Quantitative Electromyography in Dengue-Associated Muscle Dysfunction

Purpose: This study was undertaken to document the muscle involvement in dengue virus infection using quantitative electromyography (QEMG). Methods: The patients with dengue myopathy were subjected to clinical examination including muscle power, tone, reflex, and sensations. Blood counts, hemoglobin, hematocrit, serum creatine kinase (CK), and electrolytes were determined. The QEMG was performed in the biceps using multimotor unit potential analysis program. Muscle biopsy was done in two patients. At 1 month, their clinical and QEMG analyses were repeated. Results: Thirteen patients whose median age was 34 years were included. Seven patients had severe and six had mild weakness, which was more marked in proximal lower limb muscles. The median CK level was 480 (300–2,477) U/L. Needle EMG did not reveal any spontaneous activity. The motor unit potentials (MUPs) were of normal to short duration, polyphasic with normal interference pattern. The QEMG revealed a significant change in the duration of MUP at 1 month compared with that of baseline. All the patients clinically and biochemically improved after 1 month. Muscle biopsy revealed interstitial hemorrhage with occasional myonecrosis and myophagocytosis without inflammation or vasculitis. Conclusions: The QEMG in dengue myopathy revealed improvement in the duration of MUP at 1-month follow-up, which paralleled with clinical and CK improvement.