Kikuchi S. 2002. Exogenous tumor necrosis—alpha induces abnormal discharges in rat dorsal horn neurons. Spine 27:1618-24. Otani K. Arai I, Mao GP, Konno S. Olmarker K, Kikuchi S. 1997. Experimental disc herniation: evaluation of the natural course. Spine 22:2894-9. Otani K. Arai I, Mao GP, Konno S. Olmarker K, K