Numbness in the thumb of the foot is considered to be peripheral neuropathy, which can be checked with an electromechanical chart, and it is recommended to check the nerve conduction velocity in the lower extremities to clarify the diagnosis.
The peripheral neuropathy is considered to be due to the following causes: a lumbar disc herniation, diabetes mellitus, and nerve injury to the foot.
1. A herniated lumbar disc can compress the nerve roots around the lumbar region, and after the nerve roots are stretched or squeezed, the corresponding symptoms occur. The numbness of the big toe is localized to the fifth lumbar vertebra of the lumbar intervertebral disc, and a lumbar imaging study reveals a herniated fifth lumbar vertebra.
2. Long-term elevated blood glucose in diabetes can lead to peripheral nerve damage and numbness of the toes.
3. Damage to the sensory nerves in the foot, a small trauma or uncomfortable shoe wear that squeezes the big toe, may cause temporary paralysis of the cutaneous nerves and also cause numbness in the toes.