HISTORY OF PRESENT ILLNESS
The patient, an 11-year-old girl, was well until 1 year prior to presentation when she was diagnosed with streptococcal pharyngitis. At that time she had severe abdominal pain that caused her to double over in pain. Appendicitis had been considered, and an abdominal radiograph showed an enlarged loop of bowel. The patient was observed, but both the clinical picture and laboratories did not suggest appendicitis. No surgery was performed. A streptococcal rapid antigen test was positive which promoted treatment with amoxicillin. Since that illness, the patient has had multiple illnesses and missed 42 days of school with episodes of headache and abdominal pain. The pain is described as noncrampy but sharp. The pain is described as generalized lower abdominal discomfort without radiation. She was diagnosed with three urinary tract infections during this time secondary to pyuria on urinalysis, but all cultures were negative. Symptoms have been particularly severe since she was diagnosed with mononucleosis 3 months ago. She has had a poor appetite and 10-pound weight loss with mononucleosis and lost 8 more pounds since then. At presentation, the patient had decreased intake secondary to a sore throat and difficulty swallowing secondary to pain. The patient just completed a full course of antibiotics for pharyngitis diagnosed clinically 3 weeks ago (cultures were negative). The patient has been missing half days of school for 2 months and has been sleeping in the afternoons. The week of presentation, the patient has complained of low-grade fevers (99.4°F-100°F), neck pain, diffuse abdominal pain, and frontal headache. On the day of admission the patient was noted to have hemoccult positive stool at the primary care provider’s office after 3 days of diarrhea and loose stools. The primary care provider’s work up-to-date has included a CT scan of the head and sinuses which was negative, stool for culture which was also negative, normal complete blood count, urinalysis, erythrocyte sedimentation rate, Lyme antibody testing, immunoglobulins, ANA, CXR, electrolytes, liver function tests, and thyroid testing.
The patient had reactive airways disease as a toddler which is no longer active. She also had a urinary tract infection at 5 years of age with a normal renal ultrasound. She sustained a concussion at day camp 2 years ago. She had no surgical history and was on no medication except for occasional albuterol with colds. Family history was significant for a maternal grandmother with diverticulitis, maternal grandfather with ulcers, and paternal grandmother with irritable bowel syndrome. There was no history of inflammatory bowel disease or childhood illnesses. The patient is in 5th grade and had done very well in school and been very involved in sports before this illness. The patient reports that she misses school and her friends.
T 38.1°C; HR 124 bpm; RR 24 bpm; BP 105/71 mmHg
Weight 37 kg (75th percentile); Height 155 cm (90th percentile)
Physical examination revealed a thin female who appeared tired and anxious. There was erythema of the pharynx with enlarged tonsils and cobblestoning. There was no exudate and no asymmetry of the tonsillar crypts or soft palate. She had good dentition, halitosis, and cracked red lips. Her neck was supple with no adenopathy. Lungs were clear to auscultation and cardiac examination revealed no murmurs, rubs, or gallops. Abdominal examination revealed good bowel sounds in all four quadrants. There was diffuse tenderness, but no guarding, no rebound, and no hepatosplenomegaly. Rectal examination revealed no excoriation, skin tags, fissures, or hemorrhoids. She had good rectal tone without any palpable masses. She was Tanner II female and there were no obvious vaginal lesions. Neurologic examination was normal.
The complete blood count revealed a white blood count of 5800 cells/mm3. Hemoglobin and platelets were normal. Erythrocyte sedimentation rate was also normal at 14 mm. Electrolytes showed a sodium of 144 mEq/L; potassium, 4.2 mEq/L; chloride, 101 mEq/L; bicarbonate, 31 mEq/L; BUN, 7 mg/dL; and creatinine, 0.6 mg/dL. Urinalysis had a high specific gravity of 1.036 as well as 1+ protein, small bacteria, and large mucus. Rapid strep test was positive for Group A Streptococcal antigen. Amylase was 40 U/L and lipase 53 U/L. Stool cultures grew normal flora and Clostridium difficile testing was negative. Abdominal radiographs were normal except for scoliosis of the lumbar spine. There was no obstruction.
COURSE OF ILLNESS
An abdominal CT revealed the diagnosis (Figure 7-3).
FIGURE 7-3. Abdominal CT. The large arrow indicates the duodenum and the small arrow indicates the aorta.
DISCUSSION CASE 7-3
Weight loss in children is a concerning symptom that requires careful thought, especially when associated with abdominal pain. Oncologic processes should be considered and are frequently the biggest concern for parents. Acute and chronic infections are probably the most common cause of weight loss in children. With acute infections like mononucleosis or pharyngitis, the child should regain the weight once the infection clears. This is one of the most concerning pieces of history in this case. In these cases more chronic, insidious infections like an abdominal abscess, chronic hepatitis, intestinal parasites, tuberculosis, urinary tract infection, or human immunodeficiency virus must be considered.
With associated abdominal pain gastrointestinal disorders such as chronic constipation, gastroesophageal reflux disease, inflammatory bowel disease (examining trends in growth parameters is key), pancreatitis, malabsorptive diseases such as celiac, or superior mesenteric artery syndrome must be considered.
Endocrinologic disorders associated with weight loss include Addison disease (abdominal pain and skin discoloration frequently seen), diabetes mellitus (with associated polyphagia, polydipsia, and polyuria), and hyperthyroidism. Cardiopulmonary disorders include asthma, chronic congestive heart failure, cystic fibrosis, and an untreated cardiac disease. Other causes include nutritional deficiencies (iron and zinc), neurologic diseases (increased intracranial disorders that lead to headache and neurodegenerative disorders), connective tissue diseases, and renal failure.
The most common causes of weight loss, particularly in adolescent girls, include dieting, increased physical activity, depression, anorexia nervosa, and bulimia nervosa. Although this patient’s age and preceding illness made an eating disorder a possibility, it did not explain her associated abdominal pain.
Abdominal CT revealed abnormal dilation of the stomach and proximal duodenum with tapering of the second part of the duodenum to the level of the space between the superior mesenteric artery (SMA) and the aorta consistent with SMA syndrome (Figure 7-3). The diagnosis is SMA syndrome.
INCIDENCE AND EPIDEMIOLOGY OF SUPERIOR MESENTERIC ARTERY SYNDROME
SMA syndrome is an uncommon disorder and has also been referred to as cast syndrome, Wilkie syndrome, duodenal ileus, and arteriomesenteric duodenal compression syndrome. Extrinsic and acute, chronic, or intermittent duodenal obstruction is caused by compression of the transverse portion of the duodenum by the SMA anteriorly and the aorta and vertebral column posteriorly, that causes classic “megaduodenum” on upper GI. Although first described in 1861 by Von Rokitansky, many have disputed the existence of the syndrome and feel that it has been confused with other causes of megaduodenum such as diabetes, collagen vascular diseases, and other causes of chronic intestinal pseudoobstruction.
The syndrome is most common in older children and adolescents, is more common in females and in those that have risk factors for narrowing the angle between the aorta and the SMA and subsequently compressing the duodenum. These risk factors include height growth during the growth spurt that is not accompanied by weight gain, extreme lumbar lordosis, rapid weight loss that decreases the mesenteric fat pad, severe trauma, or surgery that requires prolonged bed rest, use of a body cast, and scoliosis surgery. Anatomic predisposition is present in persons with a short suspensory ligament of Treitz. Recently, there has been a connection with eating disorders in that it can clinically appear like an eating disorder and sometimes precipitate an eating disorder because of the development of food avoidance to avoid pain.
Presenting symptoms can be either acute or chronic (usually with exacerbations) and typically include epigastric and abdominal pain, bilious emesis, and pain after eating. Infrequently, patients present with small bowel obstruction. Severe cases that have gone undiagnosed may present with signs of malnutrition, dehydration with prostration, and electrolyte abnormalities.
Abdominal imaging. While plain abdominal radiographs are often normal, they can show gastric distention. The diagnosis is usually made by upper GI series which shows dilatation of the first two portions of the duodenum with a cutoff at the third potion of the duodenum. Hypotonic duodenography can also display the site of obstruction and CT can provide more detailed information about the aortomesenteric angle and anatomic issues that are creating the obstruction.
Treatment should begin with stabilization of the patient. To avoid gastric perforation, nasogastric decompression with a nasogastric tube should be performed and intravenous fluids administered to correct electrolyte imbalances. The patient should be counseled to avoid positions which exacerbate the obstruction (the supine position) and either remain upright or in the left lateral decubitus position to open up the aortomesenteric angle. Although some patients will not tolerate even slow nasogastric feeds, parental nutrition is rarely warranted and nasojejunal feeds are often successful. The patient is treated conservatively until weight gain is achieved. Surgical interventions such as the Ladd procedure or duodenojejunostomy are indicated in cases that fail other therapies.
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