BackgroundCerebral angiography through the transradial approach (TRA) is associated with a low risk of complications, but in rare cases, these complications can be life-threatening.Case presentationA 56-year-old female patient was admitted for transradial cerebral angiography due to the complaint of right limb weakness and the diagnosis of cerebral infarction and cerebral artery stenosis. During the procedure, the patient coughed with expectoration and complained of throat discomfort, palpitations, and pains in the right shoulder and back. Emergency CT scan indicated hematoma in the middle mediastinum and the right thoracic cavity, and perforation of a branch of the subclavian artery was highly suspected. Subclavian artery angiography was conducted immediately, which revealed a patchy contrast medium overflow in a branch of the right costocervical trunk. Selective endovascular occlusion therapy was performed successfully with gelfoam particles and placement of 2 microcoils. At 12 days after cerebral angiography, the patient recovered well and was discharged from the hospital.ConclusionMediastinal and thoracic hematoma may occur due to vessel perforation during TRA cerebral angiography, in which guidewire advancement must be cautious. Early detection and appropriate countermeasures can reduce the severity of vascular perforation and subsequent hematoma.