Letter to editor regarding "The Efficacy and Safety of Topical Saline Irrigation with Tranexamic Acid on Perioperative Blood Loss in Patients Treated with PELD".

Letter: We have read the recent article published by Zhang et al titled "The Efficacy and Safety of Topical Saline Irrigation with Tranexamic Acid on Perioperative Blood Loss in Patients Treated with Percutaneous Endoscopic Interlaminar Diskectomy: A Retrospective Study". In this retrospective study, authors performed interlaminar endoscopic lumbar discectomy (IELD) for L5-S1 disc herniations, categorizing patients into two groups. One group underwent IELD with saline irrigation fluid containing 0.33 gm of tranexamic acid (TXA) per 1L of saline, while the other group received only saline irrigation fluid. We appreciate the authors' efforts in shedding light on the use of TXA in irrigation fluid, which currently has limited literature available. However, we wish to highlight several points of concern that, in our view, warrant further discussion. Upon reviewing the manuscript, our initial concern centers on the reported amount of blood loss, a crucial outcome in this study. The blood loss figures presented in this study appear significantly higher compared to the existing literature. In both study groups, the authors indicate total blood loss (TBL) exceeding 300 ml and intraoperative blood loss (IBL) surpassing 40 ml. In contrast, a systematic review and meta-analysis by Jitpakdee et al. (1) reported a range of blood loss from 10.9 ml to 23.35 ml for interlaminar endoscopic discectomy without any systemic or local use of tranexamic acid. Accurately assessing blood loss in endoscopic spine surgery poses a challenge, and the accuracy of indirect calculation methods is questionable, particularly when bleeding is minimal. Endoscopic discectomy has been proven benefits by minimal tissue damage and negligible blood loss. Another significant concern we would like to address is related to the safety and efficacy of topical tranexamic acid (TXA) use in endoscopic spine surgery. The existing literature generally accepts the safety profile and efficacy of use of intravenous TXA in open spine surgery where the blood loss incurred is substantial (2, 3). However, when it comes to the safety of topical TXA, it is important to note that TXA is known to have neurotoxic and epileptogenic properties when applied to central nervous system (CNS) tissue (5, 6). This is due to its interference with central GABAA receptors and glycine receptors (7). In endoscopic spine surgeries, small dural tears can sometimes go unnoticed due to continuous irrigation fluid pressure. In such cases, the potential CNS side effects associated with topical TXA could pose a real danger. Furthermore, even when dural tears are identified during surgery, it can be challenging to completely washout all the irrigation fluid containing TXA from the surgical field. The accumulation of excessive epidural or intrathecal TXA, especially after a dural tear, can lead to life-threatening conditions such as seizures or arrhythmias, significantly increasing morbidity and mortality in what is often intended as a day-care procedure. Moreover, the authors have not mentioned any exclusion criteria for patients with conditions that are suspected to elevate risk of developing TXA-related side effects, such as a history of thromboembolic events and/or coagulopathy, convulsive disorders and dural disruption. Lastly, in terms of the efficacy of TXA, there are limited studies demonstrating the use of local TXA in spine surgeries to reduce blood loss. For example, Krohn et al(4) used topical TXA irrigation in open instrumented spinal fusion surgery before wound closure. Their study showed a reduction in postoperative blood loss, with drain output decreasing from 525 ml in the non-TXA group to 252 ml in the TXA group. However, it had no significant effect on intraoperative blood loss. We would like to raise a pertinent question regarding endoscopic discectomy procedures, which are characterized by minimal blood loss and are often conducted as day-care surgeries. It becomes a matter of concern whether the potential advantages of using topical TXA in reducing blood loss outweigh the associated risks of neurological damage to the central nervous system (CNS) and other potentially life-threatening complications.