Hamartia in hippocampal sclerosis-associated mesial temporal lobe epilepsy.

Hamartia are small collections of rounded glioneuronal cells that are thought to be due to aberrant cell migration. Their presence has been recognized in association with mesial temporal lobe epilepsy; their prevalence among cases of hippocampal sclerosis (HS) and any potential association with patient demographics and outcomes is unknown. This study examines hamartia in a series of 292 patients with pathologically confirmed HS. Medical records were reviewed for pertinent patient clinical information (follow-up mean 5years). Hamartia were identified in 96 cases (33%) and were seen primarily in the amygdala (n=88) and less commonly in the hippocampus (n=10) and temporal lobe (n=4). A statistically significant relationship was found between the presence of hamartia and male gender, younger age of seizure onset, and history of childhood febrile seizures and developmental delay. It is unclear if these associations represent a real association or are a result of the underlying pathologies related to chronic epilepsy. At follow-up, there were no significant differences between patients who had hamartia and those who lacked this finding. Hamartia were observed in all subtypes of HS and there was a significant difference found in subtype distribution as well as proportion of cases between subtypes, but no association with any specific subtype overall. The presence of hamartia was not associated with the coexistence of focal cortical dysplasia or any specific histologic pattern of dysplasia. Hamartia are a common concomitant finding in HS and indicates evidence of aberrant cell migration in the hippocampal and parahippocampal regions in these patients.

In vivo and in vitro ketamine exposure exhibits a dose-dependent induction of activity-dependent neuroprotective protein in rat neurons.

Anesthetic doses of ketamine induce apoptosis, as well as gene expression of activity-dependent neuroprotective protein (ADNP), a putative homeodomain transcription factor in rat pups (P7). This study investigated if ketamine induced ADNP protein in a dose-dependent manner in vitro and in vivo using primary cultures of cortical neurons and neonatal pups (P7). In vivo immunohistochemistry demonstrated a sub-anesthetic dose of ketamine increased ADNP in the somatosensory cortex (SCC) which was previously identified to be damaged by repeated exposure to anesthetic doses of ketamine. Administration of low-dose ketamine prior to full sedation prevented caspase-3 activation in the hippocampus and SCC. Primary cultures of cortical neurons treated with ketamine (10 µM-10mM) at 3 days-in vitro (3 DIV) displayed a concentration-dependent decrease in expanded growth cones. Furthermore, neuronal production and localization of ADNP varied as a function of both ketamine concentration and length of exposure. Taken together, these data support the model that ADNP induction may be partially responsible for the efficacy of a low-dose ketamine pre-treatment in preventing ketamine-induced neuronal cell death.