Muscle weakness associated with H7N9 infection: report of two cases

The emerging avian influenza A (H7N9) virus, a subtype of influenza viruses, was first discovered in March 2013 in China. Infected patients frequently present with pneumonia and acute respiratory disorder syndrome with high rates of intensive care unit admission and death. Neurological complications, such as Guillain-Barré syndrome(GBS), and intensive care unit-acquired weakness, including critical illness polyneuropathy and myopathy, have only rarely been reported previously.

In this study, we report on two Chinese patients with H7N9 severe pneumonia presenting neurological complications. These two patients had non-immune diseases prior to the onset of virus infection. A 56-year-old female patient (case 1) and a 78-year-old female patient (case 2) were admitted because of fever, cough, chest tightness and shortness of breath. These patients were confirmed to have H7N9 infection soon after admission followed by the development of acute respiratory distress syndrome and various severe bacterial and fungal infections. The case 1 patient was found to have muscle weakness in all extremities after withdrawing the mechanical ventilator, and the case 2 patient was found when withdrawing extracorporeal membrane oxygenation, both of these conditions prolonged ventilator-weaning time. Furthermore, the case 1 patient carried the H7N9 virus for a prolonged period, reaching 28 days, and both of them stayed in the hospital for more than two months. A clinical diagnosis of intensive care unit-acquired weakness could be confirmed. However, based on results from electrophysiological testing and needle electromyography of these 2 patients, it is difficult to differentiate critical illness polyneuropathy from GBS, since no lumbar puncture or muscle and nerve biopsy were conducted during hospitalization. Following a long-term comprehensive treatment, the patients' neurological condition improved gradually.

Although there is great improvement in saving severe patients' lives from fatal respiratory and blood infections, it is necessary to pay sufficient attention and to use more methods to differentiate GBS from intensive care unit-acquired weakness. This unusual neurological complication could result in additional complications including ventilator associated pneumonia, prolonged hospital stay and then would further increase the death rate, and huge costs.