Numbness and weakness of the left foot can be caused by brain lesions, peripheral neuropathy and other reasons. 1. Brain lesions: common clinical diseases include cerebral infarction, cerebral hemorrhage, intracranial infections, brain tumors, etc. All of the above diseases may cause damage to the central nervous system, resulting in numbness and paralysis of the distal limbs. 2. Peripheral neuropathy: people with lumbar disc herniation, the sciatic nerve will be compressed, resulting in persistent or paroxysmal pain, numbness and other symptoms in the area innervated by the sciatic nerve, mostly in the buttocks, the back of the thighs, and calves and other parts of the body; people with diabetes mellitus may be complicated with diabetic peripheral nerve injury, which may cause damage to the end of the limb nerves, resulting in limb numbness, pain, and so on. Other reasons: In addition to the above, there are other reasons. 3. Other causes: In addition to the above diseases, ankle tube syndrome, thrombosed vasculitis, acid-base imbalance and electrolyte metabolism disorders, etc., may cause the normal physiological function of the foot tissues and cells to be affected or damaged, with clinical manifestations of weakness, pain and numbness in the feet. Numbness and weakness of the left foot can be caused by a variety of reasons, and it is recommended that people with this symptom should go to the hospital for an examination to clarify the cause of the disease, and then give nutritional nerve treatment.