Left dorsal foot numbness may have the following causes: first, lumbar disc herniation, lumbar disc herniation compression of the left nerve root will appear the left dorsal foot numbness, can be accompanied by weakness of the left toes and the symptoms of lower limb pain, especially in the bending holding objects, sitting when the dorsal foot numbness is obvious. Second, the pear-shaped muscle syndrome, when there can be pressure pain in the hip, often due to trauma around the pear-shaped muscle of the hip, inflammation or tumor compression, resulting in sciatic nerve compression, the symptoms of numbness of the left dorsal foot, then the relevant neuromyography examination and related physical examination, further diagnosis and treatment. Third, the common peroneal nerve injury, when the common peroneal nerve inflammation, trauma or tumor, can appear numbness of the skin of the innervation area of the common peroneal nerve, can lead to the left foot dorsolateral numbness, then also to electromyography examination and related physical examination, further diagnosis.