Abstracts

Ionized magnesium (iMg) acts as a calcium (Ca) channel blocker and hypomagnesemia can present as tetany or seizures. An increase in pH decreases iMg and iCa activities. Clinically, certaiin epileptic seizures can be induced by hyperventilation (HV) which raises pH. In this study, concentrations of iMg and iCa, and pH were measured in the cerebrospinal fluid (CSF) of children with generalized seizures following HV and in the cerebral extracellular fluid (CEF) of newborn piglets to investigate the relationship between seizure manifestations and changes in cerebral iMg and iCa concentrations, and pH. CSF was obtained from 3 patients, aged 10-18 months, with generalized seizures following prolonged and vigorous bouts of crying in infancy, being misdiagnosed of breath holding spells. CEF was obtained from 2 anesthetized, ventilated newborn piglets before and after HV. Levels of CSF iMg and iCa, and pH were measured with an automatic ion selective electrode analyzer immediately after generalized seizures. In total, 26 age-matched non-convulsive children[apos]s CSF samples were obtained as controls from patients who underwent lumber puncture for diagnosis of possible meningitis and were demonstrated to have normal CSF. 3 patients with HV (crying) -induced epilepsy had following characteristics. The seizures present between the ages of 10 to 18 months, the patients had normal development, and showed generalized tonic clonic seizures following only crying. The seizures usually last no longer than 1 minute and their EEG showed focal spikes in interictal and generarized spikes in ictal states. The seizures were well controlled with VPA. Levels of CSF iMa and iCa, and pH in the 3 patients did not differ from controls. Significantly decreased iMg and iCa levels, and increased pH were seen in CEF of newborn piglets following mechanical HV. These results suggest that there is a relationship between changes in the concentrations of extracellular iMg and iCa, and pH in the brain and seizures in this HV (crying)-induced epileptic sndrome.