The following is the classic method of investigating the low back and the lower extremities for the cause of neurological symptoms, (parathesia or anesthesia; with/without motor dysfunctions) and/or the causes of suspected neurologically sourced pain.
September 28, 2009 By David A. Zulak MA RMT
The following is the classic method
of investigating the low back and the lower extremities for the cause of neurological symptoms, (parathesia
or anesthesia; with/without motor
dysfunctions) and/or the causes of suspected neurologically sourced pain.
One of the tests most commonly employed is the modified Straight Leg Raise (SLR).1 As modified it is also know as “Laseque’s Sign” or Test.
By passively placing a stretch on
the sciatic (and tibial) nerve we can provoke symptoms caused by a disc herniation or prolapse, (or any other “space occupying lesion” such as a tumour, or overgrowth of osteophytes, protruding into the neural foramen), that is pressing on one or more of the nerve roots that make up the sciatic nerve as they pass by on their way
out of the neural foramen. This test is made up of progressive movements that are used to pinpoint the source
of the client’s chief complaint.
The positive neurological sign is the reproduction of client’s neurological signs. This includes various combinations of pain, numbness (anaesthesia), tingling, burning or paraesthesia into the buttock, and possibly down the back of the leg. These signs can arise from as small a movement as 15°-30° (in a very acute lesion, where weight bearing on the affected side is difficult) and up to 70° during a modified SLR. (A more chronic, or less severe lesion). Remember, for sciatica nerve compression syndromes the symptoms will run down the path of the sciatic nerve. Other neurological symptoms could be from other nerve roots or peripheral nerve compressions. Also, Sacroiliac (SI) joint and ligament injuries and dysfunctions can mimic neurological symptoms: for example, an inhibited S1-2 Deep Tendon Reflex (DTR) can occur on the side of an SI. joint dysfunction, (and be returned to normal by manipulating the SI joints alone).
After 70° of hip flexion during the SLR the sciatic nerve is not placed on any further stretch, therefore, local low back pain experienced beyond 70° of hip flexion is most often due to other lumbar spine structures or tissue. Note that local pain at the sacroiliac joint will also most often occur from 0 to 70°.2
Performing The Test
Have the client lay supine and as relaxed as possible. Have the client’s leg adducted and allow it to be medially rotated if it rests that way. Lift the straight leg slowly until the client reports pain or other symptom in the buttock or the back of that leg. Now, lower the leg until the symptoms are gone. Continue to hold the leg in this position.
The client’s foot is then passively dorsiflexed, which places a stretch along the nerve (via the tibial nerve), if the client’s symptoms return the test is positive. This dorsiflexion of the foot is sometimes called Bragard’s test.3
If dorsiflexion of the foot does not
provoke the recurrence of symptoms then you can ask the client to actively forward flex their head, while you sustain the dorsiflexion of the foot.
This forward flexion of the cervical spine now places a stress through the meninges,
especially the dura mater and pulls the spinal cord superiorly, putting
further stretch down through the cauda equina and thus on the nerve roots that contribute to the sciatic nerve. This third stage of the test is referred to as Brudzinski’s sign. (It has also confusingly been referred
to a Kernig’s sign/test4).
During this later stage of the test, forward
flexion of the cervical spine, may be positive
for meningeal irritation if the client reports symptoms of pain or restriction up in the spine. During forward flexion of the cervical spine the client will reflexively flex the hip and knees, in an involuntary attempt, to release the tension from the meninges.
By flexing the knee the sciatic nerve can
be freed of tension, and allow the spinal
cord to slide up the spinal column, at least enough to reduce the tension on the meninges.
If this reflexive flexion of the hip and knee occurs during the straight leg test, and the client experiences pain up in the spine/back, then the therapist should cease testing the lumbar spine and do the tests that are referred to as Sotto-Hall (or Brudzinski-Kernig’s sign) and/or Kernig’s sign, testing specifically for meningeal irritation.5
If the client suffers from meningitis (bacterial or viral) they will not usually be able to dorsiflex the foot and flex the head at all, and remain pain free.
While meningeal irritation arising from adhesion of
the dura mater etc. in the spinal canal, or adhesion at the neural foramen, usually allows some pain free flexion till enough tension is put through the meninges to tug on where the adhered tissue is (i.e. put enough tension through the tissue for it to feel restricted and/painful).
Modifying the Straight Leg Raise test:
This Straight Leg Raise test can be modified for the
client who cannot lay supine on the table with the legs extended. This is common for the client who suffers from low back pain. Have the client start side lying with the knees bent comfortably. The therapist stands in front of the client’s legs. Straighten the lower leg (in line with the torso), and then while supporting the weight of the upper leg bring it straight as well. With both legs now straightened, slowly raise the upper leg by flexing the hip while keeping the knee extended. Proceed through the test’s progressions or stages as above.
Well Leg Raise:
This test is performed on the leg that does not have
any symptoms down its posterior aspect, (the unaffected leg). This test will be positive by reproducing the client’s symptoms down the affected leg. NOTE: If the therapist is following the rules of testing (testing the unaffected leg first) the “Well leg raise” test will have been done prior
to the Straight Leg Raise test above.
With the client supine slowly raise the unaffected leg till either it reaches end range or you reproduce their chief complaint of pain or paraesthesia down the affected leg that has remained on the table. A positive sign here points to a space-occupying lesion that is pressing on the nerve root(s) that govern the affected limb.
How does this work?
Raising the unaffected leg (the ‘well leg’) causes the ipsilateral ilia to rotate posteriorly causing torsion of the sacroiliac joints. This ‘un-levels’ the sacral base causing the lumbar spine to side bend toward the affected side. This sidebending causes any herniation on the contralateral side of the spine to be exaggerated
by the ‘closing’/squeezing of the vertebral bodies on that contralateral side, increasing pressure on the irritated nerve root(s). (Whew!)
If the Straight Leg Raise test is
positive, or if chronic irritation and inflammation of the
sciatic nerve is suspected, the sciatic nerve may be directly palpated in the popliteal fossa of the knee. Pressure on, or strumming across, the nerve will cause symptoms to be felt locally and usually will refer up and down the leg from the part of the nerve being irritated by the palpation. For this test to be positive the sciatic nerve usually needs to be inflamed and the neurolemma swollen, down to, or near the section of the nerve being strummed.
Eliciting a Bowstring Sign:
With the client still supine passively raise the leg until pain or paraesthesia is felt down the back of the leg, now flex the knee and place the lower portion of the leg on your shoulder to support it. Palpate with your thumb just medially to the tendon of the biceps femoris in the popliteal fossa. If the inflammation has been chronic the nerve itself can be palpated, feeling like a braided cord. If not, pressure applied or a strumming action on the fossa will bring on the symptoms. The positive sign is a return of the client’s neurological signs and symptoms, and the therapist may be able to feel the swollen irritated nerve.
By increasing the intrathecal pressure in the spinal cord the positive sign of pain or paraesthesia will felt locally in the spine or traveling down into the
legs if there is a space occupying lesion such as a tumour, herniated disc, or osteophytes. Have the client take a deep breath and hold it while bearing down as if having a bowel movement. If you wish, you can describe the test
as such: have the client place the tip of their thumb in their mouth and pretend they are blowing up a balloon, not letting air release through the lips.
Side flexion with extension: This combined movement of the lumbar spine, may be used at this point if the client’s chief complaint is neurological symptoms, but that have not been provoked by the testing to this point.
The movement created with Kemp’s test simply provides greater provocation by decreasing the intervertebral
foramen of the lumbar spine on the side to which the client bends. This test also puts maximal stress on the facet joints by placing them in their closed packed position. Facet joint pain may be site specific to the facet provoked, or may radiate several centimetres around the joint. Localized pain on the same side may also come from;
an injured muscle being placed in a shorten position and then spasming, pressure placed on inflamed iliolumbar
ligaments, or from compression of the joint surfaces of
the sacroiliac joint. The later can mimic neurological pain in the gluteal-hip region.6 Pain from the side not being tested usually comes from tissue being stretched.
Performing Quadrant/Kemp’s Test
With the client standing, have them place the hand on the side to be tested on the back of that leg. Have them slowly slide the hand down the back of the leg as far as they can.
Instruct the client to tell you when they feel any discomfort or pain or if they have a recurrence of any neurological signs or symptoms. (If the client is young, or extremely flexible, have them place their hand on the posterior aspect of the leg on the opposite leg to the side they are rotating.) The positive sign for sciatic nerve involvement may be pain into the buttock and/or down the back of the leg following the nerve path.
Myotome testing for Lumbar Spine:
Remember, the client must use their full strength in
neurological tests, (and when doing strength testing too), otherwise they may inadvertently mislead the therapist
about the true strength of a muscle.
• Rational: If you ask for only half their strength, when
testing, the client will often only be able to gage that by the resistance they feel being applied. Hence they may use 50% of their strength on the uninjured side of their body being tested first, and 70% on the other – pushing against the therapist’s resistance till both sides feel the same.
The client is not trying to “trick” the therapist, they
will believe they have applied the same force because it felt the same. The only time using half strength may be able to be clearly distinctive is with a radical differences between sides, when recruitment of more of the muscle
or its synergists is evident.
Initially, the therapist may wish to do some quick testing for sensory nerve innervation dysfunctions. Have the client stand. Test bilaterally at the same time. To do so, brush with the back of your fingers several times in the midrange of each of the lower dermatomes, asking the client if they notice any difference from one side to the other.
Often, a delayed response, uncertainty on the client’s part, can be considered a possible positive sign. If you wish, you can repeat this with deep touch, hot and then cold, and two-point discrimination
Deep Tendon Reflexes (DTR):
It is wise to test each side with seven to 10 strikes to
see if there is a progressive lessening of the response,
a decreasing response is a positive sign. The obvious
positive sign is a difference bilaterally.
Note, however, that if you get little or no response from both sides, that is what is normal for that person and in no way is a positive sign. The lack of response is due to the fact that we are using a stretch reflex to test innnervation. If the muscle is long, or low in tone the response could
be minimal or absent.
With the Achilles tendon the therapist can increase the likelihood of a stretch reflex response by placing one hand under the client’s foot and slightly dorsiflexing the foot.
Do both tests with the client seated on the table so that their feet are off of the floor.
• L4 is tested by striking the Infrapatellar tendon and
comparing the knee jerk bilaterally.
• S1 is tested by striking the Achilles tendon and then watching for plantar flexion. Note: If the client’s foot
plantarflexes but very slowly returns to neutral it would
be wise to refer them to their physician as this may
Pathological Reflexes: Babinski’s Sign implies an upper motor neuron lesion.With the client supine take the end of the reflex hammer’s handle and use it to stroke from the heel of the foot up the lateral side of the plantar surface of the foot and then across the ball of the foot medially. The positive sign is the extension of the big toe and splaying and slight flexion of the toes. A negative sign is flexion or ‘scrunching’ of the toes, or no reaction at all. This test will only work on someone one year old or older (having learned to walk).
When tests are positive and the client has not seen their family Doctor about these, they should be referred to/back to their Doctor.
If at this point in your testing the source of your client’s chief complaint has not been clarified or they are exhausted by the testing done so far, it would be best to move onto testing the sacroiliac and pelvic joints.
Keep an eye open for autonomic nerve dysfunctions by noting when discreet areas of skin are blanched, perspiring, or having pilomotor responses (goose bumps), while adjoining areas of skin are not having these responses. These autonomic signs can be from various causes such
as dysfunctions of spinal joints, or a red flag for organ
dysfunction, or underlying disease processes. Refer out.
Performing the Myotome test:
Have the client lying supine with their knees bent and feet flat on the table. The bent knees are necessary for the client who suffers from low back pain to be comfortable. This position is also helpful in reducing the apprehension of pain that otherwise may prevent the client from using their full strength during testing. This position can be the starting position for each test below.
The following muscles or groups of muscles have been chosen to facilitate this position of comfort for the client. Other muscles can be used to test these myotomes Do the following resisted testing, either having the therapist resist their movement, or better still, have them hold their position while the therapist applies increasing pressure/force.
L2 = resisted hip flexion, (iliopsoas). Place one hand on the clients shoulder and another on their knee. Have them try to flex their hip while you provide resistance. You may wish to have the client flex their hip 90° (leaving their knee bent) and tell them to hold this position while you slowly build up your force. Remember to ease off slowly, and to do so if the client begins to allow movement during the testing, (i.e., you are overpowering them).
L3 = knee extension, (quadriceps), (also tests the obturator nerve). Reach under the knee of the leg to be tested with the arm closest to the clients head and place the palm of your hand on the clients other knee.
Lift the clients leg slightly until your forearm is parallel to the table and their leg is now draped over your forearm. Their knee should remain flexed to roughly 80°-90°. With your other hand on their ankle turn your body till it faces the client’s upper body so you are in a position of mechanical advantage to resist their attempt to extend their knee. Be sure to keep your wrist neither flexed nor extended while you resist knee extension.7
L4 = ankle dorsiflexion, (tibialis anterior). Stabilize the lower leg with one hand by pushing the heel into the table, while you place the ankle/foot in neutral (roughly having the ankle in 90°) and have them hold this position while you try to bring the sole of their foot to the table.
L5 = extension of the big toe, (Extensor hallucis longus). Stabilize across the metatarsal with one hand, with the ankle/foot in a neutral position, and ask the client to raise their big toe towards their head. Have them hold this while you try to flex the joint.
S1 = ankle eversion, (peroneus longus & brevis). With the client’s ankle in neutral have them evert their foot (outside of foot upward). Again, have them try to hold this position while you attempt to bring the foot into inversion.
S1&2 = knee flexion, (hamstrings). While standing at the end of the table clasp both hands around the client’s ankle and resist their attempt to bring their ankle towards their buttock.
- The SLR will on its own will primarily test the length of the hamstrings. When speaking of, or implying neurological testing, the SLR refers to itself with the following modifications.
Magee 3rd; pages 390-91iii. I prefer to refer to specific test by an anatomic or biomechanical tag, and avoid using personal names. We could call this the “Zulak nomenclature for Orthopeadic Testing” (sic)
- See Magee 3rd p.394-95. These names strictly speaking refer to meningel testing: In ABrudzinski-Kernig test@ the client actively flexes their head to their chest and further provocation can then be added by them actively raises their leg straight by flexing at the hip. When pain is felt along the spine the client is then asked to flex the knee, or the knee will all by itself flex, releasing the pull on the lower spinal cord by easing the tension on the sciatic nerve. If the pain felt along the spinal cord is relieved by the flexion of the knee the test is then positive for dura/menigeal issues. ABrudzinski’s sign@ therefore occurs when a supine client forward flexes their cervical spine and the resultant meningeal irritation causes them to flex the hip and knee (i.e. to draw the calcaneus of the foot towards the buttocks along the table) to ease the pull or tension on the spinal cord by easing the tension on the sciatic nerve. AKernig’s sign@ occurs when the client can not keep the knee straight when flexing the hip. Again, the reflexive flexing of the knee is done to take tension of the spinal cord by releasing tension on the sciatic nerve. For these signs see Porth, 3rd, page 959. Hoppenfeld confuses the issue by referring to the test usually named “Brudzinski’s sign” as “Kernig’s.” Hoppenfeld p. 258 (& fig.42) Again, further reason to drop the personal names and go with the action done to provke a specific result when testing.
See Magee, 3rd page 397ff.
Ibid. viii. See the previous column in the last issue of MT Canada for images.
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