Numbness and lack of sensation in the big toe can be attributed to the following common causes:1. Peripheral neuritis of the big toe, which is commonly seen in diabetic patients, can lead to abnormal sensory conduction and the symptom of lack of sensation due to the problem of the nerve itself.2. Cranio-cerebral diseases, such as cavernous infarction and cerebral infarction, can lead to the corresponding sensory abnormalities, which will result in the corresponding symptoms.3. Herniated lumbar disc or Spinal stenosis, due to the compression and stimulation of the nerve root of the sciatic nerve, can also lead to abnormal sensory conduction in the big toe, resulting in corresponding symptoms. 4, the blood circulation of the big toe is abnormal, can also lead to abnormal nerve function, the nerves will function abnormally due to ischemia, hypoxia, common causes include vasculitis of the toes, or acute injuries to the toes and other conditions.