The Tinel Sign is a simple, non-invasive examination method used by healthcare professionals to evaluate the status of peripheral nerves. This neurological assessment tool helps determine if a nerve is irritated or actively undergoing regeneration following an injury or compression. Named after the French neurologist Jules Tinel, the sign offers a quick, preliminary indication of peripheral nerve health. Its primary utility lies in screening patients for potential nerve damage before moving on to more complex diagnostic procedures.
The Physical Assessment Technique
The process of eliciting the Tinel Sign involves the clinician lightly striking the skin directly over the presumed course of the affected nerve. This mechanical stimulus is delivered using either the tip of a finger or the rubber end of a standard reflex hammer. The goal is to apply a gentle, focused percussion force directly onto the nerve sheath.
The clinician systematically performs this tapping action along the anatomical pathway of the nerve that is suspected to be damaged or compressed. Percussion often begins at a point farthest from the nerve’s origin (distal) and moves progressively toward the nerve’s root (proximal). This directional approach helps pinpoint the precise location where the nerve fibers are most compromised.
By moving the point of percussion, the practitioner can define the boundary of the nerve lesion or the area of maximum sensitivity.
Interpreting the Sensory Response
A positive Tinel Sign is defined by the patient experiencing an immediate, distinct sensory phenomenon upon the percussion of the nerve. This response is often described as a sharp tingling, an electric shock-like sensation, or the feeling of “pins and needles,” medically termed paresthesia. The occurrence of this sensation indicates that the underlying nerve fibers are hypersensitive to mechanical stimulation.
The paresthesia arises because the nerve is either compressed, known as an entrapment neuropathy, or is in the early stages of regenerating its damaged axons. In a state of compression, the nerve’s protective myelin sheath may be compromised, making the underlying axon membrane unstable and easily triggered by the tap. This mechanical irritation causes an abnormal discharge of nerve impulses, which the brain interprets as tingling in the nerve’s distribution area.
When a nerve is regenerating after a complete injury, the newly growing axonal sprouts are delicate and sensitive. Percussion over the site where these sprouts are actively forming irritates them, producing the characteristic tingling sensation. This specific finding helps clinicians confirm that the nerve is attempting to repair itself.
The location of the maximum sensory response is also highly informative for diagnosis and prognosis. If the point of maximum tingling sensation moves progressively outward, or distally, over a period of weeks or months, it is referred to as Tinel’s traveling sign. This distal movement is a strong indicator of successful, ongoing nerve regeneration.
Conversely, a positive sign that remains fixed at a specific anatomical location often suggests a stable point of chronic irritation or compression. Differentiating whether the sign is fixed or traveling helps distinguish between an active healing process and a static entrapment neuropathy requiring intervention.
Key Nerve Entrapment Syndromes
The most frequent clinical application of the Tinel Sign involves evaluating the median nerve at the wrist for suspected Carpal Tunnel Syndrome (CTS). The median nerve passes through the narrow carpal tunnel, and a positive response suggests irritation from compression by surrounding structures. Percussing the nerve directly over the flexor retinaculum often reproduces the patient’s characteristic hand symptoms.
Another common site for this assessment is the ulnar nerve, where it passes through the cubital tunnel on the inner side of the elbow. A positive Tinel Sign here suggests Cubital Tunnel Syndrome, which is the second most common peripheral nerve entrapment. The nerve is vulnerable due to its superficial position and mechanical stress during elbow flexion.
The posterior tibial nerve is assessed as it passes behind the medial malleolus of the ankle, a region associated with Tarsal Tunnel Syndrome (TTS). Reproduction of paresthesia in the sole of the foot upon tapping this area provides preliminary evidence of nerve compression within the tarsal tunnel. These three sites represent the primary points of clinical utility for this screening method.
The test may also be applied to nerves like the common peroneal nerve near the fibular head or the radial nerve in the forearm. In all these applications, the underlying principle remains the same: mechanically irritating a hypersensitive nerve at a known point of anatomical vulnerability.
While a positive result provides valuable directional information, the Tinel Sign is not a standalone diagnostic tool. Because it is highly subjective and depends on the patient’s perception and the practitioner’s technique, its results must be correlated with the patient’s medical history and other objective findings. Confirmation of an entrapment neuropathy requires more objective neurophysiological tests, including nerve conduction studies (NCS) and electromyography (EMG). The Tinel Sign functions primarily as an initial, bedside screening test to guide the need for these detailed confirmatory procedures.