INTER-EXAMINER RELIABILITY OF THE INTERPRETATION OF PARASPINAL THERMOGRAPHIC PATTERN ANALYSIS
 
   

Inter-examiner Reliability of the
Interpretation of Paraspinal
Thermographic Pattern Analysis

This section is compiled by Frank M. Painter, D.C.
Send all comments or additions to:
   Frankp@chiro.org
 
   

FROM:   J Can Chiropr Assoc 2015 (Jun);   59 (2):   157-164 ~ FULL TEXT

Barbara A. Mansholt, DC, MS, Robert D. Vining, DC,
Cynthia R. Long, PhD, Christine M. Goertz, DC, PhD

Associate Professor, Clinic,
Palmer College of Chiropractic
barbara.mansholt@palmer.edu


INTRODUCTION:   A few spinal manipulation techniques use paraspinal surface thermography as an examination tool that informs clinical-decision making; however, inter-examiner reliability of this interpretation has not been reported. The purpose of this study was to report inter-examiner reliability for classifying cervical paraspinal thermographic findings.

METHODS:   Seventeen doctors of chiropractic self-reporting a minimum of 2 years of experience using thermography classified thermographic scans into categories (full pattern, partial +, partial, partial -, and adaptation). Kappa statistics (k) were calculated to determine inter-examiner reliability.

RESULTS:   Overall inter-examiner reliability was fair (k=0.43). There was good agreement for identifying full pattern (k=0.73) and fair agreement for adaptation (k=0.55). Poor agreement was noted in partial categories (k=0.05-0.22).

CONCLUSION:   Inter-examiner reliability demonstrated fair to good agreement for identifying comparable (full pattern) and disparate (adaptation) thermographic findings; agreement was poor for those with moderate similarity (partial). Further research is needed to determine whether thermographic findings should be used in clinical decision-making for spinal manipulation.


From the FULL TEXT Article:

Introduction

Doctors of chiropractic (DCs) use complex clinical decision- making when determining where, when, and when not to perform spinal manipulation. [1] Factors considered may include the diagnosis, symptom severity, presence of co-morbid conditions, patient preferences, and other examination findings [2, 3] such as static or segmental motion palpation, [4, 5] posture analysis, leg length analysis, [6] biomechanical interpretation of spinal radiographs, the presence of spinal/paraspinal tenderness, and abnormal muscle tone. [7] Some chiropractic spinal manipulation techniques, particularly those focusing on upper cervical manipulation, use thermographic and other diagnostic instruments to provide primary information to determine whether treatment should or should not occur. [8] The use of unique diagnostic instrumentation is not new to the chiropractic profession. B.J. Palmer, considered the “developer” of chiropractic, used an instrument called the electroencephaloneuromentimpograph and later, the neurocalometer. [9] The neurocalometer was the predecessor of the current nervo-scope, which is still used by some practitioners using the Gonstead technique system. [10, 11]

A few studies indicate that there may be some potential for thermography to provide information suggestive of underlying physiological processes [12] that may help inform spinal manipulation decisions. [13] Roy reported changes in paraspinal surface temperature (comparing one side to the opposite side) using infrared thermographic methods following spinal manipulation. [14, 15] These findings suggest that paraspinal cutaneous and/or subcutaneous blood perfusion may be altered following spinal manipulation. However, without further study, it is unclear if these findings represent specific physiological mechanisms initiated by the manipulation or simply from normal changes over time or from tissue perturbation.

One application of thermography used by some practitioners, referred to as “pattern analysis,” is the interpretation of a series of skin surface temperature recordings obtained over the cervical spine. Similar thermographic findings obtained several hours apart are thought to suggest spinal dysfunction, which presumably contributes to a diminished autonomic response to external environmental cues resulting in muted adaptive changes in cutaneous and/or subcutaneous blood flow. [8] The theory behind this interpretation is based on the following physiological principles:

1)   skin temperature can serve as an indirect gauge of autonomic function, [16]

2)   small variations in skin temperature over time suggest that the autonomic nervous system is appropriately functioning by adapting to an ever-changing environment, [17, 18] and

3)   normal or abnormal environmental adaptation can be estimated by comparing sequential skin temperature measurements.

When an individual is “adapting” to their surroundings, it is assumed that autonomic mechanisms are functioning normally, resulting in subcutaneous blood flow change over time, detectable with thermography. [19] Abnormal spinal function (vertebral subluxation complex) is thought to adversely impact spinal joints and neurological function, and initiate a compensatory neurovascular response( s) causing joint motion restriction, muscle contraction, vasomotor changes, and localized tenderness. [20, 21] Due to an impaired ability to maintain homeostasis over nearby spinal regions, these changes can potentially result in static thermographic findings.

A paraspinal thermographic “pattern” is determined when multiple scans, obtained over a period of several hours, reveal similar or identical temperature findings. When this occurs, autonomic malfunction is assumed to be caused by upper cervical spinal dysfunction and manipulative treatment is then considered appropriate. If few or no similarities exist between thermographic scans over several hours, a static pattern cannot be designated and treatment is usually considered unnecessary. [22]

Establishing the reliability of a measurement tool is a necessary first step in determining whether information gained from its use can be used in a clinically meaningful way. Several authors have reported on the reliability of surface thermography in a chiropractic setting. [18, 19, 23-26] Though thermography appears to reliably measure temperature, stable readings are dependent on strict environmental control [27, 28] and a single paraspinal measurement procedure has not yet been extensively tested, leading a recent systematic review to conclude that evidence is unfavorable for paraspinal skin temperature to be used to locate the site of manipulation. [29] However, the literature does not yet adequately address whether paraspinal skin temperature readings can inform a clinician regarding the need for spinal manipulation. Before that question can be logically answered, it is first necessary to determine if clinicians are able to interpret paraspinal thermographic findings consistently. In other words, what is the inter-examiner reliability with respect to interpreting paraspinal thermographic findings?

The purpose of this study was to determine the inter-examiner reliability of interpreting paraspinal thermographic findings. Study findings are needed to help determine whether thermography can be a tool that informs clinical decision-making for spinal manipulation and to provide useful data to chiropractic educational institutions and practitioners seeking information that further informs evidence- based clinical practice.


Methods

Institutional review board approval for this project occurred in June 2011 through Palmer College of Chiropractic, IRB Assurance # X2011-6-15-M. The use of de-identified study data was determined exempt according to 45 CFR 46.101(b)(4); informed consent was obtained from the DCs who participated. The study was conducted from August of 2011 through January of 2012. This study complies with reporting standards as recommended by the Guidelines for Reporting Reliability and Agreement Studies (GRRAS). [30]

This study used thermographic scans obtained in a separate clinical trial conducted to determine the effectiveness of upper cervical chiropractic manipulation on stage 1 hypertensive patients during February through June of 2010, NCT 01020435. [31] Paraspinal cervical scans were performed using the Tytron C-3000 (Titronics Research & Development, Oxford, Iowa), as follows:

1)   participants were instructed to avoid caffeine for 2 hours and tobacco for 4 hours prior to assessment;

2)   upon arrival to the study site, participants acclimated in a room maintained at 70-75 degrees for approximately 15 minutes;

3)   during the scan, participants sat with their head flexed slightly to allow exposure of the cervical area with the feet flat and hands resting on the thighs; and

4)   the examiner moved hair away from the posterior neck (when present) with one hand, held the paraspinal thermographic scanning instrument with the other hand, and obtained measurements between the vertebral prominence (T1 area) and the base of the occiput. The entire procedure lasted approximately 30 seconds.

The resulting scan image appeared on a computer screen and consisted of 3 lines. The left line (or channel) represented the temperature gradient on the left paraspinal region from T1 to occiput; the right line (or channel) represented the temperature gradient on the right paraspinal region; and the center line (Delta) graphically displayed the difference between the right and left readings. Prior to recruiting DC participants, de-identified scan pairings (2 scans from a single participant with at least 24 hours between scans), viewable on a computer monitor, were randomly selected. The final set included 17 scan pairings, which DC participants reviewed and classified.

      Participant recruitment and eligibility

DCs self-reporting a minimum of 2 years of experience working with the Tytron software and using pattern analysis as a primary treatment indicator on a majority of their patients were eligible for this study. DCs were recruited at a chiropractic college event during a technique review class – a class that emphasizes the theories and application of thermography and pattern analysis. Knowledge of the study spread by word of mouth, and additional DCs volunteered over a period of six (6) months. Chiropractic college faculty DCs involved in teaching or research of pattern analysis or Tytron software were eligible if they met the above criteria. Basic demographic information was collected to determine eligibility.

      Participant interpretation of scans

Interested DCs completed the basic demographic survey to determine eligibility. When eligibility was confirmed, interested DC participants signed an informed consent document. DC participants were instructed to classify each scan pairing (left channel readings, delta readings, and right channel readings) into one of the following categories (see Figure 1):

  1. Pattern:   3 lines are the same
  2. Partial (+):   2 lines are the same and the 3rd line is similar
  3. Partial:   2 lines are the same
  4. Partial (-):   1 line is the same
  5. Adaptation:   3 lines are different


Figure 1.   Thermographic scans.


Lines in each column represent temperature readings over the cervical spine.
Left column = left cervical spine region,
Right column = right cervical spine region,
Center column = average of left and right readings.

Blue lines represent a static thermographic reading “pattern” obtained over the cervical spine (established by more than 1 reading over a ≥ 24 hour period) and overlaid with a current reading represented by green, red, or orange lines.
Categories are based on subjectively comparing a patient’s designated “pattern” (blue lines) with current findings (green, red, or orange lines).

Examples of scans representing categories used in this study are displayed:
Adaptation = completely dissimilar,
Partial (-)= modest similarity,
Partial = moderate similarity,
Partial (+) mostly similar,
Full Pattern = virtually identical.


Participating DCs either met in person or corresponded via e-mail and telephone with the lead author (BAM). All were provided the study objectives, instructions for participants and categorical classification definitions. If participants completed the study in person, they were guided through the Tytron software, viewed the scan pairings on the Tytron software, and categorized the scan pairings on the data collection form. The remainder of DCs received an Adobe® PDF file of scan pairings with written instructions and the scan analysis data collection form. DC participants designated each scan into one of five categories, and returned the data collection form via e-mail. Each participant viewed 17 unique scan pairings.

      Data Entry and Analysis

Both the scan pairings and the DC raters were samples of convenience. The data were double key-entered and exported to and analyzed in SPSS for Windows (Version 17.0.0, SPSS, Inc. Somers, NY). The multi-rater unweighted Kappa statistic [32] and 95% confidence intervals based on Fleiss’ corrected standard error [33] were calculated overall and for each of the 5 categories. Because SPSS does not calculate Kappa and associated confidence intervals for the multi-rater case, we used a publicly available SPSS macro. [34] Kappa statistics (k) were interpreted according to Fleiss: k>0.75 was considered excellent, 0.40 ≤ k ≤ 0.75 was fair to good agreement, and k <0.40 was poor or less than expected by chance. [35]


Results

Seventeen DCs participated in the study, reporting use of the Tytron software a mean of 7.7 years (SD 4.5). Five DCs viewed scan pairings in person; 12 viewed scan pairings and returned the scan analysis form via e-mail. DCs reported using Tytron analysis as a primary clinical decision- making indicator on a mean of 82% of patients. While practicing DCs used various spinal manipulative techniques, 14 primarily focused their treatment on the upper cervical region, 7 of whom reported using upper cervical manipulative procedures exclusively. Five DCs held chiropractic college faculty positions (Table 1). Overall inter-examiner reliability was fair, k=0.43 (95% CI 0.38, 0.47) (Table 2). Reliability coefficients were highest for the individual categories of full pattern (k=0.73) and adaptation (k=0.55), and lowest for partial pattern (k=0.05).


Table 1:   Demographics of doctors of chiropractic interpreting thermographic scan pairings (n=17).
Female/Male 3/14


Table 2:   Kappa (k) statistics measuring inter-reliability [kappa] statistics of thermographic pattern identification.



Discussion

To our knowledge, this is the first study investigating inter-examiner reliability of interpreting thermographic pattern scans as taught and practiced by a few chiropractic techniques (e.g., Toggle Recoil or Blair) focused exclusively on the cervical spine. Though paraspinal thermography has been studied in chiropractic settings, strong evidence demonstrating how it can be best used clinically is currently lacking, in part because of wide variations in how these findings are interpreted to relate to abnormal physiological states.

One method of interpretation compares paraspinal skin temperature at single vertebral levels from the occiput to the sacrum, i.e., segmental analysis. Findings potentially indicate subsurface hyperemia from abnormal physiology such as unilateral hypertonic muscle contraction or local inflammation; [12, 23] another method compares the temperature of the right and left mastoid fossa (slightly anterior and inferior to the mastoid process) as an indicator of general health.36 Hart investigated paraspinal thermographic patterns and thermographic mastoid fossa temperature differences with patient health perceptions. However, no definitive conclusions were reached regarding a relationship between mastoid fossa temperature and health perceptions. [36-38] Hart also recently proposed a statistical approach to tracking a patient’s paraspinal thermographic mastoid fossa findings, which has not yet been validated. [39] Brown explored the association between mastoid fossa temperature findings and paraspinal thermographic patterns, concluding that mastoid fossa asymmetry does not necessarily co-exist with paraspinal thermographic patterns. [40] Roy identified statistically significant temperature changes at the L5 vertebral level after a lumbar side posture manipulation when compared to a sham treatment. [15]

Thermographic pattern interpretation differs significantly from “segmental” analysis because it assumes the ability to adapt to a changing environment (homeostasis) will result in disparate sequential time-delayed findings. According to this theory, these differences suggest normal physiological function and thus, no need for treatment. A patient’s “pattern” is established when multiple scans, obtained over a period of several hours, reveal similar or identical temperature findings. Subsequent readings are compared to this “thumbprint” pattern to determine the need for additional treatment. If completely similar, the patient is considered to be non-adapting, and treatment to the upper cervical spine is indicated (see example “pattern,” Figure 1). If completely dissimilar, no treatment is indicated (see example, “adaptation,” Figure 1). Partial categories are defined to clarify readings on the continuum between the two clear readings – perhaps where many clinical presentations fall. When a “partial” reading appears closer to the patient’s pattern (but not completely similar), a practitioner may rely on a few additional clinical findings (static or motion palpation findings, postural abnormalities, tenderness, or muscle tone) to determine the need for treatment. Conversely, when a “partial” reading appears closer to adaptation, a practitioner may determine clinical findings are present. Note “partial +,” “partial,” and “partial -,” in Figure 1. This study found inter-examiner reliability for identifying or interpreting “partial” patterns to be very poor. Thus we recommend reducing to three categories (pattern, partial, and adaptation).

If reliability regarding this interpretation classification system is established, further investigation is needed regarding its validity. With this pattern interpretation theory, a patient’s adjustment is considered “successful” if the consistent static readings (pattern) begin to change after treatment. Future studies should focus on whether pattern readings do change after treatment, as well as whether pattern vs. adaptation readings correlate with patient outcomes.

Thermography provides relatively reliable and objective information compared with other measures used in a clinical exam such as motion palpation.4 However, the results of this study indicate that there is substantial subjectivity in interpreting thermographic findings creating a challenge with utilizing the information gained in a consistent and clinically meaningful manner. Thus, largely due to the need for additional evidence, there does not appear to be a consensus on how thermographic findings should influence clinical decisions regarding spinal manipulation.

This study identified “full” or “adaptation” reliability as good and fair, respectively. If the use of this instrument in education and practice will continue, research should focus on the validity of its use. Further, clinical outcomes based on this form of clinical decision-making have not yet been reported, and more research is needed to determine if inter-examiner reliability can be enhanced (by increasing the participation, providing more rigorous standardized training, and reducing the number of category classifications) or whether clinical decisions based on this technology are associated with clinical improvement.


Limitations

This study used a convenience sample consisting of self-reported experienced DCs in the use of thermographic pattern analysis. However, there are currently no criteria other than years of experience by which to determine relative expertise. The method by which each DC viewed the scans (i.e., consecutive on PDF v. guided through software) may have had an effect on the results of their interpretation. Future studies may want to include DCs who use this method, regardless of how often, and those who do not. Study findings from a sample size of 17 also limits the generalizability of results. Further, as the scans were performed on patients being assessed for stage 1 hypertension, it may be argued that the scans were not representative of typical chiropractic patients.


Conclusion

Overall inter-examiner reliability of thermographic findings was fair. Although the reliability of those designated as “pattern” (completely similar to a reference scan) was good, reliability of those designated as “adaptation” (completely dissimilar to a reference scan) was fair, and there was poor agreement for scans with partial similarity. These findings indicate that other clinical findings should be relied upon to determine treatment necessity. Further research is needed to better understand if treatment decisions based on thermographic findings are related to clinical outcomes.


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