The Japanese journal of neuropsychology

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ArticleTitle	Organic neurobehavioral disorder after traumatic brain injury and psychoneurotic reaction -with respect to the role of neuropsychological tests-
Language	J
AuthorList	Hideaki Masuzawa
Affiliation	Kawakita Rehabilitation Hospital
Publication	Japanese Journal of Neuropsychology: 27 (2), 110-121, 2011
Received
Accepted
Abstract	Diffuse axonal injury is commonly characterized by loss of consciousness immediately after head impact, neurological findings, namely, cerebellar ataxia and spastic hemiparesis or quadriparesis, and neurocognitive/neurobehavioral disorder, such as memory deficit, dysexecution, aggressiveness and impaired self-awareness. They show definite tendency of gradual improving in the long span. Duration of the initial coma, gravity of the residual deficits measured by, for instance, Glasgow Outcome Scale, and degree of diffuse ventriculomegaly shown on CT/MR imaging are highly correlated each other. They are in dose-response relationship and on a continuum from mild to severe. Brain concussion and mild traumatic brain injury are the mildest form of diffuse axonal injury. They should not be isolated as if something different. Diffuse axonal injury is established as the main cause of sequelae after TBI (traumatic brain injury). However, it is occasionally misinterpreted as frontal lobe dysfunction by experts previously devoted in classic-type higher brain dysfunction and by those who simply believe in the frontal lobe myth. Distinction from non-organic post-traumatic neuropsychological reaction such as adjustment disorder and depressive state in cases of post-concussive syndrome and whiplash injury has recently become a major issue, especially in legal world. These are characterized by showing little improvement for years or even worsening episodes, keen self-awareness in seeking medical and legal support, and medically uncreditable neurological symptoms, and often predisposed by hypotensive-migraineous-perfectionist constitution. Neuropsychological tests are utilized to evaluate severity of the post-traumatic sequelae. It is often claimed that they can differentiate between organic and non-organic causes of the deficit. However, limitations do exist in neuropsychological tests such as dissociation from the real world behavior. Recent development of symptom validity tests and its impact on legal neuropsychology as well as on general neuropsychology is overviewed. Assessment of the symptom validity is not popular yet but is warranted in Japan for better objectivity and future development of scientific neuropsychology.
Keywords	diffuse axonal injury, mild traumatic brain injury, frontal syndrome, psychoneurotic reaction, symptom validity test