Westphal's sign is the clinical correlate of the absence or decrease of patellar reflex or knee jerk.

Patellar reflex or knee jerk is a kind of deep or stretch reflex where an application of a stimulus to the patellar tendon such as strike by a solid object or hammer caused the leg to extend due to such stimulus causes the quadriceps femoris muscle to contract.

[citation needed] It is named for Karl Friedrich Otto Westphal (1833–1890).

[1][2] Westphal's sign has a clinical significance used in determining neurological disorders or diseases such as:[citation needed]

This medical sign article is a stub.