Stimulus Induced Rhythmic, Periodic, or Ictal Discharges (SIRPIDs) and its Association with Non-convulsive Status Epilepticus in Critically Ill Patients.

Stimulus induced repetitive periodic or ictal discharges (SIRPIDs) are a commonly observed EEG pattern in critically ill patients. However, the epileptic significance of SIRPIDs remain unclear. We identified and reviewed 55 cases with SIRPIDs according to the ACNS criteria. SIRPIDs occurred after standardized painful stimuli during a standard 20-minute EEG. These cases were investigated regarding their relation to non-convulsive status epilepticus (NCSE) according to Salzburg Consensus Criteria and in-hospital mortality. In 37/55 patients (67.3%), SIRPIDs were associated with NCSE. In most patients (26/37 cases, 70.3%) with concurrent status epilepticus, SIRPIDs occurred after status epilepticus (on average 4.8 days later), but in 3/37 patients (8.1%) they were observed before a later status epilepticus. In four cases (4/37 cases, 10.8%), SIRPIDs appeared both before and after an episode of NCSE and in other four cases the two patterns coexisted in the same EEG. In 50% of the patients, status epilepticus was refractory, super-refractory or the patient died before its resolution. The overall mortality in the cohort was high at 58.2%. These findings corroborate the hypothesis that SIRPIDs might represent a state with increased epileptogenic potential, commonly co-occurring with NCSE. Furthermore, SIRPIDs are associated with therapy-refractory course of status epilepticus and high mortality.

The medial pulvinar as a subcortical relay in temporal lobe status epilepticus.

PURPOSE: Mutual cortico-thalamic interactions are assumed to be the basis for sustained ictal activity during status epilepticus. We aimed to investigate thalamic involvement during focal status epilepticus through the analysis of ictal diffusion-weighted MR-imaging. METHODS: We retrospectively analyzed a cohort of 62 patients who received an MRI scan during an episode of focal onset status epilepticus in our center between 2001 and 2018. RESULTS: Thalamic diffusion restrictions during focal status epilepticus were found in 29 of 62 cases (46.8 %). As the most frequent localization, the medial pulvinar was affected in 22 cases (75.9 %). Temporal status epilepticus was associated with thalamic DWI-findings (20/33, 60.6 %), in particular in the medial pulvinar (18/33, 54.5 %). To the contrary, the medial pulvinar was less frequently involved in parietal (3/11, 27.3 %) and only rarely in frontal status epilepticus (1/15, 6.7 %). CONCLUSION: The medial pulvinar appears to be a frequently involved subcortical relay for maintenance of ictal activity in temporal onset focal status epilepticus. Our findings provide possible novel insights regarding the interpretation of thalamic DWI restrictions in patients with unclear neurological conditions.

Selective deep brain stimulation in the substantia nigra reduces myoclonus in progressive myoclonic epilepsy: a novel observation and short review of the literature.

We report the case of a patient suffering from pharmacotherapy-resistant bilateral progressive myoclonic epilepsy (PME) showing a beneficial response upon selective deep brain stimulation (DBS) of the substantia nigra pars reticulata. As an individual experimental therapeutic approach, we implanted DBS electrodes in the transitional zone between the subthalamic nucleus (STN) and the substantia nigra pars reticulata (SNr). Electrode placement allowed for a selective stimulation of either the STN, SNr, or both targets. Postoperatively, we observed a moderate subjective and objective improvement in positive and negative myoclonus by high-frequency DBS of the STN/SNr transitional zone. However, a systematic exploration of different stimulation settings revealed that monopolar stimulation of the substantia nigra alone was more effective than high-frequency monopolar DBS of either the motor STN (monopolar) or stimulation of both targets (STN/SNr). This observation confirms earlier findings showing that patients with PME benefit from high-frequency DBS. However, in contrast to previous reports stimulating the STN/SNr transitional zone, our patient showed the most significant effect upon selective stimulation of the SNr. We propose that in patients undergoing DBS for myoclonus, at least one electrode contact should be placed in the SNr allowing for selective monopolar stimulation of this target.