MRI findings: Coronal T2W and T1W images showing
hyperintensity of the left hippocampal gyrus, with evidence of mild atrophy
as evidenced by mild dilatation of the ipsilateral temporal horn (on T2WI).
It has been postulated that mesial temporal sclerosis may be related to
a complicated delivery, febrile convulsions during childhood, and status
epilepticus. These circumstances are believed to cause metabolic disturbances
in neurons in the hippocampus, which may disappear and be subsequently
replaced by gliosis.
The MR criteria include: increased signal in the hippocampus (which is
the most consistent finding), a decreased size of the hippocampus (which
is the second most common finding), atrophy of collateral white matter
adjacent to the hippocampus, enlargement of the temporal horn, diminished
gray-white matter demarcation in the temporal lobe, and reduction in size
of the temporal lobe. Coronol T2 weighted images allow for the best visualization
of the abnormality. Unilateral dilatation of the hippocampal or choroidal
fissure of the temporal horn is a common noramal variant and not necessarily
indicaative of hippocampal atrophy.
Deepak Patkar, MRI Centre, Nanavati Hospital, Mumbai