Neural Tension and Adverse Neural Dynamics: When Nerves Are the Source of Pain

How Nerves Move

Peripheral nerves are not passive cables strung through the body — they are dynamic, mobile structures that must adapt continuously to the length changes imposed by joint movement. During limb movement, nerves undergo three primary mechanical adaptations: elongation (tensile stress when a nerve is placed under stretch), transverse compression (compressive stress from adjacent structures), and excursion (sliding and gliding of the nerve through its surrounding connective tissue interface). A median nerve, for example, moves approximately 14 millimetres longitudinally through the carpal tunnel during full wrist and elbow movement. The sciatic nerve elongates by several centimetres during a straight-leg raise. This remarkable mobility is facilitated by the neural connective tissue system — the epineurium, perineurium, and endoneurium — which provides both structural integrity and sufficient flexibility for these adaptations.

What Are Adverse Neural Dynamics?

Adverse neural dynamics (AND) — also termed neural tension, neurodynamic dysfunction, or neural mechanosensitivity — describe a state in which the normal mechanical and physiological properties of the nervous system are altered, producing symptoms when the nerve is placed under tensile or compressive stress. This can occur through several mechanisms: intrinsic pathology within the nerve (inflammation, demyelination, axonal damage); perineural adhesion (scar tissue or fascial restriction limiting nerve gliding at a specific interface); mechanical compromise at a tunnel or foramen (carpal tunnel, cubital tunnel, neural foramina); or sensitisation of the nerve's mechanosensors following local or central sensitisation processes. In practice, these mechanisms frequently coexist.

Neurodynamic Assessment Tests

Neurodynamic tests systematically load the nervous system by moving multiple joints in sequence to produce tension along a specific neural pathway. The most clinically used tests are: the straight leg raise (SLR) for the sciatic nerve and lumbar nerve roots; the slump test, which adds spinal flexion to increase neural tension and is more sensitive for lumbar radiculopathy; the upper limb neurodynamic test (ULNT) 1, which sequences shoulder depression, abduction, elbow extension, wrist and finger extension, and cervical lateral flexion to assess the median nerve; and variations of the ULNT for the radial and ulnar nerves. A test is considered positive when it reproduces the patient's familiar symptoms (not just local discomfort), when the symptoms are altered by structural differentiation (changing a distal joint position while holding the proximal sequence), and when responses are asymmetrical compared to the unaffected side.

Neural Mobilisation Techniques

Neural mobilisation uses movement to restore nerve gliding mechanics and reduce mechanosensitivity. Sliders (or neurodynamic mobilisations) move the nerve through its tissue interface by alternately loading and unloading the nerve — for example, extending the knee while flexing the ankle, then reversing — creating a flossing motion through the neural pathway. Sliders are preferred when the nerve is acutely sensitive or when neural tension is high. Tensioners place the entire neural pathway under sustained or progressively increasing tension and are introduced once symptoms have settled and nerve mobility has improved. Both are performed within a pain-free or low-pain range. The principle is the same as restoring mobility to any other tissue: progressive, graded mechanical stimulus drives adaptation. Research supports neurodynamic mobilisation as an effective adjunct to manual therapy and exercise for cervical radiculopathy, carpal tunnel syndrome, and lumbar radiculopathy.