Suspected autoimmune encephalitis: A retrospective study of patients referred for therapeutic plasma exchange.

INTRODUCTION: Autoimmune encephalitis (AE) comprises a heterogeneous group of autoantibody-mediated disorders targeting the brain parenchyma. Therapeutic plasma exchange (TPE), one of several first-line therapies for AE, is often initiated when AE is suspected, albeit prior to an established diagnosis. We sought to characterize the role of TPE in the treatment of suspected AE. METHODS: A single-center, retrospective analysis was performed of adults (≥18 years) who underwent at least one TPE procedure for "suspected AE." The following parameters were extracted and evaluated descriptively: clinicopathologic characteristics, treatment course, TPE-related adverse events, outcomes (e.g., modified Rankin scale [mRS]), and diagnosis once investigation was complete. RESULTS: A total of 37 patients (median age 56 years, range 28-77 years, 62.2% male) were evaluated. Autoimmune antibody testing was positive in serum for 43.2% (n = 16) and cerebrospinal fluid for 29.7% (n = 11). Patients underwent a median of five TPE procedures (range 3-16), with 97.3% (n = 36) via a central line and 21.6% (n = 8) requiring at least one unit of plasma as replacement fluid. Fifteen patients (40.5%) experienced at least one TPE-related adverse event. Compared with mRS at admission, the mRS at discharge was improved in 21.6% (n = 8), unchanged in 59.5% (n = 22), or worse in 18.9% (n = 7). Final diagnosis of AE was determined to be definite in 48.6% (n = 18), probable in 8.1% (n = 3) and possible in 27.0% (n = 10). Six (16.2%) patients were ultimately determined to have an alternate etiology. CONCLUSION: Empiric TPE for suspected AE is generally well-tolerated. However, its efficacy remains uncertain in the absence of controlled trials, particularly in the setting of seronegative disease.

Therapeutic plasma exchange for the treatment of refractory necrotizing autoimmune myopathy.

INTRODUCTION: Necrotizing autoimmune myopathy (NAM) is strongly associated with pathognomonic autoantibodies targeting 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) or signal recognition particle (SRP), whose levels in turn are correlated with serum creatine kinase (CK) and necrosis. Thus, NAM may be amenable to therapeutic plasma exchange (TPE) to remove pathogenic antibodies and improve patient symptoms. METHODS: A retrospective case series and literature review of patients presenting with NAM and undergoing treatment with TPE was performed. Clinical data including patient demographics, symptoms, physical exam findings, muscle biopsy, lower extremity imaging, prior therapy, and duration from diagnosis to TPE initiation were collected retrospectively for adult patients with NAM treated with TPE after failing to respond to immunomodulatory therapy. Laboratory data including change in CK levels and myositis-specific antibody titers from baseline were measured in some patients. RESULTS: Six patients (median age at diagnosis 52.5 years, interquartile range [IQR] 35.8-64.5 years, four male/two female) underwent a median of 7.5 (IQR: 5-10) TPE procedures with 5% albumin as replacement. All patients exhibited a statistically significant reduction in CK level from pre-TPE baseline (range: 43.0%-58.7% reduction). Responses in this cohort were best in patients with antibodies targeting HMGCR and SRP, which are most strongly associated with NAM. These results compare favorably to a literature review of NAM patients (n = 19) treated with TPE, who also exhibited positive clinical and laboratory responses across varying treatment lengths. CONCLUSION: TPE can play a role in the management of NAM, particularly in patients with HMGCR or SRP antibodies who are refractory to pharmacologic immunosuppression.

Solvent detergent treated pooled plasma and reduction of allergic transfusion reactions.

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) patients have increased risk for allergic transfusion reactions (ATR) due to the number of plasma products they require. This study evaluated the efficacy of solvent detergent treated plasma (S/D treated plasma) to reduce ATRs. STUDY DESIGN AND METHODS: All TTP patients who presented from April 2014 to February 2015 and experienced a moderate-severe ATR to untreated plasma with TPE were switched to S/D treated plasma (Octaplas) for their remaining procedures and included in the study. Patient records were retrospectively reviewed. RESULTS: The overall ATR rate per procedure decreased from 35.0% (95% CI = 15.4%-59.2%) with untreated plasma to 1.4% ([1/73] 95% CI = 0.0%-7.4%) with S/D treated plasma. The moderate-severe ATR rate decreased from 20.0% ([4/20] 95% CI = 5.7%-43.7%) with untreated plasma to 0.0% ([0/73] 95% CI = 0.0%-4.9%) with S/D treated plasma. The overall ATR rate per plasma unit decreased from 2.6% (95%CI = 1.0%-5.1%) with untreated plasma to 0.1% (95% CI = 0.0%-0.4%) with S/D treated plasma. No patients experienced VTE while receiving untreated plasma. Four patients experienced VTE events while receiving S/D treated plasma. All patients who experienced a VTE had additional risk factors for VTE. CONCLUSION: S/D plasma has promise as an effective product to reduce the risk of ATRs in TTP patients. Given the high risk of ATR in TTP patients, consideration of S/D plasma instead of untreated plasma for TPE in these patients may be warranted, especially for patients with a history of moderate to severe ATR. More extensive studies are needed to confirm these findings.