Neurodynamic techniques are widely used as part of a multimodal strategy for treating patients with compression neuropathies. This blog will go through the use of neurodynamic testing as a diagnostic tool.

Neurodynamic tests use particular combinations of spine and limb motions that impart mechanical stresses to a region of the nervous system to establish whether a patient’s symptoms are attributable to enhanced nerve mechanosensitivity (Elvey RL. 1997; Smart K. et al. 2010). Joint movements used in neurodynamic testing enhance nerve strain, sliding, and compression, according to biomechanical data (Breig A, Troup J. 1979; Gilbert K, et al. 2007; Nee RJ, et al. 2012; Boyd BS, et al. 2013; Rade M, et al. 2014; Ridehalgh C, et al. 2014). Non-neural tissues are also subjected to mechanical stresses in neurodynamic testing (Elvey RL, 1997; Butler DS, 2000).

When the neurodynamic test response varies with movement of a distant body part that further loads or unloads the nervous system (e.g., relaxing neck flexion diminishes a sensory response in the posterior thigh during the slump test), it is assumed to be connected to neural tissue sensitivity. Elvey RL. 1997; Butler DS. 2000; Hall TM; Elvey RL. 1999 call this a structural difference. When a joint movement is conducted at the conclusion of a neurodynamic test, the biomechanical effects travel throughout the nerve (Nee RJ, et al. 2012; Coppieters MW, et al. 2006; Alshami AM, et al. 2008).

Experimental pain caused by hypertonic saline injections into the thenar or calf muscles is unaffected by structural differentiation techniques connected with the median nerve, straight leg raise (SLR), or slump tests (Coppieters MW, et al. 2005, 2006). This suggests that neurodynamic testing could be used to differentiate pain caused by muscle irritation from pain caused by enhanced nerve mechanosensitivity (Nee RJ et al. 2012).

The majority of asymptomatic people (80%) display sensory responses at the extremes of neurodynamic testing that alter with structural differentiation (Nee RJ, et al. 2012; Walsh J, et al. 2007; Lai W, et al. 2012; Martinez M, et al. 2014). Stretching, hurting, soreness, burning, and tingling are common adjectives (Nee RJ, et al. 2012; Walsh J, et al. 2007; Lai W, et al. 2012; Martinez M, et al. 2014). Because asymptomatic people report a wide range of sensory responses, it is critical to define the sort of sensory response that counts as a ‘positive’ neurodynamic test in symptomatic populations. To be certain that a neurodynamic test is identifying a patient with heightened nerve mechanosensitivity, the test must mimic at least some of the patient’s symptoms, and the symptoms must alter with structural differentiation (Nee RJ et al. 2012).

Resistance to movement (ROM) and range of motion (RTM) have also been offered as criteria for defining a ‘positive’ neurodynamic test (Elvey RL. 1997; Butler DS. 2000). The initiation of resistance is unlikely to be sensitive enough to define a ‘positive’ neurodynamic test (Nee RJ et al. 2012). The ROM of a neurodynamic test can be evaluated by measuring the joint angle during the beginning of pain or pain tolerance (e.g., elbow extension for the median nerve neurodynamic test, knee extension for the slump test). The ROM of neurodynamic tests in asymptomatic and symptomatic patients is highly variable (Nee RJ, et al. 2012; Herrington L, et al. 2008; Walsh J, Hall T. 2009; Johnson E, Chiarello C. 1997; Boyd B, Villa P. 2012). There is also significant overlap in neurodynamic test ROM between asymptomatic and symptomatic people, as well as between symptomatic involved and uninvolved limbs (Nee RJ, et al. 2012; Walsh J, Hall T. 2009).

Based on current understanding, a ‘positive’ neurodynamic test should at least partially reproduce the patient’s symptoms, and the symptoms should alter with structural differentiation (Nee RJ et al. 2012). When applied to symptomatic populations, this definition of a ‘positive’ neurodynamic test is trustworthy (Walsh J., Hall T., 2009; Philip K., et al., 1989; Schmid AB, et al., 2009).

When electrodiagnostic tests are used as the reference standard to establish the diagnostic accuracy of neurodynamic tests, evidence suggests that the neurodynamic test for the median nerve can help diagnose cervical radiculopathy (Wainner R. et al. 2003). but not CTS (Wainner R. et al., 2005; Vanti C. et al., 2011; Vanti C. et al., 2012). However, due to the limitations of using electrodiagnostic testing as the reference standard, these data must be interpreted with caution. Even when routine electrodiagnostic testing is normal, increased nerve mechanosensitivity can be evident in cervical radiculopathy and CTS (Slipman C. et al., 1998; Witt J. et al., 2004). This means that patients with peripheral neuropathic pain who have increased nerve mechanosensitivity rather than conduction loss are frequently misclassified as not having peripheral neuropathic pain under the reference standard. The reference standard in studies looking into the ability of the SLR and slump tests to detect lumbar radicular pain was electrodiagnostic testing or surgical or imaging proof of lumbar disc herniation. The SLR’s diagnostic performance is relatively poor when employing these reference standards (van der Windt D. et al. 2010; Scaia V. et al. 2012). Positive reactions to a crossing SLR (a rather unusual clinical finding) or the slump test may aid in the confirmation of the presence of lumbar radicular discomfort caused by lumbar disc herniation (van der Windt D. et al. 2010; Majlesi J. et al. 2008). Again, significant limitations in the reference standards necessitate caution in interpreting these findings. A surgical reference standard reduces the generalizability of diagnostic performance findings since it narrows the range of patients who can be included in the study and may change the prevalence of the target condition (van der Windt D. et al. 2010; Fritz J., Wainner R. 2001).

Imaging reference standards, like electrodiagnostic reference standards, may misclassify patients and distort estimates of neurodynamic test diagnostic performance (Reitsma J. et al. 2009). The challenge in examining the diagnostic performance of neurodynamic testing is that there is no agreed-upon reference standard for determining whether or not a certain patient has increased nerve mechanosensitivity (Walsh J., Hall T. 2009). This means that there is a misalignment between the purpose of neurodynamic tests (finding greater nerve mechanosensitivity) and the numerous reference standards employed in published studies. Using neurodynamic tests for diagnostic purposes is mostly dependent on lesser evidence from biomechanical and experimental pain model data until a reference standard for greater nerve mechanosensitivity can be agreed upon.

the idea of sequence

Although standardised sequences for performing the movements included in many neurodynamic tests have been defined, doctors have always been urged to vary the order of movement to match the presentation of an individual patient (Elvey RL. 1997; Butler DS. 2000; Maitland G. 1979). The sequencing of neurodynamic tests is based in part on the assumption that different orders of movement can impose varying levels of strain on a specific nerve segment at the end of a neurodynamic test (Butler DS. 2000). However, when joints are pushed through similar ranges of motion, nerve strain at the end of the test does not differ with different orders of movement (Boyd BS, et al. 2013; Nee RJ, et al. 2010). However, When various neurodynamic test sequences are used in clinical settings, joints are likely to go through distinct ranges of motion. Potential changes in joint motion sequences may be more likely to alter nerve biomechanics at the end of a neurodynamic test than any specific effects from movement order (Nee RJ et al. 2010). There is no published or recent research that I am aware of that has investigated whether alternative sequences can improve the diagnostic performance of a neurodynamic test. Neurodynamic test sequencing may still have clinical utility, regardless of any potential impact on diagnostic performance. When done in the later stages of a neurodynamic test, a joint movement is unlikely to reach complete ROM (Coppieters MW et al. 2002).

When examining a patient with a sensitive or stiff body region, this knowledge can assist the clinician in modifying a neurodynamic test. A variety of neurodynamic test sequences may also aid in structural distinction.

References:

1. Elvey RL. Physical evaluation of the peripheral nervous system in disorders of pain and dysfunction. J Hand Ther 1997;10(2):122–9.
2. Butler DS. The Sensitive Nervous System. 1st ed. Unley, S. Aust.: Noigroup Publications; 2000.
3. Smart K, Blake C, Staines A, et al. Clinical indicators of ‘nociceptive’, ‘peripheral neuropathic’ and ‘central’ mechanisms of musculoskeletal pain. A Delphi survey of expert clinicians. Man Ther 2010;15:80–7.
4. Breig A, Troup J. Biomechanical considerations in the straightleg-raising test: cadaveric and clinical studies of the effects of medial hip rotation. Spine 1979;4(3):242–50.
5. Gilbert K, Brismee J, Collins D, et al. 2006 Young Investigator Award Winner: lumbosacral nerve root displacement and strain. Part 2. A comparison of 2 straight leg conditions in unembalmed cadavers. Spine 2007;32(14):1521–5.
6. Nee RJ, Jull GA, Vicenzino B, et al. The validity of upper-limb neurodynamic tests for detecting peripheral neuropathic pain. J Orthop Sports Phys Ther 2012;42(5):413–24.
7. Boyd BS, Topp KS, Coppieters MW. Impact of movement sequencing on sciatic and tibial nerve strain and excursion during the straight leg raise test in embalmed cadavers. J Orthop Sports Phys Ther 2013;43(6):398–403.
8. Rade M, Kononen M, Vanninen R, et al. 2014 Young Investigator Award Winner: in vivo magnetic resonance imaging measurement of spinal cord displacement in the thoracolumbar region of asymptomatic subjects. Part 1: straight leg raise test. Spine 2014; 39(16):1288–93.
9. Ridehalgh C, Moore A, Hough A. Normative sciatic nerve excursion during a modified straight leg raise test. Man Ther 2014;19: 59–64.
10. Hall TM, Elvey RL. Nerve trunk pain: physical diagnosis and treatment. Man Ther 1999;4(2):63–73.
11. Coppieters MW, Alshami AM, Babri AS, et al. Strain and excursion of the sciatic, tibial, and plantar nerves during a modified straight leg raising test. J Orthop Res 2006;24(9):1883–9.
12. Alshami AM, Babri AS, Souvlis T, et al. Strain in the tibial and plantar nerves with foot and ankle movements and the influence of adjacent joint positions. J Appl Biomech 2008;24(4):368–76.
13. Coppieters MW, Kurz K, Mortensen TE, et al. The impact of neurodynamic testing on the perception of experimentally induced muscle pain. Man Ther 2005;10(1):52–60.
14. Coppieters MW, Alshami AM, Hodges PW. An experimental pain model to investigate the specificity of the neurodynamic test for the median nerve in the differential diagnosis of hand symptoms. Arch Phys Med Rehabil 2006;87(10):1412–17.
15. Walsh J, Flatley M, Johnston N, et al. Slump test: sensory responses in asymptomatic subjects. J Man Manipulative Ther 2007;15(4):231–8.
16. Lai W, Shih Y, Lin P, et al. Normal neurodynamic responses to the femoral slump test. Man Ther 2012;17:126–32.
17. Martinez M, Cubas C, Girbes E. Ulnar nerve neurodynamic test: study of the normal sensory response in asymptomatic individuals. J Orthop Sports Phys Ther 2014;44:450–6.
18. Herrington L, Bendix K, Cornwell C, et al. What is the normal response to structural differentiation within the slump and straight leg raise tests? Man Ther 2008;13(4):289–94.
19. Walsh J, Hall T. Agreement and correlation between the straight leg raise and slump tests in subjects with leg pain. J Manipulative Physiol Ther 2009;32:184–92.
20. Johnson E, Chiarello C. The slump test: the effects of head and lower extremity position on knee extension. J Orthop Sports Phys Ther 1997;26(6):310–17.
21. Boyd B, Villa P. Normal inter-limb differences during the straight leg raise neurodynamic test: a cross sectional study. BMC Musculoskelet Disord 2012;13:245.
22. Philip K, Lew P, Matyas T. The inter-therapist reliability of the slump test. Aust J Physiother 1989;35:89–94.
23. Schmid AB, Brunner F, Luomajoki H, et al. Reliability of clinical tests to evaluate nerve function and mechanosensitivity of the upper limb peripheral nervous system. BMC Musculoskelet Disord 2009;10:11.
24. Wainner R, Fritz J, Irrgang J, et al. Reliability and diagnostic accuracy of the clinical examination and patient self-report measures for cervical radiculopathy. Spine 2003;28(1):52–62.
25. Wainner R, Fritz J, Irrgang J, et al. Development of a clinical prediction rule for the diagnosis of carpal tunnel syndrome. Arch Phys Med Rehabil 2005;86:609–18.
26. Vanti C, Bonfiglioli R, Calabrese M, et al. Upper limb neurodynamic test 1 and symptoms reproduction in carpal tunnel syndrome. A validity study. Man Ther 2011;16:258–63.
27. Vanti C, Bonfiglioli R, Calabrese M, et al. Relationship between interpretation and accuracy of the upper limb neurodynamic test1 in carpal tunnel syndrome. J Manipulative Physiol Ther 2012; 35:54–63.
28. Slipman C, Plastaras C, Palmitier R, et al. Symptom provocation of fluoroscopically guided cervical nerve root stimulation: are dynatomal maps identical to dermatomal maps? Spine 1998;23(20):2235–42.
29. Witt J, Hentz J, Stevens J. Carpal tunnel syndrome with normal nerve conduction studies. Muscle Nerve 2004;29:515–22.
30. Reitsma J, Rutjes A, Khan K, et al. A review of solutions for diagnostic accuracy studies with an imperfect or missing reference standard. J Clin Epidemiol 2009;62:797–806.
31. van der Windt D, Simons E, Riphagen I, et al. Physical examination for lumbar radiculopathy due to disc herniation in patients with low back pain. Cochrane Database Syst Rev 2010;(2):CD007430.
32. Scaia V, Baxter D, Cook C. The pain provocation-based straight leg raise test for diagnosis of lumbar disc herniation, lumbar radiculopathy, and/or sciatica: a systematic review of clinical utility. J Back Musculoskeletal Rehabil 2012;25:215–23.
33. Majlesi J, Togay H, Unalan H, et al. The sensitivity and specificity of the slump and the straight leg raising tests in patients with lumbar disc herniation. J Clin Rheumatol 2008;14:87–91.
34. Fritz J, Wainner R. Examining diagnostic tests: an evidence-based perspective. Phys Ther 2001;81(9):1546–64.
35. Walsh J, Hall T. Reliability, validity and diagnostic accuracy of palpation of the sciatic, tibial and common peroneal nerves in the examination of low back related leg pain. Man Ther 2009; 14(6):623–9.
36. Maitland G. Negative disc exploration: positive canal signs. Aust J Physiother 1979;25(3):129–34.
37. Nee RJ, Yang CH, Liang CC, et al. Impact of order of movement on nerve strain and longitudinal excursion: a biomechanical study with implications for neurodynamic test sequencing. Man Ther 2010;15(4):376–81.
38. Coppieters MW, Van de Velde M, Stappaerts KH. Positioning in anesthesiology: toward a better understanding of stretch-induced perioperative neuropathies. Anesthesiology 2002;97(1):75–81.