NEURODYNAMIC

Question 1

Periph nerve as MSK soft tissue

Answer 1

• Body presents nervous system with mechanical interface via musculoskeletal system
• With mvt, musculoskeletal system exerts non-uniform stresses & mvt in neural tissues, depending on local anatomical & mechanical characteristics & pattern of body mvt
• This activates array of mechanical & physiological responses in neural tissues, including neural sliding, pressurisation, elongation, tension & changes in intraneural microcirculation, axonal transport & impulse traffic

Question 2

Structure designed to handle tension

Answer 2

During functional activities, peripheral nervous system needs to be able to accommodate substantial amounts of nerve tension & elongation
Composite limb mvts typically expose peripheral nerves to approximately 5 to 20% strain
Peripheral nerves = heterogeneous structures: although well- organized, multilayered structure of extracellular matrix bears considerable mechanical loads, response of peripheral nerves to mechanical load characterized by their ability to glide, bend & twist
Neuroprotective architectural features, such as unique undulating pattern, offer additional protective strength
Mechanical properties of peripheral nerves not equal along their length, revealing complex tissue ultrastructure

Question 3

Mechanical interface

Answer 3

Nerves protected by & ‘move‘ through surrounding structures (muscles, bones, ligaments…)
⚠ Mechanical interface – affect nerve properties (nerve entrapment, including radiculopathy)

Question 4

Nerve morphology

Answer 4

Schema

STRUCTURE DESIGNED TO HANDLE TENSION
- Nerve layer connections structure explain nerve response to stretch: mesoneurium, epineurium, & perineurium coupled via viscoelastic physical connections & interact with loosely coupled perineurium & endoneurium, allowing axons to glide & unravel throughout length of nerve
- Collectively, mechanical features allow nerves to straighten without bearing significant stresses while maintaining functional & structural integrity of delicate axons within

Question 5

Response to stretch

Answer 5

During stretching, nerve stretches but other components also stretch. There is not only nerve that stretches

Question 6

Changes in nerve properties

Answer 6

Physiological effects of tensile forces acting on peripheral nerve
- Impact nerve conduction
- Change intraneural blood flow => decreases blood flow as tension increases
After immobilization periods, affecting myelin sheet & fiber diameter - Mobilization causes decreased of capacity to move & to support load or tension
People with Carpal Tunnel syndrome, affecting longitudinal excursion & stiffness
People with lumbar radiculopathy, affecting cross-sectional area

Prolonged stress/overload of nerve (compressive or tensile forces) impact mechanical (gliding) & physiological (intraneural blood flow) nerve properties

Question 7

≠ nerve injury

Answer 7

• Impaired fascicular gliding
• Edema
• Ischemia
• Impaired axonal transport
• Mechanosensitivity
• Adhesions

Question 8

Periph nerves & ROM

Answer 8

Joint ROM influenced by peripheral nerves
In stretching position, there is less dorsiflexion than in normal position because sciatic nerve already in tension

Question 9

Nerve biomechanics

Answer 9

Nerves = viscoelastic tissues & exhibit non-linear viscoelastic responses to tensile loading
Nerves not static structures, presenting:
- Longitudinal & transverse excursion (gliding) - Strain
- Stiffness
- Convergence
- Divergence
- Stress relaxation/Creep

Question 10

Convergence & divergence concepts

Answer 10

• Joint contraction => nerve gliding toward moving joint => increase tension nerve = CONVERGENCE
• Opposite: decrease tension in nerve => nerve gliding far from moving joint = DIVERGENCE
  ⚠ Convergence & divergence not dependent of movement but depend on tension (increase tension = convergence & no tension = divergence)

Question 11

≠ studies in vitro, in animals and on humans & in optimal tension / absent tension

Answer 11

Tableau

Question 12

Distinct nerve disorders

Answer 12

Schema

Question 13

Neurodynamic tests

Answer 13

• Neurodynamic tests first described in late 19th century based on abnormal tension concept
• This view changed in examining neural mechanosensitivity (neural tissue provocation tests or neurodynamic tests)
• Nomenclature not used uniformly, leading to misconceptions in medical field
  Interpretation of these tests & what constitutes positive test vary greatly in literature:
• Partial reproduction of symptoms & structural differentiation = essential criteria for positive test
• Sensitizing maneuvers = crucial for differentiating nerve-related mechanosensitivity from other soft tissue-related mechanosensitivities

Question 14

Increased mechanosensitivity

Answer 14

How much nerve able to support load or tension
- Examination includes evaluation of increased mechanical sensitivity of nervous system
- Related to increased excitability of small-diameter afferents & sensitization of nociceptors in nervi-nervorum & sinuvertebral nerves
Neurodynamic tests used by physiotherapists in order to identify changes of mechanosensitivity in nervous system, thus assessing gain of function

Question 15

Positive neurodynamic test criteria

Answer 15

• Partial reproduction of neurogenic pain (“burning” or “lightning-like” pain, tingling sensation, according to dermatome pattern in nerve root pathology) in neck & arm
• Increased/decreased symptoms with structural differentiation
• Differences in painful radiation between right & left sides

Question 16

Neurodynamic as treatment: def sliders & tensioner

Answer 16

SLIDERS
Nerve elongation at one end while releasing tension at other end

TENSIONER
Nerve elongation at both ends

Question 17

Peripheral nerve assessment: functional neural mechanosensitivity testing

Answer 17

• Elevation of shoulder: reduce of tension of brachial plexus & peripheral nerve originates in plexus
• Lateral flexion of neck toward affected side
  => reduce tension in nerve

Question 18

Guideline to perform neurodynamic testing

Answer 18

1. Instruct patient & ask him to actively perform mvt
2. Follow logic sequence of mvts
3. Consider testing first non affected side
4. Bilateral comparison
5. Maintain each movement before adding new one
6. Take time & ask for constant feedback
7. Perform structural differentiation

Question 19

≠ tests of neuro dynamic

Answer 19

Straight leg raise
Sensitizing maneuver
Differentiation mvt
Diagnostic accuracy for sciatica
Diagnostic accuracy for cervical radiculopathy

Question 20

STRAIGHT LEG RAISE description

Answer 20

• Assess to radiculopathy & lumbosacral neural structures
• To test movement & mechanical sensitivity of lumbosacral neural structures & their distal extensions
• Gradually add components of maneuver to progressively load nerve
• SLR = hip flexion > knee extension > sensitizing maneuver > differentiation movement
  If nerve involved in tension => pain increase If nerve not involved => pain does not change

Question 21

SENSITIZING MANEUVER description

Answer 21

• Sciatic nerve: ankle eversion & inversion - Additional mvts that increase load in specific neural structures
• Hip adduction / medial rotation: stress more common peroneal nerve
• Overload specific nerve
• Nerve impact ROM of people
• Affective nerve => decrease in ROM

Question 22

DIFFERENTIATION MVT

Answer 22

• Adding mvts distant to location of symptoms that affect neural structures in limb without affecting non-neural tissue local to area of symptoms
• Cervical flexion, as differentiator, between somatic pain (fascia or muscle-tendon units) & neural pain

Question 23

DIAGNOSTIC ACCURACY FOR SCIATICA description

Answer 23

Increase validity, high Sp & Sn
- SLR: reliability moderate when testing included structural differentiation (ankle dorsiflexion)
- Extended SLR (ESLR): by adding location-specific structural differentiation mvts (hip internal rotation or ankle dorsiflexion) better differentiate neural symptoms from musculoskeletal compared to traditional SLR
ESLR showed high validity in detecting neural symptoms & strongly associated with pathology seen in MRI when judged positive. ESLR showed 0.85 Sn & 0.45 Sp for Lumbar Disc Herniation & 0.75 Sn & 0.50 Sp for Nerve Root Compression
- In isolation, diagnostic performance of most physical tests poor
- SLUMP: test performed slightly better, but number of studies too small for strong conclusion

Question 24

DIAGNOSTIC ACCURACY FOR CERVICAL RADICULOPATHY description

Answer 24

4 tests for UL:
- 2 for median nerve (higher Sn) - 1 for ulnar (higher Sp)
- 1 for radial(higher Sn)
Combined ULNTs have Sn = 0.97 & Sp = 0.69 - ULNT3 (ulnar) = highest Sp = 0.88
- ULNT1 (median) = highest Sn = 0.83