CASE REPORT N RAPPORT DE CAS Lateral medullary syndrome: a diagnostic approach illustrated through case presentation and literature review Gregory S. Day, MD, MSc*3; Richard H. Swartz, MD, PhD*4; Jordan Chenkin, MD, MEd41; Adil I. Shamji, MDI; David W. Frost, MD3"# ABSTRACT accident vasculaire ce´re´ bral. L’association entre l’infarctus du bulbe late´ ral et la dissection de l’arte` re verte´ brale fait Patients with lateral medullary syndrome classically present ressortir l’importance de reconnaıˆtre cette premie` re affection with crossed hemisensory disturbance, ipsilateral Horner au service des urgences. Moyennant le meilleur traitement syndrome, and cerebellar signs, all of which are attributable possible, le syndrome bulbaire late´ ral porte un pronostic to infarction of the lateral medulla. However, variability in the favorable quant au re´ tablissement. presentation of this syndrome is the rule, as illustrated in this case presentation and literature review. We propose an approach to diagnosis and management of the lateral Keywords: lateral medullary infarct, lateral medullary syn- medullary syndrome and illustrate the need to integrate drome, posterior fossa, stroke, vertebral artery dissection, clinical information with an understanding of brainstem Wallenberg syndrome anatomy with the goal of determining which patients require urgent neuroimaging and acute stroke therapies. The importance of recognition of this condition in the emergency The lateral medullary (Wallenberg) syndrome arises department is underscored by the association between from compromise of the posterior inferior cerebellar lateral medullary infarction and vertebral artery dissection. artery (PICA) leading to infarction of the lateral With optimal therapy, the prognosis for recovery from lateral medulla. Patients with the complete syndrome present medullary syndrome is good. with crossed hemisensory disturbance (ipsilateral face, contralateral body), ipsilateral Horner syndrome, and ´ ´ RESUME ipsilateral cerebellar signs. A historical article published Les patients qui souffrent du syndrome bulbaire late´ ral in 1961 estimated that the syndrome accounts for 2.5% pre´sentent ge´ne´ ralement des troubles he´misensoriels of ischemic strokes1; however, given the diagnostic croise´ s, un syndrome de Claude Bernard-Horner homolate´ ral challenges involved, this is likely an underestimate. et des signes ce´re´ belleux, manifestations qui re´ sultent toutes d’un infarctus du bulbe late´ ral. Toutefois, le tableau clinique Accurate interpretation of clinical signs and symptoms is habituel du syndrome est variable, comme en te´ moignent un critical to establishing the diagnosis and determining expose´ de cas et l’examen de la documentation. Nous ferons which patients require urgent neuroimaging and acute donc e´ tat de l’approche diagnostique et de la prise en charge stroke therapies. Clinical recognition of patients with du syndrome bulbaire late´ ral, et soulignerons la ne´ cessite´de lateral medullary infarction is of particular importance rassembler tous les renseignements d’ordre clinique et de les mettre en relation avec l’anatomie du tronc ce´re´ bral afin due to its association with vertebral artery dissection in de distinguer les patients devant subir d’urgence des 15 to 26% of cases2,3 and the favourable prognosis examens en neuro-imagerie et des traitements pour un associated with optimal management. From the *Division of Neurology, Department of Medicine, University of Toronto; 3University Health Network Hospitals; 4Sunnybrook Health Sciences Centre; and 1Division of Emergency Medicine, Department of Medicine, University of Toronto; IDepartment of Family and Community Medicine, University of Toronto; "Division of General Internal Medicine, Department of Medicine, University of Toronto and #Herbert HoPingKong Centre for Excellence in Education and Practice, University of Toronto, Toronto, ON. Correspondence to: Dr. Gregory Day, Division of Neurology, University of Toronto, Toronto Western Hospital, 399 Bathurst Street, Toronto, ON M5T 2S8; [email protected]. This article has been peer reviewed. ß Canadian Association of Emergency PhysiciansCJEM 2014;16(2):164-170 DOI 10.2310/8000.2013.131059 164 2014;16(2) CJEM N JCMU Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.139, on 27 Sep 2021 at 02:27:10, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.2310/8000.2013.131059 Lateral medullary syndrome CASE PRESENTATION A B A previously well 67-year-old man presented to the emergency department (ED) with a 4-hour history of vertigo, nausea, and vomiting. He had a 50-pack-year smoking history and was not taking any medications. There was no history of neck trauma or manipulation. While in the ED, his condition deteriorated. He developed slurred speech, numbness and paresthesias of the left hemibody (with preserved facial sensation), C and difficulty swallowing liquids. His blood pressure was 195/90 mm Hg, and his pulse was regular at 66 beats/min. Cardiovascular, respiratory, and abdominal examinations were all unre- markable, and his mental status was normal. Verbal comprehension, naming, and repetition were normal; however, his speech was dysarthric. Cranial nerve examination revealed right-sided ptosis and miosis, consistent with a partial Horner syndrome. The patient’s Figure 1. A, Magnetic resonance angiogram of vertebral visual fields were normal on confrontational testing, and arteries confirming occlusion of the proximal right vertebral artery (arrow). B, The posterior inferior cerebellar artery is his extraocular movements were full and without visualized (arrow). C, Diffusion-weighted image showing an nystagmus. There was symmetrical contraction of the area of restricted diffusion in the right lateral medulla, muscles of facial expression. Pinprick sensation was compatible with acute ischemic infarct. decreased throughout the right face, and his right corneal reflex was absent. His uvula was deviated to the left, and of the brain identified an area of restricted diffusion in his gag reflex was absent. There was mild pyramidal the right lateral medulla (Figure 1C). pattern weakness in his right arm and leg (flexors weaker Within 48 hours, he improved dramatically. His than extensors in the arm; extensors weaker than flexors speech returned to normal, his dysmetria resolved, and in the leg). Deep tendon and superficial reflexes were he was able to sit unassisted. Fasting blood glucose was normal. Sensation to pain and temperature was decreased normal, and no arrhythmias were identified with 48 below the neck on the left side. Coordination assessment hours of cardiac monitoring. The patient’s dysphagia with finger-to-nose and heel-to-shin testing revealed persisted, requiring placement of a gastric tube. Blood severe right-sided dysmetria. When sitting or standing, pressure control was optimized with dual antihyper- the patient had marked truncal ataxia, with a tendency to tensive therapy (an angiotensin-converting enzyme fall to the right. He was unable to ambulate. inhibitor and a thiazide diuretic). A statin was Routine laboratory investigations and an electrocar- commenced for management of newly diagnosed diogram were normal. An unenhanced (noncontrast) dyslipidemia. Smoking cessation counselling was pro- computed tomographic (CT) scan of the brain was vided, and warfarin was commenced for ongoing normal. The diagnosis of lateral medullary infarction anticoagulation. Ten days after admission, the patient was made on clinical grounds. Acute treatment with was eating modified-consistency meals and was trans- intravenous tissue plasminogen activator was not ferred to a stroke rehabilitation centre. At 3 months offered due to the delayed presentation (clinical assess- postdischarge, he had recovered almost entirely ment was completed 6 hours following symptom onset). (Modified Rankin Scale [MRS] 5 14). He no longer Magnetic resonance angiography (MRA) of the head required the gastric tube and was ambulating indepen- and neck vessels showed occlusion of the proximal right dently. Repeat neurovascular imaging prior to the 6- vertebral artery, suspicious for extracranial dissection month follow-up showed recanalization of the vertebral (Figure 1A). The PICA was patent (Figure 1B). with artery. His warfarin was discontinued, and antiplatelet supply through collateral flow via the basilar and left therapy (acetylsalicylic acid) was prescribed for long- vertebral arteries. Magnetic resonance imaging (MRI) term secondary stroke prevention. CJEM N JCMU 2014;16(2) 165 Downloaded from https://www.cambridge.org/core. IP address: 170.106.40.139, on 27 Sep 2021 at 02:27:10, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.2310/8000.2013.131059 Day et al DISCUSSION inferior cerebellar peduncle, vestibular nuclei, and nucleus ambiguus (Figure 2). Variations arise when The triad of Horner syndrome, ipsilateral ataxia, and areas at risk are preserved through residual perfusion contralateral hypoalgesia clinically identifies the or collateral flow or when perfusion in surrounding patient with lateral medullary syndrome5,6; however, areas is compromised. Patients with infarction pre- the diagnosis should be considered in all patients with dominantly affecting the caudal medulla tend to sudden-onset symptoms and signs localizing to the present with vertigo, nystagmus, and ataxia owing to medulla. Table