Sudden onset of back pain.

Patients attending a back pain clinic completed a structured interview, with particular reference to whether onset of the first episode of back pain was sudden or insidious. They were classified into four diagnostic groups. A significantly higher proportion of patients who had experienced a sudden onset of pain suffered from sciatic pain with positive root tension signs than was the case with patients whose pain had started more insidiously (50.8% vs. 20.6%; P < 0.001). These patients were also more likely to be male, to have been lifting or twisting with a weight, and to have been confined to bed or hospitalised, and have undergone manipulations, than patients with insidious onset of their pain.