Controversies of mild traumatic brain injury

The experimental and scientific understanding of mild traumatic head injury (MTHI) has evolved over the past twenty years, with a plethora of research being generated and documented within the scientific literature. At the same time, clinical experience across multidisciplinary lines has increased as health care professionals have continued to interact with this population of patients. It has recently been estimated that approximately two million people annually in the United States experience closed head injury (Brown, & Fann, 1994). Closed head injury represents a significant cause of morbidity and mortality, especially within the younger populations. This has resulted in a considerable increase in health problems associated with the residual sequelae of closed head injury.

Epidemiological studies have documented that within the incidence of closed head injury in general, injuries that are classified as mild or minor typically account for the greater percentage of cases evaluated in emergency room and out patient settings (Goodwin, 1989). This is also the case outside the United States, where estimates range as high as eighty percent (Cohadon, Richer, & Castel, 1991).

While the current body of research literature and experience from clinical practice has provided a greater understanding of MTHI, there continues to be controversy with respect to definition and classification (Kibby, & Long, 1996). Any approach for neuropsychiatric and/or neuropsychological evaluation of MTHI must take into account the confusion that exists in understanding this injury as it is differentiated from more severe injuries and from other neuropsychiatric disorders. Earlier attempts at defining the parameters of MTHI have been seen in the research literature (Colohan, Dacey, Alves Rimel, Jane, 1986, Davidoff, Kessler, Laibstain, & Mark, 1988). The Mild Traumatic Brain Injury Committee of the Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine has proposed definitive guidelines, which have been utilized by the research community in more recent studies (Kay, et al, 1993). More current proposals for classification of the spectrum of MTHI have also been suggested (Esselman & Uomoto, 1995).

Despite the clearer definitive guidelines, there continues to be clinical confusion in evaluating and understanding the pathophysiology, symptomatology, and differential diagnosis of MTHI. The use of the terms postconcussive syndrome (PCS)and posttraumatic syndrome (PTS) has been used to describe the pattern of symptom presentation seen in this population of patients. However, this has not led to a clearer understanding of MTHI with respect to evaluation and assessment. In addition, there have been suggestions that mild head injuries should be differentiated from mild brain injuries. Furthermore, there is often the development of secondary psychiatric disorders that may have a physiological and/or psychosocioenvironmental basis, typically referred to among clinicians as psychological overlay, that complicate the clinical presentation of MTHI and make the evaluative process more complex.

Clearly, the greatest scientific and clinical controversy has been associated with the postconcussive nomenclature (Binder, 1986, Lowden, Briggs & Cockin, 1989, Alves, Macciocchi, & Barth, 1993, Kibby & Long, 1996). In general, PCS has been understood to represent the synergistic and interactive effects of physical, cognitive and psychological symptoms seen upon clinical presentation. The assumption is made that there may be physiologic, pharmacologic, psychologic, socioenvironmental, circumstantial, and medicolegal bases underlying the perpetuation of symptomatology. There is also typically a presentation of chronic pain syndrome that may have both physical and psychological factors contributing to the pattern of symptoms and complaints. Neuropsychiatric and neuropsychological evaluation of these patients presents the clinician with a complex task of deciding how to explain the nature of PCS and more importantly what to recommend with respect to treatment.

There is also disagreement among researchers and clinicians as to the duration of PCS and what factors predispose individuals to developing a persistent PCS. Within this context, the issue of premorbid factors such as personality characteristics, past psychiatric history, previous substance abuse, prior incidence of MTHI, and general health problems certainly appears to have an influence on the chronicity of symptoms (Goodwin, 1989).

Because of the confounding issues inherent in the diagnostic assessment of the MTHI patient, a comprehensive time based neuropsychiatric evaluation is proposed to clinically deal with the complexities seen in this patient population. Such a time based evaluation process may not always be necessary, but in cases where there are confusing diagnostic differentials, a time based approach will be helpful in guiding the clinician through the evaluation process. The time based approach will be presented later on in this chapter.

We further propose a neuropsychiatric nomenclature and classification based on the practical aspects of evaluation, which are more meaningful to the clinician in everyday practice. These clinical distinctions should not be considered distinct entities, but rather as clinical aspects of a dynamic post head trauma spectrum that can be useful in guiding the clinician in the evaluation process. We will attempt to integrate current research findings and clinical experience into a methodology for neuropsychiatric evaluation that is first of all useful to the patient and secondly reflects clinical acumen and multiclinical diversity.