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Gulf War and Health, Volume 7: Long-Term Consequences of Traumatic Brain Injury
Clinical Studies. Despite continuing efforts of the International Brain Injury Association, the Brain Injury Association of America, and other international and national surgical and neurosurgical associations, there is no consensus about the management of patients who have suffered brain injury caused by missiles and other penetrating objects. The lack of consensus could underlie apparent discrepancies in clinical studies concerning diagnosis, therapy, and rehabilitation of patients with penetrating TBI (Blissitt, 2006; No Author, 2001a, 2001b; Pabuscu et al., 2003). For example, there are differing opinions about the usefulness of decompressive craniotomy, a method to convert the confined-space skull into an open one by removing part of the skull (Sahuquillo and Arikan, 2006); use of hypertonic saline solution vs mannitol in posttraumatic brain-edema treatment; aggressive vs less aggressive debridement of the wound (Taha et al., 1991; Levy, 2000; Tong et al., 2004); and treatments of CSF leaks, a frequent consequence of penetrating head wounds (Brandvold et al., 1990; Aarabi et al., 1998). Guidelines that have a sound scientific basis are necessary to achieve a consistent approach to the management of penetrating TBI patients.
Diffuse Brain Injury
As described above, movement of the brain caused by sudden acceleration followed by deceleration, in which the inertial effect depends on the brain mass and determines the extent of tissue deformation, has been identified as one of the most important mechanisms of diffuse brain injury (Ommaya and Gennarelli, 1974; Adams et al., 1989). In military settings, diffuse brain injury is often caused by tertiary blast effects (for example, a body flying through the air and hitting other objects), which then contribute to the complexity of BINT. Diffuse axonal injury, characterized by morphologic changes in axons throughout the brain and brainstem, has contributions from both primary and secondary injury mechanisms, and is recognized as one of the main consequences of nonmissile TBI leading to the diffuse degeneration of cerebral white matter (Adams et al., 1989). It is noteworthy that the distribution of the types of diffuse axonal injuries seen in BINT are substantially different from that of TBI of nonblast origin (Cernak et al., 2001b). The most common locations involve the brainstem, the cerebellum, gray matter–white matter junctions, and the internal capsule.
SEVERITY SCORING OF BLAST INJURIES AND TRAUMATIC BRAIN INJURY
Severity Scoring of Blast Injuries
The severity of injuries inflicted by explosive weaponry is usually scored by using the Abbreviated Injury Scale (AIS) or the Injury Severity Score (ISS). The AIS was first reported in 1971 for classification of anatomic injury from motor-vehicle collisions (Committee on Medical Aspects of Automotive Safety, 1971); it was not designed primarily to measure penetrating injury and high-velocity ballistic injuries. In an attempt to develop an improved injury-scoring system, the ISS was derived from the AIS and the Comprehensive Injury Scale, both of which were established to measure anatomic injury (Baker et al., 1974). The ISS correlated well with survival of the multiply injured blunt-trauma patient (Bull, 1978), but a similar relation for penetrating and war or gunshot injuries was not seen (Beverland and Rutherford, 1983) until the 1985 version of the AIS (American Association of Automotive Medicine, 1985). That was important not only for the improvement of injury scaling of blunt trauma but as an extension that made it possible to include penetrating injuries. The last revision of the AIS (AIS, 2005) contains