Diagnosing Mild Traumatic Brain Injury (MTBI) in the Whiplash Patient
Whiplash injuries are a common sequela of motor vehicle collisions. Symptoms of whiplash include neck pain, back pain, headaches and pain or paresthesia in the upper extremities. A less common, but often more life altering result of whiplash is mild traumatic brain injury (MTBI). MTBI may also be referred to as closed head injury or post concussion syndrome. Trauma sustained in motor vehicle collisions (MVCs) is the single most common cause of both fatal and mild brain injuries, causing 67% of all cases.
The mechanism of MTBI is thought to be the stretching or shearing of axons. An axonis a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron’s cell body. This injury involves damage to individual neurons and loss of connections among neurons which can lead to a breakdown of overall communication among neurons in the brain. In motor vehicle crashes, axonal shearing is the result of excessive forces generated by the rapid change in direction of the head secondary to vehicle acceleration upon impact.
MTBI and post concussion syndrome are often associated with direct trauma to the head. This, however, is not necessarily the case in motor vehicle collisions. The unique forces generated in these collisions are sufficient to injure brain cells in the absence of direct trauma. Collision speeds of 7-10 mph are sufficient to cause symptoms of MTBI. In fact, cognitive and emotional deficits from MTBI may be more prevalent in less severe injuries than those with greater trauma and more prolonged loss of consciousness.
Symptoms of MTBI include headaches, dizziness, nausea, ringing in the ears and blurred vision. Emotional symptoms may include irritability, anxiety, depression and sleep disturbances. A typical chronology of this syndrome is that of relatively few symptoms at the time of hospital or emergency room discharge. Symptoms increase in frequency up to 90 days post trauma. Thereafter, many symptoms tend to improve with time. Headaches, dizziness and cognitive problems tend to persist for longer periods and may lead to chronic disability.
Since standard diagnostic tools such as MRI and CT are not helpful in diagnosing MTBI, it must be diagnosed via a multi-faceted clinical approach. Open ended questions about symptoms following a motor vehicle collision also result in the under reporting of symptoms due to confusion on the part of the patient as to the varied nature of their complaints. Physician intake forms should have a checklist of the more common symptoms associated with MTBI. If multiple symptoms are checked the clinician should suspect MTBI. The next clinical step is to differentiate pre and post injury symptoms. A good tool for this is the Rivermead Post Concussion Questionnaire.
The Rivermead test consists of two sections. The first section (RPQ-3) consists of three items (headaches, feelings of dizziness and nausea) and the second section (RPQ-13) contains items including sleep disturbance, fatigue and poor concentration. The total score for RPQ-3 items is potentially 0-12 and is associated with early clusters of MTBI symptoms. If there is a higher score on the RPQ-3, earlier reassessment and closer monitoring is recommended. The RPQ-13 score is potentially 0-52, where higher scores reflect greater severity of MTBI symptoms. The RPQ-13 items are associated with a later cluster of symptoms, although the RPQ-3 symptoms of headaches, dizziness and nausea may also be present. The later cluster of symptoms is associated with having a greater impact on participation, psychosocial functioning and lifestyle. The Rivermead test should be repeated at 60-90 day intervals. Persistent high scores warrant further testing by a neuropsychologist.
Neuropsychological evaluation for MTBI consists of a battery of questionnaires and tests designed to describe and quantify changes in cognition, personality, emotional functioning, behavior and to monitor functioning over time.
Due to the subjective nature of many of the complaints attributed to MTBI, the issue of malingering is often associated with these cases. Clinicians must be aware of this and properly document any inconsistencies with patient history, activities of daily living and reports from family members. The many social and emotional issues that accompany a motor vehicle collision must also be factored into the diagnostic equation. The frustration of dealing with police reports, insurance claims and lost work often exacerbate MTBI symptoms.
The literature on whiplash and mild traumatic brain injury (MTBI) contains disagreements among authors regarding the type and severity of brain injuries that can and do occur following motor vehicle crashes. Despite disagreements, it is clear from the literature that brain injury can result from whiplash. The diagnosis of MTBI following whiplash injury is made based on the patient’s history, specific questioning on intake forms, clinical monitoring of symptoms, Rivermead questionnaire and neuropsychological evaluation results. Given the fact that relatively minor motor vehicle crashes can result in brain injury, often in the absence of direct head trauma, it is essential that practitioners evaluating these cases be aware of MTBI as a possible diagnosis.