Benign acute myositis in association with acute dengue viruses' infections

ABSTRACT

Dengue is the most common and widespread arthropod-born arboviral infection in the world today. Early diagnosis and prompt management would help prevent evolution into the more devastating sequelae with hemorrhagic manifestations and dengue shock syndrome. However, the diagnosis of dengue fever in the early febrile phase with undifferentiated symptoms and signs is difficult. The frequent observation of myalgia [sometimes severe] and increased serum CK in patients with dengue fever attending our hospital inspired us the idea of this study. To study myositis associated with dengue viruses' infections. Also, to study if the elevated serum CK levels in the early febrile phase among suspect cases with acute dengue viruses' infections has value in the early diagnosis of dengue fever. This was a prospective study that was carried out on all cases of dengue fever and dengue hemorrhagic fever presented to Hay Aljamea Hospital, Jeddah, Saudi Arabia from January 2006 till December 2006. All clinics in the hospital were alerted and asked to report suspected cases of dengue viruses' infections according to the WHO 1997's case definition. Paired serum samples were collected from 525 patients and MAC-ELIZA was done on them. Patients with positive serological tests for acute dengue viruses' infections were re-examined by the investigators and thorough neurological assessment and EMG studies were performed. Serological tests were positive for acute dengue viruses' infections in 101 patients. One hundred nine patients had elevated serum CK levels in the first serum samples. Among them, 47 patients had acute dengue viruses' infection by testing the first serum sample. The number increased to 92 patients by testing the second serum sample. This gives the elevated CK levels among febrile patients with suspected criteria of acute dengue viruses' infection according to the case definition mentioned above, a positive predictive value of 84% and a negative predictive value of 98% in the diagnosis of dengue fever. If the criteria of patients suspected to have dengue fever had been narrowed to only include those who have elevated CK levels, the pre-test probability for the diagnosis of acute dengue viruses' infection would have been 92.7%. Myalgia was found in 64 patients [63.4%]. However, it was severe in 12 patients only. Mild proximal muscle weakness especially in the lower limbs was found in only three patients and they recovered completely before discharge. Nerve conduction studies were normal in all the patients. EMG showed features of muscle hyperirritabilities in 4 patients only; 3 of them had muscle weakness. Benign acute myositis is a very common manifestation in association with dengue viruses' infection. Serum CK level should be checked in every patient suspected to have dengue fever in the febrile phase and be used as a diagnostic marker till the serology results for dengue viruses are available