Hot Nose Sign

The presence of early, increased activity in the nasopharyngeal region at radionuclide (99mTc) blood flow scanning, which is seen in patients with a decreased blood flow in one or both internal carotid arteries, leading to increased or collateral flow through the external carotid artery on the involved side, producing markedly increased perfusion to the nasal region. It is regarded as an early, albeit secondary sign of brain death, especially if there is no intracranial perfusion
DiffDx Any mechanical or functional carotid artery occlusion—e.g., cerebrovascular accident; transient ischemic attack, psychotropic drugs, subdural hematoma, hyperthyroidism, and hepatic encephalopathy may increase intracranial pressure, and cause functional carotid artery occlusion. However, some degree of intracranial perfusion exists in these conditions
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