A patient presents with signs of an L4-L5 disk herniation. Which finding would best aid confirmation?

• A. Paresthesia dorsum of foot
• B. Deficit with Achilles reflex
• C. Paresthesia medial aspect of tibia
• D. Deficit with patellar reflex

Answer: (A)

When a disk herniation occurs at the L4–L5 level, the traversing L5 nerve root is most likely to be affected. The L5 nerve root provides sensation to the dorsum (top) of the foot, among other areas. Therefore paresthesias on the dorsum of the foot are a classic sign of L5 radiculopathy from an L4–L5 disk herniation and best help confirm the level of involvement.

Paresthesia on the medial aspect of the tibia points more toward the L4 distribution, while deficits in the patellar reflex indicate L4 involvement and deficits in the Achilles reflex indicate S1 involvement. Those signs would suggest different nerve-root levels than L5, making them less specific for an L4–L5 herniation.