This negative correlation, and the lack of specificity indicates that headache occurring 3 months or more after concussion is not caused by the head or brain injury. Rather it may represent an episode of one of the primary headaches, possibly induced by the stress of the situation.
In an earlier historical cohort study on the post-concussion syndrome (PCS) in Lithuania, a country in which there are few confounding factors, the validity of this condition as a disease entity could not be confirmed. In order to register the post-traumatic symptoms, the influence of sociodemographic factors, and the effect of expectation on these symptoms more reliably, we performed a controlled prospective study. Three hundred subjects with concussion were followed up with repeated questionnaires for 1 year. For each study subject, a sex- and age-matched control person with minor non-head injury was identified. These controls received similar questionnaires. Headache both after 3 months and after 1 year did not differ significantly between the head-injured participants and the non-head-injured controls. Several other symptoms attributed to PCS did not differ significantly between the groups after 3 months. After 1 year the vast majority of symptoms did not differ significantly. Exceptions were slightly significant differences concerning memory problems, concentration problems, dizziness and tiredness. These differences were insignificant when analysing symptoms in unmarried and/or people with lower education, separately. No relationship between cognitive dysfunction and the severity of concussion was found. Although the possibility of a mild organic brain injury cannot be completely ruled out, our results cast doubt on the validity of PCS as a useful clinical entity, at least for head injuries with loss of consciousness for <15 min. Sociodemographic factors and expectation seem to influence reporting of symptoms after concussion.
In Lithuania, expectation of chronic symptoms after minor head injury is less than in western countries and possibilities for monetary compensation are minimal. Therefore, an opportunity exists to study the post-concussion syndrome (PCS) without several confounding factors present in western societies. We sent questionnaires about symptoms attributed to PCS to 200 subjects who had a concussion with loss of consciousness between 35 and 22 months before the study. For each study subject, a sex- and age-matched control person with minor non-head injury was identified. These controls received similar questionnaires. All the responding post-concussion patients stated that they had had acute headache after the trauma but this headache had disappeared in 96% of cases within 1 month. Headache and dizziness at the time of the questioning were not significantly more prevalent in the patients with concussion than in the controls, and there was no significant difference concerning subjective cognitive dysfunction. Scores of visual analogue scales of symptoms attributed to PCS showed no significant differences except for depression, alcohol intolerance and worry about brain injury, which were more frequent in the concussion group. No specific effect of the head injury was detected when various definitions and different constellations of core symptoms of PCS were used. These findings question the validity of the PCS as a useful clinical entity.
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