Central Nervous System Complications after Allogeneic Hematopoietic Stem Cell Transplantation: Incidence, Manifestations, and Clinical Significance

Neurologic Complications of the Central Nervous System after Allogeneic Stem Cell Transplantation: The Role of Transplantation-Associated Thrombotic Microangiopathy as a Potential Underreported Cause

Neurologic complications (NCs), especially those of the central nervous system (CNS), represent a severe complication after allogeneic stem cell transplantation (allo-HSCT) and are associated with relevant morbidity and mortality. We aimed to characterize the potential risk factors for the development of CNS-NC, with a special focus on the role of calcineurin inhibitors (CNIs) as a predisposing factor. For this purpose, we compared cyclosporin A (CsA) versus tacrolimus (TAC) with respect to their influence on the incidence and type of CNS-NC after allo-HSCT. We retrospectively analyzed the incidence, risk factors, and impact on outcomes of CNS-NC diagnosed during the post-transplantation follow-up in patients with different high-risk hematologic malignancies who underwent allo-HSCT at our institution over a 20-year period. All patients included in the analysis received CNI (CsA or TAC) as graft-versus-host disease (GVHD) prophylaxis. We evaluated a total of 739 consecutive patients who underwent transplantation between December 1999 and April 2019. During a median follow-up of 6.8 years, we observed a CNS-NC incidence of 17%. The development of CNS-NC was associated with decreased overall survival (OS) and increased transplantation-related mortality (TRM). The most frequent CNS-NCs were infections (30%) and neurologic adverse events related to the administration of CNI, TAC, or CsA as GVHD prophylaxis (42%). In the multivariable analysis, age, total body irradiation (TBI), and severe acute GVHD and chronic GVHD were significant risk factors in the development of CNS-NCs. TAC compared with CsA emerged as an independent predisposing factor for CNS-NCs. The TAC-associated risk of CNS-NCs was related mostly to the occurrence of transplantation-associated thrombotic microangiopathy (TA-TMA) with neurologic manifestations (neuro-TA-TMA), although the general TA-TMA incidence was comparable in the 2 CNI subgroups. CNS-NCs are associated with poor prognosis after allo-HSCT, with TAC emerging as a potential yet insufficiently characterized predisposing factor.

Diagnosis and management of endothelial disorders following haematopoietic stem cell transplantation

Haematopoietic stem cell transplantation is a mainstay of therapy for numerous malignant and nonmalignant diseases. Endothelial activation and dysfunction occur after stem cell transplantation, driven by various patient- and transplant-specific factors. This can manifest as one of the relatively uncommon endothelial injury syndromes, such as sinusoidal obstruction syndrome, transplant-associated thrombotic microangiopathy, idiopathic pneumonia syndrome, capillary leak syndrome, engraftment syndrome or posterior reversible encephalopathy syndrome. This review focuses on the pathogenesis, classification and diagnosis of these disorders, as well as provides guidance on risk mitigation and treatment.

Reduced Incidence of Neurologic Complications after Allogeneic Hematopoietic Stem Cell Transplantation with Calcineurin-Free Graft-versus-Host Disease Prophylaxis

Calcineurin inhibitors (CNIs), including cyclosporine and tacrolimus, are frequently associated with neurologic complications after allogeneic hematopoietic stem cell transplantation (HSCT). However, there is a lack of studies comparing the incidence and characteristics of neurologic complications in patients undergoing HSCT based on CNI-free or CNI-based GVHD prophylaxis. This retrospective single-center study analyzed the neurologic complications in 2 cohorts of patients undergoing HSCT with either CNI-based GVHD prophylaxis (n = 523) or CNI-free prophylaxis with post-transplantation cyclophosphamide, sirolimus, and mycophenolate mofetil (n = 371). The latter cohort included older patients and received more reduced-intensity conditioning and transplants from matched unrelated and haploidentical donors. The 2-year cumulative incidence of neurologic complications was significantly lower in the CNI-free cohort (6.9% versus 11.9%; P = .016), and GVHD prophylaxis was the sole statistically significant variable in multivariate analysis (hazard ratio, 2.2; 95% confidence interval [CI], .25 to 3.13; P = .0017). The distribution of neurologic types was similar in the 2 cohorts, with encephalopathy the most prevalent complication, except for headaches and myopathy, which decreased equally from 15% in the CNI-based cohort to 4% in the CNI-free cohort. Neurologic complications had negative impacts on mortality and survival rates, with a significantly higher 2-year cumulative incidence of nonrelapse mortality (NRM) (44% [95% CI, 34% to 54%] versus 16% [95% CI, 13% to 18%]; P < .0001) and inferior overall survival (66% [95% CI, 62% to 69%] versus 46% [95% CI, 37% to 58%]; P < .0001) in patients with neurologic complications. This study suggests that CNI-free GVHD prophylaxis with post-transplantation cyclophosphamide, sirolimus, and mycophenolate mofetil may reduce not only the incidence of GVHD incidence, but also the rates of neurologic complications and NRM, leading to improved survival outcomes in patients undergoing HSCT.

Complex I inhibitor of oxidative phosphorylation in advanced solid tumors and acute myeloid leukemia: phase I trials

Although targeting oxidative phosphorylation (OXPHOS) is a rational anticancer strategy, clinical benefit with OXPHOS inhibitors has yet to be achieved. Here we advanced IACS-010759, a highly potent and selective small-molecule complex I inhibitor, into two dose-escalation phase I trials in patients with relapsed/refractory acute myeloid leukemia (NCT02882321, n = 17) and advanced solid tumors (NCT03291938, n = 23). The primary endpoints were safety, tolerability, maximum tolerated dose and recommended phase 2 dose (RP2D) of IACS-010759. The PK, PD, and preliminary antitumor activities of IACS-010759 in patients were also evaluated as secondary endpoints in both clinical trials. IACS-010759 had a narrow therapeutic index with emergent dose-limiting toxicities, including elevated blood lactate and neurotoxicity, which obstructed efforts to maintain target exposure. Consequently no RP2D was established, only modest target inhibition and limited antitumor activity were observed at tolerated doses, and both trials were discontinued. Reverse translational studies in mice demonstrated that IACS-010759 induced behavioral and physiological changes indicative of peripheral neuropathy, which were minimized with the coadministration of a histone deacetylase 6 inhibitor. Additional studies are needed to elucidate the association between OXPHOS inhibition and neurotoxicity, and caution is warranted in the continued development of complex I inhibitors as antitumor agents.

Long-term health outcomes of allogeneic hematopoietic stem cell transplantation

Background

Fifty years of hematopoietic cell transplantation (HCT) has ushered in an exciting era of cellular therapy and has led to enormous progress in improving the outcomes of patients with both malignant and non-malignant hematologic disease. As the survival of transplanted patients has increased, so has the recognition of long-term complications related to this therapy.

Purpose

The goal of this review is to highlight some of the most common long-term complications of HCT.

Data sources

To this end, we have conducted a review of the published literature on the long-term complications of HCT encompassing the past 50 years.

Study selection

We have endeavored to include long-term complications reported in research articles, case series and case reports, reviews, and abstracts. We have focused primarily on adult allogeneic HCT, but have included some data from studies of pediatric allogeneic HCT as well. We have also prioritized the literature published in the last 15 years.

Data extraction

Key data supporting the onset and prevalence of the most common long-term complications was extracted.

Limitations

While the list of long-term complications extracted and reported was comprehensive, it was not exhaustive.

Conclusions

We have endeavored to highlight some of the most common long-term complications of HCT, the recognition and management of which constitutes an important part of HCT survivorship care.

Neurological complications in adult allogeneic hematopoietic stem cell transplant patients: Incidence, characteristics and long-term follow-up in a multicenter series

Neurological complications (NCs) represent a diagnostic and clinical challenge in allogeneic hematopoietic stem cell transplant (alloHSCT) patients. We retrospectively analyzed NC incidence, etiology, timing, characteristics, outcome, and long-term effects in 2384 adult patients transplanted in seven Italian institutions between January 2007 and December 2019. Ninety-three (3.9%) patients were affected by 96 NCs that were infectious (29.2%), immune/inflammatory (26%), drug-related (12.5%), cerebrovascular (5.2%), metabolic (3.1%), related to central nervous system disease relapse (11.5%) and malignancy (3.1%), or undefined (9.4%). Six patients (6.4%) had neurological manifestations of chronic graft-versus-host disease (GVHD). NCs occurred on average at day +128 (from -5 to +4063). Early (< day +120) and late NCs had similar frequencies (46.9% vs 53.1%, p = 0.39). Thirty-one patients (33.3%) were affected by acute or chronic GVHD at the NC onset. With a median follow-up of 25.4 (0.4-163) months, the overall mortality due to NCs was 22.6%. The median time between NC onset and death was 36 (1-269) days. Infectious NCs were the main cause (61.9%) of NC-related mortality. A persistent neurological impairment occurred in 20.4% patients, 57.9% of whom being affected by immune/inflammatory NCs. This study highlights the rare, yet severe impact of alloHSCT-associated NCs on patient survival and long-term functional ability.

Metabolic Disease Incidence After Allogeneic Stem Cell Transplantation: A Nationwide Korean Case-Control Study

CONTEXT

There have been no large-scale reports elucidating the relative risks of developing metabolic diseases in adult allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients compared to the general population.

OBJECTIVE

This work aimed to investigate the relative risk of developing metabolic diseases and cerebrovascular or cardiovascular disease (CVA) in allo-HSCT recipients compared to the general population in a real-world setting, using a large Korean cohort under long-term observation.

METHODS

We conducted a population-based case-control study and analyzed data of 8230 adult allo-HSCT recipients and 32 920 healthy individuals matched for age, sex, and index date in a 1:4 ratio, using a nationwide database of the Korean National Health Insurance Service. Thereafter, we established 4 substudies to investigate the relative risks of metabolic disease development following allo-HSCT: hypertension (cohort A study), diabetes (cohort B study), dyslipidemia (cohort C study), and CVA (cohort D study).

RESULTS

The 10-year cumulative incidence of metabolic disease in each experimental cohort was statistically significantly higher than that in the control cohort (overall P value < .001 for all): cohort A study, 17.6% vs 11.8%; cohort B study, 23.5% vs 14.4%; cohort C study for dyslipidemia, 44.5% vs 32.1%; and cohort D study for CVA, 4.2% vs 3.2%. In comparison to the incidence of metabolic diseases in the general population, allo-HSCT recipients presented adjusted hazard ratios of 1.58 for hypertension, 2.06 for diabetes, 1.62 for dyslipidemia, and 1.45 for CVA.

CONCLUSION

Recipients of allo-HSCT need to be rigorously monitored for the development of metabolic diseases, including hypertension, diabetes, dyslipidemia, and CVA, based on an enhanced lifelong health care policy including a robust screening program compared to the general population.

Neurologic Complications in Pediatric Allogeneic Stem Cell Transplantation: Analysis of Risk Factors and Outcome

Neurologic complications following stem cell transplantation are of utmost importance owing to their high morbimortality. Although many studies have been performed in the adult population, reports in children are scarce. Our objective was to determine the most common neurologic complications in a pediatric population and to analyze possible risk factors for their development. We performed an exploratory retrospective study of neurologic complications in pediatric patients who had allogeneic stem cell transplantation over the last 18 years. We identified 66 neurologic complications in 178 allogeneic stem cell transplantations. The most frequent neurologic complications were those involving the peripheral nervous system and those related to drug toxicity. Survival decreased significantly in the presence of neurologic complications. Multivariate logistic regression analysis showed that independent risk factors for developing neurologic complications were development of chronic extensive graft-vs-host disease requiring treatment, cytomegalovirus reactivation, and central nervous system radiation. Prompt diagnosis and preemptive treatment, if possible, are necessary to avoid long-term sequelae or mortality.

Total Body Irradiation-Based Conditioning Regimen Improved the Survival of Adult Patients With T-Cell Lymphoblastic Lymphoma After Allogeneic Peripheral Blood Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is one of the consolidation modalities for adult patients with T-cell lymphoblastic lymphoma (T-LBL). However, the optimal conditioning regimen needs to be explored. In the present study, 40 patients with T-LBL undergoing allo-HSCT were retrospectively analyzed, including 23/40 (57.5%) with total body irradiation (TBI)–based conditioning regimen and 17/40 (42.5%) with busulfan (BU)-based regimen. TBI–based regimen significantly increased the cumulative incidence (CI) of grade II to IV acute graft-versus-host disease (aGvHD) as compared with BU-based regimen (13.0% vs 0%, P = 0.000). The relapse risk was significantly lowered in TBI-based group with a 2-year CI of relapse (CIR) of 9.1% as compared with that of 49.6% in BU-based group (P = 0.008). The 1-year and 2-year non-relapse mortalities (NRMs) for all patients were 5.0% and 10.3%, respectively. The 1-year and 2-year NRMs were 8.9% and 16.0% in TBI-based group, and 0.00% and 0.00% in BU-based group (P = 0.140). The 2-year probabilities of overall survival (OS) and relapse-free survival (RFS) were 83.0% [95% confidence interval, 63.4%–100%] and 74.0% (95% confidence interval, 54.4%–93.6%) in TBI-based group, which were higher than that of 35.0% (95% confidence interval, 0.0%–72.2%) and 50.0% (95% confidence interval, 24.5%–75.4%) in BU-based group, respectively (P = 0.020 for OS and P = 0.081 for RFS). In multivariate analysis, TBI-based regimen significantly reduced the risk of relapse [subdistribution hazard ratio (SHR) = 0.030, 95% CI, 0.002–0.040, P = 0.000] and improved the OS [hazard ratio (HR) 0.121, 95% CI, 0.021–0.683, P = 0.017] as an independent prognostic factor. These results suggested that TBI-based regimen might be an optimal choice for adult patients with T-LBL undergoing allo-HSCT.

Unique Challenges to Diagnosing Human Herpesvirus-6 (HHV-6) Encephalitis Following Post-Hematopoietic Stem Cell Transplant: A Case and Brief Review

A patient with an ultimate diagnosis of human herpesvirus-6 (HHV-6) encephalitis developed central nervous system (CNS) symptoms 13 days after undergoing myeloablative haploidentical allogeneic hematopoietic stem cell transplant (HSCT). Due to the patient's body habitus, magnetic resonance (MR) imaging was not obtained until the onset of retrograde amnesia on day +24. MR imaging and other clinical findings eliminated all skepticism of HHV-6 encephalitis and HHV-6 antivirals were initiated on day +28, leading to gradual recovery. This case demonstrates some of the factors that may complicate the diagnosis of post-alloHSCT HHV-6 encephalitis. Because HHV-6 encephalitis and viremia can occur without warning, a single negative study should not exclude future development, especially if CNS symptoms are present. Acute graft-versus-host disease and cord blood transplantation are both significant risk factors for HHV-6 encephalitis. Human leukocyte antigen (HLA) mismatch, engraftment complications, or certain HLA alleles have also been associated with HHV-6 encephalitis. Chromosomally integrated HHV-6 must also be ruled out to prevent inappropriate and potentially harmful administration of antivirals. Due to the severe short- and long-term sequelae of HHV-6 encephalitis, appropriate treatment should be administered as soon as possible.

Predicting mortality from intracranial hemorrhage in patients who undergo allogeneic hematopoietic stem cell transplantation

Intracranial hemorrhage (ICH) is a rare but fatal central nervous system complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, factors that are predictive of early mortality in patients who develop ICH after undergoing allo-HSCT have not been systemically investigated. From January 2008 to June 2020, a total of 70 allo-HSCT patients with an ICH diagnosis formed the derivation cohort. Forty-one allo-HSCT patients with an ICH diagnosis were collected from 12 other medical centers during the same period, and they comprised the external validation cohort. These 2 cohorts were used to develop and validate a grading scale that enables the prediction of 30-day mortality from ICH in all-HSCT patients. Four predictors (lactate dehydrogenase level, albumin level, white blood cell count, and disease status) were retained in the multivariable logistic regression model, and a simplified grading scale (termed the LAWS score) was developed. The LAWS score was adequately calibrated (Hosmer-Lemeshow test, P > .05) in both cohorts. It had good discrimination power in both the derivation cohort (C-statistic, 0.859; 95% confidence interval, 0.776-0.945) and the external validation cohort (C-statistic, 0.795; 95% confidence interval, 0.645-0.945). The LAWS score is the first scoring system capable of predicting 30-day mortality from ICH in allo-HSCT patients. It showed good performance in identifying allo-HSCT patients at increased risk of early mortality after ICH diagnosis. We anticipate that it would help risk stratify allo-HSCT patients with ICH and facilitate future studies on developing individualized and novel interventions for patients within different LAWS risk groups.

Neurological complications in Chinese children undergoing hematopoietic stem cell transplantation

BACKGROUND

Hematopoietic stem cell transplantation, despite being a curative treatment for various pediatric disorders, is associated with significant acute and chronic complications.

METHODS

This retrospective review of 196 hematopoietic stem cell transplantation episodes (144 allogeneic, 52 autologous) performed in a tertiary pediatric unit focused on neurological symptoms and complications occurred from the start of conditioning to within 3 years of transplantation. Indications for transplantation included both benign and malignant diseases. For episodes involving allogeneic transplantation, 42% of donors were matched-unrelated, 19% were matched-sibling, and 12% were haploidentical.  RESULTS: Neurological complications developed in 17% of all hematopoietic stem cell transplantation episodes. Tumors of central nervous system and leukemia or lymphoma were two indications reported to have higher incidence of 42% and 21%, respectively. The occurrence of neurological complications was significantly associated with primary diagnosis (p = 0.01), central nervous system involvement by underlying disease (p = 0.001), and radiation-based conditioning (p = 0.018). Upon multivariate analysis, central nervous system involvement by underlying disease remained to be the only significant factor (p = 0.019), while radiation-based containing conditioning (p = 0.029) is revealed to be associated when considering allogeneic transplantation alone. Pre-transplant central nervous system-directed treatment, allogeneic versus autologous donor, stem cell source, donor type, busulfan use, and cyclosporin use were not significantly associated with neurological complications. Patients with neurological complications were also found to have an inferior 2-year overall survival (53.9% ± 8.8% versus 63.8% ± 4.2%; p = 0.016).

CONCLUSION

Neurological complications were common in pediatric hematopoietic stem cell transplantation and were associated with adverse outcome; non-radiation containing conditioning regimens might be beneficial in mitigating the risk of such complications.

Patterns of central nervous system complications of post-hematopoietic stem cell transplant in pediatric oncology patients: a single institute experience

Background

Hematopoietic stem cell transplant (HSCT) has been increasingly used in the last few decades, with improved success in offering a cure. CNS complications are an important contributor to morbidity and mortality in HSCT patients. The aim of the study was to evaluate the role of imaging in the detection and assessment of CNSC (central nervous system complications) after HSCT in pediatric oncology patients.

The study included consecutive pediatric patients who underwent HSCT for hematologic or solid malignancies at CCHE-57357 (Children Cancer Hospital–Egypt 57357) from January 2011 to March 2019. The age of the patients in the study ranged from 0.9 to 25 years (median age 6.5 years). CT (computed tomography) and/or MRI (magnetic resonance imaging) studies were evaluated for the detection and characterization of CNSC.

Results

The incidence of post-HSCT CNSC was 13% with a day 100 and 5-year cumulative incidence of 9.3 and 12.5%, respectively. The most commonly observed CNSC detected was disease recurrence, followed by PRES (Posterior reversible encephalopathy syndrome). CNS recurrence of the initial diagnosis, atrophy, and infection were more common at the > 100-day post-HSCT transplant period, while PRES was much more common at < 100-day post-HSCT.

Conclusion

CNS complications are an important contributor to morbidity and mortality in HSCT patients that require MRI protocols distinctively tailored for each patient, clinical suspicion, and proper imaging assessment for early detection and follow-up.

Neurologic complications of acute myeloid leukemia. Diagnostic approach and therapeutic modalities

Acute myeloid leukemia (AML) comprises a heterogeneous group of aggressive blood malignancies that arise from clonal expansion of malignant hematopoietic precursor cells in the bone marrow. Neurologic manifestations of these malignancies are manifolds. AML is the most common form of acute leukemia in adults and this review describes the neurologic complications in this age group. Neurologic symptoms and signs may develop in AML either from a direct neoplastic involvement of the central or the peripheral nervous system or as an indirect effect of the disease process. Direct involvement of the nervous system includes invasion of the central or the peripheral nervous system (parenchymal and leptomeningeal dissemination, myeloid sarcoma, neuroleukemiosis). Thrombotic and hemorrhagic events are common manifestations of indirect involvement of the nervous system and they are the outcome of hyperleukocytosis, thrombocytopenia and coagulopathy. Many neurologic complications are iatrogenic and include diverse categories such as lumbar puncture and intrathecal or systemic chemotherapy and targeted therapies, radiotherapy and allogeneic stem cell transplantation. Most neurologic manifestations require urgent treatment and confer a poor prognosis. This review describes the neurologic complications of acute myeloid malignancies in the era of contemporary treatment. Those manifestations require expert consideration of their origin as they are being identified with increasing frequency as patients survive longer.

Clinical risk factors and prognostic model for idiopathic inflammatory demyelinating diseases after haploidentical hematopoietic stem cell transplantation in patients with hematological malignancies

Idiopathic inflammatory demyelinating diseases (IIDDs) of the central nervous system (CNS) are rare but serious neurological complications of haploidentical hematopoietic stem cell transplantation (haplo-HSCT). However, the risk factors and a method to predict the prognosis of post-transplantation CNS IIDDs are not available. This retrospective study first reviewed data from 4532 patients who received haplo-HSCT during 2008-2019 in our center, and 184 patients (4.1%) with IIDDs after haplo-HSCT were identified. Grades II to IV acute graft-versus-host disease (aGVHD) (p < 0.001) and chronic GVHD (cGVHD) (p = 0.009) were identified as risk factors for developing IIDDs after haplo-HSCT. We then divided the 184 IIDD patients into a derivation cohort and validation cohort due to transplantation time to develop and validate a model for predicting the prognosis of IIDDs. In the multivariate analysis of the derivation cohort, four candidate predictors were entered into the final prognostic model: cytomegalovirus (CMV) infection, Epstein-Barr virus (EBV) infection, IgG synthesis (IgG-syn) and spinal cord lesions. The prognostic model had an area under the receiver operating characteristic curve of 0.864 (95% CI: 0.803-0.925) in the internal validation cohort and 0.871 (95% CI: 0.806-0.931) in the external validation cohort. The calibration plots showed a high agreement between the predicted and observed outcomes. Decision curve analysis indicated that IIDD patients could benefit from the clinical application of the prognostic model. The identification of IIDD patients after allo-HSCT who have a poor prognosis might allow timely treatment and improve patient survival and outcomes.

Acute Graft-Versus-Host Disease, Infections, Vascular Events and Drug Toxicities Affecting the Central Nervous System

Allogeneic hematopoietic cell transplantation (allo-HCT) is a curative therapy for patients with hematological malignancies. Acute Graft versus host diseases (GVHD) is a major immune mediated side effect of allo-HCT that can affect the central nervous system (CNS) in addition to post-allo-HCT vascular events, drug toxicity or infections. Here we summarize and discuss recent preclinical data on the CNS as a target of acute GVHD and the known mechanisms contributing to neurotoxicity with a focus on microglia and T cells. We also discuss open questions in the field and place the findings made in mouse models in a clinical context. While in mice the neurological deficits can be assessed in a controlled fashion, in patients the etiology of the CNS damage is difficult to attribute to acute GVHD versus infections, vascular events, and drug-induced toxicity. Ultimately, we discuss novel therapies for GVHD of the CNS. Our understanding of the biological mechanisms that lead to neurotoxicity after allo-HCT increased over the last decade. This review provides insights into CNS manifestations of GVHD versus other etiologies of CNS damage in mice and patients.

Comparison of Total Body Irradiation-based Versus Chemotherapy-based Conditionings for Early Complications of Allogeneic Hematopoietic Stem Cell Transplantation in Children With ALL

BACKGROUND

Total body irradiation (TBI) is the cornerstone of conditioning regimens in pediatric hematopoietic stem cell transplantation for acute lymphoblastic leukemia. As the late effects and survival comparison between TBI and chemotherapy were well analyzed before, in this study, we aim to focus on the first 100 days and early complications of transplantation.

METHODS

This retrospective study involves 72 pediatric patients (0 to 18 y) underwent first hematopoietic stem cell transplantation for acute lymphoblastic leukemia between October 2015 and May 2019. Patients are divided into 2 groups regarding conditioning regimens. Conditionings includes either TBI 1200 cGy/6 fractions/3 days and etoposide phosphate or busulfan, fludarabine, and thiotepa. Busulfan was administered IV and according to body weight.

RESULTS

The incidences of acute graft versus host disease grade 2 to 4, veno-occlusive disease, capillary leakage syndrome, thrombotic microangiopathy, blood stream infection, hemorrhagic cystitis and posterior reversible encephalopathy syndrome before day 100 were similar for both conditioning regimens; however, patients received TBI-based conditioning had significantly longer neutrophil engraftment time (17.5 vs. 13 d, P=0.001) and tended to have more engraftment syndrome (ES) (45.5% for TBI vs. 24.0% for chemotherapy, P=0.069). Multivariate analysis showed that TBI-based conditioning was associated with a longer neutrophil engraftment time (hazard ratio [HR]=1.20, P=0.006), more cytomegalovirus (CMV) reactivation (HR=3.65, P=0.038) and more ES (HR=3.18, P=0.078).

CONCLUSIONS

Our findings support chemotherapy-based regimens with early neutrophil engraftment, less ES and CMV reactivation compared with TBI. Although there is no impact on survival rates, increased incidence of ES and CMV reactivation should be considered in TBI-based regimens.

Epileptic Seizures After Allogeneic Hematopoietic Stem Cell Transplantation

Technique in allogeneic hematopoietic stem cell transplantation has greatly advanced over the past decades, which has led to an increase in the number of patients receiving transplantation, but the complex procedure places these transplant recipients at high risk of a large spectrum of complications including neurologic involvement. As a common manifestation of neurological disorders, epileptic seizures after transplantation have been of great concern to clinicians because it seriously affects the survival rate and living quality of those recipients. The aim of this review is to elucidate the incidence of seizures after allogeneic hematopoietic stem cell transplantation, and to further summarize in detail its etiologies, possible mechanisms, clinical manifestations, therapeutic schedule, and prognosis, hoping to improve doctors' understandings of concurrent seizures following transplantation, so they can prevent, process, and eventually improve the survival and outlook for patients in a timely manner and correctly.

Association of Inherited Chromosomally Integrated Human Herpesvirus 6 with Neurologic Symptoms and Management after Allogeneic Hematopoietic Cell Transplantation

Reactivation of human herpesvirus 6 (HHV-6) after allogeneic hematopoietic cell transplantation (HCT) is associated with neurologic complications, but the impact of donor and/or recipient inherited chromosomally integrated HHV-6 (iciHHV-6) on post-HCT central nervous system (CNS) symptoms and diagnostic and therapeutic interventions is not well understood. The aims of the present study were (1) to compare the cumulative incidence of CNS symptoms in the first 100 days following allogeneic HCT among patients with donor and/or recipient iciHHV-6 (iciHHV-6^pos)with that of patients with neither donor nor recipient iciHHV-6 (iciHHV-6^neg) and (2) to assess the role of HHV-6 detection in driving potentially unnecessary interventions in iciHHV-6^pos patients. We performed a retrospective matched cohort study of 87 iciHHV-6^pos and 174 iciHHV-6^neg allogeneic HCT recipients. HHV-6 testing was performed at the discretion of healthcare providers, who were unaware of iciHHV-6 status. The cumulative incidence of CNS symptoms was similar in iciHHV-6^pos (n = 37; 43%) and iciHHV-6^neg HCT recipients (n = 81; 47%; P = .63). HHV-6 plasma testing was performed in similar proportions of iciHHV-6^pos (n = 6; 7%) and iciHHV-6^neg (9%) patients and was detected in all tested iciHHV-6^pos HCTs and 2 (13%) iciHHV-6^neg HCTs. This resulted in more frequent HHV-6-targeted antiviral therapy after iciHHV-6^pos HCT (odds ratio, 12.8; 95% confidence interval, 1.5 to 108.2) with associated side effects. HHV-6 plasma detection in 2 iciHHV-6^pos patients without active CNS symptoms prompted unnecessary lumbar punctures. The cumulative incidence of CNS symptoms was similar after allogeneic HCT involving recipients or donors with and without iciHHV-6. Misattribution of HHV-6 detection as infection after iciHHV-6^pos HCT may lead to unnecessary interventions. Testing for iciHHV-6 may improve patient management.

Posterior Reversible Encephalopathy Syndrome in Childhood Hematological/Oncological Diseases: Multicenter Results

The aim of the study was to analyze the characteristics of posterior reversible encephalopathy syndrome (PRES) cases treated at 10 different institutions in our country. Fifty-eight patients diagnosed with PRES were included in this study. The data of PRES cases from 10 departments of pediatric hematology/oncology were analyzed. The mean age of the patients at the time of diagnosis of PRES was 8.95±3.66 years. Most patients (80.4%) had a primary diagnosis of acute leukemia. Patients received chemotherapy (71.4%) and/or used steroids within 14 days before the diagnosis of PRES (85.7%). Hypertension was found in 83.9% of the patients. Twenty-six patients had infections and 22 of them had febrile neutropenia. The most common electrolyte disorders were hypocalcemia, hypomagnesemia, and hypopotassemia. Six patients had tumor lysis syndrome and 4 had inappropriate antidiuretic hormone syndrome. Magnetic resonance imaging was used for diagnosis in all patients. The most commonly involved regions by magnetic resonance imaging were occipital (58%), parietal (51%), and frontal lobes (45%), respectively. Twenty-five patients required intensive care and 7 patients were intubated. In conclusion, PRES may develop during the follow-up and treatment of hematological diseases. In addition to steroid and intense combined chemotherapies, immunosuppressive agents and hypertension are also factors that may be responsible for PRES.

Metagenomic next-generation sequencing for identifying pathogens in central nervous system complications after allogeneic hematopoietic stem cell transplantation

A prospective study was conducted to compare metagenomic next-generation sequencing (mNGS) and conventional testing in investigating the pathogens of central nervous system (CNS) infections in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients. A total of 53 patients with CNS disorders after allo-HSCT were enrolled in this study. A total of 35 patients were diagnosed as CNS infections, including 28 viral, 2 bacterial, 1 fungal, 3 mixed infections, and 1 infection with unknown pathogen. Among these 35 patients with CNS infections, mNGS identified 5 patients who were not identified by conventional testing. For the remaining 30 infections, mNGS made concurrent diagnoses with conventional testing in 29, while 1 was diagnosed according to the good response to the antimicrobial treatment without etiological evidence. The presence of Aspergillus detected by mNGS only in one patient was considered false positive due to lack of validation. The sensitivity of mNGS and conventional testing for diagnosing CNS infections post transplant were 97.1% and 82.9%, respectively (P = 0.106), while the specificity of mNGS and conventional testing were 94.4% and 100%, respectively (P = 1.000). These results suggest that mNGS might be a promising technology for diagnosis of CNS infections post transplant. Viruses were the most common pathogens of CNS infections in allo-HSCT recipients.

A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself. The majority of the literature on this subject is focussed on adults. The impact of the combination of neurotoxic drugs given before and during HSCT, radiotherapy and neurological complications on the developing and vulnerable paediatric and adolescent brain remains unclear. Moreover, the age-related sensitivity of the nervous system to toxic insults is still being investigated. In this article, we review current evidence regarding neurotoxicity following HSCT for acute lymphoblastic leukaemia in childhood. We focus on acute and long-term impacts. Understanding the aetiology and long-term sequelae of neurological complications in children is particularly important in the current era of immunotherapy for acute lymphoblastic leukaemia (such as chimeric antigen receptor T cells and bi-specific T-cell engager antibodies), which have well-known and common neurological side effects and may represent a future treatment modality for at least a fraction of HSCT-recipients.

Noninfectious neurologic complications of hematopoietic cell transplantation: A systematic review

OBJECTIVE/BACKGROUND

Neurological complications occur at a high frequency after hematopoietic cell transplantation (HCT). However, an absence is noted in the published literature as regards the quantification of the exact burden and the outcomes thereof. In this systematic review, we endeavored to detail if the recipients of HCT developed any noninfectious neurological events/complications.

METHODS

According to the PICO criteria, medical literature was searched. Complications that were evaluated included: stroke, peripheral neuropathy, myasthenia gravis, seizures, and posterior reversible encephalopathy syndrome. After strictly defining relevant variables and parameters, data from 173 eligible articles were then extracted accordingly, from the full text for each, for quantitative analysis; additionally, two American Society of Hematology conference abstracts were also subject to data extraction.

RESULTS

As is evident from the results of the data analysis, an increased frequency of these complications was seen in the HCT recipient population in comparison to the general population. The relative risk ranged from 1.33× to 142× depending on the complication studied.

CONCLUSION

These findings demonstrate that the recipients of HCT had a significantly higher risk of neurological complications and that their early recognition can enhance the monitoring of HCT survivors for the early developmental signs of neurological toxicity. This would facilitate timely interventions, thus ensuring a better quality of life.

Comparison of hemorrhagic and ischemic stroke after allogeneic hematopoietic stem cell transplantation

Stroke is an important complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Nevertheless, few studies have been published to analyzed the occurrence and prognosis of stroke after allo-HSCT. From January 2007 to December 2018 in Peking University People's Hospital, 6449 patients received HSCT and there were 2.3% of patients diagnosed with stroke after allo-HSCT (hemorrhagic: 1.0%, ischemic: 1.3%). The median time to hemorrhagic and ischemic stroke after HSCT was 161 days and 137 days, respectively. In total, 8.4% of patients experienced neurological sequelae. The outcome was much worse in patients with stroke than in control subjects. The comparison of prognosis showed no statistical differences between patients with hemorrhagic stroke and those with ischemic stroke. Significant risk factors for hemorrhagic stroke were pretransplant central nervous system leukemia (CNSL), and delayed platelet engraftment. Risk factors associated with the occurrence of ischemic stroke included high-risk disease, prior venous thromboembolism (VTE), grade III-IV acute graft-versus-host disease (aGVHD), and thrombotic microangiopathy (TMA). Haplo-identical transplantation was not a risk factor for stroke and had no impact on the prognosis compared with HLA-matched HSCT. Altogether, these results show that stroke is a severe complication after allo-HSCT. The prognosis of posttransplant stroke did not differ between hemorrhagic and ischemic stroke.

Posterior reversible encephalopathy syndrome (PRES) after haploidentical haematopoietic stem cell transplantation: incidence, risk factors and outcomes

Posterior reversible encephalopathy syndrome (PRES) is a gradually recognised neurological complication of allogenic haematopoietic stem cell transplantation (allo-HSCT). However, there is a paucity of information on PRES after haploidentical HSCT (haplo-HSCT). We performed a retrospective nested case-control study in patients following haplo-HSCT for malignant and nonmalignant haematologic diseases between January 2009 and December 2018 in our centre. A total of 45 patients were diagnosed with PRES after transplant, accounting for an incidence of 1.17%. Grades II to IV acute graft-versus-host disease (aGVHD) (HR 2.370, 95% CI 1.277-4.397, p = 0.006) and hypertension (HR 14.466, 95% CI 7.107-29.443, p < 0.001) were identified as risk factors for developing PRES after haplo-HSCT. There was no difference in overall survival (OS), disease-free survival (DFS), the cumulative incidence of relapse or nonrelapse mortality (NRM) between patients with PRES and controls without PRES following haplo-HSCT in either adults or children. All but one patient with PRES showed nearly complete clinical and neurologic recovery. In conclusion, PRES is a rare condition with benign outcomes following haplo-HSCT. Further multicentre prospective studies are needed to confirm the results and help to establish the standard therapy for posttransplant PRES.

Etiologies, Cerebral Vasomotion, and Endothelial Dysfunction in the Pathophysiology of Posterior Reversible Encephalopathy Syndrome in Pediatric Patients

The posterior reversible encephalopathy syndrome was characterized by Hinchey and colleagues in the 1990s. The condition frequently afflicts patients suffering from hematologic and solid organ malignancy and individuals undergoing transplantation. Cases are more frequently described in the adult population compared with children. In the pediatric population, malignancy, transplantation, renal disease, and hypertension represent the most common etiologies. Theories on pathogenesis have centered upon cerebrovascular dysautoregulation with increases in blood–brain barrier permeability. This generates vasogenic edema of the cerebral parenchyma and consequent neurologic deficits. The parietal and occipital lobes are affected with greatest prevalence, though frontal and temporal lobe involvement is frequent, and that of the contents of the infratentorial posterior cranial fossa are occasionally described. The clinical presentation involves a characteristic constellation of neurologic signs and symptoms, most typically inclusive of headache, visual-field disturbances, abnormalities of visual acuity, and seizures. Supportive care, withdrawal of the offending agent, antihypertensive therapy, and prophylactic anticonvulsants affect convalescence in majority of cases. The principal challenge lies in identifying the responsible agent precipitating the condition in patients with malignancy and those having undergone transplantation and thus deciding which medication among a multidrug treatment regimen to withhold, the duration of drug cessation required to effect clinical resolution, and the safety of resuming treatment with the compound. We accordingly reviewed and evaluated the literature discussing the posterior reversible encephalopathy syndrome in children.

Rituximab for acute demyelinating myelopathy after allogeneic hematopoietic stem cell transplantation: a case report

Acute demyelinating myelopathy after allogeneic hematopoietic stem cell transplantation (HSCT) is rare, and the exact pathogenesis remains unclear. Here, we report the case of a 20-year-old patient with B-cell acute lymphocyte leukemia (B-ALL) who developed acute demyelinating myelopathy approximately 10 months after HSCT. Magnetic resonance imaging revealed high T2 signal intensity lesions from the C2-T4 levels of the spinal cord. Treatments with high doses of corticosteroids, immunoglobulins, and rituximab improved his neurologic symptoms, and he achieved 44 months of leukemia-free and graft-versus-host disease (GVHD)-free survival, with no recurrence of the demyelination myelopathy. An understanding of the contribution of immune reconstitution to the pathogenesis of demyelinating myelopathy after HSCT and the association of this disease with GVHD will require more clinical cases.

Diagnosing acute encephalitis in patients with hematological disorders: caveats and pitfalls

The aim of this study was to review the quality of the diagnostic work-up for acute encephalitis carried out at our center in a cohort of patients with hematological disorders. Our data showed substantial heterogeneity in investigating patients. Not all patients had their CSF tested for viruses commonly responsible for encephalitis in immunocompetent individuals (e.g., VZV, enterovirus). A blood sample for the calculation of the CSF/blood replication ratio was collected in 74% of cases. CSF cultures and immunophenotyping of CSF cells were performed in 77% and 21% of patients, respectively. A multidisciplinary consensus is needed to improve current guidelines and standardize diagnostic protocols.

Clinical practice recommendations for the diagnosis and management of human herpesvirus-6B encephalitis after allogeneic hematopoietic stem cell transplantation: the Japan Society for Hematopoietic Cell Transplantation

Reactivation of human herpesvirus (HHV)-6B is relatively common after allogeneic hematopoietic stem cell transplantation (HSCT) and HHV-6B diseases may consequently develop. Among them, HHV-6B encephalitis is a serious and often fatal complication. The aim of these clinical practice recommendations is to provide diagnostic and therapeutic guidance for HHV-6B encephalitis after allogeneic HSCT. In this evidence-based review, we critically evaluated data from the published literature. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assist in generating recommendations. We have summarized the findings that contribute to decision-making and we have provided our recommendations. In cases where rigorous clinical data are unavailable, recommendations have been developed in discussions with physicians who have relevant expertize.

Central Nervous System Complications after Allogeneic Hematopoietic Stem Cell Transplantation in Children

Central nervous system complications (CNSCs) after allogeneic hematopoietic stem cell transplantation (allo-HSCT) are common and may be a significant source of morbidity and mortality. We performed a retrospective study of 153 pediatric patients who underwent allo-HSCT to determine CNSC type, incidence, and impact on survival. A total of 34 patients (22.2%) developed CNSCs. The cumulative incidence of CNSCs at 100 days and 3 years was 18.30 and 22.73%, respectively. The most common CNSC was calcineurin inhibitor (CNI)-associated neurotoxicity (50.0%). Risk factors for CNSCs were the time from diagnosis to HSCT ≥4.8 months (p = 0.032) and the development of acute graft-versus-host disease (aGVHD) grade III-IV (p = 0.002). CNSCs after allo-HSCT negatively impacted overall survival (hazard ratio [HR] 1.97, p = 0.043) and nonrelapse mortality (HR 4.84, p < 0.001). In conclusion, CNSCs after allo-HSCT are associated with poor outcomes; patients with severe aGVHD and/or late transplantation should be given more attention.

Neurologic Complications of Transplantation

Neurologic disturbances including encephalopathy, seizures, and focal deficits complicate the course 10-30% of patients undergoing organ or stem cell transplantation. While much or this morbidity is multifactorial and often associated with extra-cerebral dysfunction (e.g., graft dysfunction, metabolic derangements), immunosuppressive drugs also contribute significantly. This can either be through direct toxicity (e.g., posterior reversible encephalopathy syndrome from calcineurin inhibitors such as tacrolimus in the acute postoperative period) or by facilitating opportunistic infections in the months after transplantation. Other neurologic syndromes such as akinetic mutism and osmotic demyelination may also occur. While much of this neurologic dysfunction may be reversible if related to metabolic factors or drug toxicity (and the etiology is recognized and reversed), cases of multifocal cerebral infarction, hemorrhage, or infection may have poor outcomes. As transplant patients survive longer, delayed infections (such as progressive multifocal leukoencephalopathy) and post-transplant malignancies are increasingly reported.

Neurologic complications after allogeneic transplantation: a meta-analysis

Objective

Neurologic adverse events remain challenging complications with poor morbidity and mortality post adult allogeneic hematopoietic cell transplantation (allo‐HCT) for hematologic diseases. We conducted a systematic review and meta‐analysis to determine their spectrum, incidence, and impact on survival.

Methods

We searched MEDLINE, COCHRANE, EMBASE through March 2019 for all types of primary studies. Two independent reviewers screened, extracted data, and assessed risk of bias (RoB).

Results

We identified 552 eligible studies describing 57.972 patients; one randomized controlled trial, two case–control, 17 prospective, 86 retrospective cohort studies, 21 case series, and 425 case reports. RoB ranged from fair to high although case series were low‐risk. The majority of studies traced infectious or drug‐related neurologic manifestations. Infectious complications were present in 2.7% (95% CI 1.9–3.6) and 3.3% (95% CI 0.8–7.1) of patients in retrospective and prospective cohort studies, respectively. In retrospective studies, 3.4% (95% CI 2.1–4.9) of patients suffered from drug‐related neurologic events. In prospective cohorts the equivalent incidence was 13% (95% CI 4.2–24.8). Neurologic complications had a detrimental impact on survival.

Interpretation

Our study highlights the wide spectrum and significant impact of neurologic complications on survival post allo‐HCT. This systematic review summarizes existing data and provides the necessary background information for every physician involved in the management of these patients.

Posterior reversible encephalopathy syndrome in pediatric patients: pathophysiology, diagnosis, and management

Posterior reversible encephalopathy syndrome (PRES) is well-described in adults, but has been reported with relative rarity in children, usually occurring in the context of chemotherapy for acute leukemia. Pathogenesis involves perturbed cerebral autoregulation leading to vasogenic edema predominantly affecting the parieto-occipital white matter, though involvement of the frontal and temporal lobes, as well as posterior fossa, is also described. We review the literature on the pathophysiology, diagnosis, and management of PRES in pediatric patients.

A case of central nervous system graft-versus-host disease following allogeneic stem cell transplantation

Graft-versus-host disease (GVHD) is a serious complication of allogeneic stem cell transplantation (SCT). Here, we report a rare case of GVHD involving the central nervous system (CNS). A 35-year-old woman was diagnosed with myelodysplastic syndrome unclassifiable and underwent allogeneic peripheral blood SCT for disease progression to myelodysplastic syndrome with excess blasts-2. One year following SCT, she experienced chronic oral and hepatic GVHD symptoms, which were managed with oral steroids and tacrolimus. Sixteen months after SCT, she developed sudden-onset, generalized, tonic-clonic-type seizures. Magnetic resonance imaging and cerebrospinal fluid evaluation showed multiple discrete white lesions and elevated IgG levels. Brain biopsy revealed periventricular plaques with the destruction of axons, representing a demyelinating disease of the CNS. We diagnosed the case as CNS GVHD. Neurologic symptoms gradually improved with methylprednisolone pulse therapy and total plasma exchange combined with a calcineurin inhibitor; the brain lesions nearly disappeared after decreasing steroid maintenance dosage, and were completely resolved 1 year after the onset of CNS GVHD. The patient is CNS GVHD-symptom-free, 3-year post-transplantation. Thus, CNS GVHD should be considered in cases of newly developed neurologic symptoms in SCT recipients showing evidence of preceding chronic GVHD.

Noninfectious Neurologic Complications after Allogeneic Hematopoietic Stem Cell Transplantation

Although allogeneic hematopoietic stem cell transplantation (allo-HSCT) can be associated with neurologic complications, data on noninfectious etiologies are scanty. Therefore, we analyzed the incidence, clinical characteristics, risk factors, and influence on outcomes of noninfectious neurologic complications (NCs) in 971 consecutive patients with hematologic malignancies undergoing allo-HSCT at our center between January 2000 and December 2016. We evaluated NCs affecting the central nervous system (CNS) and peripheral nervous system (PNS). The median duration of follow-up of survivors was 71 months (range, 11 to 213 months). A total of 467 patients received a matched sibling donor (MSD) transplant, 381 received umbilical cord blood (UCB), 74 received a haploidentical transplant, and 49 received a matched unrelated donor (MUD) transplant. One hundred forty-nine (15.3%) NCs were documented at a median of 78 days after transplantation (range, 5 days before to 3722 days after). The cumulative incidence risk of developing NC was 7.5% (95% confidence interval, 6% to 8.2%) at day +90 and 13% at 5 years. The 5-year cumulative incidence of NCs was 10.8% after MSD allo-HSCT and 15.3% after alternative donor (UCB, MUD, haploidentical) allo-HSCT (P = .004). There were 101 (68%) CNS complications, including encephalopathy, n = 46 (31%); headache, n = 20 (13%); stroke, n = 15 (10%); seizures, n = 9 (6%), posterior reversible encephalopathy syndrome, n = 6 (4%), and myelopathy, n = 5 (3%). PNS complications (32%) included neuropathies, n = 25 (17%), and myopathies and neuromuscular junction disorders, n = 23 (17%), with 17% of the total PNS complications being immune-related. In multivariable analysis, donor type other than MSD, age ≥40 years, development of acute graft-versus-host disease (GVHD) grade II-IV (hazard ratio [HR], 3.3; P < .00001), and extensive chronic GVHD (HR, 3.2; P = .0002) were independently associated with increased risk of NCs. The 5-year overall survival (OS) was 21% in patients who developed NCs and 41% for those who did not (P < .0001). This difference in OS was observed in patients developing CNS NCs, but not in those developing PNS complications. In conclusion, our study reveals NCs as a frequent and heterogeneous complication that, when affecting CNS, is associated with poor prognosis following allo-HSCT.

Neurological adverse events post allogeneic hematopoietic cell transplantation: major determinants of morbidity and mortality

BACKGROUND

Despite advances in the field, diagnosis and management of the wide spectrum of neurological events post allogeneic hematopoietic cell transplantation (alloHCT) remain challenging. Therefore, we investigated their incidence, diagnosis, management and long-term prognosis in alloHCT recipients.

METHODS

We retrospectively recorded data from consecutive alloHCT recipients with or without neurological complications in our center.

RESULTS

Among 758 alloHCT recipients, 127 (16.8%) presented with neurological complications. Complications developed in central nervous system (89.7%) during the late post-transplant period. Neurological adverse events included a wide spectrum of infectious and non-infectious etiologies. With a median follow-up of 11.4 months, incidence of chronic graft-versus-host disease (GVHD) was 52.8%, relapse mortality 48.6%, transplant-related mortality 39.1% and 5-year overall survival (OS) 25.8% in patients with neurological complications. Timing of appearance of neurological complications, early or late, was associated only with acute and chronic graft-versus-host-disease/GVHD. Independent pre-transplant risk factors of neurological complications in the multivariate model were unrelated or alternative donors, ALL diagnosis and non-myeloablative conditioning. In multivariate analysis of post-alloHCT events, favorable OS was independently associated with resolution of neurological syndromes, absence of chronic GVHD and sibling transplantation. In our cohort, 10-year OS was significantly lower in patients with neurological complications and independently associated with acute and chronic GVHD, relapse, fungal and bacterial infections and neurological complications.

CONCLUSIONS

Our large study with long-term follow-up highlights the wide spectrum of neurological complications in alloHCT. Accurate recognition is required for adequate management, a major determinant of survival. Thus, long-term increased awareness and collaboration between expert physicians is warranted.

Incidence, Risk Factors, and Outcome of Immune-Mediated Neuropathies (IMNs) following Haploidentical Hematopoietic Stem Cell Transplantation

Immune-mediated neuropathies (IMNs) following hematopoietic stem cell transplantation have been described recently, which, excluding Guillain-Barré syndrome and chronic inflammatory demyelinating polyneuropathy, may present with atypical patterns. This retrospective, nested, case-control study reviewed data from 3858 patients who received haploidentical hematopoietic stem cell transplantation (haplo-HSCT) during the past 10 years at a single center, and 40 patients (1.04%) with IMN following haplo-HSCT were identified. Chronic graft-versus-host disease (cGVHD) (P = .043) and cytomegalovirus (CMV) viremia (P = .035) were recognized as independent risk factors for the development of IMN after haplo-HSCT. There were no significant differences in overall survival (P = .619), disease-free survival (P = .609), nonrelapse mortality (P = .87), or the incidence of relapse (P = .583) between patients with and without IMN after haplo-HSCT. However, patients with post-transplant IMN were at higher risk of developing cGVHD (P = .012) than patients who did not develop IMN. Twenty-four of the 40 patients with IMN (60%) attained neurologic improvement after treatments including vitamins B₁ and B₁₂ and/or immunomodulatory agents. However, 19 (47.5%) patients still had persistent motor/sensory deficits despite receiving timely treatment. More studies are needed to help develop standardized diagnostic and therapeutic strategies for patients with post-transplant IMN.

Cerebrovascular disease after allogeneic hematopoietic stem cell transplantation: incidence, risk, and clinical outcome

Cerebrovascular complications after hematopoietic stem cell transplantation (HSCT) cause serious morbidity and often contribute to mortality. The incidence, risk factors, and outcome of cerebrovascular disease (CVD) after allogeneic HSCT remain poorly defined. We retrospectively evaluated 459 adult patients who underwent allogeneic HSCT at a tertiary medical center between January 2003 and December 2015. A total of 20 patients (4.4%) developed post-transplant CVD. All cerebrovascular accidents occurred in the first two years post-transplant. The two-year incidences of post-transplant CVD, intracranial hemorrhage, and cerebrovascular infarction were 6.1%, 3.2%, and 3.2%, respectively. The incidence rate of CVD within two years after HSCT was 34.7 (95% CI 22.3 to - 53.7) per 1000 person-years, which was about tenfold higher than the general Taiwanese population. The only significant risk factor associated with post-transplant CVD is prior exposure to three or more courses of high-dose cytarabine. Post-transplant CVD is associated with dismal outcome and early mortality. The median overall survival of patients with post-transplant CVD was markedly reduced compared with those without CVD (8.0 vs. 60.6 months). Most patients with post-transplant CVD died within two months after the CVD events. Our study demonstrates that CVD remains a devastating complication after allogeneic HSCT in the modern era.

Immune Mediated Cerebellar Ataxia: An Unknown Manifestation of Graft-versus-Host Disease

Neurologic complications of allogeneic hematopoietic cell transplantation (allo-HCT) include infections, cerebrovascular events, therapy-induced neurotoxicity, recurrent malignancies, and neurologic manifestations of graft-versus-host disease (GVHD). Anti-glutamic acid decarboxylase (GAD) antibody-associated cerebellar ataxia is a well-established disorder of autoimmune origin, but there are no reports in the literature of its occurrence following allo-HCT. We describe a middle-aged woman with chronic GVHD after allo-HCT who presented with a rapidly progressive cerebellar syndrome. Thorough investigation revealed only cerebellar atrophy on brain imaging and positive anti-GAD65 antibodies in serum and cerebrospinal fluid suggesting the diagnosis of anti-GAD antibody-associated cerebellar ataxia. Despite prompt treatment with high-dose corticosteroids, intravenous immunoglobulins, and rituximab, the patient's condition rapidly deteriorated, and she died 4 months later. This case suggests that anti-GAD antibody-associated cerebellar ataxia may be a rare manifestation of chronic GVHD.

[Post-transplant neurological complications: Guidelines from the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Neurological complications post-allogeneic hematopoietic stem cell transplantation are well-characterized; however, given their variable impact, they remain a significant cause of morbidity. The etiologies for these complications are vast. Causes may be linked to toxicity and infection or could be vascular or tumor-related. Regardless, these complications require early investigation, which is often multidisciplinary and hierarchical. Preventive measures may be considered in some situations. It is essential to respond early and quickly with a diagnosis and the appropriate therapeutic approach when faced with neurological complications. Focusing on the axes of etiology, diagnosis and treatment, this article offers a review of neurological complications post-allogeneic hematopoietic stem cell transplantation.

PRES in Pediatric HSCT: A Single-Center Experience

Posterior reversible encephalopathy syndrome (PRES) has diverse etiologies and is closely linked to hematopoietic stem cell transplant (HSCT). Headache and seizures are the most common clinical presentations. Although near total recovery is seen in the majority of patients with appropriate management, the implications of its occurrence in the setting of an HSCT is much more than the residual neurological deficits. Graft rejection and occurrence of graft versus host disease has been reported. We analyzed retrospectively our data of 35 pediatric HSCT recipients over the last 2 years at our center. In total, 17% (n=6) patients developed PRES. Headache and seizures were the most common clinical presentations. All patients were on calcineurin inhibitors at the onset of symptoms. The median time after HSCT to the onset of PRES was 21 days. In total, 34% (n=2) patients developed residual neurological deficit. One patient died of acute graft versus host disease at a later date, and 50% (n=3) patients had graft rejection and return to transfusion dependence. The implications of PRES on HSCT outcomes are grave, and better immunosuppression transition protocols need to be developed.