Assistant Professor

School of Health Sciences

Rama University

Kanpur  Uttar Pradesh, India 

Assistant Professor

School of Health Sciences

CSJM University

Kanpur, Uttar Pradesh, India.

Learning objectives

1. Establish the potential presence of neurodynamic limitations.

2. Assess neurodynamics using peripheral nerve tension testing and neurodynamic testing.

3. Based on the outcomes of peripheral nerve tension testing and neurodynamic testing, identify which neural mobilizations to do.

Definition: Various parts of nervous system talk to each other and nervous system itself make contact with the musculoskeletal system and others systems, is considered as neurodynamics.  As far as neurodynamics is concerned, is a method to treat the physical pain, also designated as neuro-mobilization. In this, mechanical interventions are carried out over neural tissues, thus pain physiology could be influenced. Typically, movement of nerves remains unaffected by others tissues. Therefore mechanical and physiological responses are the results after neural mobilization. Mechanical activities are; neural sliding / gliding, tension/stretch, pressure and elongation. Resultant physiological responses are;   altered intraneural microcirculation, axonal transport and transmission of the nerve information. Doubtlessly, neurodynamics has less favour from published studies to date, nonetheless, positive impact of neurodynamics over neuro-dysfunctions cannot be deselected. [1]

Neurodynamic techniques are attributed to focus on either assessment or treatment. During assessment, actually mechanical sensitivity of the neural structures in the context of pain and mobility against others tissues interfaces are tested. Thus, mechanical loading and mobility of the nervous system can be managed with adopting proper joint position and posture. Biomechanically both the techniques (‘tensioning techniques’ and ‘sliding techniques’) in terms of exercises can be distinct from each other, since sliding techniques can mobilize the nervous tissues without significant strain and tensioning technique mobilize the neural tissues against others neural structures with considerable strain. Because sliding techniques have a bigger nerve excursion while putting fewer loads on the body. The idea that sliding procedures are therapeutically superior to tensioning techniques is a widespread one. Although they do differ biomechanically, there is no scientific proof that one kind of procedure is superior to the other. [3]

 

Structure : Nervous System

Neurodynamic Assessment

A neurodynamic assessment is concerned with the length and mobility of nervous system and its components. In this, gradual pressure is applied over the nerves in terms of stretch force and tension to test the neural dysfunctions. Following standards are applicable to examine the mobility and functionality of the neural structures.

1. Upper limb tension test; ULTT1 (median nerve bias)

2. Straight leg raising SLR (sciatic, tibial, and peroneal nerve biases)

3. Upper limb tension test; ULTT2a (median nerve, musculocutaneous nerve and axillary nerve biases)

4. Upper limb tension test; ULTT2b (radial nerve bias)

5. Upper limb tension test; ULTT3 (ulnar nerve bias)

6. Proprioceptive neuromuscular facilitation PNF (Lhermitte’s Test)

7. Prone knee bending PKB (femoral nerve bias)

8. Slump test (dura) [2]

Functional Sliding and Tensioning Techniques;

Throwing a dart is a sliding technique for the median nerve where wrist extension loads the median nerve; elbow flexion simultaneously unloads the median nerve; and Elbow extension loads the median nerve; wrist flexion simultaneously unloads the median nerve, but a tensioning technique for the ulnar nerve where wrist extension and elbow flexion both load the ulnar nerve; and elbow extension and wrist flexion both unload the ulnar nerve. Reverse activities can also be taken as others examples. The peripheral nervous system must be able to handle significant levels of nerve tension and elongation during functioning tasks. Peripheral nerves are commonly subjected to 5 to 10% strain during composite limb motions; however other authors report substantially larger increases of up to 20% strain. The capacity of peripheral nerves to glide, bend, and twist in response to mechanical strain is another characteristic. [3]

Table1. Comparison between effects of optimal tension and tensile overloading over the nerves/neural structures

	Optimal Stress (Controlled and (Within Physiological Limits)	Over Stress (Excessive and Beyond Physiological Limits)
1	Improved Nerve Gliding	Nerve Injury
2	Enhanced Nerve Nutrition	Reduced Nerve Blood Flow
3	Pain Reduction	Nerve Entrapment
4	Reduced Nerve Irritation	Increased Sensitivity
5	Improved Neural Conduction	Altered Neural Conduction
6	Increased Flexibility and mobility	Neuropathy
7	Prevention of Scar Tissue Formation	Long-Term Nerve Dysfunction
8	Enhanced Range of Motion	Loss of Motor Control
9	Positive adaptation	Delayed healing
10	Enhanced nerve function	Inflammation
11	Controlled nerve gliding during treatment	Excessive stretching, trauma, or compression

Neurodynamics:

An approach to treating nervous system diseases is called neural mobilisation. When the peripheral nervous system was functioning improperly in the past, neural tension was used to describe it. It has been reported that neural mobilisation is a successful therapeutic strategy. The combined biomechanical, physiological, and morphological functions of the nervous system are now more commonly referred to as neurodynamics. It is crucial that the neural system can adjust to mechanical demands regardless of the underlying build, and it must go through distinct mechanical events like elongation, sliding, cross-sectional change, angulation, and compression. The nervous system is susceptible to neural edoema, ischaemia, fibrosis, and hypoxia if these dynamic protective systems fail, which may lead to altered neurodynamics. The main theoretical goal of neural mobilisation, which is used to treat adverse neurodynamics, is to try to reestablish the dynamic equilibrium between the relative movement of neural tissues and surrounding mechanical interfaces. This will reduce the intrinsic pressures on the neural tissue and support optimal physiologic function. [4]

Effect of Neuromobilization on Neuromuscular Conditions:

A lesion or condition affecting the peripheral nervous system might cause arm pain connected to the neck and leg pain related to the low back. Additionally, typical entrapment neuropathies including carpal tunnel syndrome (CTS) and cubital tunnel syndrome damage the peripheral nerve system. Other disorders like lateral epicondylalgia and plantar heel pain may also have an impact. It is yet unknown whether neural mobilisation (NM) is beneficial for treating neuromusculoskeletal problems. By mobilising the neural system or the tissues that surround it, neurodynamics (NM) is a treatment that aims to reestablish equilibrium in and around the nervous system. Through manual methods or exercise, neural mobilisation promotes mobility between brain structures and their surroundings (interface). Intraneural edoema, intraneural fluid dispersion, thermal and mechanical hyperalgesia, and enhanced immunological responses as a result of nerve injury have all been shown to be decreased or reversed by NM, according to investigations on humans and animals. In some neuromusculoskeletal diseases, neural mobilisation is useful in lowering pain and impairment. [5]

Neuromuscular Effects:

The JBI grades of evidence allow for the recommendation of NM in the cases of N-LBP, N-NAP, tarsal tunnel syndrome, and plantar heel pain. The evidence that is now available is insufficient to support the use of NM for cubital tunnel syndrome, post-lumbar surgery, and CTS.

Effects on Neurophysiology

Numerous investigations have shown an improvement in neurophysiological parameters, including a reduction in intraneural edoema. Restoring homeostasis in and around the targeted nerve is one of NM's goals. The use of NM may also improve sensory characteristics.

neurodynamic (NM) Techniques

In circumstances regarded as being difficult to treat, two NM approaches consistently provided positive results.73,94 As well as reducing pain and disability in N-LBP, cervical lateral glides also reduced pain in N-NAP and epicondylalgia. According to our research, tensioning techniques are effective in treating chronic nerve-related diseases including N-LBP25 and plantar heel pain.66,93 Sliding approaches, on the other hand, have become more popular in recent years since they expose the nervous system to less stress and more mobilisation, which may be more useful when nerve mechanosensitivity is still elevated.32 As a result, the procedure selection should be supported by solid clinical justification. [5]

Neurodynamics therapy [NDT] is characterized by using specific manual techniques to change the mechanical characteristics around peripheral nerves. The effect of neurodynamics manual therapy has been found to be inconclusive in multiple systematic reviews. The application of Neurodynamics-based therapy was more effective compared to exercise therapy in decreasing pain and improving function and strength and avoiding surgery in patients with carpal tunnel syndrome (CTS). These improvements were maintained after 6 months of therapy. A cervical lateral glide technique, Slump and SLR mobilisation, and patients with chronic N-LBP, N-NAP, and plantar heel pain have all been proven to improve pain and function in patient populations that are frequently treatment-resistant. [5, 6]

Median Nerve Excursion:

WRIST				ELBOW
DIRECTION	Average distance	Joint	Motion	Average distance	Joint	Motion
DISTAL	24mm	Shoulder	Abduction30°	15mm	Shoulder	Abduction30°
		Elbow	Flexion 90°		Elbow	Flexion 10°
		Forearm			Forearm	Pronation60°
		Wrist	Extension 60°		Wrist	Extension 60°
		Finger	Extension 35°		Finger	Extension35°
PROXIMAL	12mm	Shoulder	Abduction 110°	15mm	Shoulder	Abduction 110°
		Elbow	Flexion 10°		Elbow	Flexion 90
		Forearm	Flexion 60°		Forearm
		Wrist			Wrist	Flexion 60°
		Finger	Flexion 35°		Finger	Flexion 35°

[7]

Neural injury:

Nerve fibers and the surrounding connective tissue are susceptible to injury– Neuropraxia – axon conduction is blocked due to a physiologic process without a histological change – Axonotmesis – loss of continuity of the nerve with continuity of the connective sheaths – Neurotmesis – loss of axon including the connective tissue

Injury of the neural tissue and surrounding areas may result in scaring and neurodynamics restrictions. Symptoms of neurodynamic restrictions include numbness or tingling with movement and/or a deep uncomfortable sensation which has never been felt before. With motor movement, the nerves and surrounding connective tissues glide with the movement.

Neurodynamic testing: Straight Leg Raise Test • Prone Knee Bend • Median Nerve Traction Test • Radial Nerve Traction Test • Ulnar Nerve Traction Test

Additional neurodiagnostic tests: Examination of motor function • Sensory examination • Integumentary and vascular examination • Deep tendon reflexes (DTR) • Abdominal reflex • Babinski reflex • Tinel sign • Functional examination [7]

Table 2 neural versus non neural

Sign/Symptom	Neural Tissue	Non-Neural Tissue
Tissue example	Median nerve	Biceps tendon
Description of pain	Unusual, never had anything like this, deep, painful, felt like a toothache, and was numb with pins and needles.	“A pulled muscle, like I worked out too much, a sharp pain”
Constancy of pain	extended sense following stretching; does not diminish immediately	Once tension removed, symptoms decrease rapidly
Palpation symptoms	Causes radicular symptoms in specific innervation pattern	Occasionally, there will be local pain and soreness with myotomal or dermatomal references.
Visualization	Therapist may see muscle fasciculations	Occasional muscle spasms

 

Neural gliding – Fixation of proximal portion of the nerve – Distal portion of nerve in controlled stretch – Symptoms typically occur distal aspect of nerve

Neural sliding (“flossing”) – Movement of proximal end toward distal end with simultaneous elongating of distal end – Movement of distal end toward proximal end with simultaneous elongating of proximal end

Neural gliding versus neural sliding techniques:

Neurodynamic concept refers to the integration of biomechanical, functional, and morphological characteristics of the nervous system^. Neural mobilization (NM) has been recommended as a conservative management approach to treat upper quadrant pain. NM can improve the neurophysiological and mechanical integrity of the peripheral nerves by restoring homeostasis in and around the nervous system, generating improvements in pain and disability. Two of the most frequently used NM techniques are the slider (i.e. nerve endings moving in the same direction) tensioner techniques (i.e. nerve endings moving in opposite directions). [8]

“Sliding/gliding” and “tensioning” techniques: Neural mobilization (NM) is a movement-based intervention aimed at integrating structural, biomechanical, and functional aspects of the nervous system. It targets restoration of homeostasis in and around the neural tissues.  NM is delivered using “sliding/gliding” and “tensioning” techniques. Though both techniques are performed to recover the normal mechanics of the peripheral neural structures and to augment the optimal neural function, the longitudinal excursion and strain exerted by them are different.  Accordingly, their impact on neural function will vary. The suggested benefits of such techniques such as improved nerve gliding, decreased nerve adherence, increased neural vascularity, improved flow of axoplasm, and dispersal of noxious substances, potentially promote the optimum neural physiologic functions. However, the comparisons and subsequent conclusions about the effectiveness of NM techniques in the majority of the previous studies were primarily focused on biomechanical factors such as range of motion, flexibility, and muscle strength. Moreover, those studies were of heterogeneous nature with each one including participants suffering from different pathologies and employing different types of NM. [9]

Neurodynamic sliders (ns) technique: it is a method of producing a sliding movement of neural structures relative to their mechanical interfaces. This technique provides tension on the targeted nerve structure proximally via joint movements while releasing tension of the nerve distally, and then reversing the sequence. Furthermore, NS may provide more excursions of the neural structures or may decrease neural mechanosensitivity. [10]

Abnormalities in mechanosensitivity are generally treated with neurodynamic slider techniques, which evoke a sliding movement of neural structures relative to their adjacent soft tissue structures by alternating tension at one end of the nervous system with slack at the other. In case of hamstring muscle, where it act as a mechanical interface for the sciatic nerve, which innervates and surpasses the hamstring muscles group, neurodynamics can play a role in hamstrings flexibility as well. Impaired neurodynamics due to adhesions between the hamstrings and the sciatic nerve might cause mechanosensitivity. If this is the case, the hamstring flexibility might be limited because mechanosensitivity will cause an earlier onset of the sensation of discomfort within the muscle elongation ROM causing an earlier protective hamstring muscle contraction. [11]

Neurodynamic Tensioners Technique:

Although excessive muscle and tendon stiffness is assumed to contribute to insufficient hamstring flexibility, some writers contend that poor hamstring extensibility and stretching tolerance may result from abnormal sciatic nerve mechanosensitivity.  One author  concluded that in patients with sciatic nerve stress, hip flexion reduced during forward bending.

Neurodynamic techniques are used in clinical scenario to mobilize the peripheral nerve.  This approach is considered as an alternative to stretching maneuver like in hamstring muscle.  According to one publication, when the neurodynamic approach was used in conjunction with muscle stretching as opposed to muscle stretching alone, a considerably better hamstring flexibility was obtained. .  Butler et al. recommended using a slider or tensioner to move the nerve tissues.  Thus, neurodynamic method can be useful for controlling hamstring flexibility and lowering neural mechanosensitivity.  Tensioners are thought to stretch the neurological system, causing more strain and tension in the nervous system.  Sliders employ a method that causes nerve structures to move relative to the nearby tissues without altering the length of the nerve.  This method accomplishes this procedure in reverse order by allowing the target nerve structure to generate tension in the proximal part through joint movement and relax the tension of the nerve in the distant part. [12]

Typical preliminaries to All Neurodynamic Tests to be completed in full before the first neurodynamic test and briefly again with each successive test. In order to prevent them from compromising the method, it is important to reassure and relax the patient and lower expectations. It is also important to inform the patient about the maneuver and obtain their permission. "If it's okay with you, I'd like to move your leg a little bit.

Procedure For Neurodynamic Testing:

1. Symptoms at rest;

2. Changes in symptoms during the test;

3. And changes in resistance to movement during the test.

4. Mental movement diagram .

5. Adaptive motions may reveal anomalies.

6. End of the range of motion and the rationale for stopping the motion

7. Symptoms' location

8. Structural differentiation's impact

9. After the technique is finished, the symptoms' characteristics are discussed.

10Detailed information on the symptoms is gathered to identify the response category.

Goals:

Simplify diagnosis; prevent symptom elicitation by shortening test time.

Procedure 1:

Can the NDT be carried out on the symptomatic side first?

1. By shifting the side that is less affected first, it may be possible to lower the patient's expectations and worries.

Perform a neurodynamic test at the point of symptom start (P1), the point of resistance (between R1 and R2), or both.

Going further is acceptable, but it must be properly considered and have value.

2. Inquire about your symptoms.

3. Choose the proximal or distal end of the test for structural distinction based on the location of the symptoms.

4. Use structural distinction to determine whether the test is successful. Keep in mind that this doesn't say whether it's abnormal at this point.

5. Get back to the starting position.

6. Examine the reaction (physical symptoms and behaviour.

7. The presence of a neurodynamic component in the adaptive movement may be suggested by a favorable influence of structural differentiation on the adaptive movement.

8. The adaptive movement can be used for reassessment and, in some cases, for treatment. Bilateral comparison is carried out similarly to the ipsilateral side.

Raising Your Right Leg Directly: [SLR]

 The lumbosacral neural structures and their distal extensions, which include the lumbosacral trunk and plexus in the pelvis, sciatic and tibial nerves and their distal extensions in the leg and foot, are tested using the straight leg raise.

Indications:

1. Pathology, dysfunction, and pain in the lower quarters

2. Thoracic spine conditions occasionally, headaches and cervical problems

Preparation :

Supine, symmetrically oriented, in its most basic form, with no pillow beneath the patient's head for consistency's sake.

Position Of The Therapist: The therapist should stand with a stride so they can change positions while still using effective technique. Motions hip flexion while keeping the knee straight. Prevent any alteration of hip adduction/abduction and internal/external rotational movements in the frontal and transverse planes.

This is because each of these motions makes the test technique more sensitive. The distal hand of the therapist softly clasps the back of the leg just proximal to the ankle.

Patients frequently complain of ankle soreness if the calcaneum is used as the point of contact, which is why this location was chosen.

This is due to the fact that as the limb is raised, its weight presses the tibia posteriorly on the talus, turning the test into an anterior draw for talocrucal instability.

Even normal people may find this painful, particularly if their ankles are loose and hypermobile.

Starting place sagittal plane hip flexion with leg raised Dorsiflexion and differentiation Keep in mind how the positions alter with each phase. To prevent compression up the limb, exert distal counter pressure with the hand closest to the application site.

Sensitising Movements: Hip adduction and internal rotation hip internal rotation/adduction Spinal contralateral lateral flexion may be added. Building Block Differentiation Use dorsiflexion and adjust your grip and body position in order to treat the proximal symptoms. Distal symptoms are likely already being produced by differential hip flexion.

Cervical Flexion That Is Active: The therapist frequently attempts structural differentiation of the straight leg raise by instructing the patient to actively flex their neck. This is regrettably completely faulty and can lead to a wide range of misleading outcomes. This technique is ineffective because the pelvis rotates posterior as a result of the abdominal muscles contracting during the head elevation. As a result of a lowering of the straight leg rise by the mechanism of reversed origin, the hip flexion angle is reduced, and symptoms are frequently alleviated. On the other hand, some patients contract their hip flexors, causing the pelvis to rotate anteriorly and increasing the straight leg lift angle.

Due to the aforementioned, it is not advised to use active neck flexion when differentiating the straight leg raise test. Frequently Occurring Technique Issues Not holding the knee fully extended - take note that the holding technique does not compel the knee to extend fully.

This calls for the therapist to pay close attention to effortlessly changing the weight on their feet and the direction of their own body. This issue is resolved by practicing this component of the technique on individuals of various sizes and shapes. Stopping hip flexion at the first pelvic movement has been a common structural differentiating strategy. According to the theory, the lumbar spine hasn't migrated if the pelvis hasn't either. Therefore, if low back discomfort can be replicated, the issue must involve the nervous system. The logic behind this strategy is sound, yet there are issues with it. The neural structures aren't pushed through their complete range since the hip flexion angle is never fully extended.

As a result, this approach is likely to result in false negatives. typical reaction pulling and stretching that starts in the back of the thigh and progresses to the back of the knee and, occasionally, the upper portion of the calf. The range of motion ranges from roughly 50° to 100°.

Assessment methods: 

Opner techniques: The techniques which produces function of opening around neural structures, named as openers? They are consisted of movements of fascia, muscles and joints under treatments. In case of muscle is tight leading to excessive pressure and compression over the neural structures if same muscle is released in any way, may result in reduced pressure on those particular structures. It is an example of openers; these openers are further classified as static and dynamic.

Static opners: for a certain period, openers causes space to increase around neural tissues, this will lead to increased blood flow towards neural structures again, ultimately good oxygenation of those tissues.

Dynamic openers: These are those use movement (either active or passive, it does not matter) of the tissue in the direction where more space can be created in terms of opening.

Closers techniques: the techniques causing or reducing the space around the neural tissues could be considered as closing. As in case of muscle contraction or stretching maneuver and flexion or extension movements. Closers could be divided into two types like openers.

Staic closers techniques: This closing technique is not suitable for the therapy purposes since it will cause ischemia if constant pressure is applied for long duration to get it therapeutic effects.

Dynamic closers:  in this, movements are performed repeatedly for certain number of time to get therapeutic effects. For an instance, same side flexion (of spine) can be exercised to on affected nerve root to take therapeutic advantages in connection with neural structural issues. [14]

Conclusion: neurodynamics can be applied for several conditions such as in carpal tunnel syndrome, cubital tunnel syndrome, and others neuropathies or neurological dysfunctions.  Mobilizing the nervous system is the physical treatment which serves as a pain reliever by changing the physiology (with the help of mechanical strategy) of the affected tissues.  Thus a spectrum of mechanical and physiological outcomes is supposed to be found after activating the tissues under treatment.

References:

1.  Neurodynamics. (n.d.). Physiopedia. https://www.physio-pedia.com/Neurodynamics

2.  Neurodynamic assessment. (n.d.). Physiopedia. https://www.physio-pedia.com/Neurodynamic_Assessment

Ellis R, Carta G, Andrade RJ, Coppieters MW. Neurodynamics: is tension contentious? J Man Manip Ther. 2022 Feb;30(1):3-12. doi: 10.1080/10669817.2021.2001736. Epub 2021 Nov 16. PMID: 34781843; PMCID: PMC8865101.

3. Ellis RF, Hing WA. Neural mobilization: a systematic review of randomized controlled trials with an analysis of therapeutic efficacy. J Man Manip Ther. 2008;16(1):8-22. doi: 10.1179/106698108790818594. PMID: 19119380; PMCID: PMC2565076.

4.  Basson A, Olivier B, Ellis R, Coppieters M, Stewart A, Mudzi W. The Effectiveness of Neural Mobilization for Neuromusculoskeletal Conditions: A Systematic Review and Meta-analysis. J Orthop Sports Phys Ther. 2017 Sep;47(9):593-615. doi: 10.2519/jospt.2017.7117. Epub 2017 Jul 13. PMID: 28704626.

5. Hamzeh H, Madi M, Alghwiri AA, Hawamdeh Z. The long-term effect of neurodynamics vs exercise therapy on pain and function in people with carpal tunnel syndrome: A randomized parallel-group clinical trial. J Hand Ther. 2021 Oct-Dec;34(4):521-530. doi: 10.1016/j.jht.2020.07.005. Epub 2020 Jul 30. PMID: 32893098.

6. Tyler a Wood PhD, ATC* & Nicholas E Grahovec, PhD, LAT, ATC, CSCS. (n.d.). Neurodynamic Testing and Neural Mobilization. Northern Illinois University.

7. Papacharalambous, C., Savva, C., Karagiannis, C., & Giannakou, K. (2022). The effectiveness of slider and tensioner neural mobilization techniques in the management of upper quadrant pain: A systematic review of randomized controlled trials. Journal of Bodywork and Movement Therapies, 31, 102–112. https://doi.org/10.1016/j.jbmt.2022.03.002

8. Alharmoodi BY, Arumugam A, Ahbouch A, Moustafa IM. Comparative effects of tensioning and sliding neural mobilization on peripheral and autonomic nervous system function: A randomized controlled trial. Hong Kong Physiother J. 2022 Jun;42(1):41-53. doi: 10.1142/S1013702522500056. Epub 2022 Mar 17. PMID: 35782695; PMCID: PMC9244596.

9.  Areeudomwong P, Oatyimprai K, Pathumb S. A Randomised, Placebo-Controlled Trial of Neurodynamic Sliders on Hamstring Responses in Footballers with Hamstring Tightness. Malays J Med Sci. 2016 Nov;23(6):60-69. doi: 10.21315/mjms2016.23.6.7. Epub 2016 Dec 7. PMID: 28090180; PMCID: PMC5181993.

10.  De Ridder, R., De Blaiser, C., Verrelst, R., De Saer, R., Desmet, A., & Schuermans, J. (2019). Neurodynamic sliders promote flexibility in tight hamstring syndrome. European Journal of Sport Science, 20(7), 973–980. https://doi.org/10.1080/17461391.2019.1675770

11.  Lim, J., Lee, I., & Kim, K. (2021). Immediate Effects of Neural Slider and Neural Tensioner on Forward Bending in Subjects with Hamstring Tightness. Journal of Musculoskeletal Science and Technology, 5(1), 6–13. https://doi.org/10.29273/jmst.2021.5.1.6

12. Jull, G., Moore, A. P., Falla, D., Lewis, J., McCarthy, C., & Sterling, M. (2015). Grieve’s Modern Musculoskeletal Physiotherapy. Elsevier Health Sciences.

13. Neurodynamics. (n.d.). PPT. https://www.slideshare.net/pavaninarasimham/neurodynamics-56319862