Abnormal sensation on the left side of the face may be caused by facial nerve palsy, trigeminal neuralgia and intracranial diseases. 1. Facial nerve palsy: most of them are caused by viral infections, manifested by incomplete eyelid closure on the affected side, inability to raise the eyebrow on the focal side, inability to wrinkle the forehead, the corner of the mouth is inclined to the healthy side when showing teeth, and food will be retained on the affected side when chewing. If accompanied by viral infection, herpes of the ear canal and external auricle, abnormal sensation outside the ear canal, and hard of hearing will occur. 2. Trigeminal neuralgia: In the distribution area of trigeminal nerve in the head and face, talking, washing face, brushing teeth or the breeze on the face, or even walking will lead to paroxysmal severe pain, i.e., abnormal sensation on the left side of the face. 3. Intracranial diseases: such as cerebral infarction, cerebral hemorrhage, lesions compressed to the nerve and nerve damage, the left side of the face discomfort. It is recommended that the patient actively consult the doctor to clarify the cause of the disease and treat it.