Patients with brain metastasis of thyroid cancer may have systemic symptoms, local symptoms and nervous system damage symptoms, which may vary from patient to patient. 1. Systemic symptoms: thyroid cancer itself is a malignant tumor, and patients may suffer from hypoproteinemia, anemia, malnutrition, decreased immunity, poor mental status, fatigue, loss of appetite and other symptoms due to long-term illness. 2. Local symptoms: in addition to the symptoms of thyroid cancer, patients with brain metastasis of thyroid cancer may also have headache, dizziness, blurred vision, double vision, hallucinations and other symptoms after brain metastasis. 3. Neurological symptoms: brain metastasis of thyroid cancer can stimulate or damage patients’ brain tissues, resulting in numbness of limbs, dull sensation, uncoordinated movement, even paralysis, impaired consciousness and other symptoms, and in serious cases, it can lead to cerebral hernia, resulting in patients’ death. When brain metastasis of thyroid cancer occurs, patients can actively cooperate with doctors to alleviate the condition through radiotherapy and chemotherapy.