domingo, 7 de junho de 2015

The Stepping Test: A Useful Tool for Cervical Rehabilitation

By Donald Murphy, DC, DACAN
The "stepping test" was first developed by Fukuda1 as a test of vestibular function. More recently, the test has been shown to greater reflect somatosensory function than that of the vestibular system.2-4 Gordon et al.2,3 had subjects who were negative for the stepping test walk on a rotating treadmill for two hours and found that upon retesting them, the stepping test became positive. 
They felt that this could only have resulted from an alteration in the central nervous system (CNS) program for stepping. This was caused by a change in somatosensory input from the locomotor system induced by walking on the rotating treadmill.
There was no stimulation of the vestibular apparatus in these experiments, because the head remained stationary while the subjects walked on the rotating treadmill. Fukushima and Hinoki4 had normal subjects perform the stepping test while they wore, alternately, cervical collars and lumbar corsets. They found that while the cervical or lumbar spine was restrained, the stepping test became positive. Their conclusion was that interruption of the afferentation from the mechanoreceptors in the spinal muscles led to alteration of the tonic neck and lumbar reflexes, resulting in rotation of the body while stepping.
How Is the Test Performed?
The test is performed by having the patient stand with eyes closed, arms outstretched and wearing ear muffs. The patient marches in place at the pace of a brisk walk while keeping the eyes closed (Figure 1). The doctor observes for any rotation that takes place. Rotation of 30 degrees or more is considered a positive test. The significance of the test is that it suggests the presence of either faulty kinesthetic sense or tonic neck reflexes (or both). In the low back pain patient, a positive test is likely a reflection of either faulty kinesthetic sense or faulty tonic lumbar reflexes.
What Is the Clinical Utility of the Test?
I have used this test for several years and have found it to be quite useful in decision- making in rehab. Experiments are ongoing at my center investigating its full utility. The alterations results of these studies may alter and enhance its use in years to come, but this is how I use it.
The test detects alterations in the motor program for stepping, part of the primitive program of gait. These result from disruption of the normal processing of afferent information from the locomotor system. Abnormal processing likely results from dysfunction of the joints, muscles, and/or skin and fascial. The theory of faulty movement patterns states that this abnormal afferentation can cause a change in the program for certain movements.5 If the faulty movement pattern becomes "fixed" in the CNS, i.e., if a plastic change in the nervous system in which the program for that particular movement becomes accepted by the CNS as "normal," correcting the afferentation may not be enough to correct the program. In this case, rehabilitation may be required to retrain the CNS in creating another plastic change, in which an attempt is made to restore the faulty program to normal.6
Let's take the example of a patient with chronic headaches. The exam reveals joint dysfunction at C0-C1; myofascial trigger points in the suboccipital muscles (which reproduce the pain); hypertonicity of the right sternocleidomastoid; and a positive stepping test. The initial outline of treatment may be manipulation to the C0-C1 segment, ischemic compression to the suboccipital muscles, and postisometric relaxation to the right sternocleidomastoid. Is sensorimotor training necessary in this case? Perhaps, but in the interest of saving time, it may make more sense to treat the peripheral dysfunction (which would have to be done anyway) and recheck the stepping test to see if the gait program has been corrected as a result of the manual treatment provided.
Theoretically, restoring normal joint and muscle function in this case would normalize mechanoreceptive input from those structures. This may be enough to normalize the gait program. If, after a reasonable amount of time to correct the peripheral dysfunction, the stepping test becomes negative, it is not likely that further treatment with sensorimotor training will be necessary. If, however, correction of joint and muscle dysfunction is made and the stepping test remains positive, there is a likelihood that the faulty program for gait has become fixed in the CNS. Further intervention in the form of sensorimotor training will be necessary.
Sensorimotor training would be the rehabilitation method of choice in this case because it allows the practitioner to induce a bombardment of the CNS with mechanoreceptive signals from the locomotor system while the patient in standing on one leg on a wobble board, a position that mimics the stance phase of gait. This, theoretically may allow the CNS to make another plastic change in the gait program, more toward normal.
The stepping test can be used as a tool to demonstrate the presence of a faulty gait-related program and to determine whether the treatment and rehabilitation is doing the job of correcting the problem. Of course, outcome measures that reflect pain intensity, such as a Visual Analogue Scale or Numerical Rating Scale, and the degree of disability the patient is experiencing as a result of the problem, such as the Neck Disability Index or Headache Disability Inventory,7 will also be necessary to assess whether the correction of the faulty program is successful in helping bring about meaningful change in the patient's clinical status.
Efficiency is of the utmost importance for effective treatment and rehabilitation of patients in the busy practice environment. Any test or procedure that I can find that allows me to save time while enhancing my ability to help my patients is of tremendous value. The stepping test is a clinical evaluative procedure that does not take a great deal of time to administer, but provides the practitioner with information that he or she can use in making decisions with regard to whether additional rehabilitative measures are required and on which methods (e.g., sensorimotor vs. stabilization) the greatest focus should be placed.
References 
  1. Fukuda T. Statokinetic Reflexes in Equilibrium and Movement.Tokyo: University of Tokyo Press, 1984.
  2. Gordon CR, Fletcher WA, Jones GM, Block EW. Is the stepping test a specific indicator of vestibulospinal function? Neurology 1995;45:2035-2037.
  3. Gordon CR, Fletcher WA, Jones GM, Block EW. Adaptive plasticity in the control of locomotor trajectory. Exp Brain Res 1995;102:540-545.
  4. Fukushima H, Hinoki M. Role of cervical and lumbar proprioceptors during stepping: an electromyographic study of the muscular activities of the lower limbs. Acta Otolaryngol(Stockh) 1985; Suppl 419:91-105.
  5. Murphy DR. Dysfunction in the cervical spine. In: Murphy DR (ed.) Conservative Management of Cervical Spine Syndromes. New York: McGraw-Hill, 2000:71-104.
  6. Janda V, Va Vrova M. Sensory motor stimulation. In: Liebenson C (ed.) Rehabilitation of the Spine: A Practitioner's Manual. Baltimore: William and Wilkins, 1996:319-328.
  7. Yeomans SG. Outcomes management of cervical spine complaints. In: Murphy DR (ed.)Conservative Management of Cervical Spine Syndromes. New York: McGraw-Hill, 2000:329-356.

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