Figure 2.

(A) Main characteristics of studies selected in the meta-analysis. Pain models: SCI, spinal cord injury; SNL, spinal nerve ligation; SNI, spared nerve injury; CCI, chronic nerve constriction injury; and “other” pain models were constriction of infraorbital nerve (n = 1), brachial plexus ablation (n = 1), postherpetic neuralgia (n = 1), and streptozotocin-induced neuropathy (n = 1). Administration route: i.t., intrathecal; i.p., intraperitoneal; and “other” routes were subcutaneous (n = 2), intranasal (n = 1), and intravenous (n = 2). Measurement techniques: “other” includes measuring withdrawal latency to cold and heat stimuli. (B) Summary of the 4 meta-analyses. No delay indicates that the measurement of neuropathic pain was performed during the period of ketamine administration. The data point of the single administration 24-72 h is without Fang et al. (Ref. 11).