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 Chapter
1. An accident reconstruction primer
Dr. Croft, a graduate of the prestigious Northwestern University’s Traffic Institute’s comprehensive program on accident reconstruction, teaches physicians the essentials of reconstruction of low speed rear impact crashes (LOSRIC). Very few of the current schools of accident reconstruction do justice to this subject. He’ll teach the most sophisticated and accurate methods currently available and, perhaps just as importantly, the limitations of reconstruction in this special area of low speed crash. He’ll cover Newton's laws of motion, vehicle dynamics, conservation of linear momentum methods, restitution and energy methods, barrier equivalent methods, computer methods, and the practical application of those laws to the understanding vehicle dynamics and occupant kinematics. Dr. Croft will also discuss the application of data retrieved from event data recorders (ERD)—the vehicle’s on-board black box—and his own research from years of crash testing. He will also go beyond classical reconstruction and correlate these reconstructions with occupant kinematics and known risk factors: a dimension in which classically-trained accident reconstructionists, biomechanists, and engineers are not trained. With a good comprehension of the principles taught in this section, along with the risk factor analysis material and other information presented in Module 1, physicians will have the necessary intellectual tools to assess the relative validity and credibility of most reconstructions and biomechanical analyses pertaining to LOSRIC. A final section critically examines the uncertainty of LOSRIC reconstruction and presents both mathematical (log-differential) and practical ways of assessing the reliability and validity of these reconstructions based on the data from which they were constructed.
This section will discuss the critically important historical information pertinent to motor vehicle crashes: what questions to ask, what information to collect and how, and what degree of detail is necessary. Dr. Croft will emphasize the historical data necessary to provide not only optimal medical/chiropractic care, but also to ensure that a comprehensive record of pertinent facts is available for forensic purposes when needed. Attendees will learn to use a standardized history form developed by Dr. Croft. From this, concise and comprehensive case reports can be produced, as will be developed in great detail in Module 3. Moreover, in cases in which permanent residuals result, it is important to make a determination concerning apportionment of any pre-existing disability that may have been present. Dr. Croft will present a standardized, scaled lexicon for severity and frequency of symptoms for general use and for use in apportionment questions. This method is formula-based and is highly dependent on accurate historical data.
In this section, attendees will review all of the important general and special examination procedures and methods, including neurological (sensory, deep tendon and superficial reflexes, motor, visual, and coordination), orthopaedic, and cognitive examination methods. Dr. Croft will discuss the use of the SCL-90-R and all of its dimensions, the postconcussion syndrome examination, and vestibular tests. He’ll also discuss musculoskeletal exam procedures, special tests, such as those for the TM joint, CTS, and TOS; tests to rule out malingering (including the AMA’s methods of assessing repetitive ranges of motion vs. the coefficient of variation methods), and the most scientific way of estimating probable normal ranges of motion using published regression equations.
Dr. Croft will discuss guideline-based radiographic procedures in terms of what views to obtain and when. He will also discuss the sensitivity and specificity of radiography in terms of its limitations in the diagnosis of both fractures and soft tissue injury, comparing emergency department films (e.g., cross-table laterals) with clinic-based films (e.g., standing 7-view studies). He’ll contrast cost containment issues with physician accountability and responsibility. He’ll additionally review the various established methods of stability assessment of motion films, using mensuration schemes as well as templating protocols, and he’ll point out their relative validity. Some are as recent as 2003. He’ll discuss the cervical curve and the SRISD’s ongoing research in that area.
CT technology remains the test of choice in the acute situation for conditions such as serious brain trauma. It is also still an important imaging study for fracture and other conditions. These are discussed in this section.
Dr. Croft will discuss some of the emerging applications of MRI, such as motion MRI and MRI neurography, as well the limitations of this technology in CAD trauma. It is now emerging that special techniques, such as proton density-weighted MRI, are required to visualize the various ligamentous components of the cervical spine and that certain cervical ligaments are better viewed using T2-weighted fast spin echo sequences, while others are better appreciated using T1-weighted sequences. Despite this, however, recent cadaver research highlights the shortcomings of even high resolution MRI in the detection of some cervical soft tissue lesions. Dr. Croft will discuss the most recent and relevant studies. He will also contrast the sensitivity of CT, MRI, and SPECT for brain injury.
In this section, Dr. Croft will review the advanced diagnostic imaging modalities which are available to clinicians today, including intravenous contrast-enhanced MRI and CT, arthrography, discography, videofluoroscopy (VF), radionuclide bone scan, single photon emission computed tomography (SPECT), positron emission tomography (PET), and color-coded duplex sonography (CCDS). The relative strengths, weaknesses, and clinical indications of each will be described. An algorithm for choosing specific tests will be developed. In this section, Dr. Croft will also review the natural history of disc disease and the prevalence of herniation among the asymptomatic population in both cervical and lumbar spines—another area rife with misinformation.
In this very comprehensive section, Dr. Croft begins with a foundational discussion of relevant neuropathophysiology which segues into an easily understood synthesis of the currently available electrodiagnostic tests which are potentially useful in CAD trauma. These include various forms of electroencephalography (EEG), brain stem auditory evoked response (BAER), visual evoked potentials (VEP), electronystagmography (ENG), brain electrical activity mapping (BEAM), electromyography (EMG and sEMG), nerve conduction velocity (NCV), and somatosensory evoked potentials (SSEP). Discussions will always include the modality’s relative strengths and weaknesses and clinical indications/contraindications. As always, tables are provided for convenient reference.
This section provides a summary and simplification of the myriad of imaging, electrodiagnostic, and other tests that are currently available on a condition-by-condition basis. For example, for MTBI, imaging studies include CT and MRI, SPECT can be used to evaluate perfusion, PET can be used to evaluate the brain’s metabolism, and potentially useful electrodiagnostic tests include QEEG, BEAM, VEP, ENG, BAER. Other available tests include chemosensory evaluation, audiologic evaluation, polysomnography, and posturography. All are available in most areas of the country.
Here Dr. Croft considers the methods of developing working, differential, and final diagnoses. This will include assembling sensible and accurate diagnoses encompassing stage, causation, condition, and complications. This is an indispensable skill which many practitioners have yet to completely master. Emphasized here are the skills required to provide clear, concise, unambiguous, and accurate communication of your objective assessment of the patient’s condition(s). Dr. Croft cautions, for example, against the use of poorly defined terminology, and against commonly misused diagnoses.
In this section, the various stages of healing are discussed: inflammatory, subacute, repair, and remodeling. The physiological processes involved in each are clarified as a prelude to latter sections of this Module.
In order to provide the most effective treatment intervention, it is first necessary to stage the injury in terms of its stage of healing. This section provides the basis for this process.
Meaningful communication between physician and patient is critical in securing patient compliance, and successful resolution of injuries is heavily dependent on patient compliance, particularly in terms of activities of daily living, stretching and exercise, and maintaining recommended treatment regimens. Patients are more inclined to follow the physicians advice, for example about home care, if they clearly understand the goals and potential benefits of that care. Dr. Croft emphasizes honest and straightforward communication with patients, avoiding the unrealistic or overly sanguine expectations commonly espoused by some authorities, while also avoiding pessimism or negativism at the other end of the spectrum. This section includes a risk-based discussion of informed consent pertaining to spinal manipulation along with a brief presentation of Dr. Croft’s published research on arterial injuries attributed to spinal manipulation.
Here, Dr. Croft discusses the CAD treatment guidelines he developed in 1992, and how to use them. These guidelines have been widely adopted in the U.S. and Canada. Grading the severity and staging the injury are important components discussed here, as well as how to deal with common complicating factors. Dr. Croft will tie in a recap of known risk factors from Module 1 here because they figure into the grading system and the topic of maximal medical improvement (MMI). Also covered are when to use cervical collars and special pillows, when to institute home cervical traction and/or exercise programs, and effective nutraceutical interventions.
Here, Dr. Croft clarifies an often neglected component of care which can have considerable positive effects on outcome. This section includes coverage of issues such as ideal bedding, low-stress chairs, computer reading glasses, adequate lighting, good spinal posture, low-stress ergonomics, and therapeutic exercise and stretching; how they can adversely affect the patient’s recovery and how their modification can hasten recovery and reduce overall health care costs and disability rates. While these factors can very significantly affect the outcome, they are subjects rarely broached in adequate detail by most health care practitioners when communicating with their patients.
This section, which addresses the special issue of spinal manipulation and its indications and contraindications, also details the special particle repositioning maneuver for treating cases of vertigo attributable to canalithiasis/cupolithiasis.
Dr. Croft will run through the gamut of physiotherapeutic modalities commonly used in CAD trauma: how they work and what they can do, therapeutically, for the patient. These modalities include ultrasound, diathermy, heat, cold, TENS, cold laser, low and high voltage galvanism, microamperage stimulation, interferential stimulation, electroacupuncture, and spinal traction.
This is an overview written by Dennis Steigerwald, DC, one of the leading chiropractic TMD experts in the multidisciplinary management of the TM joint. He and Dr. Croft authored a textbook on the subject several years ago.
In this final section of Module 2, Dr. Croft revisits the staging and grading systems from previous sections and fits this into the accepted doctrine of MMI, making simple work of this frequent conundrum.
Spine Research Institute of San Diego, Inc. Voice: (619) 423-9867 or (619) 423-5475 |
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In-depth
training on all aspects of management of trauma, from beginning
to end; a comprehensive primer
on crash reconstruction.
Coronado, CA 92118
| Copyright © 2007 Spine Research Institute of San Diego. |