MRI and asymptomatic coarctation of the frontal lateral ventricle horn.

Six patients (ages ranging from 19 days to 58 years: three females and three males) with frontal horn coarctations are included into this study. Four of these six patients were found during our consecutive evaluation of 1022 cranial MR imaging examinations, obtained on a 0.5 Tesla unit. The condition was compared with ependymitis granularis. The sizes (largest diameter) of the frontal horn coarctations varied between 7 to 18 mm. There were five patients with unilateral coarctation, and one was bilateral. In a patient the frontal horn coarctation resulted from the fusion of the left leaf of the septum pellucidum to the ventricular ependyma. Another patient was associated with unilateral megalencephaly. We found a frequency of approximately 0.38% for frontal horn coarctation, and this is apparently lower than that (6%) described in previous CT studies. The frequency of "ependymitis granularis" was approximately 65.5%.