The Tinel test is a fundamental physical examination technique used in orthopedics and neurology to assess the function of peripheral nerves. It is a simple, non-invasive diagnostic tool used to evaluate patients presenting with symptoms suggesting a nerve problem. Physicians use this maneuver to pinpoint the location of nerve irritation or injury, which helps determine the underlying cause of symptoms. The test guides further diagnostic procedures and helps establish an appropriate treatment plan.
The Underlying Principle of the Tinel Sign
The physiological basis of the Tinel sign lies in the mechanical hypersensitivity of damaged or regenerating nerve fibers. When a peripheral nerve is compressed or injured, the protective myelin sheath surrounding the axon can become compromised. This damage alters the nerve’s electrical state, making it sensitive to physical stimulus.
The application of light pressure or percussion over the affected site causes a brief, abnormal electrical discharge. The brain interprets this discharge as a tingling or “pins-and-needles” sensation, known medically as paresthesia, which travels along the nerve’s distribution. This reaction indicates that the nerve is either irritated by mechanical compression or actively attempting to heal itself.
The sign is named after French neurologist Jules Tinel, who studied nerve injuries during World War I. Tinel observed that the tingling sensation could also mark the point of new nerve growth, or regeneration, following trauma. The phenomenon was described independently by German physiologist Paul Hoffmann, which is why it is occasionally referred to as the Hoffmann-Tinel sign.
Performing the Tinel Test
The procedure for the Tinel test is straightforward, involving the application of a light physical stimulus to the suspected nerve. The clinician first identifies the anatomical course of the nerve causing the patient’s symptoms. The patient is positioned comfortably, and the limb is supported to ensure muscle relaxation.
The clinician uses one or two fingers, or sometimes a small reflex hammer, to lightly tap or percuss directly over the identified nerve path. The force used is a firm tap, intended only to create a minimal mechanical disturbance to the nerve beneath the skin. Tapping often begins away from the suspected injury and progresses toward the area of potential compression.
The test is commonly performed at anatomical bottlenecks where nerves are vulnerable to entrapment. For example, the median nerve is tested at the flexor crease of the wrist. The ulnar nerve is checked by tapping the groove at the elbow, known as the cubital tunnel. The posterior tibial nerve is tested along the inner aspect of the ankle.
Interpreting Results and Diagnostic Applications
A positive Tinel sign is recorded when the patient reports a sudden, radiating tingling, prickling, or electric shock sensation in the nerve’s distribution, felt distal to the point of percussion. This response indicates that the underlying nerve is structurally irritated, experiencing compression, or actively regenerating its axons. The location of the most sensitive point helps the clinician localize the precise site of the nerve problem.
A positive sign serves as a strong clinical indicator of a peripheral nerve entrapment syndrome, where the nerve is squeezed by surrounding tissue. The test is routinely used in the diagnosis of common conditions. These include Carpal Tunnel Syndrome (median nerve compression at the wrist), Cubital Tunnel Syndrome (ulnar nerve at the elbow), and Tarsal Tunnel Syndrome (posterior tibial nerve in the ankle).
Conversely, a negative Tinel sign means the patient feels no abnormal sensation when the nerve is tapped. While this suggests the nerve may not be acutely irritated, it does not exclude a nerve condition. Other diagnostic tests are often necessary if the patient reports symptoms like numbness or weakness. Following a nerve repair, a positive Tinel sign that slowly moves down the limb over time is a favorable observation, indicating successful axonal growth and healing.