The postconcussional syndrome reappraised.

Despite the apparently benign nature of mild head injury, reflected by the short post-traumatic amnesia duration, relative absence of CNS signs and brief hospital stay, a significant number of patients report persistent symptomatology over the weeks or months afterwards. Largely subjective in nature, such symptom clusters are termed the postconcussion syndrome. The discrepancy between the predominantly subjective complaints and negative examination findings has generated uncertainty and debate about the respective causation roles of organic and psychogenic factors. Over the past 30 years evidence for organic brain changes has accumulated through studies of cerebral circulation, neuropsychological deficits, evoked potential recordings and neuroimaging. This paper reviews data from two UK prospective studies of the evolution and course of postconcussional symptomatology using parallel psychosocial, neuropsychiatric, quantitative EEG and brainstem auditory evoked potential recordings. Changes in theta power occurred early with resolution within 10 days. Prolonged brainstem evoked response I-V intervals were seen in between 27% and 46% of patients. Symptom chronicity noted in a minority of people (13%) was associated with a high prevalence of brainstem dysfunction, while the degree of QEEG recovery appeared to relate to the intensity of early symptom reaction to the trauma. Levels of perceived stress at the time of the injury or afterwards were not related to symptom formation, but chronic social difficulties were a feature of the 21% of patients who initially improved but had a late exacerbation of symptoms between 6 weeks and 6 months after the trauma.