Static Palpation of Muscle Imbalance as
Compared to Radiographic Evaluation of C1

From The Journal of Straight Chiropractic

By: Nicholas Spano, DC

Paravertebral hypertonicity has been documented in Chiropractic, Orthopedic and Osteopathic literature.1 Muscular tension has been noted upon physical examination of the spine to be associated with spinal misalignment, dysfunction and instability.   These observations have often been anecdotal and incidental to other more objectifiable findings.   It is most often assumed that the hypertonicity, even when found on only one vertebral level, represents spasm.  The inference is that continued muscular activity while the subject is at rest must be a pathological or a "facilitated state."2  That this activity is segmental in nature has only rarely raised suspicion as to the nature of such a localized spasm.   It has gone almost without question that the "spasm" is causally related to the subluxation.   Further, even when authors have suggested the reverse (i.e., that the muscle is an effect of the subluxation), they still often argued that this muscle activity is counter-productive.   It is my contention that resting segmental muscular activity is homeostatic in nature.   The muscles of the spine represent the active stabilization for the functional spinal unit.3,4  A disturbance in the three-joint complex stimulates proprioceptive neural sensory impulses that apprise the spinal cord and subcortical brain.5  The central nervous system could then stimulate guarding muscular action, seeking to reestablish functional balance.  This phenomenon may take place often and be involved whenever there is a difference between the actual and intended movement or position of a functional spinal unit.6,7  In this way resting activity of the muscles would be physiologic and protective in nature.  The mechanism which is thought to underlie such behavior is the stretch reflex.8  The muscles may be serving to return the misaligned segment to its "normal" position.   Such subtle muscle activity would also serve to alert the examining Doctor of Chiropractic as to the existence of the dysfunctional segment.   Presupposing the predictive value of this hypothesis and the accuracy of the palpator’s assessment, this method would also have value in determining the proper line of force application for the adjustment.   The purpose of this study was to understand paravertebral muscular activity and its ability to accurately predict misalignment patterns.


Methods

The examiner was instructed not to speak to the patients.   All the participants had been recently x-rayed.  Radiographic technique and analysis were is accordance with precise Grostic upper cervical methodologies.9 The examiner had no prior knowledge of the patients’ radiographic findings nor their case histories.  During the examination no verbal exchange occurred between the examining doctor and the participants.  No perception of tenderness, pain or symptoms was discussed.  Palpation pressure was minimized so as not to elicit any response from the patient of areas of tenderness.

Palpation was limited to the small paravertebral muscles of the two upper cervical vertebrae (see Table 1 ).  Examination was done with the subject supine, with the head in a neutral position, in which the muscles were assumed to be at rest.
 
 

Paravertebral muscles palpated in study
· Superior oblique
· Levator scapula (first branch) 
· Rectus capitis posterior minor
· Rectus capitis posterior major 
· Semispinalis cervicis
· Levator scapula (second branch)
· Scalenus medius 
Table 1
 

Resting muscles tension was discriminated from normal muscle tone during static palpation.  This assessment was then interpreted according to the untested predictive value of this tension to discern abnormal joint position (e.g., articular dysrelationships).  The anatomical relationship of the muscles to the vertebral motion segments and the theoretical muscular response to the suspected subluxation were assumed from the author's personal publication.  Therefore, palpatory conclusions were derived consistent with the typical muscle pattern activity models described by the author.8 This analysis resulted in a descriptive designation of the direction of malposition for the involved segment, commonly called "listings." The listing abbreviations used by the examining doctor were simplified into four categories and are described in Table 2.

 
Listing abbreviations used in study 
C-1 abbreviations: ASL, ASR 
C-2 abbreviations: PR, PL 
Table 2 

The findings were then recorded before the examiner had any knowledge of the previous radiographic findings.  Radiographic interpretation resulted in listing the involved level of the spine according to the Grostic upper cervical method.

The Palmer listing system describes the anterior and superior (in reference to the relative position of the anterior tubercle of the atlas vertebra) malposition of C-1; thus, "A" is the first letter and "S" (is often) the second to designate a C-1 listing.  "L" or "R" is used for describing the X-axis translation of left or right.  "A" or "P" may be appended as the last letter to define possible C- 1, Y-axis rotation.  These are comparative "movements" of malposition relative to the opposing side of the same segment.

This study was limited not only to the upper cervical spine but was also focused on translation in the transverse plane.  Therefore, palpatory examination was restricted to those muscles thought to demonstrate C-1 translation of left or right and did not take into consideration the muscles that might be used to evaluate the atlas for rotation about the Y axis.  Grostic listings included rotational findings as these findings were obtained prior to and not exclusively for the purposes of this comparison.


Results

The muscle palpation findings for all twelve of the patients are listed in Table 3.  Advanced Muscle Palpation and Grostic analysis concurred in ten of the twelve subjects studied (see Table 4).  There was total agreement between the two methods of evaluation in the X-axis translation of the atlas in four subjects.  Agreements occurred in five out of twelve subjects, designating the atlas as "clear" or "balanced." Although the Grostic upper cervical analysis does not concern itself with listing the C-2 vertebra, note was taken of the apparent axis rotation in two subjects.  On this basis, agreement occurred in two of the twelve subjects concerning the rotation of the axis vertebra.  In two of the subjects, analytical conclusions were reached for which Grostic upper cervical analysis and Advanced Muscle Palpation did not share a common listing.  Therefore, comparison of radiographic interpretation and muscle palpation resulted in total agreement in ten of twelve subjects.  The findings differed only where there was a difference in the subluxation dynamics between the two methods (i.e., where agreement was not possible).
 
 

Table 3


Discussion

Attempting to use the muscles of the spine as a criterion to determine the direction of segmental misalignment, and therefore an appropriate line of force for an adjustment, requires insight into the nature of the muscular activity involved and its relationship to joint dysfunction.  Is there an underlying cascade of influences that consistently produce muscular action in the resting spine? Furthermore, is this activity more definitive when it occurs on only one or two levels in any one region of the spine? To understand muscular forces acting on the spine, it becomes imperative to discuss the biomechanical dysfunction that precipitates them.  Segmental failure occurs as a result of instability of a functional spinal unit which is subjected to repetitive asymmetrical loading and movement.  Buckling of the spinal segments can take place with or without any internal disc disruption, which in turn produces unequal load sharing of the facets and further disturbed kinematics.11,12 Gertzbein revealed that the major abnormality of instability is erratic motion rather than excessive movement.13 Kirkaldy-Willis suggests that the earliest changes that take place in the facet joints is synovitis.14 This may well explain the added instability of the acute subluxation.  This mechanical dysfunction could then produce relative rotations and translations of the affected segment/s.

Excluding disc involvement (of which the atlas has none), facet effusion is also likely to imbalance C-1 function and set the stage for improper loading of the opposing facet and therefore fixation.  Misalignment of the articular structures is an inevitable result of spinal column short segment buckling, due to mechanical derangement of the connective tissues, including deformation of the articular surfaces (e.g., collagen/proteo-glycan gel matrix of the disc or facet cartilage).10,15 The implication is that fixation represents an inability "...for the vertebral motor units to keep in step with surrounding vertebrae..." or "come to rest naturally in any given posture."8 Thus, buckling can take place gradually with successive "cyclic or vibrational loading conditions...," but ultimately, "...the unstable Functional Spinal Unit is characterized by a decrease in stiffness and a resultant increase in motion under load; both the quantity and quality of spinal motions are altered; the buckling motion appears to occur faster than the muscles can respond..."10 Subsequent to any initial failure of the muscles to prevent the misalignment, it seems reasonable to assume a muscular response to a functional spinal unit (i.e., buckled).  It is likely that resting, segmental muscular activity is a response to mechanical stretch and derangement from the vertebral malposition.  The muscular guarding may be an attempt to reestablish facet and therefore vertebral position.  Where a distinctive "rest position"15 has not been recognized by research, it is undeniable that functional efficiency would demand that the vertebrae articulate according to the dictates of neural expectations.  The central nervous system employs reflex mechanisms to maximize the performance of subordinant structures.5 The stretch reflex is the dominate controlling factor of the musculoskeletal system16 and sets precise neural parameters with structural and functional considerations.  Concerning vertebral placement, only the muscle spindle can generate segment specific activity, whereas most of the other stimuli arise from afferent receptors which ultimately communicate polysynaptically with the paravertebral muscles."17,18 Although Kirkaldy-Willis equivocates on the subject of cause and effect, reflex, segmental muscular activity in the resting spine can be thought to guard the affected tissues of the dysfunctional segment.  He notes that "The posterior segmental muscles protect the joint by sustained hypertonic contraction."19
 
 

Patient Number
Grostic Analysis of C-1
Notation of C-2 Rotation from X-ray
AMP* Analysis of C-1
AMP Analysis of C-2
1
ASLA
Spinous Left
----
PL
2
ASLA
Spinous Right
ASL
PR
3
Clear
Clear
Clear
Clear
4
ASLA "Kink"
----
ASR
----
5
ASR
----
ASR
PL
6
ASLP "Kink"
----
ASR
PR
7
Clear
Clear
Clear
Clear
8
Clear
Clear
Clear
Clear
9
Clear
Clear
Clear
Clear
10
Clear
Clear
Clear
Clear
11
ASLP
----
ASL
PL
12 
ASLP 
---- 
ASL 
 ---- 
TABLE 4
*Advanced Muscle Palpation

Conclusion

The apparent corroboration of the independent methods of analysis in this small study seems to confirm the hypothesis that muscular hypertonus may have a role in guarding the functional spinal unit.  The obvious inference is the ability of this muscular "biobalancing" to predict subluxation location.  Even more intriguing are the implications for this mechanism to describe the type of joint dysrelationships.  This primary question was this: Can resting, segmental, reflex, muscular activity be understood and consistently interpreted? Although this is an admittedly small and uncomplicated study, it is an encouraging first step toward understanding muscular behavior of this kind.  These findings suggest a possible homeostatic phenomenon occurring among the paravertebral muscles associated with the vertebral subluxation.  Advanced Muscle Palpation has incorporated the misalignment model of the subluxation and in so doing has sought to describe vertebral "listings" using transversospinal and subocciptial muscular tension.

REFERENCES
1 Denslow, J.  S., Clough G H, "Reflex activity in the spinal extensors," Journal of Neurophysiology, V.  4:1941; 430- 437.
2 Denslow, J.  S., Hassett C C, "The central excitatory state associated with postural abnormalities," Journal of Neurophysiology, V. 5:1942; 393-402.
3 Dupuis, P.R., "Radiologic diagnosis of degenerative lumbar instability," Spine 10, No.  3:1985; 262-276.
4 Donisch, E.  W., Basmajian J V, "Electromyography of deep back muscles in man," American Joumal of Anatomy, 133: 26-36.
5 Cohen, H., Neuroscience for Rehabititation, J B Lippincott Company, Philadelphia 1993.
6 Mains, R. E., Soechting J F, "A model for the neuromuscular response to sudden disturbances," Journal of Dynamic Systems, Measurement, and Control, December: 1971;1.
7 Wright, J.  "Mechanics in relation to derangement of the facet joints of the spine," Archives of Physical Therapy,1944; 201-206.
8 Spano, N., The Innate Biomechanics of the Spine. Self published, l984.
9 Grostic, J.  D., Grostic Procedure Notes.  Self published,1993.
10 Weinstein J.  N., Wiesel S W, The Lumbar Spine, 614- 618, W B Saunders Company, Philadelphia 1990.
11 Panjabi, M.  M., Krag, M.  H., Chung, T.  Q., " Effects of disc injury on mechanical behavior of the human spine," Spine, V.  9, No.  7 1984; 707-713.
12 Jayson, M.  I.  V., The Lumbar Spine and Back Pain, Churchill Livingston, New York,1987; 51, 373.
13 Gertzbein, S.  D., et al, "Centrode patterns and segmental instability in degenerative disc disease," Spine, V.10, No.  3,1985; 257-261.
14 Kirkaldy-Willis, W.  H., "The relationship of structural pathology to the nerve roots," Spine, V.  9, No.1,1984; 49-52.
15 Haldeman,S., Principles and Practice of Chiropractic, Appleton & Lange, Norwalk, CT,1992; 248-251.
16 Grieve, G.  P., Modem Manual Therapy of the Vertebral Column, Churchill Livingstone, New York,1986; 500.
17 Wyke, B., "The Neurological Basis Of Thoracic Spinal Pain," Rheumatol Phys. Med., V.10,1970; 356-367.
18 Schafer, R.C.  Basic Principles of Chiropractic, The American Chiropractic Association, Arlington, VA, 1990; 270.
19 Kirkaldy-Willis, W.H.  Burton C V Managing Low Back Pain, Churchill Livingstone, New York, 1992.

I would like to thank Dr.  John Grostic and Life Chiropractic College, for the use of their research facility and cooperation.  I would also like to thank the students of Life Chiropractic College who participated in the study.