What Do You See? Signature Pedagogy in Continuous Electroencephalography Teaching

PURPOSE

Electroencephalography (EEG) is commonly used in neurology, but there is variability in how neurologists interpret EEGs, potentially from variability in EEG teaching. Little is known about how EEG teaching is done to prepare neurologists for professional practice.

METHODS

We interviewed a group of EEG experts to characterize their teaching practices around continuous EEG (cEEG). We used signature pedagogy as a framework to analyze and interpret the data.

RESULTS

We identified pervasive and characteristic forms of cEEG teaching. Teaching is based on apprenticeship, relying on "learning by doing" in the context of real-life clinical practice. There are habitual steps that learners take to anchor teaching, which typically occurs during rounds. There is a common language and core knowledge that trainees need to master early in their training.

CONCLUSIONS

There are pervasive characteristic forms of cEEG teaching. These findings can help facilitate instructional design and implementation of complementary or enhanced cEEG teaching practices.

The association between surgical characteristics and cognitive decline following deep brain stimulation of the subthalamic nucleus in Parkinson's disease

OBJECTIVE

Despite optimal improvement in motor functioning, both short- and long-term studies have reported small but consistent changes in cognitive functioning following STN-DBS in Parkinson's disease (PD). The aim of the present study was to explore whether surgical characteristics were associated with cognitive decline one year following STN-DBS.

METHODS

We retrospectively analyzed 49 PD patients who underwent bilateral STN-DBS. Cognitive change scores were related to the number of microelectrode recording (MER) trajectories, the STN length as measured by MER, and cortical entry points. Regression analyses were corrected for age at surgery, disease duration, education and preoperative levodopa responsiveness. Patients were then divided into a cognitive and non-cognitive decline group for each neuropsychological test and compared regarding demographic and surgical characteristics.

RESULTS

One year postoperatively, significant declines were found in verbal fluency, Stroop Color-Word test and Trail Making Test B (TMT-B). Only changes in TMT-B were associated with the coronal entry point in the right hemisphere. The number of MER trajectories and STN length were not associated with cognitive change scores. When comparing the cognitive decline and non-cognitive decline groups, no significant differences were found in surgical characteristics.

CONCLUSIONS

The electrode passage through the right prefrontal lobe may contribute to subtle changes in executive function. However, only few patients showed clinically relevant cognitive decline. The use of multiple MER trajectories and a longer STN length were not associated with cognitive decline one year following surgery. From a cognitive point of view, DBS may be considered a relatively safe procedure.

Tonic and phasic changes in anteromedial globus pallidus activity in Tourette syndrome

BACKGROUND

Tourette syndrome is a hyperkinetic neurodevelopmental disorder characterized by tics.

OBJECTIVE

Assess the neuronal changes in the associative/limbic GP associated with Tourette syndrome.

METHODS

Neurophysiological recordings were performed from the anterior (associative/limbic) GPe and GPi of 8 awake patients during DBS electrode implantation surgeries.

RESULTS

The baseline firing rate of the neurons was low in a state-dependent manner in both segments of the GP. Tic-dependent transient rate changes were found in the activity of individual neurons of both segments around the time of the tic. Neither oscillatory activity of individual neurons nor correlations in their interactions were observed.

CONCLUSIONS

The results demonstrate the involvement of the associative/limbic pathway in the underlying pathophysiology of Tourette syndrome and point to tonic and phasic modulations of basal ganglia output as a key mechanisms underlying the abnormal state of the disorder and the expression of individual tics, respectively. © 2017 International Parkinson and Movement Disorder Society.

Thalamic Deep Brain Stimulation for Refractory Tourette Syndrome: Clinical Evidence for Increasing Disbalance of Therapeutic Effects and Side Effects at Long-Term Follow-Up

OBJECTIVE

Thalamic deep brain stimulation (DBS) is effective in reducing tics in patients with refractory Tourette syndrome at the short-term. Here, we report on the long-term outcome.

MATERIALS AND METHODS

Seven patients underwent bilateral DBS between 2001 and 2008. The target was the centromedian nucleus, substantia periventricularis and nucleus ventro-oralis internus cross point of the thalamus. The effect on tics and side effects were evaluated with a variable follow-up duration of 12 to 78 months.

RESULTS

Patient 1 and 2 showed good tic improvements of 81.6% (60 months) and 50% (36 months), respectively. However, side effects like reducing levels of energy and visual disturbances increased. In patient 1, the target was changed to the anterior part of the internal pallidum and patient 2 switched the stimulator permanently off. Patient 3 experiences still satisfying results with a tic improvement of 88.9% (78 months). Patient 4 and 7 showed minor tic improvements of 34% (16 months) and 9% (60 months), respectively. In both patients side effects became more severe and the target was changed to the anterior part of the internal pallidum. Patient 5 showed a tic improvement of 27.5% (12 months) and went abroad for stimulation of the external globus pallidus. Patient 6 developed cerebellar atrophy. He experienced several nonstimulation related side effects and turned the stimulator off.

CONCLUSIONS

There seems to be an increasing disbalance of therapeutic effects and side effects at long-term follow-up, often leading to either switching the stimulator off or new surgery with a different neuro-anatomic target.

An improved qEEG index for asymmetry detection during the Wada test

The Wada test is commonly used to evaluate language and memory lateralization in candidates for epilepsy surgery. The spatial Brain Symmetry Index (BSI) quantifies inter-hemispheric differences in the EEG. Its application has been shown to be feasible during Wada testing. We developed a method for the quantification of EEG asymmetry that matches visual assessments of the EEG better than BSI. Fifty-three patients' EEG data, with a total of 85 injections were analyzed. In a step-wise, data-driven manner, multiple electrode and frequency band combinations were evaluated. Eventually, BSI, calculated using only the frontal electrodes F3 and F4, was combined with a temporal measure of delta power in the central electrodes, C3 and C4, into a new measure: cBSI. Using the area under the ROC curve (AUC), we showed that cBSI performs significantly better relative to BSI (median AUC 0.98 versus 0.96, p=0.0015, Wilcoxon signed rank test). Our results showed that asymmetry detection was significantly improved by combining temporal with spatial qEEG measures. In the future, our combined qEEG measure could allow for a more objective way of monitoring EEG asymmetry, thereby increasing the feasibility of using EEG as a monitoring tool during the Wada test. Future studies should, however, validate our cBSI method in real time in the operating room or radiology suite.

A detailed analysis of intracerebral hemorrhages in DBS surgeries

OBJECTIVES

Deep brain stimulation is nowadays a frequently performed surgery in patients with movement disorders, intractable epilepsy, and severe psychiatric disorders. The most feared complication of this surgery is an intracerebral hemorrhage due to the electrode placement, either for intraoperative electrophysiology (microelectrode recording) and/or implantation of the final electrode (macroelectrode). Here, we have investigated the risk of developing an intracerebral hemorrhage in our cohort of deep brain stimulation patients over a period of 15 years.

PATIENTS AND METHODS

We have collected demographic data and analyzed the effect of performing surgery with single-electrode versus multiple electrode guided DBS. The effect of using single-dose versus double-dose contrast enhanced MRI to visualize vessels for the electrode trajectory planning has been investigated as well.

RESULTS

We have found that the overall calculated risk of an intracerebral hemorrhage in our series was 1.81% per patient, 0.3% per recording electrode and 0.23% per brain insertion. While three out of four patients recovered without neurological deficits, there was one mortality in a patient with cardiovascular comorbidities. Statistical comparisons between the groups of single-electrode versus multiple electrode guided surgery and single-dose gadolinium versus double-dose contrast enhanced MRI revealed no significant differences. In addition, there was no meaningful correlation between the age at surgery and the risk of bleeding.

CONCLUSION

We have found that the risk of developing an intracerebral hemorrhage due to deep brain stimulation surgery is low. The clinical course of the patients with an intracerebral hemorrhage was generally favorable.

Subthalamic nucleus high-frequency stimulation for advanced Parkinson's disease: motor and neuropsychological outcome after 10 years

BACKGROUND

Since the introduction of subthalamic nucleus deep brain stimulation (STN DBS), many clinical studies have shown that this therapy is safe and effective in the short and medium term. Only little is known about long-term results.

OBJECTIVES

To provide an analysis of motor and cognitive outcome 10 years after STN DBS.

METHODS

In this observational cohort study, we report on the motor and cognitive outcome in a cohort of 26 Parkinson's disease patients who were prospectively followed up for 10 years after STN DBS surgery.

RESULTS

In the early post-operative phase, improvement in the Unified Parkinson's Disease Rating Scale (UPDRS) III (10.6, p < 0.01) and IV (2.5, p < 0.01) was seen as well as a 32% reduction in levodopa equivalent dose (p < 0.01). After 5 years, a worsening of the motor performance was observed. The worsening of motor performance was mainly due to a deterioration in bradykinesia (12.4 ± 4.6, p < 0.05) and axial symptoms (6.9 ± 2.8, p < 0.01). Memory function seemed to improve in the short term, but there was a significant decline between 1 and 5 years after surgery (p < 0.01). Mood remained relatively stable during follow-up, and one third of the patients showed impulsive behaviour after surgery.

CONCLUSIONS

The motor performance of patients showed deterioration over time, due to an increase in bradykinesia and axial symptoms.

Subthalamic neuronal responses to cortical stimulation

BACKGROUND

Deep brain stimulation of the subthalamic nucleus alleviates motor symptoms in Parkinson's disease patients. However, some patients suffer from cognitive and emotional changes. These side effects are most likely caused by current spread to the cognitive and limbic territories in the subthalamic nucleus. The aim of this study was to identify the motor part of the subthalamic nucleus to reduce stimulation-induced behavioral side effects, by using motor cortex stimulation.

METHODS

We describe the results of subthalamic nucleus neuronal responses to stimulation of the hand area of the motor cortex and evaluate the safety of this novel technique.

RESULTS

Responses differed between regions within the subthalamic nucleus. In the anterior and lateral electrode at dorsal levels of the subthalamic nucleus, an early excitation (∼5-45 ms) and subsequent inhibition (45-105 ms) were seen. The lateral electrode also showed a late excitation (∼125-160 ms). Focal seizures were observed following motor cortex stimulation.

CONCLUSIONS

To prevent seizures the current density should be lowered, so that motor cortex stimulation-evoked responses can be safely used during deep brain stimulation surgery.

Single electrode and multiple electrode guided electrical stimulation of the subthalamic nucleus in advanced Parkinson's disease

OBJECTIVE

It is still debated to what extent intraoperative electrophysiological techniques contribute to the outcome of subthalamic nucleus (STN) deep brain stimulation (DBS). Intraoperative electrophysiological recordings for identification of the STN can be made with one electrode or with multiple, simultaneously implanted electrodes. The latter provide more detailed information about the electrophysiological boundaries of the STN; however, implantation of several electrodes at one time might increase the risk of bleeding. Here we report the results of a study of patients with advanced Parkinson's disease, in which one group of patients underwent bilateral STN DBS with electrophysiological recordings from a single electrode, and the other group received STN DBS with multiple (five or fewer) simultaneously implanted electrodes.

PATIENTS AND METHODS

Fifty-five patients suffering from advanced Parkinson's disease who underwent bilateral STN stimulation were included in this study. Thirty-two patients underwent STN DBS guided by a single semi-microelectrode, and 23 patients underwent STN DBS guided with simultaneously implanted multiple microelectrodes. All patients were examined preoperatively and 3 and 12 months postoperatively with regard to activities of daily living, motor functions, and neuropsychological functions.

RESULTS

We found that the simultaneous implantation of multiple electrodes does not increase the risk of bleeding or any other major intracranial complication. The use of multiple electrodes resulted in better motor results when compared with patients who underwent STN DBS guided with a single recording electrode. There were significantly more improvements in patients' tremor and rigidity, and as a consequence, a better total Unified Parkinson Disease Rating Scale, Part III score was identified during the medication-off phase. Despite better motor effects, patients treated with multiple electrodes showed subtle deterioration in neuropsychological functions, particularly in memory function.

CONCLUSION

STN DBS performed with multiple electrophysiological recording electrodes resulted in better motor outcome but induced specific mild declines in neuropsychological functions.