Spontaneous Subdural Hematoma Secondary to Influenza Vaccine-Induced Immune Thrombocytopenia

Influenza vaccine-induced immune thrombocytopenia (ITP), though rare, can present with a wide spectrum of clinical manifestations, ranging from mild asymptomatic thrombocytopenia to life-threatening complications, such as gastrointestinal (GI) bleeding, diffuse alveolar hemorrhage (DAH), or intracranial hemorrhage (ICH), particularly when platelet count drops below a critical level of less than 5,000/µL. We report a rare case of spontaneous subdural hematoma (SDH) due to severe ITP following the influenza vaccine that showed a dramatic response to high-dose methylprednisolone and intravenous immunoglobulin (IVIG), with platelet count returning to normal and complete resolution of symptoms by the third day of therapy initiation.