Six patients (ages ranging from 19 days to 58 years; three females and
three males) with frontal horn coarctations are included into this st
udy. Four of these six patients were found during our consecutive eval
uation of 1022 cranial MR imaging examinations, obtained on a 0.5 Tesl
a unit. The condition was compared with ependymitis granularis. The si
zes (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 vent
ricular ependyma. Another patient was associated with unilateral megal
encephaly. We found a frequency of approximately 0.38 % for frontal ho
rn coarctation, and this is apparently lower than that (6 %) described
in previous CT studies. The frequency of ''ependymitis granularis'' w
as approximately 65.5 %.