New Painless Cervical Nerve Root Mobilisations - taking tension off the system for nerve root pain

As many of you will remember, earlier this year we presented an article on the use of contralateral neurodynamic movements as a means of reducing tension in the nerve roots (Link). This article takes the subject further by presenting exactly how to do this with lower limb movements in the case of neck pain. In this sequel, the physical mechanisms and various clinical techniques are discussed.

Downward (caudal) movement of the spinal cord producing a reduction in tension in the nerve roots
(from Breig 1960, Shacklock 2007a, © NDS 2007).

Rubenach (1985) found that 62% of asymptomatic subjects reported a reduction in the symptom response to the median neurodynamic test 1 (MNT1) with performance of a contralateral MNT1. If we consider that tension in the nervous system is key the mechanism of symptoms with the MNT1, adding more tension to the nervous system with a contralateral neurodynamic movement should theoretically increase symptoms with the contralateral test. But, since the symptoms often reduce, a different mechanism related to contralateral effects must operate. Well, Dr Alf Breig provided a possible answer to this conundrum in 1960 with his observations of spinal cord and nerve root movement in cadavers. He showed that nerve root tension reduces when the spinal cord displaces caudad/downward in the canal (compare left and right sides of figure). This produces a reduction in distance between exit point of the nerve root from the spinal cord and the intervertebral foramen, resulting in a reduction in tension in the nerve root.

As Shacklock (2005, 37-39) proposed, it appears that it is this downward movement of the spinal cord that produces reduction in tension in the nerve roots. Additionally, the bilateral straight leg raise was shown to produce a reduction in symptoms with the MNT1 by Alison Bell in 1987. As far as we know, this was discussed at least verbally by Robert Elvey in the early 1980s, a particularly significant observation that can now be applied clinically. The notion of reduction of tension with contralateral testing or use of the straight leg raise is now part of a progressional system proposed by Shacklock (2005, pp 156-158; Shacklock 2007).

In summary, the SLR may be used to reduce tension in the cervical nerve roots by moving the cord downward in the canal. Clinical application of this technique is potentially wide. It means that:

• in certain circumstances, lower limb movements can be used to ease pain and mobilise the nerve roots, including thoracic and cervical regions
• this produces a series of progressions which, for low back and sciatica are described in the last article on this subject (Link)
• lower limb movements can substitute contralateral upper limb neurodynamic testing, consistent with IN-OUT position and movement system provided in the last article (Link) and are described in more detail in (Shacklock 2005, Clinical Neurodynamics, updated in the NDS course manual, 2007).
• if, for instance, the contralateral MNT1 does not relieve a patient’s neck and or upper limb pain, the SLR can be applied instead.

This subject is developed in detail on NDS courses globally. If you would like more information about this, do come to one of our courses (see the NDS Global Teaching Programme).

Piriformis Syndrome

Piriformis Syndrome is quite a controversial clinical phenomenon because the diagnostic criteria are not entirely agreed on and reliability of clinical tests is not fully proven. However, some key issues with this condition are:

• what are the biomechanical relationships between the sciatic nerve and piriformis muscle?
• how can the nerve component be detected and treated?

PIRIFORMIS SYNDROME AS A CAUSE OF SCIATICA

BIOMECHANICS

Based on the work of Dr Alf Breig, it can be seen that significant interactions between the sciatic nerve and the piriformis muscle occur with the straight leg raise (SLR).

During the SLR, the muscle and nerve perform an action similar to two blades of a pair of scissors, sliding diagonally and compressing one another as they attempt to pass the shortest distance between the spine and distal edges of the pelvis (Figure 1).

Hence, it becomes clear that it may at times be important to use physical techniques in diagnosis that help ascertain if the patient problem contains an emphasis of one or other components or if the interactions themselves are the key aspect.

Therefore differentiation tests can be performed to establish clinical evidence of these components.

Biomechanical interactions between the neural tissues in the pelvis and piriformis muscle during the SLR.

Fig. 1A (left) Neutral SLR Position - Fig. 1B (right) Straight Leg Raise
From Breig 1978, © Neurodynamic Solutions (NDS)

Fig. 1C (left) Anatomical Relations
Fig. 1D (right) Top Part: Lumbar Spine - To the Left: Caudad
From Breig 1978, © Neurodynamic Solutions (NDS)

• Fig. 1A: Neutral SLR position - spinal nerves (L4-S1) joining the lumbosacral trunk and sacral plexus on their course toward the greater sciatic foramen. The curved rim at the bottom of the picture is the bony outline of the foramen. Note that the neural tissue is loose.
• Fig. 1B: Straight leg raise produces increased tension and distal sliding in the nerves toward the greater sciatic foramen, indicated by the black marker placed on the nerve immediately proximal to the foramen.
• Fig. 1C: Anatomical relations between the piriformis muscle and sciatic nerve, neutral SLR.
• Fig. 1D: The top part of the picture is the lumbar spine, caudad is to the left.
  • Abbreviations:
  • PMM - psoas major muscle;
  • ARLN5 - anterior ramus of the fifth lumbar nerve root;
  • LST - lumbosacral trunk;
  • ON - obturator nerve;
  • SGA - superior gluteal artery;
  • PM - piriformis muscle;
  • SP - sacral plexus;
  • IGA - inferior gluteal artery.
  During the SLR the muscle and nerve approximate and are aligned more parallel, producing a scissor action between the two.

The dynamic interactions between the muscle and nerve during the SLR have important clinical implications in relation to both diagnosis and treatment (for detailed more information, see Shacklock 2005, Clinical Neurodynamics).

CLINICAL TESTING

A key aspect of assessment of the piriformis syndrome is neurodynamic testing. A technique that evaluates the neural and musculoskeletal component is the neurodynamic test for the peroneal or tibial nerve components because each of these may be involved. An early technique of choice is the neurodynamic test in Figures 2 and 3.

Figure 2. Internal RotationFigure 2. The straight leg raise test with plantarflexion/inversion and internal rotation below 70° of hip flexion. The leg raise component applies distal force to the sciatic nerve (Goddard and Reid 1965), the internal rotation stretches piriformis onto the nerve and simultaneously applied distal tension to the nerve (Breig 1978; Breig and Troup 1979). The plantarflexion/inversion component applies tension to the peroneal component of the nerve. The reason this last movement may be used is that sciatica due to piriformis problems sometimes involves the peroneal component. Naturally, the problem may also involve the tibial part of the sciatic nerve and this is where dorsiflexion is used to test this component.

Figure 3. External RotationFigure 3. The SLR test with plantarflexion/inversion and external rotation at or above 70° of hip flexion. External rotation is performed because this accommodates the tendency of the muscle to internally rotate at 70° or more of hip flexion. This helps to stretch the muscle onto the nerve and test the dynamics between the two.

The aim of changing the rotation from external to internal from below to above 70° is to use the natural biomechanics of the muscle to maintain pressure on the nerve. Resisted static muscle contraction can also be performed to apply further pressure.

The piriformis syndrome can definitely involve the sciatic nerve in some cases (see references) and therefore neurodynamic testing is an essential ingredient of all examinations for the syndrome.

Higher level progressions for assessment can be achieved by use of the 3b neurodynamic sequences and the slump test, applying similar principles. The proximal components of slump test are performed. Since the hip joints are flexed to approximately 90°, passive external rotation and active internal rotation of the hip are used to integrate muscle with neural functions (Figure 4).

As mentioned, dorsiflexion or plantarflexion/inversion can be used to emphasize the peroneal or tibial components.

Figure 4. Piriformis Slump TestFigure 4. Piriformis slump test. The proximal components of slump test consist of thoracic, lumbar and cervical flexion. The hip is externally rotated and plantarflexion/inversion or dorsiflexion can be performed. The neural component is differentiated with neck movements. Active internal rotation of the hip is performed actively against the therapists resistance, if so desired for a higher degree of sensitization (Shacklock 2005).

In searching for a link between a symptomatic piriformis muscle and nerve involvement, it can be necessary to produce muscle contraction at the same time as the neurodynamic test (eg. SLR). Because of its increased sensitivity, it is often suited to patient’s whose symptoms are small the problem is difficult to detect, athletes, occupational overuse and sporting situations. Lower levels of testing can be performed at levels 1 and 2.

The subject of progressing neurodynamic diagnosis and treatment is elaborated on in Clinical Neurodynamics. The techniques presented above are classified as a level/type 3c (multistructural) technique (see chapter 6 and pages 218-233).

Since the nerve may be involved in some cases, it is essential that a neurological evaluation be performed, including vibration sense which is a particularly sensitive indicator of neuropathy.

Muscle anomalies and intrapelvic pathologies can cause sciatica at the piriformis and obturator regions, such that several variations in anatomy have been identified some of which are described in Figure 5. However, another surgically proven pathology is that of pressure of obturator internus being applied to the nerve and endometriosis also.

Figure 5. Anatomical variations in the passage of the sciatic nerve past piriformis. The peroneal component sometimes passes through the muscle.Figure 5. Patterns in which the peroneal component of the sciatic nerve anomalously passes through the piriformis muscle.

The tibial nerve has also been described to be compressed between piriformis and gamelli, along with the smaller gluteal nerves.

Treatment of Piriformis Syndrome - Neural Component

The treatment for piriformis syndrome when it involves the sciatic nerve is derived from the clinical presentation, in particular what level the patient is at. For instance, if the patient is at level 1, the treatment will be quite different from if they are at level 3c.

Here are some basic progressions which form a part of what the therapist can do for the problem.

Figure 6. Static Off-LoaderFigure 6. Static off-loader for releasing the sciatic nerve adjacent piriformis; hip flexion/abduction/external rotation.

This position is likely to place the sciatic nerve in an off-loaded position and at the same time take tension off the nerve, as long as the amount of hip flexion is not too great.

1. The patient is positioned so as to reduce tension from the sciatic nerve and also eliminate as best possible any compression between the nerve and piriformis. The patient can use this as a rest position and, from here, neural mobilisations can be performed and they can be performed as a home exercise (Figure 6).
2. Knee extension can be performed as a one-ended distal slider and as the patient improves.
3. Dorsiflexion can be added. This will naturally produce more distally directed tension in the nerve and must be performed with more care than the earlier progression.
4. Add neck flexion and spinal flexion and repeat 2.
5. More tension can be added to the nerve by positioning the patient in hip internal rotation. This may also apply more pressure of the muscle on the nerve.
6. Then the piriformis slump can be performed (Figure 4.) as a neural technique in which the patient’s hip is positioned external rotation to apply pressure of the muscle on the nerve.
7. Resisted static contraction piriformis can then be performed then, as the muscle is relaxed, the hip is moved into more external rotation and the piriformis is stretched once the technique is finished.

These are a few of the techniques that can be used to treat sciatica when the piriformis muscle is involved. For more information on openers, closers, more progressions and exercises, refer to Clinical Neurodynamics (pp. 218-223).

Use of the Contralateral Neurodynamic Tests to Reduce Tension in Lumbar Nerve Roots: Systematic Progression of Techniques

BIOMECHANICS

One of the common beliefs about neurodynamics is that the addition of the contralateral neurodynamic test to an ipsilateral one is a way of adding tension to the nervous system. If we consider the nerve roots, this is in some circumstances incorrect. So, contrary to popular belief, application of the contralateral neurodynamic test can reduce tension in the ipsilateral nerve root.

Figure 1. From Shacklock 2005, © Elsevier, Oxford. Figure 1. Diagramatic representation of the nerve roots as they interact across the spinal cord and produce movement in the cord during contralateral neurodynamic testing.

Part A (left), the nerve roots are in their neutral position.

Part B (middle), this ipsilateral nerve root is pulled and tensioned by the first (ipsilateral) neurodynamic test.

Part C (right), the ipsilateral nerve root has loosened because the spinal cord has moved downward by the pulling of the contralateral nerve root with the contralateral neurodynamic test.

This permits the ipsilateral nerve root to get looser and challenges past assumptions that contralateral testing produces an increase in neural tension in the ipsilateral nerve root. This may be why the clinician often notices that people with severe lumbar nerve root pain can get relief with the techniques presented below.

PROGRESSIONS

First Progression - One of the early progressions is to position the ipsilateral (in this case right side) sciatic nerve and lumbar nerve roots out of tension by performing ipsilateral (right) hip external rotation, slight abduction and flexion with knee flexion and ankle plantarflexion.

The next step is to perform components of the contralateral (left) straight leg raise so as to reduce tension in the ipsilateral (right) lumbar nerve roots. So in this case, left knee extension is used (Figure 2A, 2B).

Figure 2A.Figure 2A. Positioning of the nerve root out of tension with the ipsilateral (right) neurodynamic off-loader in preparation for the knee extension component of the contralateral (left) straight leg raise.

Figure 2B.Figure 2B. Add contralateral (left) knee extension to reduce tension in the ipsilateral (right) lumbar nerve root. Hold for a short period (up to 30-60 seconds). Be careful not to stretch the contralateral leg too much and technique should not produce symptoms from other problems. The contralateral (left) knee extension can be performed either passively or actively - passive in the clinic and, once a good response is established, this can be performed as a home exercise with the patient supporting their knee with their hands. Make sure the patients can relax their abdominal and back muscles as they perform the exercise.

Next Progression - The patient lies on their side, painful (right) side up. The nerve root is positioned in slightly more tension than in the previous progression. This is the starting position (position slightly into the dysfunction ie. into tension or in Clinical Neurodynamics, position TOWARD to the dysfunction).

The next step is to move the neural tissues out of tension so as not to provoke symptoms (move AWAY from or OUT of the dysfunction - tension). So the movement consists of contralateral knee extension to pull the contralateral (left) nerve roots and spinal cord downward in the canal and ease tension in the ipsilateral (right) nerve root. This technique should not provoke the patient's symptoms (Figure 3A, 3B).

Figure 3A.Figure 3A. Positioning of the ipsilateral (right) nerve root in a small degree of tension compared with the previous progression.

Figure 3B.Figure 3B. Mobilising it OUT of (AWAY from) tension with contralateral (left) knee extension to prevent provocation.

Next Progression - The level 2 tensioner for a neural tension dysfunction could be another progression in which the sensitivity of the nerve root may have reduced and will tolerate more activity. The nerves are gently and sensitively loaded from both ends with neck flexion and knee extension with or without dorsiflexion. This is like the standard slump test and is therefore selected when the patient is at level 2 (Figure 4, see Clinical Neurodynamics, chapter 6 for definition).

Figure 4.Figure 4. Standard slump test tensioners are performed gently and do not provoke symptoms (level 2 progression).

Next Progression - Ultimately, if it is appropriate for the patient, the technique can be progressed to level 3a with a sensitised slump test but this would only be chosen when appropriate and only if it is safe and likely to be effective. Selection of this technique should be performed in accordance with the recommendations in chapter 6, including contraindications (see Clinical Neurodynamics). Often good results can be achieved without using techniques as severe as this.

Figure 5.Figure 5. The level 3a neurodynamic tensioner technique.