Case Report

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American Journal of Emergency Medicine

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Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episode leading to recurrent Superior mesenteric artery syndrome

Abstract

Mitochondrial encephalomyopathy, lactic acidosis, and stroke- like events (MELAS) is a rare neurodegenerative disorder caused by a mitochondrial DNA point mutation. Besides neurologic and metabolic manifestations, patients sometimes present with pseu- do-obstruction of the bowel due to vomiting and anorexia. This report describes the case of a 28-year-old female with MELAS who presented with recurrent superior mesenteric artery syndrome (SMAS). She complained of severe vomiting and malaise, and had a past history of congestive heart failure and SMAS. Severe weight loss following Gastrointestinal symptoms was the most important factor leading to bowel obstruction. The patient’s SMAS was improved with conservative treatment, but she expired due to heart and renal failure. This is the first case of MELAS syndrome leading to recurrent SMAS.

A 28-year-old female presented to the emergency department with a 3-day history of vomiting and malaise. At the age of 17, the patient was diagnosed with Hypertrophic cardiomyopathy. The patient suddenly developed right-sided hemiplegia both 5 and 2 years earlier, therefore confirming mitochondrial encephalomyopa- thy, lactic acidosis, and stroke-like episodes (MELAS). The finding of brain magnetic resonance imaging at that time was chronic cerebral infarction at the right frontotemporal lobe (Fig. A). One year before this presentation, she had a superior mesenteric artery syndrome (SMAS) and was treated conservatively. She was alert and oriented, but cachexic. Her vital signs included a body temperature of 38.6?C, blood pressure 90/60 mmHg, pulse rate 104 beat/min, respiratory rate 20 breaths/min, and SaO2 96% on room air. She complained of anorexia, postprandial nausea and vomiting, and diffuse abdominal pain. Physical examination revealed her abdomen was soft, but there was tenderness in the epigastric region. laboratory examinations revealed leukocytosis (white cell count of 11.9 x 10⁹/L with 79% neutrophil), renal dysfunction (blood urea nitrogen/creatinine 114/ 2.2 mg/dL), and elevated serum lactic acid (9.64 mmol/L). Arterial blood gas analysis showed mild metabolic acidosis with respiratory compensation, with a pH of 7.44, a PCO2 of 27 mmHg, a PO2 of 81 mmHg, and actual bicarbonate of 21.7 mEq/L. Urinalysis revealed many red blood cells and leucocytes per high-power field. An electrocardiogram revealed a sinus tachycardia with Right ventricular hypertrophy. Chest radiograph and plain abdominal x-ray disclosed cardiomegaly and severe Gastric dilatation with no gas in the rest of the intestinal tract, respectively. We inserted a nasogastric tube urgently, and an abdominal computed tomographic (CT) scan was performed to investigate the possibility of Small bowel obstruction. The CT scan showed a superior mesenteric artery syndrome (SMAS). The high-level bowel obstruction and the collapsed rest bowel loops

were seen (Fig. B). The stomach and the proximal duodenum were dilated because the second part of the duodenum was compressed between the aorta and superior mesenteric artery (Fig. C). The aorto- mesenteric angle was less than 10? (Fig. D). The finding of transthoracic echocardiography was severe left ventricular dysfunc- tion (ejection fraction 28%) with decreased global left ventricular wall motion. She was admitted to the intensive care unit and received hydration and parenteral nutrition. Subsequently SMAS was im- proved quickly by conservative management, but she died of heart and renal failure on hospital day 15.

MELAS is a neurodegenerative disorder caused by a mitochondrial DNA point mutation [1]. It is a rare Genetic disorder, transmitted by maternal mode but with no current data concerning its prevalence. The absolute prevalence of the m.3243A N G mutation (an adenine- to-guanine transition at point 3243 of the mitochondrial genome) most commonly associated with MELAS has been estimated to be as high as 0.06% [2]. initial symptoms begin during childhood, and common clinical features are seizure, recurrent headache, gastroin- testinal symptoms, stopped growth, stroke, Altered consciousness, hearing loss, and visual symptoms [3]. Patients sometimes present with hypertrophic cardiomyopathy leading to heart failure and pseudo-obstruction of the bowel due to recurrent vomiting and anorexia [4]. The first symptom in our case was heart failure due to hypertrophic cardiomyopathy, which started at her age of 17, and she also had right hemiplegia and gastrointestinal symptoms. She had a history of severe symptoms of anorexia and vomiting and, so, was grossly emaciated (body weight 30 kg). Repeated gastrointestinal symptoms may worsen patients’ Nutritional status and lead to serious complications such as SMAS.

SMAS results from vascular compression of the third part of the duodenum, in the angle between the aorta and the superior mesenteric artery. It has some Predisposing factors including weight loss (i.e., dietary disorders and malabsorption), external causes (i.e., scoliosis surgery with instrumentation or body casting, ileoanal pouch anasto- mosis), and intraAbdominal compression or mesenteric tension (i.e., neoplastic growth, aortic aneurysm) [5]. Management of SMAS is either by conservative or surgical method. Initial treatment is often conserva- tive, including the nasogastric decompression, change of the patients’ position, and administration of fluid and parenteral nutrition. For patients in whom conservative treatment fails, the surgical procedures should be considered. In our case, severe weight loss following intractable gastrointestinal symptoms was the most important factor that led to obstruction of the duodenum. The patient had lost a lot of weight during 1 year. In the both times of SMAS, the gastrointestinal symptoms resolved just by nasogastric decompression and total parenteral nutrition. Only a few cases with MELAS syndrome and

0735-6757/(C) 2014

Fig. A, Brain magnetic resonance imaging scan with T1-weighed images shows low signal intensity as cerebrospinal fluid in the right frontotemporal lobe. B, abdominal coronal CT scan represents severe gastric and duodenal dilatation (arrows) and the collapsed rest bowel loops (arrowheads). The thrombus in the left ventricle was seen (black arrow). C, Axial CT scan reveals the second part of duodenum (arrowheads) was compressed between the aorta (lower arrowhead) and superior mesenteric artery (upper arrowhead). D, Sagittal CT scan shows narrowing of the angle (less than 10?) between aorta (right arrow) and superior mesenteric artery (left arrow), and compressed duodenum (arrowhead).

gastrointestinal involvement have been reported. To our knowledge, there is just one report of an adolescent patient with MELAS syndrome with SMAS [6].

In summary, we report a first case of MELAS syndrome leading to recurrent SMAS. The suspicion of mitochondrial disease may be difficult in the emergency department. Unknown cause of nausea and vomiting, lactic acidosis, and stroke-like events will be the clues to recognize MELAS.

The authors report no conflicts of interest.

Oh. Young Kwon, MD, PhD Seong Gwan Lim, MD Sung Hyuk Park, MD

Department of Emergency Medicine, Graduate School of Medicine, Kyung Hee University, Seoul 130-701, Republic of Korea E-mail address: [email protected]

http://dx.doi.org/10.1016/j.ajem.2014.01.059

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