Delayed severe median nerve palsy due to undiagnosed brachial pseudoaneurysm.

Post-catheterization pseudoaneurysms are a well-known complication of many endovascular procedures at the site of arterial puncture. However, long-term neurological complications due to undiagnosed compression are rare. A 60-year-old man presented to our unit for round, non-pulsatile, painless swelling in the inner side of his upper arm. Clinical examination showed finger paralysis, associated with amyotrophy of the forearm. Large brachial pseudoaneurysm with median nerve compression was diagnosed. The patient underwent autologous vein bypass, with poor 6-month neurological recovery. Early diagnosis of pseudoaneurysms is paramount because, when associated with nerve compression, the longer the diagnostic delay, the poorer the neurological prognosis.