Influence of dosing pattern of antipsychotics on treatment outcome of delirium in patients with advanced cancer.

BACKGROUND: Clinical guidelines recommend antipsychotics for the treatment of delirium; however, there has been no confirmed recommendation regarding their administrating patterns. This study aims to investigate whether different dosing patterns of antipsychotics (single or multiple administrations) influence the outcomes of delirium treatment. METHODS: This is a secondary analysis of a prospective observational study involving patients with advanced cancer and delirium receiving antipsychotics. The Delirium Rating Scale Revised-98 was administered at baseline and after 72 h of starting pharmacotherapy. Patients were classified into single administration group (received a single dosage within 24 h before the assessment) and multiple administration group (received more than one dosage). RESULTS: A total of 555 patients (single administration 492 (88.6%); multiple administration 63 (11.4%)) were subjected to analyses. The patients in the multiple administration group were more likely to be male, in psycho-oncology consulting settings, with lower performance status, with hyperactive delirium and with severer delirium symptoms. In the multivariate analysis, single administration was significantly associated with better improvement of delirium (p < 0.01, 95% confidence interval: 1.83-5.87) even after controlling covariates. There were no significant differences in the mean dosages of antipsychotics per day in chlorpromazine equivalent (single administration 116.8 mg/day, multiple administration 123.5 mg/day) and the incidence of adverse events between the two groups. CONCLUSIONS: In this observational study sample, Delirium Rating Scale severity score improvement in single administration was higher than that seen in multiple administration. There was no difference in adverse events between the two groups.

Variegatic acid from the edible mushroom Tylopilus ballouii inhibits TNF-α production and PKCß1 activity in leukemia cells.

Variegatic acid, isolated from Tylopilus ballouii dry fruiting bodies, is an inhibitor of ß-hexosaminidase release and tumor necrosis factor (TNF)-α secretion from rat basophilic leukemia (RBL-2H3) cells, with IC50 values of 10.4 µM and 16.8 µM, respectively. On the other hand, it inhibits PKCß1 activity with an IC50 value of 36.2 µM.

How successful are we in relieving terminal dyspnea in cancer patients? A real-world multicenter prospective observational study.

PURPOSE: Parenteral morphine is widely used for dyspnea of imminently dying cancer patients, but the outcomes to expect over time remain largely unknown. We examined outcomes after the administration of parenteral morphine infusion over 48 h in cancer patients with a poor performance status. METHODS: This was a multicenter prospective observational study. Inclusion criteria were metastatic/locally advanced cancer, ECOG performance status = 3-4, a dyspnea intensity ≥ 2 on a Support Team Assessment Schedule, Japanese version (STAS-J), and receiving specialized palliative care. After initiating parenteral morphine infusion, we measured dyspnea STAS-J as well as Memorial Delirium Assessment Scale (MDAS), item 9, and Communication Capacity Scale (CCS), item 4, every 6 h over 48 h. RESULTS: We enrolled 167 patients (median survival = 4 days). The mean age was 70 years, 80 patients (48%) had lung cancer, and 109 (65%) had lung metastases. The mean STAS-J scores decreased from 3.1 (95% confidence interval (CI) = 3.0-3.2) at the baseline to 2.1 (95%CI = 1.9-2.2) at 6 h, and remained 1.6-1.8 over 12-48 h. The proportion of patients with dyspnea relief (STAS-J ≤ 1) increased to 39% at 6 h, and ranged between 49 and 61% over 12-48 h. In contrast, up to 6.6 and 20% of patients showed hyperactive delirium (MDAS item 9 ≥ 2) and an inability to communicate (CCS item 4 = 3), respectively, over 48 h. CONCLUSIONS: Overall, terminal dyspnea was relatively well controlled with parenteral morphine, though a significant number of patients continued to suffer from dyspnea. Future efforts are needed to improve outcomes following standardized dyspnea treatment using patient-reported outcomes for imminently dying patients.

Organization of the Claustrum-to-Entorhinal Cortical Connection in Mice.

The claustrum, a subcortical structure situated between the insular cortex and striatum, is reciprocally connected with almost all neocortical regions. Based on this connectivity, the claustrum has been postulated to integrate multisensory information and, in turn, coordinate widespread cortical activity. Although studies have identified how sensory information is mapped onto the claustrum, the function of individual topographically arranged claustro-cortical pathways has been little explored. Here, we investigated the organization and function of identified claustro-cortical pathways in mice using multiple anatomical and optogenetic techniques. Retrograde and anterograde tracing demonstrated that the density of anterior claustrum-to-cortical projection differs substantially depending on the target cortical areas. One of the major targets was the medial entorhinal cortex (MEC) and the MEC-projecting claustral neurons were largely segregated from the neurons projecting to primary cortices M1, S1, or V1. Exposure to a novel environment induced c-Fos expression in a substantial number of MEC-projecting claustral neurons and some M1/S1/V1-projecting claustral neurons. Optogenetic silencing of the MEC-projecting claustral neurons during contextual fear conditioning impaired later memory retrieval without affecting basal locomotor activity or anxiety-related behavior. These results suggest that the dense, anterior claustro-MEC pathway that is largely separated from other claustro-cortical pathways is activated by novel context and modulates the MEC function in contextual memory. SIGNIFICANCE STATEMENT: The claustrum is a poorly understood subcortical structure reciprocally connected with widespread neocortical regions. We investigated the organization and function of identified claustro-cortical projections in mice using pathway-specific approaches. Anatomical tracing showed that the density of anterior claustrum-to-cortical projection is dependent on the target cortical areas and that the medial entorhinal cortex (MEC) is one of the major projection targets. Novel context exposure activated multiple claustro-cortical pathways and a large fraction of the activated neurons projected to the MEC. Optogenetic silencing of the claustro-MEC pathway during contextual fear learning suppressed subsequent memory retrieval. These results suggest that the dense claustro-MEC pathway is activated by novel context and modulates MEC function in contextual memory.

Novel Technique for Rapid and Accurate Insertion of a Microguidewire Tail Into Low-Profile Devices During Endovascular Procedures: The Paper Rail Method.

PURPOSE: To report a novel technique ("paper rail") to facilitate inserting the tail of a microguidewire into the tip of a low-profile device during endovascular procedures. TECHNIQUE: A sterilized nonwoven fabric tape with a smooth glossy paper backing is used. The tape has several linear folds ideal for a paper rail. Holding each piece of equipment about 5 cm from its respective tip, both the tail of the guidewire and the tip of the catheter are navigated at a 30° angle toward each other in the crease until the guidewire enters the catheter. The paper rail technique was compared with the conventional freehand method under varying luminosities found in an operating room. The paper rail technique was most effective in suboptimal lighting, where the mean time was reduced from 83 seconds with the conventional method to 20 seconds with the paper rail maneuver. The times required to insert the wire with the paper rail method were comparable (~22 seconds) at all light levels. CONCLUSION: The paper rail method may help improve the speed and accurate insertion of the tail of a microguidewire into the tip of low-profile devices during endovascular procedures. It may be particularly useful for physicians in a low-light environment or trainees.

Discovery of Cryoprotective Activity in Human Genome-Derived Intrinsically Disordered Proteins.

Intrinsically disordered proteins (IDPs) are an emerging phenomenon. They may have a high degree of flexibility in their polypeptide chains, which lack a stable 3D structure. Although several biological functions of IDPs have been proposed, their general function is not known. The only finding related to their function is the genetically conserved YSK2 motif present in plant dehydrins. These proteins were shown to be IDPs with the YSK2 motif serving as a core region for the dehydrins' cryoprotective activity. Here we examined the cryoprotective activity of randomly selected IDPs toward the model enzyme lactate dehydrogenase (LDH). All five IDPs that were examined were in the range of 35-45 amino acid residues in length and were equally potent at a concentration of 50 µg/mL, whereas folded proteins, the PSD-95/Dlg/ZO-1 (PDZ) domain, and lysozymes had no potency. We further examined their cryoprotective activity toward glutathione S-transferase as an example of the other enzyme, and toward enhanced green fluorescent protein as a non-enzyme protein example. We further examined the lyophilization protective activity of the peptides toward LDH, which revealed that some IDPs showed a higher activity than that of bovine serum albumin (BSA). Based on these observations, we propose that cryoprotection is a general feature of IDPs. Our findings may become a clue to various industrial applications of IDPs in the future.

Posterior Meningeal Artery Origin Patterns among 300 Cases and Their Clinical Importance.

BACKGROUND AND PURPOSE: The posterior meningeal artery (PMA) is known as a dura mater-nourishing vessel. We encountered a patient with Wallenberg syndrome during transarterial embolization of the PMA associated with the dural arteriovenous fistula (DAVF). METHODS: After development of Wallenberg syndrome in the patient, we assessed origins of the PMA patterns in 300 cases and divided them into 3 types. CASE PRESENTATION: A 63-year-old man was incidentally diagnosed as having transverse-sigmoid sinus DAVF with a cortical venous reflux. During the transarterial embolization, the patient complained of vertigo and numbness of the right extremities. Postoperatively, the patient exhibited Wallenberg syndrome. Diffusion-weighted magnetic resonance imaging showed a high-intensity area on the lateral side of the right medulla. CONCLUSIONS: While performing arterial embolization of the PMA that directly originates from the intracranial vertebral artery, the possibility of deficient brainstem nourishment must be considered.

Novel Vertebral Artery Flow Reversal Method for Preventing Ischemic Complication during Endovascular Intervention.

BACKGROUND AND PURPOSE: We report a secure endovascular approach for the treatment of vascular lesions of the posterior circulation. Even if a large profile guide catheter is wedged in the unilateral vertebral artery (VA), our VA flow reversal method can prevent ischemic complications, including the spinal cord infarction. CASE PRESENTATION: The patient was a 64-year-old woman who had been followed up for arteriovenous malformation (AVM) and an unruptured aneurysm of the basilar artery-superior cerebellar artery bifurcation. Endovascular treatment was performed because minor bleeding occurred from the AVM. When a 6-French guide catheter was navigated into the right VA, the guide catheter became completely wedged, and blood flow between the tip of the catheter and the VA union was fully stagnated. Because ischemia of the anterior spinal artery and right posterior inferior cerebellar artery could persist for a few hours during the endovascular procedure, we built a continuous reversal circulation from the guiding catheter tip to the femoral vein. The flow stagnation disappeared immediately. There was no complication during embolization of both the AVM and aneurysm. CONCLUSIONS: The VA flow reversal method was secure in this case in which the tip of the guide catheter became wedged in the VA during the endovascular procedure.

Predictors of response to corticosteroids for dyspnea in advanced cancer patients: a preliminary multicenter prospective observational study.

PURPOSE: Although corticosteroids can relieve dyspnea in advanced cancer patients, factors predicting the response remain unknown. We aimed to explore potential factors predicting the response to corticosteroids for dyspnea in advanced cancer patients. METHODS: In this preliminary multicenter prospective observational study, we included patients who had metastatic or locally advanced cancer, were receiving specialized palliative care services, and had a dyspnea intensity of ≥3 on a 0-10 Numerical Rating Scale (NRS) (worst during the last 24 h). The primary endpoint was NRS of dyspnea on day 3 after the administration of corticosteroids. Univariate/multivariate analyses were conducted to identify factors predicting ≥1-point reduction in NRS. RESULTS: Of 74 patients who received corticosteroids, 50 (68%) showed ≥1-point reduction in dyspnea NRS. Factors that significantly predicted the response were an age of 70 years or older (82 vs. 53%, p = 0.008), absence of liver metastases (77 vs. 46%, p = 0.001), Palliative Prognostic Index (PPI) ≤ 6 (90 vs. 61%, p = 0.041), presence of pleuritis carcinomatosa with a small collection of pleural effusions (84 vs. 55%, p = 0.011), presence of audible wheezes (94 vs. 60%, p = 0.014), and baseline dyspnea NRS ≥7 (76% vs. 52%, p = 0.041). In a multivariate analysis, factors predicting response included PPI <6 (odds ratio (OR), 36.2; p = 0.021), baseline dyspnea NRS (worst) ≥7 (OR, 6.6; p = 0.036), and absence of liver metastases (OR, 0.19; p = 0.029) or ascites/liver enlargement (OR, 0.13; p = 0.050). CONCLUSIONS: The patient characteristics, etiologies of dyspnea, and clinical manifestations may predict responses to corticosteroids for dyspnea. Larger prospective studies are promising to confirm our findings.

Predictors of responses to corticosteroids for anorexia in advanced cancer patients: a multicenter prospective observational study.

PURPOSE: Although corticosteroids are widely used to relieve anorexia, information regarding the factors predicting responses to corticosteroids remains limited. The purpose of the study is to identify potential factors predicting responses to corticosteroids for anorexia in advanced cancer patients. METHODS: Inclusion criteria for this multicenter prospective observational study were patients who had metastatic or locally advanced cancer and had an anorexia intensity score of 4 or more on a 0-10 Numerical Rating Scale (NRS). Univariate and multivariate analyses were conducted to identify the factors predicting ≥2-point reduction in NRS on day 3. RESULTS: Among 180 patients who received corticosteroids, 99 (55 %; 95 % confidence interval [CI], 47-62 %) had a response with ≥2-point reduction. Factors that significantly predicted responses were Palliative Performance Scale (PPS) > 40 and absence of drowsiness. In addition, factors that tended to be associated with ≥2-point reduction in NRS included PS 0-3, absence of diabetes mellitus, absence of peripheral edema, presence of lung metastasis, absence of peritoneal metastasis, baseline anorexia NRS of >6, presence of pain, and presence of constipation. A multivariate analysis showed that the independent factors predicting responses were PPS of >40 (odds ratio = 2.7 [95 % CI = 1.4-5.2]), absence of drowsiness (2.6 [1.3-5.0]), and baseline NRS of >6 (2.4 [1.1-4.8]). CONCLUSIONS: Treatment responses to corticosteroids for anorexia may be predicted by PPS, drowsiness, and baseline symptom intensity. Larger prospective studies are needed to confirm these results.

A novel anti-microtubule agent with carbazole and benzohydrazide structures suppresses tumor cell growth in vivo.

BACKGROUND: The mitotic spindles are among the most successful targets of anti-cancer chemotherapy, and they still hold promise as targets for novel drugs. The anti-mitotic drugs in current clinical use, including taxanes, epothilones, vinca alkaloids, and halichondrins, are all microtubule-targeting agents. Although these drugs are effective for cancer chemotherapy, they have some critical problems; e.g., neurotoxicity caused by damage to neuronal microtubules, as well as innate or acquired drug resistance. To overcome these problems, a great deal of effort has been expended on development of novel anti-mitotics. METHODS: We identified novel microtubule-targeting agents with carbazole and benzohydrazide structures: N'-[(9-ethyl-9H-carbazol-3-yl)methylene]-2-methylbenzohydrazide (code number HND-007) and its related compounds. We investigated their activities against cancer cells using various methods including cell growth assay, immunofluorescence analysis, cell cycle analysis, tubulin polymerization assay, and tumor inhibition assay in nude mice. RESULTS: HND-007 inhibits tubulin polymerization in vitro and blocks microtubule formation and centrosome separation in cancer cells. Consequently, it suppresses the growth of various cancer cell lines, with IC50 values in the range 1.3-4.6µM. In addition, HND-007 can inhibit the growth of taxane-resistant cancer cells that overexpress P-glycoprotein. Finally, HND-007 can inhibit HeLa cell tumor growth in nude mice. CONCLUSIONS AND GENERAL SIGNIFICANCE: Taken together, these findings suggest that HND-007 is a promising lead compound for development of novel anti-mitotic, anti-microtubule chemotherapeutic agents.

Interleukin-6, MCP-1, IP-10, and MIG are sequentially expressed in cerebrospinal fluid after subarachnoid hemorrhage.

BACKGROUND: Interleukin-6 (IL-6), an inflammatory cytokine, plays important roles in cerebrospinal fluid (CSF) after subarachnoid hemorrhage (SAH). Chemokines are chemoattractant cytokines that regulate trafficking of monocytes/macrophages and lymphocytes to sites of inflammation. However, no studies have been reported regarding the temporal expression of these cytokines in CSF after SAH. FINDINGS: The concentrations of IL-6, monocyte chemoattractant protein-1 (MCP-1), interferon-γ-inducible protein-10 (IP-10), and monokine induced by interferon-γ (MIG) in the CSF of ten patients with SAH were measured using ELISA kits over a period of 14 days. All aneurysms were located in the anterior circulation. CSF samples from patients with unruptured aneurysms were used as controls. The concentration of IL-6 significantly increased during the acute stage of the disease. The concentration of MCP-1 increased from days 1 to 5, peaking on day 3, and decreased thereafter. The concentrations of IP-10 and MIG progressively increased, peaked on day 5, and then gradually decreased. There were strong correlations between the maximum levels of IL-6 and MCP-1 and IP-10 and MIG on day 5. The maximum level of IL-6 was much higher in poor outcome patients than in good outcome patients. CONCLUSIONS: The present investigation demonstrated that increases in IL-6 levels may induce the expression of MCP-1 in CSF after SAH, followed by increases in the expression of IP-10 and MIG. Dynamic changes in the levels of these cytokines may induce inflammation and may be closely associated with the development of delayed ischemic neurological deficits after SAH.

Use of olanzapine for the relief of nausea and vomiting in patients with advanced cancer: a multicenter survey in Japan.

Nausea and vomiting are among the most common and distressing symptoms in patients with advanced cancer. Olanzapine, an antipsychotic agent, is known to have an affinity for multiple neurotransmitter receptors. Previous studies have reported olanzapine to be efficacious in the treatment of nausea and vomiting. Although it has been administered at a number of facilities, its applicability to treat nausea and vomiting in patients with advanced cancer is poorly understood. We investigated the use of olanzapine for nausea and vomiting in patients with advanced cancer at multiple centers. This retrospective study was carried out at seven palliative care units and three facilities with palliative care teams in Japan from 2013 to 2015. The dosage of olanzapine, treatment duration, and duration from initial use until death were collected from the medical records. One hundred and eight patients met our inclusion criteria. The average dose of olanzapine was 3.6 mg (2.5 mg, n = 61; 5 mg, n = 46; 10 mg, n = 1) and average treatment duration was 18.7 days. The average duration from initial use until death was 39.0 days. There were no differences in the duration of administration until death between olanzapine doses (2.5 and 5 mg). Our results suggest that olanzapine have been used in patients with poor prognoses for nausea and vomiting in patients with advanced cancer. Conducting a prospective trial would further yield promising results.

Prevalence of C7 level anomalies at the C7 level: an important landmark for cervical nerve ultrasonography.

BACKGROUND: Recently, various examination and intervention techniques using cervical nerve ultrasonography have been developed. The specific shapes of the C7 transverse process and vertebral artery in front of the C7 transverse process have become landmarks. PURPOSE: To determine the prevalence of anomalies and anomalous vertebral artery entrances at the C7 transverse process. MATERIAL AND METHODS: The records of patients who underwent plain or contrast-enhanced neck or cervical spine computed tomography (CT) were reviewed. The examinations were scored for the anomalous presence of anterior tubercles or cervical ribs as well as vertebral artery entrances in the C7 transverse process. The prevalence of anomalies was compared based on patient sex and age. RESULTS: Evaluating the examinations from 2067 patients (1046 men; 1021 women), 1% of patients exhibited an anomalous presence of anterior tubercles, and 0.3% of patients displayed cervical ribs at the C7 transverse process. The prevalence of anomalies process was significantly higher in men aged less than 40 years than in older men (P < 0.001), whereas the prevalence was not higher in women aged less than 40 years than in older women. The prevalence of vertebral artery entry into the C7 transverse foramen was 0.6%. CONCLUSION: Although an anomalous vertebral artery entry into the C7 transverse foramen was rare, the prevalence of an anomaly at the C7 transverse process was higher in men aged less than 40 years. Therefore, we recommend performing CT in younger men before cervical nerve ultrasonographic intervention to avoid misinterpretations at the cervical level.

Expression of suppressor of cytokine signaling 3 in cerebrospinal fluid after subarachnoid hemorrhage.

BACKGROUND: IL-6 is a proinflammatory cytokine reported to play an important role in the induction of cerebral vasospasm after subarachnoid hemorrhage (SAH). Suppressor of cytokine signaling 3 (SOCS3) is known to act as an inhibitor of signal transduction of IL-6. However, there have been no reports on the expression of SOCS3 in cerebrospinal fluid (CSF) after SAH. FINDINGS: The concentration of IL-6 was measured serially up until day 10, in CSF of eight patients with SAH. CSF samples obtained from patients suffering from an unruptured aneurysm were used as controls. The expression of SOCS3 in CSF was further examined by immunoprecipitation methods. Concentrations of IL-6 in CSF increased immediately after the onset of SAH and remained chronically elevated over control values. SOCS3 was significantly expressed in CSF on days 1 to 3 after SAH. CONCLUSIONS: Our findings suggest that SOCS3 regulates IL-6 signaling as an antagonist in CSF, immediately following SAH. As the expression of SOCS3 decreases after day 5, IL-6 signals might then be more easily transmitted, presumably resulting in cerebral vasospasm.

A Novel Training Method for Endovascular Clot Retrieval Using a Portable Vascular Model and Red Film.

Hands-on training is a crucial part of education in neuroendovascular treatment to ensure safe and rapid acquisition of techniques. However, there is a significant gap between training and actual clinical practice. This study will introduce innovations for more practical thrombus retrieval training that was developed in this process. A Smart Vascular Model 3 in 1 was used. A pink pseudothrombus was inserted into the M1 (horizontal segment of the middle cerebral artery) section of the model. Then, a "red underlay" purchased at a stationery store was placed to cover the proximal part of M1 and beyond so that the pseudothrombus was not visible. The thrombus was retrieved during training by looking for the location of the thrombus based on the behavior and resistance of the tip of the guidewire and deployment of the stent retriever. The participants were required to have detailed observation skills and precise manipulation skills using a red film to prevent the direct visualization of the pseudothrombus. The implementation of this innovation to the previous hands-on training made the training more practical and effective. If the exact thrombus location can be determined by the behavior of the wire tip, the device's capabilities can be maximized, and rapid retrieval can be expected. It could also reduce complications, as unnecessary peripheral guidance of the device could be avoided.

Relationship between Shape Retention and X-ray Absorption Value of the Tip of Microcatheters in Neuroendovascular Treatment.

Objective We noticed that the X-ray absorption value of the tip of each microcatheter used for aneurysm treatment varied from product to product. We hypothesized that the differences were caused by variations in the metal's density braid, which could be related to the ability of the tip to retain its shape. Methods The X-ray absorption value of each microcatheter tip was measured. Next, heat forming was performed using a shaping mandrel at 6 mm and 90 degrees to determine whether there was a correlation between the X-ray absorption value and the forming angle. Next, the optimal mandrel angle for forming each microcatheter at 90 degrees was investigated. We also examined the shape retention after 20 times wire insertions into each microcatheter. Conclusion It was found that the higher the X-ray absorption value, the harder it was for the microcatheter to be formed. The mandrel angle required to form 90 degrees was determined by the X-ray absorption value. The higher the X-ray absorption value, the higher the shape retention of the tip shape. The heat formation and shape-retention conditions of the microcatheter tip were correlated with the X-ray absorption value of the metal braid. Even for unknown microcatheters, the optimum shaping conditions can be inferred from the X-ray absorption value.

Persistent representation of the environment in the hippocampus.

In the hippocampus, environmental changes elicit rearrangement of active neuronal ensembles or remapping of place cells. However, it remains elusive how the brain ensures a consistent representation of a certain environment itself despite salient events occurring there. Here, we longitudinally tracked calcium dynamics of dorsal hippocampal CA1 neurons in mice subjected to contextual fear conditioning and extinction training. Overall population activities were significantly changed by fear conditioning and were responsive to footshocks and freezing. However, a small subset of neurons, termed environment cells, were consistently active in a specific environment irrespective of experiences. A decoder modeling study showed that these cells, but not place cells, were able to predict the environment to which the mouse was exposed. Environment cells might underlie the constancy of cognition for distinct environments across time and events. Additionally, our study highlights the functional heterogeneity of cells in the hippocampus.

A novel remote hands-on training for neuroendovascular-based treatment in the era of the COVID-19 pandemic.

The COVID-19 pandemic has demanded a change in learning modalities, which led us to develop a remote personal training system for clinicians performing neuroendovascular procedures. A portable vascular model designed for practicing catheter navigation guidance, thrombus retrieval, and intracranial aneurysm coil embolisation was established. We created an environment that enabled interactive dialogue and communication across long distances using the Internet. The instructor conducted approximately 2 h of hands-on training with two to four trainees at a time. Despite the restrictions enforced by the Government of Japan due to the COVID-19 pandemic, 17 online hands-on training were successfully conducted throughout Japan over 1 year for a total of 48 trainees. The developed remote training programme, to avoid the aggregation of a large number of trainees at a developed time, proved to be at par with the conventional learning system. The training was well-received since the operation time was longer and the question and answer sessions were more fulfilling compared to the conventional format in which a group of trainees had got a brief opportunity to receive actual hands-on experience.

Hairball-Like Migration of "Onyx Threads" into the Draining Vein during Transarterial Embolization of a Dural Arteriovenous Fistula: A Case Report and Experimental Validation.

Transarterial embolization using Onyx is a well-established treatment for dural arteriovenous fistulas (DAVFs). However, complications can arise when Onyx migrates into the venous side, impairing the draining veins. We encountered a case where Onyx, injected through the arterial side, strayed into the jugular vein, forming a hairball-like structure. Our study aimed to investigate the underlying mechanism of this unusual phenomenon. We postulated that Onyx precipitates into thread-like shapes when passing through extremely narrow openings. To test this, we extruded Onyx from a syringe through a 27-gauge needle into a silicone tube with flowing water. By varying the flow speed, we observed the hardening behavior of Onyx. Under slow flow, the extruded Onyx quickly solidified at the needle tip, forming a round mass. Conversely, high-speed flow resulted in Onyx being dispersed as small pieces. We successfully replicated the formation of "Onyx threads" under continuous slow flow conditions, similar to our case. This phenomenon occurs when Onyx unexpectedly migrates to the draining vein through a tiny opening during transarterial embolization for arteriovenous shunt diseases. Early recognition and appropriate measures are necessary to prevent occlusive complications in the draining veins and the pulmonary system.