Educational Objective:

Describe the role of imaging to search for embolic sources in the evaluation of cerebrovascular events.

Key Point:

The standard cardiac/carotid artery evaluation for sources of embolic stroke will miss hereditary arteriovenous malformations (AVMs) in the lung as a source of embolic strokes.

Explanation:

The patient’s cutaneous findings on the physical examination, along with history of nosebleeds, suggest hereditary hemorrhagic telangiectasia (also known as Osler-Weber-Rendu disease). People with hemorrhagic telangiectasia are at risk for stroke at a young age due to paradoxical emboli through large pulmonary arteriovenous malformation (AVMs). These AVMs can also result in intermittent hypoxia. Treatment involves embolization or removal of the malformation.

A diagnosis of pulmonary AVMs can be made by contrast echocardiography, in which agitated saline (making bubbles) is intravenously injected during the echocardiogram and bubbles are seen to appear first on the right side of the heart and then, after a delay, on the left side of the heart. In a normal patient, the bubbles would dissipate into the alveoli from the capillary system.

The emergency physician’s task is not so much to actually order the contrast echocardiography but to recognize this patient as someone who is at risk for occult AVMs as a source of embolic strokes and to know that the standard stroke work-up will be inadequate. This might affect transfer decisions to a higher level of care. Also, the emergency department and admission team share responsibility for a missed diagnosis of something that was detectable upon initial presentation.

References:

Faughnan ME, Palda VA, Garcia-Tsao G, et al; HHT Foundation International - Guidelines Working Group. International guidelines for the diagnosis and management of hereditary haemorrhagic telangiectasia. J Med Genet. 2011;48(2):73-87. 

McDonald J, Bayrak-Toydemir P, Pyeritz RE. Hereditary hemorrhagic telangiectasia: an overview of diagnosis, management, and pathogenesis. Genet Med. 2011;13(7):607-616. 

van Gent MW, Post MC, Snijder RJ, Westermann CJ, Plokker HW, Mager JJ. Real prevalence of pulmonary right-to-left shunt according to genotype in patients with hereditary hemorrhagic telangiectasia: a transthoracic contrast echocardiography study. Chest. 2010;138(4):833-839.

Ribeiro, E., Cogez, J., Babin, E. et al. Stroke in hereditary hemorrhagic telangiectasia patients. New evidence for repeated screening and early treatment of pulmonary vascular malformations: two case reports. BMC Neurol 11, 84 (2011). https://doi.org/10.1186/1471-2377-11-84

Educational Objective:

Describe the clinical features suggestive of potential cerebellar ischemia rather than benign peripheral causes to facilitate optimal emergency management.

Key Point:

In patients with persistent symptoms of nausea and vertigo, careful clinical examination is necessary to ensure that a diagnosis of cerebellar infarct is not missed. Appendicular ataxia is present when the cause is central but is absent in more benign causes, and the presence of arm dysmetria may signal cerebellar vascular accident.

Explanation:

This patient has multiple risk factors for cardiovascular disease that, coupled with new-onset nonpositional vertigo, headache, and vomiting, raise concern for a unilateral cerebellar vascular accident. Unilateral cerebellar insults can present with the same intense symptoms as peripheral vertigo, and they are the exception to the rule that central vertigo does not have very prominent symptoms. Unilateral ataxia may be the only other diagnostic clue, and it must be specifically sought in order to be discovered. The presence of vertigo with ataxia, especially the wide-based gait of a "seemingly drunk" person that is classic for cerebellar ataxia or vertigo that does not improve with opening of the eyes and visual fixation suggest a central problem, such as cerebellar vascular insufficiency (hemorrhagic or ischemic).

Horizontal nystagmus is commonly seen with peripheral causes of vertigo. Cerebellar vascular accident may result in nystagmus that is dominantly vertical or torsional or that changes direction with the gaze. However, horizontal nystagmus may also be seen clinically, so it is not useful for discriminating the cause in isolation.

Sensorineural hearing loss is commonly seen in conjunction with Meniere disease, not cerebellar ischemia. Gentamicin toxicity typically causes bilateral peripheral vestibular damage with equal effects on both sides. As a result, no central nervous system imbalance of vestibular input is present and vertigo is not a typical feature.

Peripheral vertigo involves a problem within the vestibular apparatus (inner ear) or cranial nerve (CN) VIII. Central vertigo is defined as a problem in the cerebellum or brain stem.

Notice that CN VIII falls under "peripheral vertigo" (separate from the brain stem) when discussing vertigo, but the CN VIII is lumped together with the brain stem under "sensorineural hearing loss" when discussing hearing loss.

A new clinical strategy is now emerging for the differentiation of central and peripheral causes of acute vestibular syndrome using the HINTS mnemonic (head impulse, nystagmus, test of skew) examination as a targeted examination. For further information and examination technique, watch this video.

References:

Edlow JA, Gurley KL, Newman-Toker DE. A new diagnostic approach to the adult patient with acute dizziness. J Emerg Med. 2018;54:469-483.

Muncie HL, Sirmans SM, James E. Dizziness: approach to evaluation and management. Am Fam Physician. 2017;95:154-162.

Wrighte J, Huang C, Strbian D, Sundararajan S. Diagnosis and management of acute cerebellar infarction. Stroke 2014;45:e56-e58.

Educational Objective:

List the various complications of chronic kidney disease.

Key Point:

Although it is often thought of as a complication of a person’s diet or their genetic predisposition, hyperlipidemia has been shown to be an independent complication of CKD. Therefore, in those with a new CKD diagnosis, it should be one (of many) things patients should be made aware of that can progress more rapidly if their disease is not optimally controlled.

Explanation:

Nearly 25% of individuals with CKD have significant hyperlipidemia. The highest rates are seen in patients with nephrotic syndrome as well as in those undergoing peritoneal dialysis (as opposed to hemodialysis). The primary lipid abnormality in patients with CKD is hypertriglyceridemia, but hypercholesterolemia is also often seen. For reasons poorly understood, the composition of high density lipoprotein particles in patients with CKD make them less protective than they are in patients without the disease. It may be that the antioxidant properties of the HDL molecule in the CKD patient are different (and less effective).

Hyperkalemia, not hypokalemia, is a complication of CKD due to the kidney’s impaired ability to maintain potassium homeostasis. Anemia, not polycythemia, is a complication of CKD that is largely due to less secretion of erythropoietin in the damaged kidney. Metabolic acidosis, not alkalosis, is a complication of CKD due to increased loss of bicarbonate and decreased renal excretion of acid.

References:

Kidney Disease Improving Global Outcomes. KDIGO 2012 clinical practice guideline for the evaluation and management of chronic kidney disease. Kidney Int Suppl. 2013;3:5. Accessed February 28, 2019.

Peev V, Nayer A, Contreras G. Dyslipidemia, malnutrition, inflammation, cardiovascular disease and mortality in chronic kidney disease. Curr Opin Lipidol. 2014;25:54-60.

Educational Objective:

Recognize the ethnic group with the highest genetic predisposition to thromboangiitis obliterans.

Key Point:

Ashkenazi Jews are genetically predisposed to thromboangiitis obliterans.

Explanation:

Thromboangiitis obliterans occurs with the least frequency in people originating from western Europe and with the highest frequency among Ashkenazi Jews. High morbidity rates are also observed in people from India, Korea, and Japan. The prevalence in the United States has been estimated to be 12.6 per 100,000 persons.

Reference:

Ferri FF. Ferri's Clinical Advisor. 2018

Rivera-Chavarría IJ, Brenes-Gutiérrez JD. Thromboangiitis obliterans (Buerger's disease). Ann Med Surg (Lond). 2016 May;7:79-82.

In general, the deep fascial spaces to which odontogenic infections may spread can be subdivided into three anatomical regions:

1. Face: buccal, canine, parotid, and masticator spaces (with the masticator space in turn consisting of the masseteric, pterygoid, and temporal sub-spaces)
2. Suprahyoid region (the first two spaces are Ludwig's Angina territory): submandibular, sublingual, and lateral pharyngeal spaces.
3. Infrahyoid region: retropharyngeal, "danger", and pretracheal spaces.

This patient is suffering from a deep space infection in the "face" category: he has a classic masticator space infection, which typically is the result of an odontogenic infection spreading from the molar teeth, especially the wisdom tooth (third molar).

Clinically, masticator space infections present with trismus and pain in the body or ramus of the mandible. Swelling is usually absent or minimal since the infection is hidden deep within the muscles of mastication. If the infection is due to the lower (mandibular) third molar, the patient might experience dysphagia due to the infection extending internally and approaching the lateral pharyngeal wall (which is MEDIAL to this MORE lateral masticator space infection). This is different from an actual displacement of the lateral pharyngeal wall towards the midline on CT scan. An actual displacement would mean that the infection has spread into a new deep space, the lateral pharyngeal space - which does not belong to the territory of the Masticator space (it belongs to territory #2: suprahyoid region). Dysphagia in the context of the masticator space infection is a critical, early clue to the fact that the infection is spreading towards this second deep space.

Suppurative orofascial deep space infections are usually due to Steptococcus viridans and other streptococci, Peptostreptococcus species, Bacteroides and other oral anaerobes. Reasonable first antibiotic regimens are: Penicillin G plus one of the following: Metronidazole, Ampicillin-Sulbactam, Clindamycin Doxycycline (IV), Cefoxitin, or Cefotetan. Some of these deep space infections will require incision and drainage in addition to antibiotic therapy.

Reference:

Mandell, Bennett, & Dolin: Principles and Practice of Infectious Diseases, 6th ed.2005: Chapter 57 - Infections of the Oral Cavity, Neck, and Head by ANTHONY W. CHOW