A neuropsychiatric perspective on traumatic brain injury.

INTRODUCTION Seen through the lens of the acute injury and its management, traumatic brain injury (TBI) would appear at first glance to be far removed from the concerns of what could properly be called neuropsychiatry. Rather, it might seem to be more a neurosurgical disorder or perhaps particularly relevant to conventional neurology or sports medicine. In the past 25 years, however, as acute management of both surgical and nonsurgical TBI has improved, impaired survivors have become increasingly common. And although these survivors face many different clinical issues, from epilepsy to motor problems to endocrine disorders, the TBI sequelae that affect their lives most profoundly are the chronic cognitive and behavioral problems that fall squarely within the domain of neuropsychiatry, a discipline that focuses on the relationship between the brain and its role in thinking, emotions, and behavior. Indeed, the paradigmatic historical patient for many of the core issues that now define neuropsychiatry was a young man from 19th century Vermont who survived a severe TBI. During the summer of 1848, a 25-year-old railroad construction foreman named Phineas Gage was directing a blasting operation to clear a path for laying new track across Vermont for the Rutland & Burlington Railroad. The operation went terribly awry, with the result that a pointed iron rod 3ft. 7 in. in length, 1 1/4in. in diameter, and 13 1/4 lb in weight was propelled through Gage's face and head by an errant explosion. The rod entered through his left cheek, continued up and through the base of his skull, traversed the anterior portions of his brain, and exited through the frontal bone at the top of his head. Remarkably, Gage survived both the wound and the subsequent infection with little in the way of adverse effects on his motor function, perception (save for the loss of his left eye), or intellect. Yet, as described in detail by Damasio on the basis of firsthand reports, Gage was an entirely different person after his physical recovery than he had been before [1]. Whereas previously he had been temperate, efficient, and capable, after the event he demonstrated aberrant social judgment, was unable to regulate his behavior normally, and could no longer use his various physical and intellectual strengths appropriately or effectively in the real world. However, while the relevance of Gage's disorder to the newly emerging field of neuropsychiatry was becoming evident, traumatic patients of that sort were uncommon. Today, by contrast, TBI is one of the largest public health problems for children and young adults in the United States [2]. Consequently, no modern broad-based review of neuropsychiatry can be complete without addressing the problem of TBI. Yet, paradigmatic as his case was, Gage's injury differed from the most common injuries of today in one important respect: it was a penetrating injury. In penetrating injuries, of course, the region of the brain penetrated puts its particular stamp on the nature of the chronic cognitive and behavioral sequelae that develop. Today's injuries, by contrast, are predominantly closed. Gage just happened to injure an area of the brain that is particularly vulnerable to the effects of closed injury and so his is a dramatic, if fortuitous, exemplary case. But other vulnerabilities exist in closed injuries that need to be accounted for in expanding our understanding of TBI beyond that provided by Gage's injury, instructive as his case has been. A major purpose of this article is the dissection of those vulnerabilities and the placement of them in the context of the neuropsychiatric insights derived from Phineas Gage's case. For several reasons then, I will focus on closed injuries in this article. First, they represent a major public health problem, as has already been pointed out, and understanding them provides clinicians with an important tool in addressing their neurocognitive and neurobehavioral consequences. …