[Association between hematopoietic stem cell transplantation and Parsonage Turner syndrome: coincidence or cause-effect relationship?].

Parsonage-Turner syndrome or idiopathic brachial neuritis is a total or partial inflammation of the brachial plexus, with a typical presentation as a sudden and very intense pain in the shoulder, followed by weakness and early amyotrophy. The etiology is still unknown, although an immune mediated mechanism is thought to be involved. Hematopoietic stem cell transplantation is a well-established treatment for hematological malignancies, but with a growing implication in the treatment of autoimmune diseases. The neurological side effects are probably underdiagnosed. The association of the Parsonage-Turner syndrome and the hematopoietic stem cell transplantation is scarce. We describe two clinical cases of idiopathic brachial plexopathy after hematopoietic stem cell transplantation. The reconstruction of the immune system after a transplant may be the trigger of a brachial plexopathy, but more studies are necessary for the etiology of this disease to be understood and to establish a cause-effect relation with the transplant.