To the Editor: It was with great pleasure that we read the article by Nakagawa et al,1 “Delayed Intracranial Parenchymal Changes After Aneurysmal Coil Embolization Procedures for Unruptured Intracranial Aneurysms.” Complications associated with endovascular treatment with devices (stent and coils) have been reported progressively in the literature. The presence of vasogenic cerebral edema after endovascular treatment is related to changes in the fluid-attenuated inversion-recovery (FLAIR) and apparent diffusion coefficient (ADC) sequence and an increase in the circumferential enhancement of the gadolinium aneurysm. Since neurointervention procedures used to be infrequent worldwide, we will increasingly see transient phenomena associated with endovascular therapy with a favorable response to medical management.2 Few studies describe the nature of those transient neurological deficits, and it is tough to define clinical categories regarding those transient events. We want to propose the term “transient phenomena associated with neuro-intervention” or TPAN instead of complications inherent to endovascular treatment. Bracard et al3 showed that from 152 patients undergoing endovascular coiling treatment in the middle cerebral artery, 2% had transient neurological deficits described as transient ischemic attacks. However, there is evidence regarding the resolution of transient deficits within 24 h.4 Zheng et al4 also identified 1.25% of patients (from a total of 1764) affected with these phenomena related to embolization, and they attribute them to the compressive effect of a coiled aneurysm, postoperative vasospasm, and postoperative hemodynamic changes. Pelz et al5 reported a rate of complication of 28% after coiling, and 41% of these were transient deficits. Twenty years later, Martinez-Perez et al6 showed a rate of complications of 7.9% of the coiling, and only 16% of these did not have any clinical implications due to its transient nature.6 These transient phenomena have been attributed to embolization and may be due to the compressive effect of a coiled aneurysm, postoperative vasospasm, and postoperative hemodynamic changes. These transient clinical and/or radiological manifestations resolve over days and months.7,8 Before, we have postulated the term “Brain Stress Timing,” which refers to complications related to surgery.9 Categorizing those transient events as an entity will encourage more objective studies toward them. Now we propose TPAN for those related to endovascular treatment. It is important to note that headache and vomiting are not symptoms of “inflammation” (termed by authors, which is unspecific); rather, it is a manifestation of raised intracranial pressure (as expected and as authors have described it was absent in all of the participants). Based on the available evidence, it is difficult to define the exact pathological nature of these events (ischemia or local inflammation) since the pathological diagnosis was not performed in any of the patients. Disclosures The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.