Injury to the hypoglossal nerve can lead to atrophy of the lingual muscle, which is often affected by cranial nerve damage, and the lingual muscle is the first to be invaded, with atrophy of the lingual muscle, accompanied by tremors, and later the palate, pharynx, larynx and masticatory muscles are also gradually atrophied and weak, resulting in slurred speech, difficulty in swallowing and weakness in chewing. Ball palsy can be the first symptom or appear after limb atrophy. Tongue muscle atrophy can also be seen in nasopharyngeal carcinoma. Based on the above etiology, the diagnosis of lingual muscle atrophy can be summarized as follows: 1. Direct invasion of nasopharyngeal carcinoma or lymph node metastasis to the posterior region of the caudate or the hypoglossal nerve canal. The invasion of the sublingual nerve causes tongue extension to the diseased side, accompanied by atrophy of the lingual muscle on the diseased side. 2. In ball palsy, the tongue muscle atrophy and tremor are obvious, while the jaw reflex is hyperactive and the sucking reflex is positive, showing combined damage of upper and lower motor neurons. According to the above diagnostic basis of lingual muscle atrophy, to prevent this symptom, the main thing to do is to avoid cranial nerve damage, control the condition of nasopharyngeal carcinoma, and prevent direct invasion or lymph node metastasis to the posterior region of the caudate or the sublingual nerve canal.