Left-sided facial numbness is mainly due to the following reasons: First, if the acute onset of the left side of the face is accompanied by left-sided numbness of the hands and feet, ask the patient whether there is left-sided hand weakness, slurred speech, tongue extension, and consider that the patient may have acute cerebrovascular disease, such as cerebral infarction, cerebral hemorrhage, and need to do a cranial magnetic resonance examination to clarify. Some patients with thalamic infarction, especially those with damage to the ventral lateral nucleus of the thalamus, may have left-sided facial numbness in the hands and feet and trunk. Third, if the left facial hand and foot numbness is a long-term chronic process, a cranial magnetic resonance examination should also be done to find out if there is any intracranial occupancy or tumor.