Prognostic value of EMG in patients with lumbar disc herniation--a five year follow up.

The prognostic value of EMG in patients treated for lumbar disc herniation was evaluated in 80 patients, 55 were operated and 25 treated conservatively. All patients had an EMG examination before the initial hospitalization or operation. The patients were followed up one year and five years later. The outcome of the treatment was evaluated using a modified WHO handicap classification. The initial EMG finding had no prognostic significance in determining the outcome five years later. A normal EMG finding both at the one year and five year follow-ups was related to a good outcome. Signs of old neuropathy, large motor unit potentials and reduced interference pattern muscles were related to a poor outcome. The EMG findings predict the outcome for these patients only to a limited extent. The overall outcome seems to be influenced to a greater extent by psycho-social aspects than by qualitative aspects of the nerve root lesion detected by the EMG.