The neurological examination in the assessment of polyneuropathy in mechanically ventilated patients

Polyneuropathy has been implicated in critical illness as a cause of difficult weaning from artificial ventilation and of rehabilitation problems. We wanted to see which clinical parameters can be used to identify patients with polyneuropathy in the intensive care. In a prospective study during 18 months, mechanically ventilated patients underwent serial neurological and EMG investigations in the general intensive care unit of a large community hospital. Fifty patients under 75 years old were studied who were on the respirator for more than 7 days. Using simple criteria, both a provisional clinical and an EMG diagnosis were made with regard to polyneuropathy during the second and fourth week and the second month of mechanical ventilation. After the intensive care period, 34 surviving patients were also given a final clinical diagnosis which was compared to earlier EMG conclusions. Even with crude criteria, such as the presence of either paresis or areflexia, maximal sensitivity of the provisional clinical judgement was only 60% as compared to concurrent EMG diagnosed polyneuropathy. EMG investigations in the intensive care, however, did not identify two out of 10 patients with a final clinical diagnosis of polyneuropathy. Thus, neurological examination is an insufficient screening method for polyneuropathy in intensive care. EMG has a fair diagnostic yield but one should realize that it is not an infallible gold standard.