Neuromuscular complications after hematopoietic stem cell transplantation

The aim of this study was to analyze the occurrence of neuromuscular symptoms in recipients of allogeneic hematopoietic stem cell transplantation (HSCT) for treatment of malignant hematopoietic disease. Among 247 outpatients after allogeneic HSCT, we conducted a prospective non-interventional study between July 2011 and August 2013. During follow-up visits, clinical and electrophysiological findings were correlated to the presence of autoantibodies/alloantibodies and to frequencies of lymphocyte subpopulations in peripheral blood. Resulting in an incidence of 8.1 %, 20 patients were diagnosed with neuromuscular complications at a median onset of 12 months post-transplant. Five patients (25 %) were identified with polyneuropathy (PNP), ten patients (50 %) with combined PNP and myopathy, four patients (20 %) with myopathy or polymyositis (PM), and one patient (5 %) with myasthenia gravis (MG). Immune-mediated sensorimotor PNP after HSCT is characterized by a predominantly axonal lesion and can be overlapping with neurotoxic side effects. The latency between HSCT and development of PM varied between 60 days and 72 months. In general, PM occurs parallel to graft-versus-host disease (GvHD) after tapering of immunosuppressive medication. Typical clinical features are proximal bilateral limb weakness with muscle atrophy. Autoantibodies (Ab) were detected in 12 patients, myositis-specific Ab only in one patient. In patients with progressive neurological symptoms, a decrease in the CD4/CD8 T cell ratio was observed. GvHD-related myositis appeared similar to idiopathic myositis regarding clinical and electromyographical findings. As outcome measure, sequential analysis of lymphocyte subpopulations in peripheral blood seems to be more suitable than Ab measurements. Whereas peripheral neuropathies are commonly observed shortly after HSCT, MG is a rare complication in the late post-HSCT phase.