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This Viewpoint discusses how neural antibody–based diagnostic criteria for autoimmune encephalitis would complement the syndrome-based diagnostic algorithm to improve sensitivity while maintaining high specificity.

Objective: To evaluate the safety and efficacy of endoscopic ultrasound-guided gallbladder drainage (EUS-GBD) using a lumen-apposing metal stent (LAMS). Background: For patients with acute cholecystitis who are poor surgical candidates, EUS-GBD using a LAMS is an important treatment alternative to percutaneous gallbladder drainage. Methods: We conducted a regulatory-compliant, prospective multicenter trial at 7 tertiary referral centers in the United States of America and Belgium. Thirty consecutive patients with mild or moderate acute cholecystitis who were not candidates for cholecystectomy were enrolled between September 2019 and August 2021. Eligible patients had a LAMS placed transmurally with 30 to 60-day indwell if removal was clinically indicated, and 30-day follow-up post-LAMS removal. Endpoints included days until acute cholecystitis resolution, reintervention rate, acute cholecystitis recurrence rate, and procedure-related adverse events (AEs). Results: Technical success was 93.3% (28/30) for LAMS placement and 100% for LAMS removal in 19 patients for whom removal was attempted. Five (16.7%) patients required reintervention. Mean time to acute cholecystitis resolution was 1.6±1.5 days. Acute cholecystitis symptoms recurred in 10.0% (3/30) after LAMS removal. Five (16.7%) patients died from unrelated causes. Procedure-related AEs were reported to the FDA in 30.0% (9/30) of patients, including one fatal event 21 days after LAMS removal; however, no AEs were causally related to the LAMS. Conclusions: For selected patients with acute cholecystitis who are at elevated surgical risk, EUS-GBD with LAMS is an alternative to percutaneous gallbladder drainage. It has high technical and clinical success, with low recurrence and an acceptable AE rate. Clinicaltrials.gov, Number: NCT03767881.

AbstractHeparin-induced thrombocytopenia (HIT) is a serious adverse drug reaction characterized by antibodies that recognize platelet factor 4/heparin complexes (PF4/H) and activate platelets to create a prothrombotic state. Although a high percentage of heparin-treated patients produce antibodies to PF4/H, only a subset also makes antibodies that are platelet activating (PA). A close correlation between PA antibodies and the likelihood of experiencing HIT has been demonstrated in clinical studies, but how PA (presumptively pathogenic) and nonactivating (NA) (presumptively benign) antibodies differ from each other at the molecular level is unknown. To address this issue, we cloned 7 PA and 47 NA PF4/H-binding antibodies from 6 patients with HIT and characterized their structural and functional properties. Findings showed that PA clones differed significantly from NA clones in possessing 1 of 2 heavy chain complementarity-determining region 3 (HCDR3) motifs, RX1-2R/KX1-2R/H (RKH) and YYYYY (Y5), in an unusually long complementarity-determining region 3 (≥20 residues). Mutagenic studies showed that modification of either motif in PA clones reduced or abolished their PA activity and that appropriate amino acid substitutions in HCDR3 of NA clones can cause them to become PA. Repertoire sequencing showed that the frequency of peripheral blood IgG+ B cells possessing RKH or Y5 was significantly higher in patients with HIT than in patients without HIT given heparin, indicating expansion of B cells possessing RKH or Y5 in HIT. These findings imply that antibodies possessing RKH or Y5 are relevant to HIT pathogenesis and suggest new approaches to diagnosis and treatment of this condition.

ImportanceAutoimmune encephalitis misdiagnosis can lead to harm.ObjectiveTo determine the diseases misdiagnosed as autoimmune encephalitis and potential reasons for misdiagnosis.Design, Setting, and ParticipantsThis retrospective multicenter study took place from January 1, 2014, to December 31, 2020, at autoimmune encephalitis subspecialty outpatient clinics including Mayo Clinic (n = 44), University of Oxford (n = 18), University of Texas Southwestern (n = 18), University of California, San Francisco (n = 17), Washington University in St Louis (n = 6), and University of Utah (n = 4). Inclusion criteria were adults (age ≥18 years) with a prior autoimmune encephalitis diagnosis at a participating center or other medical facility and a subsequent alternative diagnosis at a participating center. A total of 393 patients were referred with an autoimmune encephalitis diagnosis, and of those, 286 patients with true autoimmune encephalitis were excluded.Main Outcomes and MeasuresData were collected on clinical features, investigations, fulfillment of autoimmune encephalitis criteria, alternative diagnoses, potential contributors to misdiagnosis, and immunotherapy adverse reactions.ResultsA total of 107 patients were misdiagnosed with autoimmune encephalitis, and 77 (72%) did not fulfill diagnostic criteria for autoimmune encephalitis. The median (IQR) age was 48 (35.5-60.5) years and 65 (61%) were female. Correct diagnoses included functional neurologic disorder (27 [25%]), neurodegenerative disease (22 [20.5%]), primary psychiatric disease (19 [18%]), cognitive deficits from comorbidities (11 [10%]), cerebral neoplasm (10 [9.5%]), and other (18 [17%]). Onset was acute/subacute in 56 (52%) or insidious (>3 months) in 51 (48%). Magnetic resonance imaging of the brain was suggestive of encephalitis in 19 of 104 patients (18%) and cerebrospinal fluid (CSF) pleocytosis occurred in 16 of 84 patients (19%). Thyroid peroxidase antibodies were elevated in 24 of 62 patients (39%). Positive neural autoantibodies were more frequent in serum than CSF (48 of 105 [46%] vs 7 of 91 [8%]) and included 1 or more of GAD65 (n = 14), voltage-gated potassium channel complex (LGI1 and CASPR2 negative) (n = 10), N-methyl-d-aspartate receptor by cell-based assay only (n = 10; 6 negative in CSF), and other (n = 18). Adverse reactions from immunotherapies occurred in 17 of 84 patients (20%). Potential contributors to misdiagnosis included overinterpretation of positive serum antibodies (53 [50%]), misinterpretation of functional/psychiatric, or nonspecific cognitive dysfunction as encephalopathy (41 [38%]).Conclusions and RelevanceWhen evaluating for autoimmune encephalitis, a broad differential diagnosis should be considered and misdiagnosis occurs in many settings including at specialized centers. In this study, red flags suggesting alternative diagnoses included an insidious onset, positive nonspecific serum antibody, and failure to fulfill autoimmune encephalitis diagnostic criteria. Autoimmune encephalitis misdiagnosis leads to morbidity from unnecessary immunotherapies and delayed treatment of the correct diagnosis.

SummaryBackgroundRumination syndrome is a functional gastroduodenal disorder characterised by effortless regurgitation of recently ingested food. Emerging evidence reports duodenal eosinophilic inflammation in a subset, suggesting a shared pathophysiology with functional dyspepsia (FD).AimTo assess the clinical features of rumination syndrome and FD in a community‐based study.MethodsWe mailed a survey assessing gastrointestinal symptoms, diet and psychological symptoms to 9835 residents of Olmsted County, MN, USA in 2017‐2018; diagnostic codes were obtained from linked clinical records. The two disorders were assessed as mutually exclusive in ‘pure’ forms with a separate overlap group, all compared to a control group not meeting criteria for either. Prevalence of associations, and univariate and independent associations with predictors were assessed by logistic regression.ResultsPrevalence of rumination syndrome and FD were 5.8% and 7.1%, respectively; the overlap was 3.83‐times more likely than expected by chance. Independent predictors for rumination (odds ratio (OR), 95% confidence interval (CI)) were female gender (1.79, 1.21‐2.63), smoking (1.89, 1.28‐2.78), gluten‐free diet (1.58, 1.14‐2.19), allergic rhinitis (1.45, 1.01‐2.08) and depression (1.10, 1.05‐1.16). FD was independently associated with female gender, depression, non‐coeliac wheat sensitivity, migraine, irritable bowel syndrome and somatic symptoms. A similar reported efficacy (≥54%) of low fat or dairy‐free diets was found with both disorders (P = 0.53 andP = 1.00, respectively). The strongest independent associations with overlapping FD and rumination syndrome were a history of rheumatoid arthritis (3.93, 1.28‐12.06) and asthma (3.02, 1.44‐6.34).ConclusionRumination syndrome overlaps with FD with a shared risk factor profile, suggesting a common pathophysiology.

Summary Peroral endoscopic myotomy (POEM) in patients with achalasia who are status post bariatric surgery may be technically challenging due to postsurgical scarring and altered anatomy. The aim of the study was to assess the efficacy and safety of POEM for achalasia in patients with prior bariatric surgery. A review of prospectively maintained databases at three tertiary referral centers from January 2015 to January 2021 was performed. The primary outcome of interest was clinical success, defined as a post-treatment Eckardt score ≤ 3 or improvement in Eckardt score by ≥ 1 when the baseline score was <3, and improvement of symptoms. Secondary outcomes were adverse event rates and symptom recurrence. Sixteen patients status post Roux-en-Y gastric bypass (n = 14) and sleeve gastrectomy (n = 2) met inclusion criteria. Indications for POEM were achalasia type I (n = 2), type II (n = 9), and type III (n = 5). POEM was performed either by anterior or posterior approach. The pre-POEM mean integrated relaxation pressure was 26.2 ± 7.6 mm Hg. The mean total myotomy length was 10.2 ± 2.7 cm. The mean length of hospitalization was 1.4 ± 0.7 days. Pre- and postprocedure Eckardt scores were 6.1 ± 2.1 and 1.7 ± 1.8, respectively. The overall clinical success rate was 93.8% (15/16) with mean follow-up duration of 15.5 months. One patient had esophageal leak on postprocedure esophagram and managed endoscopically. Dysphagia recurred in two patients, which was successfully managed with pneumatic dilation with or without botulinum toxin injection. POEM appears to be safe and effective in the management of patients with achalasia who have undergone prior bariatric surgery.

Background: Endoscopic ultrasound–guided rendezvous (EUS-RV) endoscopic retrograde cholangiopancreatography (ERCP) is an alternative to interventional radiology–guided rendezvous ERCP in patients who failed biliary cannulation with conventional ERCP. However, there is significant variation in reported rates of success and adverse events associated with EUS-RV-assisted ERCP. We performed a systematic review and a proportion meta-analysis to reliably assess the effectiveness and safety of the EUS-RV-assisted ERCP. Materials and Methods: We conducted a comprehensive search of multiple electronic databases and conference proceedings (from inception through August 2020) to identify studies reporting EUS-RV-assisted ERCP in patients who failed biliary cannulation with conventional ERCP techniques. Using the random-effects model described by DerSimonian and Laird, we calculated the pooled rates of technical success, clinical success, and adverse events of EUS-RV-assisted ERCP. Results: Twelve studies reporting a total of 342 patients were included in the meta-analysis. The pooled rate of technical success (12 studies reporting a total of 342 patients) was 86.1% [95% confidence interval (CI): 78.4-91.3]. The pooled rate of clinical success (4 studies reporting a total of 94 patients) was 80.8% (95% CI: 64.1-90.8). The pooled rate of overall adverse events (12 studies; 42 events in 342 patients) was 14% (95% CI: 10.5-18.4). Low to moderate heterogeneity was noted in the analyses. Conclusions: EUS-RV-assisted ERCP appears to be effective and safe in patients who failed biliary cannulation with conventional ERCP. Given the risk of adverse events, it should be performed in centers with expertise in therapeutic endoscopic ultrasound.