Transverse section across the wrist and digits. (The median nerve is the yellow dot near the center. The carpal tunnel is not labeled, but the circular structure surrounding the median nerve is visible.)
Tinel's sign is a way to detect irritated nerves. It is performed by lightly tapping (percussing) over the nerve to elicit a sensation of tingling or "pins and needles" in the distribution of the nerve. It takes its name from French neurologist Jules Tinel (1879-1952).
For example, in carpal tunnel syndrome where the median nerve is compressed at the wrist, Tinel's sign is often "positive" causing tingling in the thumb, index, middle finger and the radial half of the fourth digit. Tinel's sign is sometimes referred to as "distal tingling on percussion" or DTP. This distal sign of regeneration can be expected during different stage of somatosensory recovery.
Although most frequently associated with carpal tunnel syndrome, Tinel's sign is a generalized term, and can also be positive in ulnar nerve impingement at the wrist (Guyon's canal syndrome), where it affects the other (ulnar) half of the fourth digit and the fifth digit.
^Tinel, J., Nerve wounds. London: Baillère, Tindall and Cox, 1917
^Tinel, J. (1915) Le signe du fourmillement dans les lésions des nerfs périphériques. Presse médicale, 47, 388-389
^Tinel, J. (1978) The "tingling sign" in peripheral nerve lesions (Translated by EB Kaplan). In: M. Spinner M (Ed.), Injuries to the Ma jor Branches of Peripheral Nerves of the Forearm. (2nd ed.) (pp 8-13). Philadelphia: WD Saunders Co
^Spicher, C.; Kohut, G.; Miauton, J. (1999). "At which stage of sensory recovery can a tingling sign be expected? A review and proposal for standardization and grading". Journal of hand therapy : official journal of the American Society of Hand Therapists12 (4): 298–308. doi:10.1016/S0894-1130(99)80068-4. PMID10622196.edit