Bu. Meyer et al., MORPHOLOGY OF ACALLOSAL BRAINS AS ASSESSED BY MRI IN 6 PATIENTS LEADING A NORMAL DAILY-LIFE, Journal of neurology, 245(2), 1998, pp. 106-110
The pattern of anatomical features of the brain revealed by magnetic r
esonance imaging (MRI) is described in six patients incidentally ident
ified as having acallosal brains. The complex of morphological feature
s associated with complete agenesis of the corpus callosum included la
teral displacement of slit-like anterior hems of the lateral ventricle
s (bullhorn-like shape), dilatation of the posterior hems of the later
al ventricles, absence of the septum pellucidum, lateral displacement
of the cingulate gyri, complete separation of fornices and the presenc
e of the anterior commissure and longitudinal callosal bundles (Probst
's bundles). No compensatory enlargement of the anterior commissure wa
s seen in the patients. The planimetrically measured cross-sectional a
reas of the anterior commissures were between 2.0 and 4.2 mm(2) (mean
3.1) (in ten normal subjects they were 4.5, SD 0.4; range 3.8-5.2 mm(2
)) and were reduced in four and normal in two patients. Inconstant mor
phological features were an absence of the posterior commissure and a
radial pattern of the sulci and gyri on the medial aspect of the hemis
pheres. Conventional clinical testing revealed no abnormalities except
a slight impairment of walking heel-to-toe in two patients. None of t
he patients had subjective restrictions of activities of daily life, w
hich shows the efficacy of unknown compensatory processes.