Tinel’s Test is a straightforward physical examination technique utilized by healthcare professionals to evaluate the condition of peripheral nerves. This diagnostic tool is applied when there is a suspicion of nerve injury, irritation, or entrapment, which are common causes of pain, numbness, and weakness in the limbs. The test is named after French neurologist Jules Tinel, who described the sign in 1915. It provides a simple, non-invasive method for clinicians to assess the status of a nerve and determine if it is actively healing or being compressed.
How the Test Is Performed
The procedure for eliciting the Tinel’s sign involves the clinician lightly striking the skin directly over the suspected course of a peripheral nerve. This technique, known as percussion, is typically executed using the examiner’s index and middle fingers, though sometimes a small reflex hammer may be used. The goal is to stimulate the nerve precisely at a point where it may be narrowed or damaged.
The clinician focuses on anatomical locations where a nerve is superficial or passes through a confined space, making it susceptible to compression. Common sites include the median nerve at the wrist crease, the ulnar nerve behind the medial side of the elbow, and the posterior tibial nerve near the ankle. The patient is instructed to remain relaxed and to immediately report any unusual sensations felt during the tapping.
To pinpoint the exact site of irritation, the clinician may tap systematically along the nerve’s pathway, often moving from a point farther away toward the body to a point closer to the body. This systematic approach helps to localize the area of maximum nerve sensitivity or damage.
Interpreting a Positive Result
A positive Tinel’s result occurs when the gentle percussion over the nerve causes the patient to experience a sudden, distinct tingling sensation or a feeling of “pins and needles.” This specific sensation is medically termed paresthesia, and it characteristically radiates outward along the nerve’s distribution path, extending into the hand or foot. The sensation is a sign of mechanical irritation or hypersensitivity of the nerve fibers at the point of tapping.
The underlying principle is that the nerve fibers are vulnerable and responsive to mechanical stimulation, which then triggers an electrical impulse. In the context of nerve compression, the delicate insulating layer around the nerve, the myelin sheath, may be damaged, making the nerve unusually reactive. Alternatively, a positive sign can indicate that a previously injured nerve is actively regenerating, as new, hypersensitive axons are regrowing distally from the injury site.
As these new nerve endings advance, the point where the tingling is felt tends to move further away from the torso over time. This phenomenon allows the test to be used serially to monitor the progress of nerve recovery following trauma or surgery. Whether indicating irritation from compression or the growth of new fibers, the positive sign confirms a localized abnormality in the nerve’s function.
Nerve Compression Syndromes Diagnosed
Tinel’s Test is most frequently associated with the diagnosis of Carpal Tunnel Syndrome (CTS), which is the most common nerve entrapment condition. The test is also utilized to assess Cubital Tunnel Syndrome and Tarsal Tunnel Syndrome. For all these syndromes, the presence of a positive Tinel’s sign helps the clinician pinpoint the anatomical site of nerve involvement.
Carpal Tunnel Syndrome (CTS)
In CTS, the median nerve becomes compressed as it travels through the carpal tunnel, a narrow passageway in the wrist formed by carpal bones and the transverse carpal ligament. A positive Tinel’s sign is elicited by tapping directly over the median nerve at the wrist crease. If the test is positive for CTS, the paresthesia will radiate into the thumb, index finger, middle finger, and the thumb-side half of the ring finger, which is the specific sensory distribution of the median nerve. Patients often report numbness and tingling in these digits, particularly at night, and may also experience weakness in the muscles at the base of the thumb. The test helps to support the clinical suspicion of median nerve entrapment before confirming with more advanced testing, such as nerve conduction studies.
Cubital Tunnel Syndrome
Another common application is in the diagnosis of Cubital Tunnel Syndrome, involving the ulnar nerve at the elbow. The ulnar nerve passes through the cubital tunnel, a tight space on the inner side of the elbow, often referred to as the “funny bone.” Tapping over this nerve just behind the medial epicondyle of the humerus will typically cause tingling that radiates into the ring and pinky fingers if the nerve is irritated or compressed.
Tarsal Tunnel Syndrome
The test is also utilized to assess for Tarsal Tunnel Syndrome, where the posterior tibial nerve is compressed as it passes behind the inner ankle bone. Percussion over this nerve on the inside of the ankle can reproduce pain and tingling that extends into the sole of the foot.