); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (J.H. ); nakayama-kk@igakuken.orjp (K.N. ); [EMAIL_ADDRESS] (Y.K. ); [EMAIL_ADDRESS] (K.N.) Yuxo Ebata  
1 Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan; hayashi-my@igakuken.orjp (M.H. ); [EMAIL_ADDRESS] (D.N. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (J.H. ); nakayama-kk@igakuken.orjp (K.N. ); [EMAIL_ADDRESS] (Y.K. ); [EMAIL_ADDRESS] (K.N.) Yuxo Ebata  
1 Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan; hayashi-my@igakuken.orjp (M.H. ); [EMAIL_ADDRESS] (D.N. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (J.H. ); [EMAIL_ADDRESS] (K.N. ); kang-yyn@igakuken.orjp (Y.K. ); [EMAIL_ADDRESS] (K.N.) Yuxo Ebata  
1 Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan; hayashi-my@igakuken.orjp (M.H. ); [EMAIL_ADDRESS] (D.N. ); [EMAIL_ADDRESS] (M.H. ); [EMAIL_ADDRESS] (J.H. ); [EMAIL_ADDRESS] (K.N. ); kang-yyn@igakuken.orjp (Y.K. ); [EMAIL_ADDRESS] (K.N.) Yuxo Ebata  
1 Addictive Substance Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan; hayashi-my@igakuken. average of 30% of cases) [3]. This form of pain, including the neuropathic component, is usually more severe than nociceptive pain and often impairs quality of life [4]. Neuropathatic pain is caused by damage or dysfunction of the peripheral or central nervous system and is highly individualized and intractable. Sensory disturbances, such as dysesthesia and hypoesthesia, often appear as prodormal symptoms of neuropathic pain. Sagittall split ramus osteotomy (SSRO) and laparoscopic surgery for benign gynecological diseases involve nerve compression or damage. In addition to acute postoperative pain, including nociceptive and inflammatory pain, nerve compression or damage causes sensory disturbances in SSRO [5; 6] and neuropathic pain in laparoscopic gynecological surgery [7]. Few reports currently show an association between sensory disturbances and gene polymorphisms. For sensory disturbances after SSRO, dysesthesia was reportedly associated with a nonsynonymous genetic polymorphism of the _METTL4_ gene, and hypoesthesia was associated with genetic polymorphisms in flanking regions of the _ARID1B_ and _ZPLD1_ genes [8]. For postoperative pain after SSRO, there are no reports of an association between postoperative pain (i.e., neuropathic pain) after SSRO and gene polymorphisms other than the association between the analgesic effect of fentanyl on postoperative pain and gene polymorphisms of _OPRM1_[9; 10]. For postoperative pain after laparoscopic gynecological surgery, associations between postoperative pain after laparoscopic gynecological surgery and gene polymorphisms of the _SCN9A_ and _SCN11A_ genes, both related to neuropathic pain, have been reported [11; 12; 13; 14]. The _METTL4_ gene encodes methyltransferase-like protein 4. The _OPRM1_ gene encodes the u-opioid receptor. The _SCN9A_ and _SCN11A_ genes encode voltage-gated sodium channel proteins type 9 subunit \(\alpha\) and type 11 subunit \(\alpha\), respectively. The _ARID1B_ gene may affect cell cycle activation, and the function of the _ZPLD1_ gene is unknown. The relationship between these genes and PAF has not been reported. Platelet-activating factor (PAF) is a lipid mediator that exerts various biological effects through the PAF receptor (PAFR). Immune cells, such as macrophages and microglia, produce PAF [15]. With regard to signaling pathways that are involved in pain or inflammation, PAF/PAFR interaction increases intracellular calcium concentrations [16], leading to adenosine triphosphate (ATP) release and the activation of ATP receptors on sensory neurons to cause pain [17; 18] and on macrophages or microglia to induce inflammation [19; 20; 21]. Phospholipase A2 on the cell membrane converts a biologically inactive precursor into lyso-PAF, which is then converted to PAF by acetyltransferase LPCAT1 or LPCAT2 [22].