DWI identifies tissue change due to prolonged ictal activity in stroke-related epilepsy

Background: DWI has been shown to detect acute ischemic lesions and also to detect early tissue changes related to ictal activity. Focally reduced water diffusion and lactate accumulation result from metabolic compromise due to prolonged ictal overactivation. Several studies have demonstrated reduced ADCs in patients with complex partial status epilepticus (CPSE).

Methods: We report 10 patients with acute unexplained prolonged clinical deficits (mean 5.3h) – (e.g. hemiparesis, somnolence, confusion) and a differential diagnosis of focal cerebral ischemia and/or CPSE. Patients had a history of chronic territorial stroke, cerebral microangiopathy or acute cerebral ischemia. Repeat EEG and MRI were performed, the latter included DWI and PWI aligned with the hippocampal formation.

Results: On preexisting tissue damage MRI showed acute hemorrhage (n=2), acute ischemia (n=2), chronic territorial stroke (n=3) and cerebral microangiopathy (n=3). Besides these findings DWI identified additional acute hyperintensity in the cortex, the hippocampal formation or the pulvinar of the thalamus or combinations of these. In 6/10 hyperperfusion of these regions was shown. All patients had EEG confirmed diagnosis of CPSE which was reversible after adequate treatment.

Conclusions: We present 10 patients with prolonged reversible clinical features and EEG findings correlating frequently exactly to the site of acute DWI abnormalities indicating that consequences of prolonged focal epileptic activity were detected by DWI and PWI. This multiparametric MRI phenomenology has all the potential to be used clinically for the assessment of acute neurological symptoms to differentiate between ischemic and ictal tissue changes.