[Intrathecal immunoglobulin administration for refractory viral central nervous system infection after allogeneic hematopoietic stem cell transplantation].

Central nervous system (CNS) viral infections after allogeneic hematopoietic stem cell transplantation are associated with poor prognosis and have limited therapeutic options. We report three cases of refractory CNS viral infection treated by combination therapy with antiviral agents and intrathecal immunoglobulin administration. Case 1 involved cytomegalovirus encephalitis, Case 2 varicella zoster virus meningitis, and Case 3 human herpesvirus 6 encephalitis; all were resistant to antiviral agents. Two patients achieved viral DNA negativity in cerebrospinal fluid, and none experienced adverse events related to intrathecal injection. Although no intrathecal immunoglobulin products have been approved for use in Japan, our findings suggest that this treatment may be a viable option in selected refractory cases. Further studies are warranted to clarify the optimal agent, dosage, and schedule.