The Centralization Phenomenon in Chiropractic
Spinal Manipulation of Discogenic
Low Back Pain and SciaticaThis section is compiled by Frank M. Painter, D.C.
Send all comments or additions to: Frankp@chiro.org
FROM: J Manipulative Physiol Ther. 2001 (Nov); 24 (9): 596–602 ~ FULL TEXT
Anthony J. Lisi, DC
Department of Technique,
Palmer College of Chiropractic West,
San Jose, Calif. 95134, USA.
lisi_a@palmer.edu
OBJECTIVE: To describe 3 cases of discogenic low back pain and leg pain in which the centralization phenomenon was used in determining chiropractic treatment and prognosis.
CLINICAL FEATURES: Three men with low back pain and sciatica, positive straight leg raise, mild neurologic deficits, and evidence of discogenic disease requested chiropractic treatment. Two of the patients exhibited centralization of pain on provocation testing; the third did not.
INTERVENTION AND OUTCOME: All patients were treated with chiropractic side-posture manipulation, ancillary therapies, and pain medications. The 2 subjects whose pain centralized had excellent outcomes to treatment. The one whose pain did not centralize had a poor outcome and eventually required surgery.
CONCLUSION: Assessment of the centralization phenomenon provided valuable diagnostic and prognostic information regarding chiropractic side-posture manipulation in this case series.
Keywords: Chiropractic Manipulation, Intervertebral Disk, Sciatica
From the FULL TEXT Article:
Introduction
Table 1 The centralization phenomenon, as first described by McKenzie [1] in 1981, occurs in certain patients who have spinal pain radiating to an extremity. Centralization is the term used to denote a decrease in extremity pain; the pain recedes from the distal area of the body, thus becoming more proximally located. The opposite of centralization, peripheralization, describes the situation in which proximal pain moves distally. Since the time of McKenzie's original classification, others have suggested refinements in these definitions (Table 1).
Centralization or peripheralization can result from various activities and positions in a patient's daily life. However, clinically, some patients' symptoms can be made to centralize, peripheralize, or both by means of mechanical (McKenzie) examination methods. [1–5]
The purpose of this article is to describe 3 cases of discogenic low back pain and leg pain in which the centralization phenomenon was used in determining chiropractic treatment and prognosis.
Case reportsCase 1
A 61–year-old maintenance worker was referred by his orthopedic surgeon. He complained of left low back pain radiating to the posterior left thigh and calf and to the lateral aspect of the left foot. The patient reported that his condition was the result of an occupational motor vehicle accident that occurred approximately 4 months before consultation. He had been out of work for those months. The patient also complained of numbness and paresthesia in the left posterior buttock and thigh and a general sense of weakness in the left lower extremity. The weakness was such that for the past 4 months the patient required a cane to walk. He reported constant pain, averaging 8/10 intensity on the numerical rating scale (NRS). Coughing and sneezing increased the patient's low back pain and leg pain.
Lumbar active range of motion was limited to 40° in flexion, 20° in extension, and 15° in left lateral flexion. The end range of these motions increased the patient's low back pain. Straight leg raise on the left increased the patient's low back pain and left leg pain at 30°. Braggard's test was equivocal.
Motor strength of the left extensor hallucis longus and left evertors was 4/5. Strength of the left hip flexors and knee extensors was inhibited because of increased low back pain. Patellar reflexes could not be elicited bilaterally; Achilles reflexes were +2 bilaterally. Sensory testing was equivocal, with a vague decrease in vibration perception at the dorsum of the left foot. No Waddell signs were present.
There was hypertonicity and tenderness of the left lumbosacral erector spinae muscles. There was tenderness of the left L4–5 and L5–S1 facet joints. Passive joint end play of L4–5 and L5–S1 was decreased bilaterally. Previous magnetic resonance imaging (MRI) scan showed decreased hydration and disk bulges lateralized to the left at L3–4 and L4–5. At L5–S1 there was a central subligamentous disk protrusion effacing the left lateral recess.
On mechanical examination, repetitive flexion increased the patient's low back pain and left leg pain. Repetitive extension increased the low back pain but decreased the leg pain. Prone press-ups also increased the low back pain but decreased the leg pain and paresthesia.
On provocation testing in the right lateral decubitus position, mobilization consistent with a left sacral base side-posture push maneuver decreased the patient's left leg pain. In the left lateral decubitus position, mobilization consistent with a right L5 side-posture mamillary push maneuver decreased the patient's left leg pain. Both positions caused a moderate increase in local low back pain and patient guarding.
The patient was treated with mobilization only and instructed to return the next day. On the second visit the patient's complaints were unchanged. Provocation testing once again decreased leg pain but only slightly increased local low back pain. Manipulation was suggested, but the patient was apprehensive about high-velocity low-amplitude (HVLA) procedures and chiropractic care in general. Therefore, he was treated with mobilization only on that visit and the subsequent 2 visits.
On the patient's fifth visit, 8 days after initial presentation, he reported a slight decrease in the intensity of his left leg pain and numbness and noted that the symptoms were no longer present in his left foot. Encouraged by this progress, the patient consented to side-posture HVLA manipulation, which was delivered consistent with the provocation testing described previously. The patient reported a moderate decrease in leg and low back pain immediately after the procedure. When he returned 4 days later for his sixth visit, the patient stated that he felt significantly improved after the previous treatment and was able to walk without a cane for the first time in 4 months.
He was treated 2 more times over the next 9 days. On his eighth visit, he complained of mild low back pain (1/10 intensity) and persistent but decreased paresthesia in the left thigh. Lumbar range of motion was full and did not increase symptoms. The patient was able to return to work without restrictions. He was seen for follow-up twice over the next 4 months without any significant exacerbations.
Case 2A 36–year-old financial consultant was seen at his home for an emergency visit. The patient complained of severe low back pain (10/10 intensity) located across the lumbosacral region and severe left leg pain (8/10 intensity) extending to the dorsum of the left foot. He also complained of weakness of the left thigh and leg and paresthesia of both legs and feet. The onset of pain was the day before — at the end of a 2–week business trip that involved significant lifting and carrying of heavy luggage. The pain was worsened by an 11–hour airline flight home. The patient showed no signs of bladder or bowel incontinence, saddle anesthesia, fever, chills, sweats, nausea, or vomiting.
Lumbar active range of motion was limited to 5° in flexion, 0° in extension, and 5° in left and right lateral flexion. The end range of these motions increased the patient's low back pain. Straight leg raise on the left increased the patient's low back pain and left leg pain at 30°; Braggard's test was positive. Straight leg raise on the right increased the patient's low back pain and left leg pain at 50°; Braggard's test was equivocal. Hallux extension was 5/5 on the right and 4/5 on the left. Foot eversion was 5/5 bilaterally. Patellar and Achilles reflexes were +2 bilaterally. Light touch sensation was decreased at the left medial foot. There was marked spasm and tenderness of the lumbosacral musculature bilaterally. Assessment of passive joint end play was not tolerated.
On mechanical examination, attempts at repetitive motion testing were not tolerated by the patient because of severe low back and left leg pain. Lying prone decreased the left leg pain but did not change the low back pain. Prone press-ups were not tolerated.
The patient was given instructions on the use of ice and over-the-counter ibuprofen. He was advised to lie prone as much as possible and to attempt partial prone press-ups periodically. The patient was advised to consult a local orthopedic surgeon if signs of cauda equina syndrome developed or if he required stronger pain medication; otherwise he was advised to follow up with an office visit the next day.
The next day, the patient presented to the orthopedic surgeon's office with symptoms essentially unchanged. An MRI was performed and showed decreased disk hydration, annular bulging, and high-signal zones consistent with annular tears at L2–3, L3–4, and L4–5. At L5–S1 there was decreased disk hydration and decreased disk height, with a broadbased posterior central disk protrusion indenting the central aspect of the thecal sac. The patient was advised that surgery was not indicated. He was given an injection of morphine and a prescription for oral hydrocodone with acetaminophen and was advised to follow up at my office.
The patient returned 2 days later still complaining of bilateral low back pain and left leg pain. He stated that the medications helped decrease the intensity of his symptoms but the distribution was unchanged. Mechanical examination was tolerated and demonstrated a slight decrease in left leg pain on prone press-ups. However, the patient could not perform a sufficient number of press-ups because of a significant increase in central low back pain.
On provocation testing in the right lateral decubitus (left side up) side-posture adjustive position, mobilization of the L4–5 and L5–S1 spinal units with the lumbosacral spine in extension by using a mamillary push contact significantly decreased the patient's leg pain, with only a moderate increase in central low back pain. The patient was treated with mobilization only and advised to return the next day. At that time the patient was manipulated by using an HVLA mamillary push maneuver consistent with the positioning mentioned previously. He reported a significant decrease in leg pain and low back pain immediately after the procedure.
He was treated in similar fashion 3 more times over the next 7 days, at which time his pain was fully resolved. The patient was seen for follow-up 4 times over the next 14 months for minor exacerbations of low back pain without any exacerbation of leg pain.
Case 3A 37–year-old human resources director had right low back pain and right leg pain of gradual onset over the past 2 weeks. The pain had worsened 3 days before while he was doing sit-ups, causing him to seek care at a local emergency room. The patient was diagnosed with a lumbar strain and given oral hydrocodone with acetaminophen, which helped decrease the pain intensity. The patient stated his pain was 8/10 intensity and of constant duration.
The patient stood with a left antalgic list. Lumbar active range of motion was limited to 45° in flexion, 15° in extension, and 5° in right lateral flexion with the end ranges increasing local low back pain. Straight leg raise on the right increased low back pain and right leg pain at 45°; Braggard's test was positive. No deficits were noted in lower extremity motor strength, deep tendon reflexes, or sensation. There was hypertonicity and tenderness of the right lumbosacral musculature, and tenderness of the right L4–5, L5–S1 facet joints. Passive joint end play of L4–5 and L5–S1 was decreased bilaterally.
On mechanical examination, repetitive flexion increased the patient's low back pain and right buttock pain. Prone extension decreased the patient's right leg pain without changing low back pain. On provocation testing in the left lateral decubitus position, mobilization of the right L5–S1 spinal unit with a mamillary push contact decreased the patient's low back pain, but the right leg pain remained unchanged.
The patient was treated with mobilization only. Prone press-ups were prescribed. He was given instructions on the use of ice and over-the-counter ibuprofen and was instructed to return the next day.
At the second visit the patient reported some improvement in pain intensity but that he was unable to centralize symptoms with prone press-ups. The patient was treated with an HVLA manipulation consistent with the positioning mentioned previously. He reported decreased low back pain immediately thereafter but no change in leg pain. He returned 2 days later, stating that his low back pain had decreased but that his leg pain was essentially unchanged. He was again treated with HVLA manipulation and noted further improvement in low back pain with a minor decrease in leg pain. The patient stated that he would be out of town on a business trip for the next week. He was advised to maintain lordotic posture and to attempt centralization of symptoms with prone press-ups.
The patient returned 1 week later complaining of a severe exacerbation of low back pain and right leg pain. He stated that his condition had worsened because of airline travel over the past week. Provocation testing showed increased low back pain and peripheralization in multiple directions. No centralizing direction could be found; therefore, the patient was not manipulated. The patient was advised of the need for imaging, including plain film radiographs and MRI. Because of insurance requirements, the patient requested to see his primary care physician to order these tests.
The patient returned 1 week later with continued severe pain. He stated that he had seen his primary care physician, who had advised him to continue with chiropractic treatment and pain medications. No imaging studies had been ordered.
Examination essentially showed a marked worsening of all findings noted at initial presentation and the presence of a decreased Achilles reflex (+1) on the right. Mechanical examination and provocation testing showed peripheralization in multiple directions but no centralization. Again, the patient was not manipulated.
The patient was referred to a local orthopedic surgeon who ordered an MRI scan at his initial consultation. MRI showed a moderate-sized right-sided disk protrusion at L5–S1 displacing the right nerve root posteriorly and cephalad extension of disk material, suggesting a free fragment. There was a moderate central and left-sided disk protrusion at L4–5 with inferior extension of disk material, suggesting a free fragment at this level also.
The patient underwent microdiskectomy at L4–5 and L5–S1.
Discussion
McKenzie methods
Table 2 A thorough description of the McKenzie system has been presented in the literature [1–3] and is beyond the scope of this article. However, in summary, McKenzie has classified mechanical low back pain into 3 syndromes: postural, dysfunction, and derangement. Each syndrome is defined by a theoretical model of the underlying pathologic condition, in addition to patient history, postural assessment, and mechanical examination findings (Table 2). McKenzie has stated that the validity of the theoretical models may be questioned but that the observed clinical phenomena in response to mechanical assessment occur regardless of the proposed mechanisms.
Table 3 The mechanical examination is a sequence of active movements performed by the patient and passive mobilizations performed by the clinician (Table 3). During these movements, the patient is assessed in terms of range of motion, symptom intensity, and symptom location. Particularly noteworthy are changes in these parameters in response to repetitive motions.
For instance, a patient with decreased range of motion and increased low back pain upon a single performance of active flexion may be seen to have progressively increasing range and decreasing pain while performing several repetitions of flexion. In this example, flexion motions would be considered beneficial and would be called the patient’s “directional preference.” Such a preference would guide treatment in terms of exercise (knees to chest rather than prone press-ups), ergonomics (sleep supine with knees elevated rather than prone), and clinician intervention (mobilization/ manipulation in flexion rather than extension).
The mechanical examination may also show centralization, peripheralization, or both. For instance, a patient with low back pain and right buttock pain may have decreased range of motion and increased pain upon a single performance of active flexion and extension. However, repetitive flexion may cause a further decrease in range of motion and further increase in pain intensity, as well as pain spreading to the right thigh. Repetitive extension may cause an increase in range of motion, a decrease in low back pain intensity, and elimination of buttock pain. In this example, flexion has peripheralized, whereas extension has centralized, the patient’s pain.
This response, the centralization or peripheralization of pain, is the element of the McKenzie method that has direct bearing on this article, and it has been well reported in the literature.
Centralization
Donelson et al [6] conducted a retrospective chart review of 87 patients with low back pain and lower extremity pain who were treated by the McKenzie protocol. On McKenzie assessment, 76 of 87 patients (87%) experienced centralization of symptoms in response to repeated end range movements in a single direction. In each case, movement in the opposite direction always exacerbated distal symptoms. Final treatment outcomes were rated excellent or good in 83% of the study population. Centralization occurred in all of the 59 (100%) patients who had excellent results, in 10 of the 13 (77%) who had good results, in 4 of the 7 (57%) who had fair results, and in 3 of the 8 (37.5%) who had poor results. In the acute group (less than 4 weeks duration), 6 of the 53 patients did not centralize, and 4 of these had poor outcomes to conservative treatment. These 4 were the only patients in this study who required surgery; 3 underwent removal of extruded fragments, and 1, a single-level fusion. Additionally, 3 of these 4 were found to peripheralize only during all initial test movements.
In a prospective, randomized, multicenter study, Donelson et al [4] examined 145 patients with low back pain with or without referred lower extremity pain. Patients underwent a repetitive motion evaluation consisting of sagittal-plane motions only, such as standing flexion/extension, lying supine/prone, and supine flexion/extension (knee to chest/prone press-up). Forty-seven percent of patients experienced pain centralization; 40% improved with extension and worsened with flexion, whereas 7% improved with flexion and worsened with extension. They suggest that limiting the study to sagittal motions only, without lateral or rotational movements, contributed to the lesser prevalence of centralization in this study compared with the previous work (47% vs 87%).
Long [7] investigated 223 patients with chronic low back pain (average 8.79 months' duration) with or without lower extremity pain. Each patient underwent McKenzie assessment and was classified as either a centralizer or a noncentralizer. In all, 105 patients (47%) were classified as centralizers, and 118 (53%) as noncentralizers. At follow-up, the centralizer group had a significantly greater decrease in maximum pain intensity ratings on the NRS-101 pain scale. Centralizers also had a significantly higher return-to-work status at 9–month follow-up (68.4% of centralizers vs 52.2% of noncentralizers).
In perhaps the most interesting study of centralization to date, Donelson et al [5] compared the clinical findings of centralization and peripheralization during McKenzie examination with findings on diskography. They studied 63 patients with chronic low back pain with varying degrees of lower extremity pain and altered sensation. On McKenzie examination, 31 patients (49.2%) were classified as centralizers, 16 patients (25.4%) as peripheralizers, and 16 patients (25.4%) as having no change. Seventy-four percent of the centralizers had positive diskograms, and 91% of these positive diskograms demonstrated annular wall competence. Sixty-nine percent of the peripheralizers had positive diskograms, but only 54% of these positive diskograms demonstrated annular wall competence. Only 12.5% of those showing no change had positive diskograms. In this study, McKenzie assessment was able to distinguish between positive and negative diskograms. In patients with positive diskograms, the assessment also was able to distinguish between those with a competent annulus (centralizers) and those with an incompetent annulus (peripheralizers only).
Delaney and Hubka [8] applied further statistical analysis to this Donelson study. They showed that for the centralizers or peripheralizers only, the McKenzie assessment had a sensitivity of 94% for detecting discogenic pain, and 100% for detecting an incompetent annulus. For the peripheralizers only, the McKenzie assessment had a specificity of 82% for detecting discogenic pain and 86% for detecting an incompetent annulus.
In a study of the relationship between Waddell's nonorganic signs, centralization, and return to work, Karas et al [9] examined 126 consecutive low back pain patients, with or without leg pain. Centralization occurred in 73.0% of patients (92/126), and low Waddell scores occurred in 82.5% of patients (104/126). A greater number of patients who centralized (n = 104) returned to work than patients who did not centralize (n = 34). A greater number of patients with low Waddell scores returned to work than patients with high scores (104 vs 22). Among those with low Waddell scores, the probability of returning to work increased with centralization.
Sufka et al [10] examined 36 patients with acute to chronic low back pain and varying degrees of lower extremity pain. Twenty-five patients (69.44%) showed complete centralization within the 14–day test period, and 11 patients (30.55%) did not centralize. Centralizers had significantly greater improvement in Spinal Function Sort scores than noncentralizers (mean of +50.76 vs +14.9). Centralizers also had a greater decrease in Oswestry scores, but this was not significant (mean of ?20.4 vs ?10.2).
Werneke et al [11] conducted a prospective descriptive analysis of the centralization phenomenon in 289 patients with low back pain or neck pain, with or without extremity symptoms. For all patients, 30.8% were classified as centralizers, 23.2% as noncentralizers, and 46% as having partial reduction. Centralizers averaged significantly fewer visits (3.9) than those with partial reduction (7.7) and noncentralizers (8.0). Centralizers and those with partial reduction had significantly greater improvement in pain intensity (0–10 point scale) and perceived function (Oswestry or Neck Disability Index) than noncentralizers. Werneke et al suggested that because of the lack of consensus regarding the definition and documentation of the centralization phenomenon, previous reports have overestimated its prevalence.
Riddle and Rothstein [12] demonstrated poor interexaminer reliability (κ = 0.26; percentage agreement of 39%) among 49 physical therapists in classifying 363 patients into McKenzie syndromes. However, because of variations in terminology used by the therapists, they were unable to analyze the data to determine agreement on centralization or peripheralization.
Fritz et al [13] demonstrated good reliability in determining whether centralization, peripheralization, or neither had occurred. Among 40 physical therapists evaluating the videotaped movements of 12 patients, the agreement was κ = 0.823; percentage agreement of 89.7%. Razmjou et al [14] demonstrated good reliability between 2 physical therapists for classifying patients into McKenzie syndromes (κ = 0.70; percentage agreement of 93%). However, when centralization or peripheralization occurred, the reliability was excellent (κ = 0.96; percentage agreement of 97%).
In summary, the above literature supports the following statements:
Centralization occurs with a frequency of 30.8% to 87%.
There is good to excellent interexaminer reliability regarding assessment of centralization.
A single preferred direction of motion typically results in centralization.
Patients whose symptoms can be made to centralize have a better prognosis for response
to conservative care than patients whose symptoms cannot.Centralization and/or peripheralization indicates discogenic pain.
Pain that centralizes likely arises from a disk with a competent annulus; pain that peripheralizes
but does not centralize likely arises from a disk with an incompetent annulus.
Treatment methods
The decision to perform chiropractic spinal manipulation in this group of patients was based on assessment of the centralization response to provocation testing. Triano [15] described provocation testing as a method to verify the appropriateness of a given manipulative procedure at a given spinal unit. Provocation testing involves positioning the patient for the manipulative procedure and applying incremental forces up to, but not exceeding, the end barrier of passive range of motion. This is analogous to mobilizing the joint through Grades I through IV movement as described by Maitland. [16]
In terms familiar to most chiropractors, this is analogous to repeatedly taking the joint up to the point of “tension” without thrusting. The patient's response to such motion is assessed; sharp pain, muscular guarding, or reproduction of symptoms is considered an indication that the given procedure is inappropriate. [15, 17]
In this case series, provocation testing was enhanced by incorporating an assessment of the centralization phenomenon. Procedures that peripheralized symptoms suggested that further movements in that direction, either mobilization or manipulative thrusting, were contraindicated.
Procedures that centralized symptoms suggested that further movements in that direction, either mobilization or manipulative thrusting, were appropriate. Consistent with the McKenzie system, [1, 2] this was followed even if the procedure that decreased leg pain caused an increase in local low back pain.
When a procedure that centralized symptoms was identified by provocation testing, the decision was made either to treat the patient with mobilization only, or to use an HVLA manipulation consistent with the given procedure. At this time, evidence is lacking to accurately guide the practitioner in making that determination. In this case series, the more severe and acute cases, as well as patient apprehension about manipulation, indicated the use of mobilization first.
The chiropractic manipulative procedures used have been well described elsewhere. [18–20] They are commonly classified as side-posture adjustments. Triano [18] has demonstrated that the mamillary push, hypothenar ischial, and long lever side-posture manipulations deliver different force and moment magnitudes to the spine. Furthermore, variation in patient prepositioning for the same procedure was also shown to vary the forces acting on the spine.
All patients were also treated with ultrasound and manual stretching and/or massage of the lumbosacral region on most visits. These were always performed before the manipulation, and there were no significant differences in these therapies among patients. The patients generally reported that these therapies made their back muscles feel looser but had no effect on their leg pain.
The 2 patients whose pain could be made to centralize upon provocative testing had excellent outcomes to chiropractic care. The 1 patient whose pain only peripheralized on provocative testing had a poor outcome to chiropractic care and required surgery. All 3 patients had MRI evidence of significant intervertebral disk disease. The 1 patient whose pain only peripheralized was seen to have multiple free fragments.
Conclusion
The following observations were noted here:
The centralization phenomenon was a valuable prognostic finding. The 2 patients whose lower extremity
pain centralized had better outcomes to chiropractic spinal manipulation than the 1 patient
whose pain did not centralize.The centralization phenomenon was used as an indicator of the appropriateness of a given chiropractic
side-posture spinal manipulation maneuver.Regarding side-posture spinal manipulation decision making, the centralization phenomenon was
the most valuable examination finding used. This was considered more important than any traditional
system of palpation, radiographic analysis, or other means of determining a “listing.”These observations, although coming from only 3 cases, are highly related to the more extensive literature on centralization and the McKenzie method in general. Particularly noteworthy is the reliability and prognostic value that has been demonstrated for the centralization phenomenon. Because there is currently no chiropractic spinal manipulation examination procedure that has been shown to have significant reliability or validity, [21–25] this may have important implications for chiropractic treatment.
There are several limitations with this study. First, like any small case series, the results are not generalizable to other populations of similar patients. Second, there was no attempt to control for other therapies used in addition to manipulation. It is possible that the different pain medications or slight differences in manual soft-tissue therapies used in each case may have affected the outcomes; however, clinical experience suggests that these types of therapies alone are not likely to significantly affect the degree of discogenic disease seen in these cases. Third, the gold standard used to classify these patients with discogenic disease was MRI. Although impractical for routine clinical practice, the additional findings of diskography would have given more information regarding nuclear morphology, annular integrity, and pain generation.
In summary, assessment of the centralization phenomenon provided valuable diagnostic and prognostic information regarding chiropractic side-posture manipulation in this case series. Future research is needed to determine the relevance of the centralization phenomenon to chiropractic manipulation in other populations. This should include larger groups of subjects with controlled delivery of treatments.
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