Stroke Vignette

Cerebrovasc Dis 2001;12:282

The Preserved Cortical Island Sign Is Highly
Predictive of Postischemic Seizures
Bernd Pohlmann-Eden, Marc Fatar, Michael Hennerici
Department of Neurology, University Clinic Mannheim,
University of Heidelberg, Germany

Underlying cerebrovascular lesions are the most common reason
for late-onset seizures in the elderly, accounting for up to 25% of
these cases [1]. Todd’s paresis following postischemic seizures (PS)
may worsen preexisting neurological deficits and lead to the misdiagnosis of recurrent stroke. Identification of these patients is important
for counseling and treatment issues.
We report the case of a 68-year-old woman with a history of lefthemispheric ischemic stroke 6 years earlier, who presented with an
acute aggravation of her right-side hemiparesis and aphasia that
resolved in the first days after admission. In the second and third
year after her stroke, the patient had already suffered two definite
epileptic seizures. Magnetic resonance imaging (MRI; fig. 1) including diffusion-weighted sequences revealed preserved cortical islands
(PCI) within an extended subcortical-cortical area of infarction,
without any signs of a new ischemic event. These results – along with
the clinical course and the electroencephalographic evidence of a
rhythmic theta-delta focus in the left temporoparietal region – led us
to the diagnosis of postictal Todd’s paresis; a treatment with antiepileptic agents was initiated.
From our experience, patients with extended combined cortical
and subcortical lesions leading to a critical interaction of these structures are at risk for PS. This relationship was confirmed by a prospective, electroencephalography- and MRI-based study in acute stroke
patients [2]; furthermore, the pattern of PCI was frequently observed
in an analysis of postischemic ‘first-seizure’ patients [3]. As illustrated by our case, patients in this special subgroup with PCI that we
refer to as the PCI sign seem to be at a particularly high risk for developing PS, emphasizing that a critical mass of intact neurons within
the infarcted area is necessary to generate an epileptogenic lesion.

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© 2001 S. Karger AG, Basel

Accessible online at:
www.karger.com/journals/ced

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References
1 Pohlmann-Eden B, Hoch DB, Cochius JI, Hennerici M: Stroke and epilepsy – Critical review of the literature. 1. Epidemiology and risk factors. Cerebrovasc Dis 1996;6:332–338.
2 Pohlmann-Eden B, Mager RD, Hoch DB, Cochius JI: The significance of
subclinical epileptiform activity after stroke; in Stalberg E, Deweerd AW,
Zidor J (eds): Neurophysiology. Bologna, Monduzzi, 1998, pp 523–532.
3 Pohlmann-Eden B, Schreiner A, Hornung T: Predictive value and morphological pattern of cerebrovascular lesions in patients presenting with a first
‘unprovoked’ seizure. Ann Neurol 1998;44:468.