P09.01NEUROLOGICAL COMPLICATIONS AFTER ALLOGENEIC BONE MARROW TRANSPLANTATION

INTRODUCTION: Allogeneic bone marrow transplantation (BMT) has now become a common procedure in the treatment of a variety of hematologic disorders. Neurological complications after BMT are a frequent event, including subtle relapses of hematologic malignancy and a number of pleomorphic conditions, ranging from CNS infections to cerebrovascular diseases, radiation-induced and toxic encephalopathies and acute/chronic graft versus host disease (GVHD). Diagnosis may be challenging due to the variety of disorders involved, and timeliness of treatment is crucial, as most of these complications may be life-threatening. We present our decennial experience in the field through a number of iconic cases, and propose an algorithm to guide the neurologist in the complex process of differential diagnosis. MATERIAL AND METHODS: Patients were recruited among our two institutions (Neuro-oncology/ General Neurology Unit, C. Mondino Institute, Pavia; Haematology and Transplantation Unit, Policlinico San Matteo, Pavia), and data collected retrospectively from clinical records referring to the period from January, 2010 to March, 2014. RESULTS: We selected eight patients with a history of bone marrow transplantation for different hematologic malignancies (acute lymphocytic or myeloid leukaemia and non-Hodgkin lymphomas). Neurological symptoms occurred between 1 month and 7 years after BMT, and were pleomorphic. In one patient the final diagnosis was of localization of the malignancy to the peripheral nervous system. Two patients had infectious complications: one acute limbic encephalitis by HHV-6, and one neuro-toxoplasmosis. Two other patients had autoimmune disorders of the CNS (one neuromyelitis optica and one chronic GvHD). One patient presented with PRES, and the final two with toxic encephalopathies induced respectively by radiotherapy and intrathecal chemotherapy. Complications occurred with a characteristic timing after engraftment, with PRES and limbic encephalitis being the earliest to occur and autoimmune disorders the latest. CONCLUSIONS: The timely and accurate diagnosis of neurological complications after BMT is a diagnostic challenge, that involves a multidisciplinary expert team. The definition of diagnostic algorithms could help to quicken the process of diagnosis, thus reducing the severe morbidity and mortality associated with these complications. We present our experience in the field and propose a joint prospective multicentric collection of data to address this unresolved issue.