TO THE EDITOR: We read with great interest the article published by Moe et al.1(Moe HK, Limandvik Myhr J, Moen KG, et al. Association of cause of injury and traumatic axonal injury: a clinical MRI study of moderate and severe traumatic brain injury.J Neurosurg.2020;133[5]:1559–1567). The authors reported their investigation of causal mechanistic effects on the incidence of traumatic axonal injury (TAI). Moe et al. accurately analyzed the role of each known cause of TAI and the underlying pathophysiology; however, some concerns need to be highlighted. It is well known that TAI is one of the main causes of impairment during the posttraumatic phase in patients who have no detectable intracranial lesions on CT,2even patients with mild traumatic brain injury. Several phenomena explain how the strong acceleration-deceleration and rotational-angular acceleration forces in high-impact trauma lead to progressive changes in the axons, resulting in deformation of the brain tissue.2
An external injury involves shearing forces that stimulate the formation of axon retraction balls, which result from a swelling phenomenon at the end of the axonal axis due to external shear force and tension that lead to the final breakage of the axon. During this process the permeability of the axon membrane changes and large amounts of Ca+进入细胞,扭转等离子tran的通量sport and activating the cysteine protein signal pathway and caspase-3. These events lead to the degradation of the axonal cytoskeleton network. During this progressive phenomenon, axons usually maintain their morphology several hours after injury, and for that reason it is crucial to perform MRI in patients days after trauma.3
虽然我们理解repor的复杂性ting hundreds of neuroimaging results and thank the authors for their investigation of this important topic, we have to note the highly heterogeneous rating of the samples reported by Moe et al.1and the possible consequences. The fact that there is substantial agreement between raters (linear Cohen's kappa 0.74) should be interpreted with caution given that some of the pitfalls in this study may have decreased the interrater reliability to an unknown degree. Having more than two raters may have masked valuable ratings in the analysis, and thus the generalized kappa may not have captured the range of potential agreement or disagreement between assessments by multiple raters.4
Disclosures
The authors report no conflict of interest.
References
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1 ↑
MoeHK,LimandvikMyhr J,MoenKG,et al.Association of cause of injury and traumatic axonal injury: a clinical MRI study of moderate and severe traumatic brain injury.J Neurosurg.2020;133(5):1559–1567.
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2 ↑
KimM,AhnJS,ParkW,et al.Diffuse axonal injury (DAI) in moderate to severe head injured patients: Pure DAI vs. non-pure DAI. Clin Neurol Neurosurg.2018;171:116–123.
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3 ↑
MaJ,ZhangK,WangZ,ChenG.Progress of research on diffuse axonal injury after traumatic brain injury.Neural Plast.2016;2016:9746313.
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4 ↑
O’LearyS,LundM,Ytre-HaugeTJ,et al.Pitfalls in the use of kappa when interpreting agreement between multiple raters in reliability studies.Physiotherapy.2014;100(1):27–35.
