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| by Jill Jonda, PT |
According to Dutton, neurodynamics is “the study of the mechanics and physiology of the nervous system.” The nervous system is comprised of the central system (brain and spinal cord) and peripheral system (spinal nerves and cranial nerves). Peripheral nerves, the nerves that trigger parts of the body to work, can get “stuck” and develop dysfunction along their pathways. As these nerves exit the spinal cord and travel to their target tissue, they must be able to adapt to movement in relationship to their surrounding tissue, which would allow for normal neurodynamics.1 If tissue is compromised anywhere along a nerve, such as injury creating adhesions or inflammation, it can produce more stretch on tissue, yielding potential nerve related symptoms (tightness, numbness, tingling, pain, or even muscle spasm).
Here are some actions and activities that can result in abnormal neurodynamics:
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| A diagram of the nervous system. It is impossible to move any joint without also moving a nerve |
- Sustained postures. Holding a position for prolonged periods of time can cause adaptive shortening of connective tissue around nerve. This could include sitting at your desk at work for 6-8hours with rounded shoulders, a forward head, and rounded low back.
- Direct trauma, such as orthopedic injuries, yielding either primary nerve injury or secondary due to damage of surrounding tissues. For example, if a golfer takes a stroke that hits more of the ground instead of the ball, it might jar the arm and injure muscle around the elbow. The muscle may become inflamed and compress the nerves, which pass through and around the elbow.
- Extremes in motion, which put excessive traction on the nerve. An example would be a “stinger,” which places excessive traction on the brachial plexus (a network of nerves which exit the neck).
- Electrical injury.
- Compression, such as a disc bulge in the lumbar spine that places compression on nerve as it exits the spine.
In the clinic, we perform different tests and measures to determine whether or not neural tissue is tight or if it’s just muscle tension. Here are 2 tests we use to rule in nerve tension.
For leg symptoms: Straight Leg Raise
- Lying on your back, raise one leg up toward the ceiling.
- Pull your toes back and point the opposite direction, pumping your ankle. If this produces tightness in the back of the thigh, it’s a positive test for neural tension, as pulling the toes back puts the nerve on a stretch.
- Another way to “sensitize” nerve tissue would be to bend the neck, drawing the chin toward the chest with the leg raised in a neutral position. Pain in the back of the leg produced upon neck flexion would be a positive test for abnormal neurodynamics.
For arm symptoms: Upper Limb Tension Test
- Pull your shoulder blades down and back.
- Raise one arm out to the side with the elbow bent at a right angle.
- Next, rotate the palm up then begin straightening the elbow, wrist and fingers. The combination of these joint movements places the nerves that exit the spine at the neck on stretch.
- Tilt your head away from the arm being tested to stretch the nerves even more. Tilt the opposite way to put the nerves on “slack.” Slack is placed on the tissue by bending the wrist/fingers. Pain in the arm with neck or wrist motion would indicate the presence of nerve tension.
If you try either of these tests and feel nerve tension after the first few steps, no need to sound alarms quite yet! It’s normal to experience a degree of nerve tension: you’re putting the nerves that pass from your spinal cord down the leg or arm in their most stretched position. This sensation can sometimes be confused with muscle tightness or trigger point tenderness. If you’re experiencing tightness in your limbs and it’s accompanied by other nerve symptoms, specific muscle stretches may not alleviate your discomfort.
If you have nerve symptoms that aren’t going away, consider making an appointment with your physical therapist to help improve your neurodynamics!
