Risk of disease flares after SARS-CoV-2 mRNA vaccination in patients with systemic lupus erythematosus.

This study aims to elucidate the effectiveness and safety of SARS-CoV-2 mRNA vaccination in patients with systemic lupus erythematosus (SLE). We enrolled uninfected SLE patients who received two vaccine doses (BNT162b2 or mRNA-1273) and historical unvaccinated patients. Neutralizing antibodies, adverse reactions, and disease flares were evaluated 4 weeks after the second vaccination. Ninety patients were enrolled in each group. Among the vaccinated patients, SLE Disease Activity Index (SLEDAI), and prednisolone doses before vaccination were 2, and 5 mg/d, respectively. After the second vaccination, 19 (21.1%) had no neutralizing antibodies. Adverse reactions occurred in 88.9% within 3 d. Negative antibodies were associated with anemia and mycophenolate mofetil administration. SLEDAI increased modestly but significantly after vaccination, with 13 (14.4%) experiencing flares and 4 (4.4%) severe flares (nephritis in three and vasculitis in one). The flare rate was higher in vaccinated patients than unvaccinated controls. The mean duration between the second vaccination and flares was 35 d, and flares occurred at least 8 days after vaccination. Multivariable analysis showed that high SLEDAI and anti-dsDNA antibodies were associated with flares. The vaccine type, neutralizing antibody titer, and adverse reaction frequency did not affect flares. Therefore, residual disease activity before vaccination increases flare risk.

Bilateral vocal cord palsy induced by long-term use of small-bore nasogastric tube.

Background: Nasogastric tube syndrome is a rare but life-threatening complication of nasogastric tube placement due to acute upper airway obstruction caused by bilateral vocal cord paresis. Case Presentation: An 86-year-old woman was brought to the emergency department with acute stridor. She had been diagnosed with stroke 106 days prior, and an 8F nasogastric tube was placed on the day following the diagnosis. A laryngeal fiberscopy revealed bilateral laryngeal edema and bilateral vocal cord palsy. Nasogastric tube removal and intubation were carried out, and the stridor disappeared. Two days later, a tracheostomy was performed. Unfortunately, the patient's vocal cord function had not improved at the 1 month follow-up upon assessment with a laryngeal fiberscope. Conclusion: Long-term small-bore nasogastric tube placement can cause upper airway obstruction due to bilateral vocal cord palsy.

Improved Liver Function After Sustained Virologic Response Enhanced Prognosis in Hepatitis C with Compensated Advanced Liver Fibrosis.

BACKGROUND AND AIM: Liver function can be improved in patients with chronic hepatitis C virus (HCV) infection who achieved sustained virologic response (SVR) with direct-acting antiviral (DAA) treatment. However, to our knowledge, the impact of liver function improvement after SVR on prognosis has not been investigated. METHODS: A total of 716 patients with chronic HCV infection and compensated advanced liver fibrosis who began receiving DAA treatment between September 2014 and August 2018 in 25 Japanese hospitals and achieved SVR were enrolled. RESULTS: The median age was 73 years, and 336 (47%) and 380 (53%) patients had albumin-bilirubin (ALBI) grade 1 and grade 2, respectively. Improvement to ALBI grade 1 at 1 year after the end of treatment (EOT) was observed in 76% of the patients with baseline ALBI grade 2. Among 380 patients with baseline ALBI grade 2, alanine aminotransferase (ALT) levels ≥ 40 U/L (p < 0.001) and modified ALBI (mALBI) grade 2a (p < 0.001) were significantly associated with improvement to ALBI grade 1 at 1 year after EOT in multivariate analysis. During the median observation period of 51.8 months, 4 and 10 patients with baseline ALBI grade 1 and 2, respectively, died. In patients with baseline ALBI grade 2, only the absence of improvement to ALBI grade 1 at 1 year after EOT was significantly associated with all-cause mortality in univariate analysis. CONCLUSIONS: Baseline ALT levels and mALBI grade were significantly associated with improvement in liver function after SVR. Patients whose liver function improved after SVR could have better prognosis.

Betuletol, a Propolis Component, Suppresses IL-33 Gene Expression and Effective against Eosinophilia.

Propolis, a resinous substance produced by honeybees, has been used in folk medicine since ancient times due to its many biological benefits such as antitumor, antioxidant, antimicrobial, anti-inflammatory, and immunomodulatory effects. Propolis contains flavonoids, terpenoids, aromatic aldehydes, and alcohols, which vary with different climate and environmental conditions. In our study, we examined the antiallergic activity of Brazilian green propolis (BGP) and isolated the active compound that can suppress an allergy-sensitive gene, IL-33, expression and eosinophilia. Ethanolic extract of BGP freeze-dried powder was fractionated with several solvent systems, and the active fractions were collected based on activity measurement. The single active compound was found by thin-layer chromatography. Using column chromatography and NMR, the active compound was isolated and identified as 3,5,7-trihydroxy-6,4'-dimethoxyflavone, also known as betuletol. Further, the antiallergic activity of that has been examined in PMA-induced up-regulation of IL-33 gene expression in Swiss 3T3 cells. Our data showed the IL-33 gene suppression both by BGP and the isolated active compound, betuletol. We also found that betuletol suppressed ERK phosphorylation, suggesting it could be effective in suppressing IL-33 mediated eosinophilic chronic inflammation and will provide new insights to develop potent therapeutics against allergic inflammations.

Age- and sex-based changes in spike protein antibody status after SARS-CoV-2 vaccination and effect of past-infection in healthcare workers in Osaka.

OBJECTIVE: We aimed to compare the changes in SARS-CoV-2 spike protein antibody titres based on age group and sex using paired blood sampling after vaccination in association with the presence of nucleocapsid protein antibody. METHODS: All participants were healthcare workers at Yao Municipal Hospital in Osaka who voluntarily provided peripheral blood samples (n = 636, men/women 151/485, mean age 45 years). We investigated the serial changes in SARS-CoV-2 spike protein antibody titres at 1 and 7 months after the second vaccination regarding their relationship with sex and age group. At 7 months, we also examined anti-nucleocapsid assays. Antibody titres were shown as logarithmic values and the differences were assessed using a paired or unpaired student's t-test as appropriate. RESULTS: Among participants younger than 30 years, the antibody titres of spike protein were significantly higher in women one (p = 0.005) and seven (p = 0.038) months after vaccination. However, among those aged 30-49 years, the antibody titres were not different between the sexes at either follow-up time point. In contrast, among those aged 50-59 years, between-sex differences in antibody titres were observed only at 7 months, which was associated with a significant reduction in men. A significant negative correlation was observed between the antibody titres for spike protein at both time points in participants with positive nucleocapsid protein antibody at 7 months (r = - 0.467, p = 0.043), although a significant positive correlation was observed in those with negative results (r = 0.645, p < 0.001), CONCLUSIONS: Between-sex differences in SARS-CoV-2 spike protein antibody titres by paired blood sampling at different time points after vaccination depended on age group. The presence of nucleocapsid protein antibody was associated with changes in spike protein antibody titres after vaccination.

Intravascular Catheter Accidentally Placed into the Right Lumbar Vein from the Right Femoral Vein: A Case Report.

BACKGROUND Severe hypothermia has a high mortality rate and necessitates aggressive warming to save lives. One of the most effective treatments for severe hypothermia is intravascular rewarming. Intravascular recuperative warming can be delivered by inserting a catheter through the cervical or femoral veins. Catheter insertion through the femoral vein is a commonly performed procedure with fewer complications than catheter insertion through the internal jugular vein. This procedure is commonly conducted by inserting a central venous catheter through the femoral vein. When a catheter is inserted through the femoral vein, a frontal abdominal radiograph is often used to confirm the position of the catheter tip. CASE REPORT We present the case of a 58-year-old Japanese man who had severe hypothermia. Under ultrasound guidance, a catheter was inserted through the femoral vein into the inferior vena cava for active rewarming. A frontal abdominal radiograph showed that a catheter tip appeared to be in the inferior vena cava. However, a subsequent computed tomography scan revealed that the catheter tip had been misplaced into the right ascending lumbar vein. CONCLUSIONS Catheters may stray into the right ascending lumbar vein if they are placed through the right femoral vein. Frontal abdominal radiographs may be insufficient to confirm catheter placement.

Risk of hepatocellular carcinoma after sustained virologic response in hepatitis C virus patients without advanced liver fibrosis.

AIM: Hepatocellular carcinoma (HCC) after sustained virologic response (SVR) has been observed even in hepatitis C virus (HCV) patients without advanced liver fibrosis. Identifying predictors for HCC incidence in patients without advanced liver fibrosis will enable efficient post-SVR HCC surveillance. This study aimed to develop a scoring system to predict the incidence of HCC after SVR in HCV patients without advanced liver fibrosis. METHODS: A total of 1682 HCV patients without advanced liver fibrosis (defined as Fibrosis-4 index <3.25) with no history of HCC who initiated direct-acting antiviral treatment between September 2014 and October 2020 at 26 institutions, and achieved SVR24, were included. We divided 1682 patients into training (1122) and validation (560) cohorts. RESULTS: In the multivariate analysis, baseline age ≥ 65 years (p = 0.030), alanine aminotransferase (ALT) levels at SVR24 ≥ 30 U/l (p = 0.001), and α-fetoprotein (AFP) levels at SVR24 ≥ 5.0 ng/ml (p = 0.001) were independent predictors for HCC incidence in the training cohort. We developed a scoring system to predict HCC incidence after SVR24 using these three factors (1 point was added for each factor). The cumulative HCC incidence rates at 5 years were 7.1% in patients who scored 2 or 3, and no patients developed HCC in those who scored 0 in the validation cohort. CONCLUSIONS: Our scoring system using the three factors of baseline age, ALT levels at SVR, and AFP levels at SVR is useful for post-SVR HCC surveillance of patients without advanced liver fibrosis.

Patho-Pharmacological Research of Anti-allergic Natural Products Targeting Antihistamine-Sensitive and -Insensitive Allergic Mechanisms.

Histamine H1 receptor (H1R) has a special up-regulation mechanism by the stimulation of H1R, mediated by protein kinase C-delta (PKCδ) signaling and H1R gene expression, resulting increase in H1R signaling. Increase in H1R mRNA in nasal mucosa was induced after the provocation of nasal hypersensitivity model rats and suppressed by the pre-treatment of antihistamines. Improvement of nasal symptoms and suppression of H1R mRNA expression in nasal mucosa were also observed by the pre-treatment of antihistamines in pollinosis patients. Elucidation of a correlation between symptoms and H1R mRNA level suggests that H1R gene is an allergic disease (AD)-susceptibility gene, targeted by antihistamines. Similar to antihistamines, pre-treatment of Kujin extract, an anti-allergic Kampo medicine improved nasal symptoms and suppressed H1R mRNA expression in nasal hypersensitivity model rats. (-)-Maackiain targeting heat shock protein 90 (Hsp90) was isolated as an inhibitor of PKCδ signaling-mediated H1R gene expression from Kujin extract. In addition to H1R-mediated activation of H1R gene expression as the first mechanism, nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression is suggested to participate to allergic symptoms as the second mechanism insensitive to antihistamines. Pyrogallol and proanthocyanidin suppressing IL-9 gene expression were discovered from Awa-tea and lotus root knots, respectively. Combination therapy using medicines suppressing both H1R gene expression and IL-9 gene expression is promising for outstanding alleviation of AD. Multifactorial diseases involving H1R gene expression may be treated by the combination therapy with antihistamine and complementary drugs, and diseases involving PKCδ signaling may be treated by drugs targeting Hsp90.

Molecular Signaling and Transcriptional Regulation of Histamine H1 Receptor Gene.

Histamine-activated histamine H1 receptor (H1R) signaling regulates many gene expressions, mainly through the protein kinase C (PKC)/extracellular signal-regulated kinases (ERK) signaling. Involvement of other signaling, including NF-κB, Wnt, RUNX-2, and Rho A signaling was also demonstrated. In addition, cAMP production through the activation of H1R signaling was reported. H1R gene itself is also up-regulated by the activation of H1R signaling with histamine. Here, we review our recent findings in the molecular signaling and transcriptional regulation of the H1R gene. Stimulation with histamine up-regulates H1R gene expression through the activation of H1R in HeLa cells. The PKCδ/ERK/poly(ADP)ribosyl transferase-1 (PARP-1) signaling was involved in this up-regulation. Heat shock protein 90 also plays an important role in regulating PKCδ translocation. Promoter analyses revealed the existence of two promoters in the human H1R gene in HeLa cells. H1R-activated H1R gene up-regulation in response to histamine was also observed in U373 astroglioma cells. However, this up-regulation was mediated not through the PKCδ signaling but possibly through the PKCα signaling. In addition, the promoter region responsible for histamine-induced H1R gene transcription in U373 cells was different from that of HeLa cells. These findings suggest that the molecular signaling and transcriptional regulation of the H1R gene are different between neuronal cells and non-neuronal cells.

Serum growth differentiation factor 15 predicts hepatocellular carcinoma occurrence after hepatitis C virus elimination.

BACKGROUND: After hepatitis C virus (HCV) elimination, patients should be followed up due to risk of hepatocellular carcinoma (HCC). Growth differentiation factor 15 (GDF15) is a cytokine induced by mitochondrial dysfunction or oxidative stress. Aim To evaluate the prognostic value of GDF15 for HCC occurrence after HCV elimination. METHODS: We measured GDF15 levels in stored serum from patients with chronic HCV infection without a history of HCC who had achieved sustained virological response with direct-acting antiviral agents (DAAs). The patients were randomly divided into derivation (n = 964) and validation (n = 642) cohorts. RESULTS: In the derivation cohort, serum GDF15 levels were higher in those with HCC occurrence after DAA treatment than in those without. Multivariate Cox proportional hazards analysis revealed baseline GDF15 (>1350 pg/mL, HR 2.54), AFP (>5 ng/mL, HR 2.00), and the FIB-4 index (>3.25, HR 2.69) to be independent risk factors for HCC. Scoring based on GDF15, AFP and the FIB-4 index stratified HCC occurrence risk. In the validation cohort, the cumulative HCC occurrence rate at 3 years was 0.64%, 3.27% and 15.3% in low-score (N = 171), medium-score (N = 300) and high-score (N = 166) groups, respectively. In the total cohort, scoring divided patients with a FIB-4 index ≤3.25, whose HCC occurrence rate was 2.0% at 3 years, into medium-score and low-score groups with HCC occurrence rates at 3 years of 3.76% and 0.24%, respectively. CONCLUSIONS: Serum GDF15 predicts de novo HCC occurrence. Scoring using GDF15, AFP, and the FIB-4 index can predict de novo HCC occurrence risk after HCV elimination.

Prediction model for hepatocellular carcinoma occurrence in patients with hepatitis C in the era of direct-acting anti-virals.

BACKGROUND: Several factors associated with hepatocellular carcinoma (HCC) occurrence after sustained virological response (SVR) in patients with hepatitis C have been reported. However, few validation studies have been performed in the era of direct-acting anti-virals (DAAs). AIMS: To develop a prediction model for HCC occurrence after DAA-mediated SVR and validate its usefulness. METHODS: We analysed 2209 patients with SVR and without a history of HCC who initiated DAA treatment at 24 Japanese hospitals. These patients were divided into a training set (1473 patients) and a validation set (736 patients). RESULTS: In the training set, multivariate Cox proportional hazards analysis showed that the baseline BMI (≥25.0 kg/m2 , P = 0.024), baseline fibrosis-4 (FIB-4) index (≥3.25, P = 0.001), albumin level at SVR (<4.0 g/dL, P = 0.010) and alpha-foetoprotein level at SVR (≥5.0 ng/mL, P = 0.006) were significantly associated with HCC occurrence. We constructed a prediction model for HCC occurrence with these four factors (2 points were added for the FIB-4 index, and 1 point was added for each of the other three factors). Receiver operating characteristics curve analysis identified a score of 2 as the optimal cut-off value for the prediction model (divided into 0-1 and 2-5). In the validation set, the sensitivity and negative predictive value for HCC occurrence were 87.5% and 99.7%, respectively, at 2 years and 71.4% and 98.0%, respectively, at 3 years. CONCLUSION: A prediction model combining these four factors contributes to an efficient surveillance strategy for HCC occurrence after DAA-mediated SVR.

Signaling Pathway of Histamine H1 Receptor-Mediated Histamine H1 Receptor Gene Upregulation Induced by Histamine in U-373 MG Cells.

Histamine H1 receptor (H1R) is one of the targets of histamine in the nervous system and the peripheral tissues. Protein kinase Cδ (PKCδ) signaling is involved in histamine-induced upregulation of H1R gene expression in HeLa cells. Histamine also upregulates H1R gene expression in U-373 MG cells. However, the molecular signaling of this upregulation is still unclear. Here, we investigated the molecular mechanism of histamine-induced H1R gene upregulation in U-373 MG cells. Histamine-induced H1R gene upregulation was inhibited by H1R antagonist d-chlorpheniramine, but not by ranitidine, ciproxifan, or JNJ77777120, and H2R, H3R, or H4R antagonists, respectively. Ro-31-8220 and Go6976 also suppressed this upregulation, however, the PKCδ selective inhibitor rottlerin and the PKCß selective inhibitor Ly333531 did not. Time-course studies showed distinct kinetics of H1R gene upregulation in U-373 MG cells from that in HeLa cells. A promoter assay revealed that the promoter region responsible for H1R gene upregulation in U-373 MG cells was different from that of HeLa cells. These data suggest that the H1R-activated H1R gene expression signaling pathway in U-373 MG cells is different from that in HeLa cells, possibly by using different promoters. The involvement of PKCα also suggests that compounds that target PKCδ could work as peripheral type H1R-selective inhibitors without a sedative effect.

Effects of narrow-band UVB on nasal symptom and upregulation of histamine H1 receptor mRNA in allergic rhinitis model rats.

BACKGROUND: Phototherapy with narrow-band ultraviolet B (narrow-band UVB) is clinically effective treatment for atopic dermatitis. In the present study, we examined the effects of intranasal irradiation with narrow-band UVB on nasal symptom, upregulation of histamine H1 receptor (H1R) gene expression and induction of DNA damage in the nasal mucosa of allergic rhinitis (AR) model rat. METHODS: AR model rats were intranasally irradiated with 310 nm of narrow-band UVB. Nasal mucosal levels of H1R mRNA were measured using real-time quantitative reverse transcriptase (RT)-PCR. DNA damage was evaluated using cyclobutane pyrimidine dimer (CPD) immunostaining. RESULTS: In toluene 2,4-diisocyanate (TDI)-sensitized rats, TDI provoked sneezes and H1R gene expression in the nasal mucosa. Intranasal pre-irradiation with 310 nm narrow-band UVB at doses of 600 and 1400, but not 200 mJ/cm2 significantly inhibited the number of sneezes and upregulation of H1R gene expression provoked by TDI. CPD-positive cells appeared in the nasal mucosa after intranasal narrow-band UVB irradiation at a dose of 1400, but not 200 and 600 mJ/cm2. The suppression of TDI-provoked sneezes and upregulation of H1R gene expression lasted 24 hours, but not 48 hours, after narrow-band UVB irradiation with a dose of 600 mJ/cm2. CONCLUSIONS: Intranasal pre-irradiation with narrow-band UVB dose-dependently inhibited sneezes and upregulation of H1R gene expression of the nasal mucosa in AR model rats, suggesting that the inhibition of nasal upregulation of H1R gene expression suppressed nasal symptom. The suppression after narrow-band UVB irradiation at a dose of 600 mJ/cm2 was reversible without induction of DNA damage. These findings indicated that low-dose narrow-band UVB phototherapy could be effectively and safely used for AR treatment in a clinical setting. LEVEL OF EVIDENCE: NA.

Impact of non-pharmaceutical interventions for the COVID-19 pandemic on emergency department patient trends in Japan: a retrospective analysis.

AIM: The coronavirus disease (COVID-19) pandemic massively impacted emergency department (ED) visits. The unavailability of specific therapies or vaccines has made non-pharmaceutical interventions (NPIs) an alternative strategy for COVID-19. We assessed the impact of NPIs (nationwide school closures and state of emergency) on ED visits during the COVID-19 pandemic in Japan. METHODS: This retrospective study compared the trends in ED visits from 1 January to 25 May, 2020 (during the pandemic) with the average during 2015-2019 (before the pandemic). The primary end-point was the change in the number of ED visits during the COVID-19 pandemic with those from before the pandemic, with the NPI application stratified across four periods in 2020: Period 0 (1-15 January), no COVID-19 cases detected in Japan; Period I (16 January-1 March), initial COVID-19 outbreak; Period II (2 March-15 April), nationwide school closures; Period III (16 April-25 May), state of emergency. RESULTS: Compared with before the pandemic, the number of walk-in ED visits significantly decreased by 23.1%, 12.4%, and 24.0% (4,047 versus 3,111; 3,211 versus 2,813; and 3,384 versus 2,573; P < 0.001 for all) in Periods I, II, and III, respectively. The number of ambulance ED visits during the pandemic significantly increased by 8.3% in Period I (1,814 versus 1,964, P = 0.002), whereas there was no significant change in Periods II and III with 2.7% and -3.1% (1,547 versus 1,589 and 1,389 versus 1,346; P = 0.335 and P = 0.284, respectively). CONCLUSIONS: The application of an NPI during the COVID-19 pandemic could have significantly reduced patient attendance in the ED.

Identification of pyrogallol from Awa-tea as an anti-allergic compound that suppresses nasal symptoms and IL-9 gene expression.

As the expression level of allergic disease sensitive genes are correlated with the severity of allergic symptoms, suppression of these gene expressions could be promising therapeutics. We demonstrated that protein kinase Cδ / heat shock protein 90-mediated H1R gene expression signaling and nuclear factor of activated T-cells (NFAT)-mediated IL-9 gene expression signaling are responsible for the pathogenesis of pollinosis. Treatment with Awa-tea combined with wild grape hot water extract suppressed these signaling and alleviated nasal symptoms in toluene-2,4-diisocyanate (TDI)-sensitized rats. However, the underlying mechanism of its anti-allergic activity is not elucidated yet. Here, we sought to identify an anti-allergic compound from Awa-tea and pyrogallol was identified as an active compound. Pyrogallol strongly suppressed ionomycin-induced up-regulation of IL-9 gene expression in RBL-2H3 cells. Treatment with pyrogallol in combination with epinastine alleviated nasal symptoms and suppressed up-regulation of IL-9 gene expression in TDI-sensitized rats. Pyrogallol itself did not inhibit calcineurin phosphatase activity. However, pyrogallol suppressed ionomycin-induced dephosphorylation and nuclear translocation of NFAT. These data suggest pyrogallol is an anti-allergic compound in Awa-tea and it suppressed NFAT-mediated IL-9 gene expression through the inhibition of dephosphorylation of NFAT. This might be the underlying mechanism of the therapeutic effects of combined therapy of pyrogallol with antihistamine. J. Med. Invest. 67 : 289-297, August, 2020.

Effects of corticosteroid on mRNA levels of histamine H1 receptor in nasal mucosa of healthy participants and HeLa cells.

The purpose of this study is to examine the effect of intranasal corticosteroid (INCS) administration on histamine H1 receptor (H1R) gene expression in the nasal mucosa of healthy participants and the effects of dexamethasone on basal and histamine-induced H1R mRNA expression, and histamine-induced phosphorylation of extracellular signal-regulated kinase (ERK) in HeLa cells. Sixteen healthy participants were given INCS once daily for a week. After pretreatment of dexamethasone, HeLa cells were treated with histamine. Levels of H1R mRNA and phosphorylation of ERK were measured using real time PCR and immunoblot analysis, respectively. Levels of H1R mRNA in the nasal mucosa of healthy participants receiving INCS was significantly decreased. Dexamethasone suppressed basal levels of H1R mRNA, and histamine-induced up-regulation of H1R mRNA and ERK phosphorylation in HeLa cells. These data suggested that corticosteroid inhibited both basal transcription and histamine-induced transcriptional activation of H1R through its suppression of ERK phosphorylation in the signaling pathway involved in H1R gene transcription. It is further suggested that pre-seasonal prophylactic administration of INCS suppresses both basal and pollen-induced upregulation of H1R gene expression in the nasal mucosa of patients with pollinosis, leading to prevention of the exacerbation of nasal symptoms during peak pollen season. J. Med. Invest. 67 : 311-314, August, 2020.

Reversible cerebral vasoconstriction syndrome: the importance of follow-up imaging within 2 weeks.

AIM: In patients with thunderclap headaches, reversible cerebral vasoconstriction syndrome (RCVS) should be considered as a differential diagnosis. However, RCVS diagnosis in the emergency department (ED) remains challenging. This report describes the clinical features and factors related to RCVS diagnosis and suggests diagnostic strategies for its management. METHODS: We retrospectively reviewed the medical records of eight patients diagnosed with RCVS from January 2010 to March 2019 (aged 18-69 years, 5 women). RESULTS: The median duration from the ED visit to RCVS diagnosis was 6 days (range, 1-11 days). Of the eight patients, seven were middle-aged, six had apparent triggers, six had subarachnoid hemorrhage (SAH), five had high systolic blood pressure, and none had any specific abnormality observed upon physical examination. At the initial visit, RCVS was diagnosed in only one patient who had a history of RCVS. Of the other patients, SAH was diagnosed in two, and primary headache was diagnosed in four patients with negative computed tomography (CT) findings. Based on follow-up angiography (e.g., magnetic resonance angiography), seven of eight patients with convexal SAH were diagnosed with RCVS (as the cause of SAH). CONCLUSION: Reversible cerebral vasoconstriction syndrome with negative CT findings at the ED visit was likely to be misdiagnosed as a primary headache. In patients with thunderclap headache and negative CT findings, physicians should consider RCVS as a differential diagnosis, inform patients of the risk of RCVS, and undertake follow-up imaging within 2 weeks.