Prognostic value of MRI findings in sciatica.

The natural course of sciatica due to disc herniation is generally favourable but individually unpredictable. Some patients recover only after prolonged conservative therapy or surgery. This study aims to ascertain whether magnetic resonance (MR) imaging features can be used to predict outcome of sciatica and help to identify patients unlikely to respond to conservative management. For a transversal diagnostic study 274 primary care patients underwent early MR imaging for leg pain. One hundred and thirty-three patients with sciatica were followed for 3 months, both patients and physicians being unaware of MR imaging findings. At 12 weeks a favourable prognosis was indicated by the following features: annular rupture (P= 0.02) and nerve root compression on MR imaging (P = 0.03). Poor prognosis was indicated by disc herniation in the foramen (P = 0.004). Our findings show that early MR imaging features are related to prognosis. However, the associations are not strong enough to justify routine use of early MR imaging to predict the prognosis of sciatica.