Abstract Number ‐ 113: A Lateral Medullary Infarct Complicated by Central Hypoventilation Syndrome
Authors: Valesky Walter , Groysman Leonid , Stern‐Nezer Sara , Chen Patrick , Akbari Yama , Paulus Jeffrey 
Published: April 2023

Introduction
A 43‐year‐old male with no known past medical history presented to a primary stroke center for sudden onset headache, nausea, vomiting, and dizziness while driving. A computed tomography angiogram of the head and neck revealed a left vertebral artery occlusion, and the patient was transferred to our comprehensive stroke center for further evaluation and treatment. Upon arrival at our facility, the patient was noted to have a national institute of health stroke scale score of 7 with left facial droop, dysarthria, and right upper extremity dysmetria. A cerebral angiogram revealed a tortuous left vertebral artery with dissection in the V4 segment. Subsequent brain diffusion weighted imaging revealed an acute infarct in the right lateral medulla measuring 1.4cm and several acute cerebellar infarcts. (fig. 1) In the postangiography period, the patient had dysphagia, sialorrhea, multiple aspiration episodes, and oral secretions requiring early tracheostomy and percutaneous endoscopic gastrostomy on hospital day (HD) #6. The subsequent hospital course was complicated by prolonged singultus lasting until HD #23 and repetitive vomiting requiring a transition from a gastric to a gastro‐jejunal feeding tube.

Methods
A central hypoventilation syndrome (CHS) prolonged ventilator weaning. Despite preserved ability to take large‐volume voluntary breaths, the patient experienced multiple episodes of sleep‐associated apnea and rapid shallow breathing pattern during daily spontaneous breathing trials (SBT). The apnea episodes were registered with ventilator apnea alarms set at 20 seconds. This pattern continued when attempting an SBT utilizing a T‐piece adaptor. The ability to maintain adequate minute ventilation in an asleep state subsequently improved, and the patient was able to tolerate 48 hours of spontaneous breathing with no apnea on HD #35.

Results
Few cases of CHS secondary to lateral medullary infarction (LMI) have been documented in the literature.(1‐3) As the respiratory drive originates from neurons in the latero‐rostro‐ventral medulla, infarcts in this brainstem region may lead to respiratory failure. More specifically to our patient, ataxic breathing may result from lesions in the rostro‐ventral medulla with yawning and hiccups being seen in lesions to the posterolateral medulla.(4) As our patient presented with a sizable 1.4cm lesion, likely impairing these brainstem centers, it is expected that his symptoms would account for multiple respiratory symptoms. The unique feature of the acquired CHS in the setting of LMI is its unilateral location implying lateralization of the respiratory control. In addition to the aforementioned symptoms, his lesion likely led to prolonged weaning from the ventilator as has been described previously.(5)

Conclusions
This case raises awareness regarding potentially disastrous complications of the lateral medullary syndrome like central hypoventilation syndrome. We urge caution and careful evaluation of patients with lateral medullary infarctions for disorders of the respiratory control system.