The Sporting Nerve Part 1 | The Sporting Nerve Part 2 | Piriformis | Contralateral Tests
Sciatica: Is Extension the Right Choice? | Trouble Shooting with Scapular Stabilisation
Wrist Technique during Median Neurodynamic Testing | Tarlov's Cysts
Asymmetry and Diagnosis: Are We Neurodynamic Mirror Images?
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.
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).
SLR treatment for 'neural tension dysfunction' in cervical nerve rootStraight leg raise (SLR) treatment for 'neural tension dysfunction' in the cervical nerve root (for classification, see Shacklock 2005, pp 60-61, English version).
It is hypothesized that the SLR pulls the cord downward in the canal which produces a reduction in tension in the cervical nerve root.
There is a progressional system for including both contralateral neural techniques and lower limb movements to reduce tension in the cervical nerve root (for progressions and definition of the 'neural tension dysfunction' see Shacklock 2005; 2007b).
Bell A 1987 The upper limb tension test and straight leg raising. In: Proceedings of the 5th Biennial Conference of the Manipulative Therapists' Association of Australia, Melbourne: 106-114
Breig 1960 Biomechanics of the central nervous system. Almqvist and Wiksell, Stockholm
Rubenach H 1985 The upper limb tension test — the effect of the position and movement of the contralateral arm. In: Proceedings of the 4th biennial conference of the Manipulative Therapists' Association of Australia: 274-283
Shacklock M 2005 Clinical Neurodynamics: a new system of musculoskeletal treatment. Elsevier, Oxford
Shacklock 2007a Shacklock M (Ed.) Biomechanics of the Nervous System: Breig revisited, NDS Neurodynamic Solutions, Adelaide
Shacklock M 2007b Clinical Neurodynamics Course Manual. Neurodynamic Solutions NDS, Adelaide
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
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: 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.
During the SLR the muscle and nerve approximate and are aligned more parallel, producing a scissor action between the two.
- 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.
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).
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.
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.
- 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).
- Knee extension can be performed as a one-ended distal slider and as the patient improves.
- 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.
- Add neck flexion and spinal flexion and repeat 2.
- 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.
- 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.
- 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).
Breig A 1978 Adverse mechanical tension in the central nervous system. Almqvist and Wiksell, Stockholm.
Breig A, Troup J 1979 Biomechanical considerations in the straight leg raising test. Cadaveric and clinical studies of medial hip rotation. Spine 4 (3): 242-250
Goddard M, Reid J 1965 Movements induced by straight leg raising in the lumbo-sacral roots, nerves and plexus, and in the intrapelvic section of the sciatic nerve. Journal of Neurology, Neurosurgery and Psychiatry. 28: 12: 12-18
Shacklock 2005 Clinical Neurodynamics: a new system of musculoskeletal treatment.
Anatomical Variations and Surgically Demonstrated Intrapelvic Causes of Sciatica (piriformis, obturator internus and endometriosis)
Filler A, Haynes J, Jordan S, Prager J, Villablanca J, Farahani K, McBride D, Tsuruda J, Morisoli B, Batzdorf U, Johnson J 2005 Sciatica of nondisc origin and piriformis syndrome: diagnosis by magnetic resonance neurography and interventional magnetic resonance imaging with outcome study of resulting treatment. Journal of Neurosurgery. Spine 2(2):99-115.
OBJECT: Because lumbar magnetic resonance (MR) imaging fails to identify a treatable cause of chronic sciatica in nearly 1 million patients annually, the authors conducted MR neurography and interventional MR imaging in 239 consecutive patients with sciatica in whom standard diagnosis and treatment failed to effect improvement.
METHODS: After performing MR neurography and interventional MR imaging, the final rediagnoses included the following: piriformis syndrome (67.8%), distal foraminal nerve root entrapment (6%), ischial tunnel syndrome (4.7%), discogenic pain with referred leg pain (3.4%), pudendal nerve entrapment with referred pain (3%), distal sciatic entrapment (2.1%), sciatic tumor (1.7%), lumbosacral plexus entrapment (1.3%), unappreciated lateral disc herniation (1.3%), nerve root injury due to spinal surgery (1.3%), inadequate spinal nerve root decompression (0.8%), lumbar stenosis (0.8%), sacroiliac joint inflammation (0.8%), lumbosacral plexus tumor (0.4%), sacral fracture (0.4%), and no diagnosis (4.2%). Open MR-guided Marcaine injection into the piriformis muscle produced the following results: no response (15.7%), relief of greater than 8 months (14.9%), relief lasting 2 to 4 months with continuing relief after second injection (7.5%), relief for 2 to 4 months with subsequent recurrence (36.6%), and relief for 1 to 14 days with full recurrence (25.4%). Piriformis surgery (62 operations; 3-cm incision, transgluteal approach, 55% outpatient; 40% with local or epidural anesthesia) resulted in excellent outcome in 58.5%, good outcome in 22.6%, limited benefit in 13.2%, no benefit in 3.8%, and worsened symptoms in 1.9%.
CONCLUSIONS: This Class A quality evaluation of MR neurography's diagnostic efficacy revealed that piriformis muscle asymmetry and sciatic nerve hyperintensity at the sciatic notch exhibited a 93% specificity and 64% sensitivity in distinguishing patients with piriformis syndrome from those without who had similar symptoms (p < 0.01). Evaluation of the nerve beyond the proximal foramen provided eight additional diagnostic categories affecting 96% of these patients. More than 80% of the population good or excellent functional outcome was achieved.
A rare variation in the high division of the sciatic nerve surrounding the superior gemellus muscle.
Babinski M, Machado F, Costa W 2003 A rare variation in the high division of the sciatic nerve surrounding the superior gemellus muscle. European Journal of Morphology 41(1): 41-42.
The sciatic nerve normally leaves the pelvis by passing through the greater sciatic foramen below piriformis. However, it may divide into its common fibular and tibial nerve components within the pelvis and its relationship with piriformis is variable. In this paper, we describe a new anatomical variation in which the common fibular nerve passed superior, and the tibial nerve inferior, to the superior gemellus muscle. Anatomical variations such as these may contribute to piriformis syndrome, coccygodynia and muscle atrophy.
Extragenital endometriosis leading to piriformis syndrome.
Hettler A, Bohm J, Pretzsch M, von Salis-Soglio G 2006 Extragenital endometriosis leading to piriformis syndrome. Nervenarzt 77(4):474-477
We report on a 44-year-old woman with a history of sciatica fluctuating with her menstrual cycle and going back over 10 years; ultimately it was present continuously and became disabling. Over the years the patient developed ipsilateral foot-drop, a sensory disorder in the lateral aspect of the lower limb and back of the foot, and atrophy of the gluteus muscle. MRI confirmed the suspicion of extragenital endometriosis, which had caused piriformis syndrome by compression with consequent damage to the sciatic and inferior gluteal nerves. After hormonal therapy had been tried without success, the endometrioma was excised to relieve the pressure on the nerves, and the diagnosis was confirmed histopathologically. The motor deficit remained up to the 15 months since surgery, but the patient is now free of pain.
The internal obturator muscle may cause sciatic pain.
Meknas K, Christensen A, Johansen O 2003 The internal obturator muscle may cause sciatic pain. Pain 104(1-2): 375-380
Six patients suspected to have piriformis syndrome were operated in the hip region in an attempt to relieve pressure on the sciatic nerve. The piriformis muscle and tendon as well as their relationship to the sciatic nerve were found to be normal. However, the internal obturator muscle was found to be very tense, slightly hyperaemic and pressing the sciatic nerve. During Lasegue's testing on the operating table the internal obturator and not the piriformis muscle impinged on the nerve at an early stage in the hip flexion movement. A sectioning of the tendon to the internal obturator muscle near its insertion at the trochanter was performed. Median pain score was found to be reduced from the preoperative value (8.5) to that at 6 weeks (3.5) (P<0.05) and 3 (3.5) (P<0.05) and 6 months (5.5) (N.S.) postoperatively. No significant reduction of pain was found in a control group of six patients followed during the same period. Three patients who needed opioids preoperatively managed without such drugs 6 months after the operation. Two patients in the operated group were at work 50% and 100% after having been out of work for 3 and 10 years, respectively.
Piriformis syndrome resulting from a rare anatomic variation.
Kosukegawa I, Yoshimoto M, Isogai S, Nonaka S, Yamashita T 2006 Piriformis syndrome resulting from a rare anatomic variation. Spine 15;31(18): E664-666
STUDY DESIGN: Case report.
OBJECTIVES: We report a rare case of piriformis syndrome accompanying anatomic variation in the piriformis muscle and sciatic nerve.
SUMMARY OF BACKGROUND DATA: Beaton classified anatomic variation in the piriformis muscle and sciatic nerve into 6 types based on cadaver studies. There has been no report in the English literature of surgical treatment for a case of piriformis syndrome accompanying Beaton type d anatomic variation.
METHODS: A patient with sciatica showing no nerve root compression in lumbar MRI underwent pelvic MRI and perineurography of the sciatic nerve followed by CT. The findings in these images suggested piriformis syndrome accompanying anatomic variation of the piriformis muscle and sciatic nerve. Surgical treatment was performed.
RESULTS: Surgical exploration of the piriformis muscle revealed Beaton type d anatomic variation. Both anterior and posterior lobes of the piriformis muscle were resected. The pain in the leg had completely disappeared after surgery.
CONCLUSIONS: This is a very rare case of surgically treated piriformis syndrome resulting from type d anatomic variation in Beaton's classification. Pelvic MRI and perineurography of the sciatic nerve were useful for diagnosis in this case.
Medline Search Link: Medline Search Link
Use of the Contralateral Neurodynamic Tests to Reduce Tension in Lumbar Nerve Roots: Systematic Progression of Techniques
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.
IMPLICATIONS - There exists the idea of applying contralateral testing to reduce the power of neurodynamic techniques in a way that they can be progressed from low to higher levels in the patient.
Based on the above, here are some techniques to progress neurodynamics for the neural tension dysfunction (Shacklock 2005, see chapter 4 for definition). Clearly this is only a small selection of techniques that are available for this problem. Fore more techniques and the method of treatment, see Clinical Neurodynamics.