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7 Articles in Volume 1, Issue #5
Accidentally Speaking
Breaking Down the Barriers of Pain: Part 5
Cancer Pain: Successful Management of Patients’ Fears
Emergency Medicine: Emergency Department Protocols
Magnets & Medicine
The Neural Plasticity Model of Fibromyalgia Theory, Assessment, and Treatment: Part 3
Thinking About Pain

Accidentally Speaking

Car accident survivors are a driving force behind the increase in soft tissue injuries seen by pain clinicians.

In the blink of an eye a routine trip to the grocery store, taking the kids to school, or going to work can turn into a deadly situation. Each day thousands of lives are changed by motor vehicle accidents (MVA).

The death rate per miles driven is on the decrease thanks in part to the development of an Emergency Medical Service (EMS) system. This system provides on site stabilization and supportive transportation to emergency equipped hospitals. Many people who would have died during an accident are now being cared for and safely transported by ambulance or helicopter lifelines. The odds of surviving an automobile accident have never been better.

In addition, the development of safer cars and improved safety systems adds to the increased likelihood of crash survival. To meet consumer demands, new car manufacturers have gone to great extremes to redesign automobiles to save lives. Without a doubt the multi-billion dollar investment by the government and private industry has paid off in lives spared.

Safer designs and efficient EMS systems have also changed society. Car accident victims who may not have previously survived are now living with soft tissue injuries. Clinicians are expected to correctly diagnose and treat these conditions and help restore a pain free quality of life. This quality must try to mimic the pre-accident condition of the survivors. In essence, issues change from purely medical to medico-legal.

The diagnosis and treatment of soft tissue trauma as a result of MVAs is an area in which all clinicians find common ground. Injury mechanism and injury patterns are consistent with the involved type of tissues. In other words, tissues respond according to the energy transmitted and their physiological make up rather than the educational degree of the treating clinician. It’s imperative that clinicians of all disciplines understand these common patterns and predictable human tissue responses to better serve injured patients and improve communication with third parties.

Thresholds for Soft Tissue Injuries

There are no set thresholds for human hard or soft tissues under which injuries never exist or above which injuries always exist. While parameters can be estimated, all injuries to individuals are anecdotal and individual responses will vary greatly according to numerous factors. According to a study by Seigmeund, et al.1 peak head acceleration varied almost 100 percent with the same subject, same seats, same vehicles, and same vehicular Delta V (5 mph Delta V) impact. As a result, it is impossible to determine individual injury potential strictly by estimating the impact velocities of the involved vehicles. The cost of car repair or amount of damage to the components of automobiles cannot be used to determine individual human response. While logic would dictate that there is more injury potential to the occupants at a 90 mph closing speed as compared to a 10 mph closing speed, the personal occupant injury response must be measured as it is found. In fact, each automobile collision categorically consists of three separate collisions.

Collision I — Vehicle to Vehicle

Determining closing speed estimates and injury potential to vehicles can be fairly accurate. A forensic engineer may be able to measure, objectively demonstrate damage, and draw conclusions regarding vehicle impact velocity. Still one must be careful when correlating data extracted from a controlled crash test to a non-staged automobile accident. Slight alterations in impact velocity, angle of impact, and a myriad of other variables leads to wide variations in vehicle damage, forces generated, and even cost of repair. Individual crash tests are considered entities unto themselves and often cannot be accurately compared. The effects of Collision I cannot be used to predict the effects of Collisions II and III.

Collision II — Occupant to Vehicle

The resulting motion of the occupants can only be demonstrated in strict test conditions utilizing high-speed film and carefully located cameras and sensors. Occupant reaction and motion are often not accurately reproducible even under the strictest of conditions and results vary greatly from occupant to occupant even within the same crash test. There has never been a published study that accurately demonstrates human motion in automobile collisions outside of strictly controlled tests under artificial conditions. Data gathered from staged crash tests indicates approximate guidelines only, not definitive answers, and should never be used to predict or determine individual injuries.

Collision III — Human Body Parts

This collision is the most overlooked aspect of automobile accidents but is the most important in actual injuries. This aspect of the collision and the resulting damage is determined much the same way as I and II. While the first two collisions are measured by forensic engineers and computerized devices, medical personnel measure the third collision. In the same manner as forensic engineers, the clinicians measure, objectify, and draw conclusions from human tissue, which they are trained to diagnose and treat. Their job is much the same as the crash test engineers only they are trained to interpret human tissue instead of man-made materials. Just as medical personnel cannot draw conclusions about the amount of damage to a car using human tissue damage or the cost and time to repair (heal), forensic engineers, insurance adjustors, or attorneys cannot draw conclusions regarding human tissue trauma based upon damage or the cost of repair to automobile components such as bumpers. On the other hand, clinicians cannot look at individual injuries and make generalizations about other accidents or even about injuries to other occupants involved in the same accident. Injury patterns to humans do exist in the same manner as injury patterns (damage) to automobiles but general assumptions to predict human injury or lack thereof cannot be assumed.

Factors Which May Influence Individual Injuries

Occupant position

Occupant position at time of impact is one of the most critical aspects determining human injury potential. Small variations of occupant positioning can result in large increases of impact forces transmitted to the injured areas.2

The position in which crash test dummies are seated is not often the position in which humans feel comfortable while driving. Humans change positions almost constantly when seated for periods of time to help distribute loads. Factors that influence injury potential to a given area can change almost instantly. Individual vulnerability at the precise moment of energy transfer during impact (.1-.2 sec.) is immeasurable in mathematical terms and can only be ascertained after the fact by symptomatic complaints and clinical assessment.

Occupant position at time of impact is one of the most critical aspects determining human injury potential.

Delta V

Delta V, or change in velocity, is another major factor in human soft tissue injury. According to Newton’s first law of motion, within each “body” lies the potential to remain at rest or remain in motion. Energy must be expended to cause a change in the state of motion. Each body part reacts uniquely under loading conditions and the resulting motion will be different according to the individual mass, structure, and absorption potential. For instance, when external forces are applied to the human head/neck complex, a differentiation of motion will exist between the head, mandible, and neck. Further inspection indicates even further relative motion between the components that make up the segments. Each vertebrae, cervical disc, ligament, condyle of the TMJ’s (both right and left), skeletal muscle, etc. will react and move differently than its attachment. This Delta V creates strain/stress at the hard and soft tissue junctions — a “lag” time that creates injury potential. The result is a tearing, stretching, bruising, and /or crushing at these junctures.

Occupant Size

Occupant size may affect individual outcomes as well, not only in total body weight, but segmental lengths as well. A short arm, short-legged individual may have his or her seat closer to the steering column. As a result, there is considerably less of a neutral zone between the torso and the steering column or airbag than a person with longer arms and legs. A longer, thinner-necked occupant of a target vehicle (struck from behind) with poor head restraint may have more injury potential in a very low impact rear end collision than an individual with a short, thick neck in the same circumstances.

Pre-existing Conditions

Pre-existing conditions also influence a crash. An occupant with cervical arthritis or degenerative disc disease may receive a greater degree of injury or resulting pain when compared to a non-diseased person under the same circumstances. An individual’s ability to go through a physiologic or even a non- physiologic range of motion without micro injury or pain may be altered by a large number of factors. This is not to say that a history of cervical dysfunction means that the occupant was already injured and that a rapid acceleration of the neck could not cause the patient to have an increase in pain or exacerbate sub-clinical conditions in an otherwise quiescent situation. Too many times the term “pre-existing” is used as an excuse to deny coverage or undermine a clinician’s diagnosis and treatment. Correlation of current conditions, causation, and the role of pre-existing conditions can only be made by a hands-on clinical assessment, record review, and patient history. A paper or radiographic review to determine a level of pain or soft tissue injury by a third party is inaccurate at best.

Common Injuries of the Head and Neck

Clinicians with a trained viewpoint must understand the principles of injury during clinical assessment. No matter which body region is the clinician’s specialty, the reasons for injury and physiologic reactions are similar. Therefore such conditions will remain relatively constant in all areas of the body and have much commonality.

The following soft tissue injuries are commonly seen in acceleration situations such as those found in rear end motor vehicle accidents:

  • Cervical Facet Joint Inflammation
  • Cervical Sprain/Strain
  • Occipital Neuralgia (greater and lesser)
  • Mayospasm
  • Myofascial Trigger Points (MFTP)
  • Temporomandibular Joint
    Dysfunction (TMD)
  • — Reducing and non reducing disc displacement
  • — Posterior and or lateral capsulitis
  • Temporal Tendonitis
  • Ernest’s Syndrome (insertion tendinosis of the stylomandibular ligament)
  • Ligamentous tears/strains

While each of these injuries has different names and clinical presentations, all have similarities due to the common origin of the forces that causes them to be stressed in a manner beyond their physiological ability to adapt, resulting in damage, dysfunction, and pain.

Diagnosis and Treatment

A correct and accurate diagnosis of soft tissue injuries can be elusive. It’s important for the clinician to have an understanding of the mechanisms of injuries giving them direction in which to begin investigation. Obviously injuries at a point of direct impact such as the chin to a steering wheel or an airbag, a forehead or knees to the dashboard, or the neck to the headrest should be primary areas of consideration of soft tissue damage. Junctures between hard and soft tissues are other areas of potential damage due to a crushing mechanism between hard and soft tissues. These areas include the spinal column, the TMJs, wrists, ankles, etc. The mechanisms of injury are common throughout regardless of the human anatomy involved. To diagnose a patient’s potential multiple sources of pain, a multi-disciplinary approach often must be utilized. Development of a treatment team, each according to their discipline, is essential to clinical success.

After an accurate diagnosis is rendered, effective treatment can ensue. Conservative therapy can help alleviate most soft tissue injuries and the resulting pain and dysfunction. These modalities include medications such as NSAIDs (including Cox 2 inhibitors), muscle relaxers, analgesics, and antidepressants. Therapeutic mobilization of the injured tissues by a physical therapist, osteopath, or chiropractor, along with ice, moist heat, and various electrical modalities can often reduce localized inflammation, promote healing, and achieve a goal of returning the injured area to a normal range of motion. More aggressive treatment such as trigger point injections, radio frequency thermoneurolysis, or surgical intervention, while effective, should be approached with caution and utilized only after conservative methods have proven ineffective.

Summary

Understanding the biomechanics and occupant kinematics of motor vehicle accidents is essential for the clinician who actively treats soft tissue injuries. While new car safety has greatly increased the chance of survival, unique diagnostic and treatment challenges have also appeared. As the complexity of the injuries increase, the complexity of the whole treatment situation with all its implications increases as well. To help achieve a pain free life for survivors a multidisciplinary approach must be utilized for comprehensive care. n

Last updated on: December 22, 2011
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