The etiology and relationships between different forms of malformations of cortical
development are poorly understood. Schizencephaly is generally regarded as unrelated
to arachnoid cysts. As part of a systematic study of epilepsy in twins we observed
a monozygotic twin pair discordant for temporal lobe epilepsy where the twin with
epilepsy had unilateral temporal schizencephaly and periventricular heterotopia. The
twin without epilepsy had an arachnoid cyst in the same temporal lobe. Although an
incidental association is possible, this observation, together with occasional reports
of schizencephaly and arachnoid cysts within one individual, suggests a shared pathogenic
mechanism. Schizencephaly can be caused by both genetic and acquired factors. We propose
that our observations in this twin pair are best explained by a genetic factor present
in both twins, with an additional environmental insult resulting in schizencephaly
in only one of the pair.
Temporal lobe epilepsy - Magnetic resonance imaging - Twins - Schizencephaly - Arachnoid
cyst
