and blood pressure may occur, and respiratory muscle weakness may result in the need for airway protection. Neurology consultation is recommended, and definitive treatment includes PLEX or IVIG. CONCLUSIONS: An understanding of GBS can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Flexor tenosynovitis.

INTRODUCTION: Flexor tenosynovitis (FTS) is a deep space infection of an upper extremity digit which carries a high rate of morbidity. OBJECTIVE: This review highlights the pearls and pitfalls of FTS, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: FTS typically occurs after direct penetrating trauma to the volar aspect of an upper extremity digit. Development of a deep space infection that quickly propagates through the flexor tendon sheath of a digit can result in serious structural damage to the hand and place the patient at risk for significant morbidity such as finger amputation or even result in death. Signs of FTS include symmetrical swelling of the affected finger, the affected finger being held in a flexed position, pain on any attempt of passive finger extension, and tenderness along the course of flexor tendon sheath, known as the Kanavel signs. Systemic symptoms such as fevers and chills may occur. Recognition of these signs and symptoms is paramount in diagnosis of FTS, as laboratory and imaging assessment is not typically diagnostic. ED management involves intravenous antibiotics and emergent surgical specialist consultation. CONCLUSION: An understanding of the presentation and risk factors for development of FTS can assist emergency clinicians in diagnosing and managing this disease in an expedited fashion.

GLP-1 agonists: A review for emergency clinicians.

INTRODUCTION: Glucagon-like peptide 1 (GLP-1) based therapies, including GLP-1 agonists, are currently in use for treatment of diabetes and obesity. However, several complications may occur with their use. OBJECTIVE: This narrative review provides a focused evaluation of GLP-1 agonist therapy and associated complications for emergency clinicians. DISCUSSION: GLP-1 agonists potentiate insulin release and reduce gastric emptying and food intake. These agents have demonstrated significant improvements in glucose control in diabetics and weight loss in obese patients. The two most common agents include subcutaneous semaglutide (Ozempic, approved for type 2 diabetes, and Wegovy, approved for weight loss) and liraglutide (Saxenda, approved for weight loss, and Victoza, approved for type 2 diabetes), though an oral formulation of semaglutide is available (Rybelsus). While these drugs are associated with improved long-term outcomes, there are a variety of associated adverse events. The most common include gastrointestinal (GI) adverse events such as nausea, vomiting, diarrhea, and abdominal pain. Pancreatitis and biliary disease may also occur. Hypersensitivity including injection site reactions have been associated with use, with reports of anaphylaxis and other rashes. Renal adverse events are most commonly associated with severe GI losses. Hypoglycemia may occur when these agents are used with sulfonylureas or insulin. There is also an increased risk of diabetic retinopathy. Due to the current shortage and expense of these medications, many patients have attempted to obtain these medications from non-licensed and unregulated agents, which may be associated with increased risk of serious complications. CONCLUSIONS: An understanding of the indications for GLP-1 agonist use and associated adverse events can assist emergency clinicians.

High risk and low incidence diseases: Lisfranc injury.

INTRODUCTION: Lisfranc injuries are uncommon but frequently misdiagnosed and carry a high rate of morbidity. OBJECTIVE: This review highlights the pearls and pitfalls of Lisfranc injuries, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Lisfranc injuries are caused by high- or low-energy trauma to the tarsometatarsal (TMT) joint complex. The severity of injury exists on a spectrum, ranging from minor subluxations to fractures and dislocations involving the TMT joint complex. They can be complicated by compartment syndrome, neurovascular compromise, and open fractures. Prompt diagnosis is critical in preventing chronic pain and mobility challenges, as even small subluxations can result in significant morbidity. Lisfranc injuries should be considered in all patients with a foot injury. Patients with Lisfranc injuries most commonly present with midfoot pain, swelling, or ecchymosis. Despite the importance of a timely diagnosis, Lisfranc injuries are commonly missed on plain radiographs due to their often subtle findings. When x-rays are negative but there is significant clinical suspicion, emergency clinicians should obtain advanced imaging such as computed tomography to aid in diagnosis. All Lisfranc injuries should be discussed with orthopedic surgery to determine definitive management. Patients who can be discharged should be made non-weightbearing and placed in a short-leg splint. CONCLUSION: The consideration of Lisfranc injuries can help emergency clinicians make a timely diagnosis to prevent future complications.

High risk and low incidence diseases: Massive hemoptysis.

BACKGROUND: Massive hemoptysis (MH) is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of massive hemoptysis, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: MH is a rare but deadly condition. It is defined clinically as any bleeding from the tracheobronchial tree that compromises respiratory or circulatory function. The bronchial artery system is the primary source in the majority of cases of MH. The most common cause is tuberculosis worldwide, but bronchiectasis, bronchogenic carcinoma, and mycetoma are more common causes in the U.S. Patients with MH require rapid assessment and management, as decompensation can be rapid. Patients with altered mental status, inability to clear their sections, respiratory distress, or hemodynamic compromise require emergent airway intervention. The imaging modality of choice is computed tomography angiography with pulmonary arterial phase contrast. A reasonable order or sequence of management includes initial stabilization; assessment for the need for airway intervention; reversal of any coagulopathy; advanced imaging; and emergent consultation of pulmonary, cardiothoracic surgery, and interventional radiology. Ongoing resuscitation including blood products may be required in some patients with MH until definitive hemostasis is achieved. CONCLUSIONS: An understanding of MH can assist emergency clinicians in diagnosing and managing this dangerous disease. Providing a prompt evaluation, obtaining intravenous access, pursuing advanced imaging, providing reversal of coagulopathy, supporting hemodynamics, and appropriate consultation are key interventions in MH.

High risk and low prevalence diseases: Botulism.

INTRODUCTION: Botulism is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of botulism, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Botulism is a neuromuscular disorder caused by toxin production of clostridium species bacteria and is a challenging diagnosis that mimics several other conditions. Children account for the majority of patients, with a foodborne source most common, followed by wound sources, typically from intravenous drug injection. Classically, patients with botulism develop bilateral cranial nerve palsies and symmetric, bilateral, descending paralysis. However, patients may initially present with vague symptomatology, such as weakness and dry mouth, which can make diagnosis challenging. A careful history elucidating exposures such as intravenous drug use or consumption of non-commercial canned products can help differentiate botulism from other disorders causing neuromuscular weakness. If suspected, the Centers for Disease Control should be notified to mobilize antitoxin for treatment as soon as the diagnosis is suspected even prior to confirmatory testing. Antibiotics should be avoided in these patients, as they can potentiate toxin release, unless there is a concomitant infection requiring antibiotic therapy. Patients with botulism can develop respiratory compromise requiring emergent airway management. Prolonged neuromuscular blockade from botulism will lead to a variety of symptoms that require comprehensive intensive care unit level care. CONCLUSION: An understanding of botulism and its many potential mimics can assist emergency clinicians in diagnosing and managing this deadly disease.

High risk and low prevalence diseases: Cavernous sinus thrombosis.

INTRODUCTION: Cavernous sinus thrombosis (CST) is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of CST, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: CST is a potentially deadly thrombophlebitic disease involving the cavernous sinuses. The most common underlying etiology is sinusitis or other facial infection several days prior to development of CST, though other causes include maxillofacial trauma or surgery, thrombophilia, dehydration, or medications. Staphylococcus aureus, streptococcal species, oral anaerobic species, and gram-negative bacilli are the most frequent bacterial etiologies. The most prevalent presenting signs and symptoms are fever, headache, and ocular manifestations (chemosis, periorbital edema, ptosis, ophthalmoplegia, vision changes). Cranial nerve (CN) VI is the most commonly affected CN, resulting in lateral rectus palsy. Other CNs that may be affected include III, IV, and V. The disease may also affect the pulmonary and central nervous systems. Laboratory testing typically reveals elevated inflammatory markers, and blood cultures are positive in up to 70% of cases. Computed tomography of the head and orbits with intravenous contrast delayed phase imaging is recommended in the ED setting, though magnetic resonance venography demonstrates the highest sensitivity. Management includes resuscitation, antibiotics, and anticoagulation with specialist consultation. CONCLUSION: An understanding of CST can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Stevens Johnson syndrome and toxic epidermal necrolysis.

INTRODUCTION: Stevens Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are serious conditions that carry a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of SJS/TEN, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: SJS/TEN is a rare, delayed hypersensitivity reaction resulting in de-epithelialization of the skin and mucous membranes. The majority of cases are associated with medication or infection. Clinicians should consider SJS/TEN in any patient presenting with a blistering mucocutaneous eruption. Evaluation of the skin, mucosal, pulmonary, renal, genital, and ocular systems are essential in the diagnosis of SJS/TEN, as well as in the identification of complications (e.g., sepsis). Laboratory and radiological testing cannot confirm the diagnosis in the ED setting, but they may assist in the identification of complications. ED management includes stabilization of airway and breathing, fluid resuscitation, and treatment of any superimposed infections with broad-spectrum antibiotic therapy. All patients with suspected SJS/TEN should be transferred and admitted to a center with burn surgery, critical care, dermatology, and broad specialist availability. CONCLUSIONS: An understanding of SJS/TEN can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Infected urolithiasis.

INTRODUCTION: Infected urolithiasis is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of infected urolithiasis, including presentation, diagnosis, and management in the emergency department based on current evidence. DISCUSSION: Although urolithiasis is common and the vast majority can be treated conservatively, the presence of a concomitant urinary tract infection significantly increases the risk of morbidity, to include sepsis and mortality. Identification of infected urolithiasis can be challenging as patients may have symptoms similar to uncomplicated urolithiasis and/or pyelonephritis. However, clinicians should consider infected urolithiasis in toxic-appearing patients with fever, chills, dysuria, and costovertebral angle tenderness, especially in those with a history of recurrent urinary tract infections. Positive urine leukocyte esterase, nitrites, and pyuria in conjunction with an elevated white blood cell count may be helpful to identify infected urolithiasis. Patients should be resuscitated with fluids and broad-spectrum antibiotics. Additionally, computed tomography and early urology consultation are recommended to facilitate definitive care. CONCLUSIONS: An understanding of infected urolithiasis can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Myocarditis.

INTRODUCTION: Myocarditis is a serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of myocarditis, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Myocarditis is an inflammatory syndrome of myocardium, most often resulting from a viral infection, that can cause life-threatening cardiovascular collapse. It has a highly variable presentation and no widely available specific diagnostic test, making it a challenging diagnosis. Emergency clinicians should obtain an electrocardiogram and perform bedside ultrasound to assess cardiac function. Treatment in the ED is largely supportive, focusing on resuscitation, cardiovascular support, cardiology specialist consultation, and appropriate disposition. CONCLUSIONS: An understanding of myocarditis can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Candida auris: A focused review for emergency clinicians.

INTRODUCTION: Candida auris is an emerging pathogen and human health threat. However, diagnosis and treatment of fungal infection due to C. auris are challenging. OBJECTIVE: This narrative review provides a focused overview of C. auris for the emergency clinician. DISCUSSION: C. auris was first identified in 2009 and is currently present on all continents except Antarctica. C. auris possesses multiple genetic factors resulting in antimicrobial resistance, increased virulence and survival within the host, and environmental adaptation. It is readily transmitted from person to person and from the environment to a person, resulting in colonization. Infection may develop days to months following colonization, most commonly in those with immunocompromised state, significant comorbidities or other underlying conditions, healthcare exposure, and recent antimicrobial therapy. Candidemia, device infection (e.g., central venous catheter), soft tissue or wound infection, burn infection, osteomyelitis, myocarditis, meningitis, and urinary tract infection have been associated with C. auris. Samples should be obtained from the suspected site of infection for microbiological culture. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with reference databases to differentiate C. auris from other species is optimal for diagnosis, though other molecular testing methods are available. Treatment is challenging due to antifungal resistance, with over 90% resistant to fluconazole. Echinocandins are most commonly used as the first line therapy. Prevention of colonization and infection are vital and include screening in high-risk populations and strict adherence to infection prevention practices with contact precautions and hand hygiene, as well as appropriate decontamination of patient areas. CONCLUSION: An understanding of C. auris can assist emergency clinicians in the care of infected or colonized patients.

Malaria: A focused review for the emergency medicine clinician.

INTRODUCTION: Malaria is a potentially fatal parasitic disease transmitted by the Anopheles mosquito. A resurgence in locally acquired infections has been reported in the U.S. OBJECTIVE: This narrative review provides a focused overview of malaria for the emergency clinician, including the epidemiology, presentation, diagnosis, and management of the disease. DISCUSSION: Malaria is caused by Plasmodium and is transmitted by the Anopheles mosquito. Disease severity can range from mild to severe. Malaria should be considered in any returning traveler from an endemic region, as well as those with unexplained cyclical, paroxysms of symptoms or unexplained fever. Patients most commonly present with fever and rigors but may also experience cough, myalgias, abdominal pain, fatigue, vomiting, and diarrhea. Hepatomegaly, splenomegaly, pallor, and jaundice are findings associated with malaria. Although less common, severe malaria is precipitated by microvascular obstruction with complications of anemia, acidosis, hypoglycemia, multiorgan failure, and cerebral malaria. Peripheral blood smears remain the gold standard for diagnosis, but rapid diagnostic tests are available. Treatment includes specialist consultation and antimalarial drugs tailored depending on chloroquine resistance, geographic region of travel, and patient comorbidities. Supportive care may be required, and patients with severe malaria will require resuscitation. Most patients will require admission for treatment and further monitoring. CONCLUSION: Emergency medicine clinicians should be aware of the presentation, diagnosis, evaluation, and management of malaria to ensure optimal outcomes.

Multiple Sclerosis: An Emergency Medicine-Focused Narrative Review.

BACKGROUND: Multiple sclerosis (MS) is a rare but serious condition associated with significant morbidity. OBJECTIVE: This review provides a focused assessment of MS for emergency clinicians, including the presentation, evaluation, and emergency department (ED) management based on current evidence. DISCUSSION: MS is an autoimmune disorder targeting the central nervous system (CNS), characterized by clinical relapses and radiological lesions disseminated in time and location. Patients with MS most commonly present with long tract signs (e.g., myelopathy, asymmetric spastic paraplegia, urinary dysfunction, Lhermitte's sign), optic neuritis, or brainstem syndromes (bilateral internuclear ophthalmoplegia). Cortical syndromes or multifocal presentations are less common. Radiologically isolated syndrome and clinically isolated syndrome (CIS) may or may not progress to chronic forms of MS, including relapsing remitting MS, primary progressive MS, and secondary progressive MS. The foundation of outpatient management involves disease-modifying therapy, which is typically initiated with the first signs of disease onset. Management of CIS and acute flares of MS in the ED includes corticosteroid therapy, ideally after diagnostic testing with imaging and lumbar puncture for cerebrospinal fluid analysis. Emergency clinicians should evaluate whether patients with MS are presenting with new-onset debilitating neurological symptoms to avoid unnecessary testing and admissions, but failure to appropriately diagnose CIS or MS flare is associated with increased morbidity. CONCLUSIONS: An understanding of MS can assist emergency clinicians in better diagnosing and managing this neurologically devastating disease.

High risk and low prevalence diseases: Acute limb ischemia.

INTRODUCTION: Acute limb ischemia is a rare but serious condition that carries with it a high rate of morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of acute limb ischemia, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: Acute limb ischemia is defined as a sudden decrease in limb perfusion resulting in cessation of blood flow and nutrient and oxygen delivery to the tissues. This leads to cellular injury and necrosis, ultimately resulting in limb loss and potentially systemic symptoms with significant morbidity and mortality. There are several etiologies including native arterial thrombosis, arterial thrombosis after an intervention, arterial embolus, and arterial injury. Patients with acute limb ischemia most commonly present with severe pain and sensory changes in the initial stages, with prolonged ischemia resulting in weakness, sensory loss, and color changes to the affected limb. The emergency clinician should consult the vascular specialist as soon as ischemia is suspected, as the diagnosis should be based on the history and examination. Computed tomography angiography is the first line imaging modality, as it provides valuable information concerning the vasculature and surrounding tissues. Doppler ultrasound of the distal pulses may also be obtained to evaluate for arterial and venous flow. Once identified, management includes intravenous unfractionated heparin and vascular specialist consultation for revascularization. CONCLUSIONS: An understanding of acute limb ischemia can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

High risk and low prevalence diseases: Open globe injury.

INTRODUCTION: Open globe injury (OGI) is a rare but serious condition that carries with it a high rate of morbidity. OBJECTIVE: This review highlights the pearls and pitfalls of OGI, including presentation, diagnosis, and management in the emergency department (ED) based on current evidence. DISCUSSION: OGI refers to full-thickness injury to the layers of the eye. OGI can be caused by blunt or sharp trauma, and subtypes include penetration, perforation, intraocular foreign body (IOFB), globe rupture, or mixed types. OGI is more common in males and usually secondary to work-related injury, but in women it is most commonly associated with falls. Emergency clinicians should first assess for and manage other critical, life-threatening injuries. Following this assessment, a thorough eye examination is necessary. Computed tomography (CT) may suggest the disease, but it cannot definitively exclude the diagnosis. While point-of-care ultrasound (POCUS) is highly sensitive and specific for some findings in OGI, its use is controversial due to potential globe content extrusion. Management includes protecting the affected eye from further injury, preventing Valsalva maneuvers that could extrude ocular contents, updating tetanus vaccination status, administering broad-spectrum antibiotics, and ophthalmology consultation for surgical intervention to prevent the sequelae of blindness and endophthalmitis. CONCLUSION: An understanding of OGI can assist emergency clinicians in diagnosing and managing this sight-threatening traumatic process.