To our knowledge, this is the first study to report that the prevalence of anatomical variants of the brain ventricles varies according to socioeconomic status, being those anatomic variants more often observed in patients from lower socioeconomic strata.
In our series, about 12.6% of the patients had at least one type of Cavum (when vestigial CSP are also included). CV and CVI were present in 3% and 3.5% of the patients in our series. CSP, and especially CV, when together with CSP, can be markers of brain malformations and neuropsychiatric diseases. Our numbers are also consistent with the same other neuroimaging studies that have evaluated the presence of the different anatomical ventricular variants in different countries[26, 31–33]. In general, cerebral Cavum were more prevalent in countries from Asia and less economically developed[20, 21, 34]. This is also another evidence that socioeconomic status may be an important risk factor for the development of brain malformations, including cerebral Cavum.
Although not strictly retrospective, the nature of our study prevents us to clear confirm this association, which was only indirectly inferred based on the differences in the distribution of high versus low-cost health insurance and the higher prevalence of neurocysticercosis and cerebrovascular disease in the hospital with the highest percentage of low-cost health insurance. Further studies based on prospective data collection and direct evaluation of salary and additional economic details are mandatory to answer this question.
Neuropsychiatric diseases are far more prevalent in lower socioeconomic status individuals, while CSP and other anatomical variants of brain ventricles are overrepresented in the population with neuropsychiatric diseases[20, 27, 29, 30, 36–38]. For instance, persons diagnosed with schizophrenia, alcohol, and victims of TBI have been found to have more frequent, longer, and wider CSP[39, 40]. Also, children diagnosed with Tourette’s syndrome may have significantly smaller CSP size; possibly also inversely associated with the severity of attention-deficit/hyperactivity disorder symptom severity. Finally, some robust associations between CSP and interpersonal traits of psychopathy seem to exist both in men and women[37, 42], including during earlier developmental stages in the form of conduct disorder, which may point towards a neurodevelopmental disruption within limbic structures with altered threat sensitivity and reduced neural responses during moral processing.
To our knowledge, our present results are also the first study describing the prevalence of cerebral cava in Brazil using a large sample. It is also important to stress, that almost all patients from our series had health insurance. Therefore, it is quite possible that the prevalence of cerebral Cavum is even higher in patients without health insurance or from lower socioeconomic status since most of the Brazilian population does not have private health insurance and must rely on a government-sponsored, public health system.
Another very interesting point that deserves to be stressed is that our study tends to mimic or represent the overall prevalence of cerebral Cavum in the middle and high class in Brazil since the prevalence in the groups with and without TBI were not statistically different. As we have previously pointed out, evaluating the prevalence in patients with TBI would more appropriately reflect the prevalence of cerebral Cavum in the general population, since the evaluation among different populations of patients with neurological diseases would include important bias towards the specific groups of neurological conditions.
Although no major demographic differences occurred between the two hospitals, it is important to emphasize that our results have some important limitations. First, this sample depicts the Brazilian middle-class population. Although both hospitals do accept low-cost health insurance, people from the lowest socioeconomic strata in Brazil were not strongly represented. Second, it would be desirable to directly evaluate each family’s income, a variable that unfortunately could not be directly obtained in our study, considering the retrospective nature consisting in restricted evaluation of collected medical records and request forms. Besides that, this was a cross-sectional evaluation of multislice head CTs. When comparing the neuroimaging literature based on imaging modality (MRI versus CT), CSP including vestigial CSP is less often detected using head CT than MRI. In MRI studies, vestigial CSP in the normal population may reach values around 84,9% and 83,7%, hence it is possible that this subgroup of vestigial CSP was under-represented in our study.