Acute Symptomatic Seizure : Clinical and Experimental Studies

Abstract: Epilepsy is defined as a condition with recurrent unprovoked seizures. When seizures are believed to be provoked they fall into another category of situation related seizures, i.e. acute symptomatic seizures (ASS). The definition of ASS is a clinical seizure occurring in close temporal relationship with an acute insult in the central nervous system (CNS), which may be metabolic, toxic, structural, infectious, or inflammatory. The prognosis after unprovoked seizures and ASS differs with regard to risk of seizure recurrence and mortality.In the present thesis, we focused on seizures occurring in relation to common dysmetabolic conditions, and subarachnoid hemorrhage (SAH).Specifically we wanted to study the occurrence of ASS in patients with different levels of hyponatremia and hypoglycemia. We also conducted an experimental study in mice to explore the relationship between chemically induced status epilepticus (SE) and hyponatremia. Furthermore, seizures in SAH were recorded and related to appearance of development of delayed cerebral ischemia (DCI). In addition we measured neurofilament light (NFL) and tau in the cerebrospinal fluid (CSF).We found a gradual increase in risk of seizures with declining sodium levels. Seizures were the only neurologic manifestation of hyponatremia in patients with moderately decreased sodium levels (> 115 mM).In study of a large number of patients with hypoglycemia, a notably low risk for seizures was found. Absolut risk for neurological symptoms at glucose < 2.0mM  (95% CI) was 0.25 (0.13-0.41). This is a finding of potentially great clinical relevance, since seizures in the presence of hypoglycemia are often presumed to be acute symptomatic.In an animal study of acute hyponatremia on kainic acid (KA) induced status epilepticus (SE) we found that hyponatremic animals displayed an increased frequency of epileptiform activity and had longer duration of seizures. These results support the clinical observations that hyponatremia aggravates SE.In the study of patients with SAH we found that ASS is common (36% of all patients) but seizures were not predictive of the development of DCI. Measurement of the CSF biomarker tau at different time points revealed increased tau concentration between days 4 and 10, which may be associated to DCI.