Cerebral lateral ventricular asymmetry on CT: how much asymmetry is representing pathology?

The purpose of this study was to evaluate the association of asymmetric lateral ventricle (ALV) with clinical and structural pathologies and assess its clinical importance.

We analyzed 170 consecutive ALV cases on computed tomography (CT) and 170 control group patients with normal head CT. Patients who had apparent etiologic causes for ALV were excluded. The differential diagnosis of ALV and unilateral hydrocephalus (UH) was made by using three different ventricle-brain ratios (VBRs). The measurements of the ALV were made at the frontal horn level. Patients with asymmetry were divided into three subgroups including mild, moderate and severe groups to eloborate the grade of the ventricular asymmetry. Additional CT findings including septal deviation, diffuse enlargement, atrophy and the densities of constant sites were also recorded systematically for each patient. Clinical and handedness data were collected and analyzed.

The prevalence of ALV in the study population was 6.1%. Headache was the most common reason for head CT examination and was significantly more common in the asymmetry group (61.7% in group A, 42.9% in group B, P = 0.001). Transient ischemic attack, focal neurologic findings, vertigo, ataxia, visual and hearing disturbances were similar in both groups (P > 0.5). There was no difference in smoking and alcohol habits in both patient groups. Ten (5.8%) patients in group A and 16 (9.4%) patients in group B had neuropsychiatric disorders, which did not achieve statistical significance. In group A patients, the larger ventricle was more common in the left side than in the right (left = 70.0%, right = 30.0%). Group A consisted of 57.0% mild (grade 1, n = 97), 26.5% moderate (grade II, n = 45) and 16.5% severe (grade III, n = 28) patients. There was no significant correlation between handedness and ALV. The density of different brain sites was found close similar on both sides in ALV and control group (P > 0.5). Choroidal cystic or solid neoplasm or periventricular dysplasia was detected in six ALV patients in group A (3.5%), on their additional MR examinations.

The physician should not overlook an ALV finding on unenhanced CT, particularly in cases with severe degree of asymmetry or diffuse ventricular enlargement, and search for possible accompanying disorders.