We have taken a keen interest in the recent article titled ‘Reduced temporal muscle thickness predicts shorter survival in patients undergoing chronic subdural haematoma drainage’ by Korhonen and colleagues [1]. The study reveals a significant correlation between the reduced temporal muscle thickness (TMT), measured preoperatively via computed tomography (CT) scans and the shortened postoperative survival period in patients who have undergone chronic subdural haematoma (CSDH) drainage surgery. The authors have conducted a comprehensive study, incorporating a range of considerations such as age, gender, BMI, imaging indicators and surgical methods, leading to convincing conclusions. However, we have noticed that several important factors may have been overlooked in the execution of the study. We would like to offer the following suggestions for the authors' consideration.

Firstly, TMT, serving as an emerging surrogate marker for muscle mass, function and nutritional status, can be measured through CT, magnetic resonance imaging (MRI) and ultrasound examinations. While the authors have nearly perfected the consideration of TMT measurement, we believe that using two or more imaging methods simultaneously could yield even better results. In addition to TMT, the literature has reported the temporal muscle area (TMA) and temporal muscle volume (TMV) as new surrogate markers related to the temporal muscle and skeletal muscle mass [2]. If the assessment of the temporal muscle in relation to CSDH prognosis were to combine all three—TMT, TMA and TMV—the results would be more compelling. Although a standard method for measuring TMT has not yet been established, nor has an artificial intelligence-based method been used for TMT measurement, several studies have used volume rendering software to measure TMV [3-5]. There have also been reports of deep learning-based quantification methods for TMA [6]. Furthermore, plasma protein levels can reflect the body's protein nutritional status, the severity of disease and the risk of surgery, with common indicators including albumin, prealbumin, transferrin and retinol-binding protein, especially the latter three being more sensitive and effective indicators of nutritional status [7, 8]. To our knowledge, no studies have reported on the relationship between plasma protein levels and CSDH prognosis, and the authors may wish to explore this further.

Secondly, this is a retrospective study that included only high-priority variables in the multivariate analysis. We have observed that there are many factors affecting the prognosis of CSDH patients, including age, gender, frailty, malnutrition, cancer, hypertension, diabetes, blood diseases, and the use of anticoagulant or antiplatelet aggregation drugs and so on [9-11]. In terms of imaging signs, factors affecting the prognosis of CSDH patients are not limited to hematoma volume and midline shift, but also include hematoma thickness, hematoma type, outer membrane formation, residual volume in the hematoma cavity and so on [10, 12]. In addition, postoperative complications such as brain tissue damage, pneumocephalus, acute subdural haemorrhage and epilepsy are also factors affecting the prognosis of CSDH [10, 13]. Therefore, we believe these factors should not be overlooked. In addition, although the authors analysed the body mass index (BMI), we suggest including weight changes in the predictive model to potentially reveal new findings. Also, the authors only counted the number of deaths, and the specific causes of death were not described in detail, which may have an impact on the final results.

Thirdly, we found that the surgical methods for CSDH patients were not completely unified. Most patients underwent cranial drilling, while some patients underwent craniotomy, with room temperature saline rinse during surgery, followed by placement of a subdural drainage tube. Studies have shown that warming the irrigation fluid temperature to body temperature during cranial drilling for CSDH can reduce the risk of recurrence by more than half, so body temperature irrigation should become the standard treatment [14]. And the pipeline can adopt non-subdural drainage (subaponeurotic or subperiosteal), this method does not only increase the recurrence rate but also can avoid iatrogenic brain tissue damage [15]. This can optimize the prognosis of CSDH patients. In addition, the author's unit tends to use general anaesthesia, and meta-analysis shows that local anaesthesia has the following advantages: shorter operation time, shorter hospital stay and fewer postoperative complications [16]. The above factors are worth considering by the authors, and we look forward to future research to further improve these aspects.

Finally, we would like to thank the authors for this study again, as these important results will be an important factor for neurosurgeons to consider after surgery in the future. Studies have reported that reduced total protein levels at admission are a new factor for poor prognosis after endoscopic removal of intracerebral haemorrhage [17]. Moreover, a high protein intake following subarachnoid haemorrhage can improve TMV, and patients in the TMV maintenance group show significantly correlated functional recovery at discharge compared to the TMV atrophy group [5]. These studies emphasize the importance of high protein intake. Therefore, dynamically assessing the changes in TMT of CSDH patients may help to carry out more effective nutritional treatment, thereby reducing the mortality rate of CSDH patients. However, further prospective studies are needed to confirm this.

我们对 Korhonen 及其同事最近发表的题为“颞肌厚度减少预测慢性硬膜下血肿引流患者生存期缩短”的文章产生了浓厚的兴趣 [1]。该研究揭示了术前通过计算机断层扫描 （CT） 扫描测量的颞肌厚度 （TMT） 减少与接受慢性硬膜下血肿 （CSDH） 引流手术的患者术后生存期缩短之间存在显着相关性。作者进行了一项全面的研究，纳入了年龄、性别、BMI、影像学指标和手术方法等一系列因素，得出了令人信服的结论。然而，我们注意到，在执行研究时可能忽略了几个重要因素。我们想提供以下建议供作者考虑。

首先，TMT 作为肌肉质量、功能和营养状况的新兴替代标志物，可以通过 CT、磁共振成像 （MRI） 和超声检查来测量。虽然作者几乎完善了对 TMT 测量的考虑，但我们相信同时使用两种或多种成像方法可以产生更好的结果。除了 TMT 之外，文献还报道了颞肌面积 （TMA） 和颞肌体积 （TMV） 作为与颞肌和骨骼肌质量相关的新替代标志物 [2]。如果对与 CSDH 预后相关的颞肌评估将这三者（TMT、TMA 和 TMV）结合起来，结果将更有说服力。虽然尚未建立测量 TMT 的标准方法，也尚未使用基于人工智能的方法进行 TMT 测量，但一些研究已经使用体积渲染软件来测量 TMV [3-5]。也有报道称，基于深度学习的 TMA 量化方法 [6]。此外，血浆蛋白水平可以反映人体的蛋白质营养状况、疾病的严重程度和手术风险，常见的指标包括白蛋白、前白蛋白、转铁蛋白和视黄醇结合蛋白，尤其是后三者是更敏感和有效的营养状况指标 [7， 8]。据我们所知，尚无研究报道血浆蛋白水平与 CSDH 预后之间的关系，作者可能希望进一步探讨这一点。

其次，这是一项回顾性研究，在多变量分析中仅包括高优先级变量。我们观察到影响 CSDH 患者预后的因素很多，包括年龄、性别、虚弱、营养不良、癌症、高血压、糖尿病、血液病，以及使用抗凝剂或抗血小板聚集药物等 [9-11]。在影像学体征方面，影响 CSDH 患者预后的因素不仅限于血肿体积和中线偏移，还包括血肿厚度、血肿类型、外膜形成、血肿腔内残余体积等 [10， 12]。此外，脑组织损伤、脑积气、急性硬膜下出血和癫痫等术后并发症也是影响 CSDH 预后的因素 [10， 13]。因此，我们认为这些因素不容忽视。此外，尽管作者分析了体重指数 （BMI），但我们建议在预测模型中包括体重变化，以可能揭示新的发现。另外，作者只统计了死亡人数，没有详细描述具体的死亡原因，这可能会对最终结果产生影响。

第三，我们发现 CSDH 患者的手术方法并不完全统一。大多数患者接受了颅钻，而一些患者接受了开颅手术，手术期间用室温盐水冲洗，然后放置硬膜下引流管。研究表明，在对 CSDH 进行颅钻时，将冲洗液温度加热至体温可以将复发风险降低一半以上，因此体温冲洗应成为标准治疗方法 [14]。并且管道可以采用非硬膜下引流（腱膜下或骨膜下），这种方法不仅可以提高复发率，还可以避免医源性脑组织损伤 [15]。这可以优化 CSDH 患者的预后。此外，作者所在科室倾向于使用全身麻醉，Meta分析显示，局部麻醉具有以下优点：手术时间短、住院时间短、术后并发症少[16]。以上因素值得作者考虑，我们期待未来的研究进一步改进这些方面。

最后，我们要再次感谢作者的这项研究，因为这些重要结果将成为神经外科医生未来术后考虑的重要因素。研究报道，入院时总蛋白水平降低是内镜下清除脑出血后预后不良的新因素 [17]。此外，蛛网膜下腔出血后高蛋白质摄入可以改善 TMV，与 TMV 萎缩组相比，TMV 维持组患者在出院时表现出显著相关的功能恢复 [5]。这些研究强调了高蛋白质摄入量的重要性。因此，动态评估 CSDH 患者 TMT 的变化可能有助于进行更有效的营养治疗，从而降低 CSDH 患者的死亡率。然而，需要进一步的前瞻性研究来证实这一点。