A Rare Case of Rotavirus-related Acute Benign Myositis

To the Editors: Acute gastroenteritis is a widespread disease that affects people of all ages and that can potentially lead to severe complications, particularly in young children and the elderly, who are more vulnerable to dehydration. Enteric viruses identified in the early 1970s are regarded as a leading global cause of gastroenteritis.1 Rotavirus, a member of the family Reoviridae, was identified as an etiologic agent in severe gastroenteritis in children in 1973.2 Rotavirus gastroenteritis manifests suddenly, generally with vomiting and watery diarrhea accompanied by low-grade fever and abdominal cramps.1 Rotavirus gastroenteritis can also result in dehydration and death. It is most frequently seen in children under the age of 5. Rotavirus can be detected in stool specimens under electron microscopy and with serologic and molecular techniques. Infection can be symptomatic or asymptomatic.3 Rotavirus is responsible for approximately 40% of hospital presentations in developing countries. The annual number of deaths worldwide caused by Rotavirus is approximately 200,000. The treatment of Rotavirus infection with viral gastroenteritis is based on fluid and electrolyte replacement only, rather than antibiotic or antiviral therapy.1 A child with leg pain or refusing to walk is a cause of anxiety for both parents and health providers. Benign acute childhood myositis is a common, self-limiting cause of leg pain in children. It was first reported by Leichtenstern in 1905 as tender thigh and calf pain representing a complication of influenza. The absolute incidence and prevalence are uncertain, and there is no specific management guideline.4 Rotavirus gastroenteritis has rarely been reported to cause extraintestinal symptoms.5 We report a case of benign acute myositis associated with Rotavirus gastroenteritis, a rare cause of extraintestinal involvement. A previously healthy boy 3 years and 1 month of age presented to our emergency clinic due to vomiting, diarrhea and fever persisting for the previous 4 days. The patient appeared mildly dehydrated, with a body temperature of 38 °C. His history was unremarkable, and no parental consanguinity was present in his family history. At physical examination, the oropharynx was hyperemic, heart sounds were rhythmic and no additional sound or murmur were present. Respiratory sounds were normal. Abdominal examination revealed increased intestinal sounds and tenderness. At neurologic examination, the patient was mildly agitated, and deep tendon reflexes were normoactive. Laboratory tests revealed a white blood cell count of 7167/mm3 (predominantly lymphomonocytic), and C-reactive protein was normal. However, in terms of biochemical parameters, alanine transferase was 65 U/L (5–40 U/L) and aspartate aminotransferase 150 U/L (5–40 U/L). Immunoglobulin values were within normal ranges. In terms of viral tests, hepatitis A, B and C, human immunodeficiency virus, rubella, cytomegalovirus and toxoplasma results were all normal. Normal flora growth was observed in stool bacteria culture. Rotavirus was detected in stool by means of latex agglutination, and due to the patient’s dehydrated appearance he was hospitalized for hydration. Neurologic examination was normal. Creatine kinase (CK) values were investigated due to the pain in the legs, inability to stand and refusal to walk at follow-ups. The patient’s CK value was 4244 U/L (29–200 U/L), and ibuprofen was added to treatment. Decreases were observed in CK and hepatic enzyme values and the other complaints improved during follow-up, and he was discharged with a recommendation of clinical control visits (Table 1). TABLE 1. - The Decrease in CK Values During Treatment Day 1 Day 4 Day 5 CK 4244 U/L 251 U/L 124 U/L Diagnosis of benign acute myositis in children is generally based on such typical clinical symptoms as symmetrical calf muscle pain, tenderness, inability or refusal to walk a few days after infectious disease, and CK elevation normalizing within 1 week.6 Benign acute childhood myositis is a rare, transient inflammatory condition. It is predominantly seen in school- and preschool-aged children and largely affects boys, and case outbreaks are seen during times of respiratory virus outbreaks (particularly influenza).7 Our case was compatible with the age range reported in the literature. Rotavirus may rarely lead to benign myositis.8 We think that this therefore makes our case particularly significant. Although the organ involved in Rotavirus infection is almost always the intestine, there have also been reports describing extraintestinal abnormalities.5,9,10 In the present case, a manifestation of myositis progressing with CK elevation alone was present at tests performed following Rotavirus gastroenteritis, and benign acute childhood myositis was diagnosed in the light of the clinical improvement observed in the following days. Myositis has been reported as an immunologic reaction or direct virus invasion into the muscle. Yamamoto et al reported a case of comorbid acute myositis with Rotavirus and Norovirus.9 Trivedi et al documented a rare presentation with Rotavirus diarrhea-related multisystem involvement in the form of encephalopathy, myositis, transaminitis and hypoalbuminemia.10 However, Hattori et al reported a case in which a manifestation of benign acute myositis developed and subsequently improved without causing any damage.8 Similarly, in the present case, only Rotavirus tested positive, and apart from elevation in CK and other hepatic enzymes, no additional pathology was observed. Our patient’s good response to fluid therapy and discharge in a completely asymptomatic state within a few days were also compatible with the existing literature. The clinical, laboratory and viral parameters show that our patient’s benign acute myositis developed together with Rotavirus gastroenteritis. We wish to emphasize that a manifestation of acute myositis can develop in patients refusing to walk following gastroenteritis caused by Rotavirus infection, and that early diagnosis is possible with a good neurologic examination and first-line laboratory testing. This case is also presented to contribute to the current literature.