Stiffness of tongue may be caused by tongue nerve damage, tongue tumor, cerebrovascular disease and so on. 1. Damage to tongue nerve: if patients suffer from cervical spondylosis or cranial neurovascular lesions and other diseases, it may lead to compression or damage of tongue nerve, causing tongue stiffness. 2. Tumor of tongue: when the tongue has a tumor, it may lead to malignant proliferation of the tumor, which is easy to invade the normal tissues of the tongue, such as nerves, blood vessels, muscles, etc., causing damage to the normal tissues of the tongue, and appearing as stiffness of the tongue. 3. Cerebrovascular disease: if patients suffer from cerebral infarction, cerebral hemorrhage and other diseases, it will easily lead to brain dysfunction, make cerebral blood vessels harden, tighten and block, and appear the phenomenon of stiffness of the tongue, and also accompanied by symptoms such as poor speech, crooked mouth, drooling and so on. Patients with tongue stiffness should go to the hospital in time, after clarifying the cause of the disease, give appropriate treatment and therapy under the guidance of doctors.