Tinel’s sign– one of the most important physical exam maneuvers in peripheral nerve injury evaluation.
- ‘Sensation of tingling’ or ‘pins and needles’, felt at the lesion site or more distally along the course of a nerve when it is percussed.
- Reflects an attempt by the injured nerve to regenerate.
- Only present when injury is significant enough to cause nerve degeneration.
- Subsequently progresses distally if regeneration is possible and occurs.
The presence or absence of a Tinel’s sign and its behavior over time gives you information about nerve injury and recovery.
It provides hints to figuring out the appropriate treatment:
- No Tinel’s seen in:
- Uninjured peripheral nerve.
- First degree neurapraxia type injury (conduction block/segmental demyelination).
- In general the only surgical intervention that might improve recovery would be a nerve decompression at a known anatomic site of compression.
- Moving Tinel’s (progresses distally along nerve over time) seen in:
- Second degree injury or axonotmesis (injury to the axon alone; the surrounding connective tissue along which the axon will regenerate remains intact).
- In general the only surgical intervention that might improve recovery would be a nerve decompression at a known anatomic site of compression.
- Third degree injury — wide variation in recovery occurs depending on amount of scarring within the nerve tissue.
- Management depends on this as well as other factors.
- Second degree injury or axonotmesis (injury to the axon alone; the surrounding connective tissue along which the axon will regenerate remains intact).
- Stationary Tinel’s (stays in one place over time) seen in:
- Fourth degree injury — scar tissue blocks all recovery.
- Some type of intervention is required to allow for recovery of function.
- Fifth degree or neurotmesis injury (transected nerve).
- Some type of intervention is required to allow for recovery of function.
- Occasionally seen in sixth degree injury.
- Depending on the injury pattern, some type of intervention may be required.
- Fourth degree injury — scar tissue blocks all recovery.
- Proximal Tinel’s sign — we talk about a proximal Tinel’s sign in patients with neuromas.
- They will have a very painful Tinel at the site of the main neuroma injury, but they will also have a less painful Tinel about 3 inches proximal to this. This phenomenon allows for easier identification of the specific nerve that is responsible for the problem.
- Therefore, the examiner can palpate well proximal to a neuroma along a specific nerve, and if it is involved in the injury the patient will have a more discrete Tinel’s response at that site also. This is helpful for example in the overlapping areas of the radial sensory nerve, versus the palmar cutaneous, versus the lateral antebrachial and posterior antebrachial nerves of the forearm and wrist. It is also helpful in areas such as the thigh where there are many small cutaneous nerves. This proximal Tinel will let you ‘map out’ the involved nerves. The proximal Tinel represents the small axons that regenerate proximally up an injured nerve for a few inches before petering out.
- Understanding the background pathophysiology of nerve injury is critical to diagnosis and treatment — consider reviewing this section.