Andrew Zillgitt

Sensory Trick in a Patient with Cervical Dystonia: Insights from Magnetoencephalography

Background: The proposed mechanisms for the sensory trick include peripheral sensory feedback to aid in correcting abnormal posture or movement. Case report: A 53-year-old woman with cervical dystonia underwent magnetoencephalography pre- and post-botulinum toxin injection and sensory trick, which was described as yawning. Study revealed connectivity between the left frontal and inferior frontal gyrus before yawning, which changed to the visual cortex and right middle frontal gyrus with yawning. Beta frequencies reduced and gamma frequencies increased after yawning. Discussion: The increase in gamma frequency bands may indicate increased GABAergic activity. Increase in connectivity in the right cerebellar region underscores the importance of cerebellum in pathogenesis of dystonia.

Controllable yawning expressed as focal seizures of frontal lobe epilepsy

Excessive yawning was described in some neurological conditions as part of periictal or ictal manifestations of epilepsy, most commonly temporal lobe. We present the first case of controllable yawning as a primary seizure semiology with dominant frontal lobe involvement in a 20-year-old man. Video electroencephalography recorded 8 yawning episodes accompanied with right arm movement correlating with rhythmic diffuse theta range activity with left hemispheric predominance. Magnetoencephalography coherence source imaging was consistent with persistent neuronal networks with areas of high coherence reliably present over the left lateral orbitofrontal region. Epileptogenic areas may have widespread networks involving the dominant frontal lobe in unique symptomatogenic areas.

Post-operative nonketotic hyperglycemic induced focal motor status epilepticus related to treatment with corticosteroids following standard anterior temporal lobectomy

Highlights • Complications from standard ATL are uncommon and the use of post-operative corticosteroids may reduce complications.• Following standard ATL, FMSE was present after treatment with corticosteroids that resolved after blood sugar control.• After epilepsy surgery, corticosteroids should be used cautiously in people with comorbid diabetes mellitus.

Cervical Dystonia and Executive Function: A Pilot Magnetoencephalography Study

Background: Cervical dystonia (CD) patients have impaired working memory, processing speed and visual-motor integration ability. We used magnetoencephalography (MEG) to investigate changes in cerebral oscillations in CD patients during an executive function test, before and after administration of botulinum toxin. Methods: MEG data were collected from five CD patients while they performed a visual continuous performance task (CPT), before and after they received a botulinum toxin injection. MEG data was also collected on five controls matched for age and gender. Coherence source imaging was performed to quantify network connectivity of subjects. Results: Controls demonstrated two errors with visual CPT; CD patients demonstrated six and three errors pre- and post-botulinum toxin respectively. After botulinum toxin, mean time from cue to correct response was 0.337 s in controls, 0.390 s in patients before botulinum toxin injection, and 0.366 s after the injection. Differences in coherence between controls and patients were found in the following brain regions: Fronto-frontal, fronto-parietal, fronto-striatal, fronto-occipital, parieto-parietal and temporo-parietal. Intrahemispheric and interhemispheric networks were affected. Post injection, there was minimal change in coherence in the above-mentioned networks. Discussion: Neuropsychological testing suggests difference in coherence in frontal circuits between CD cases and controls during the visual CPT, which may reflect subjects’ increased difficulty with the task. Botulinum toxin is associated with minimal improvement with executive function in CD.

The Effect of Botulinum Toxin on Network Connectivity in Cervical Dystonia: Lessons from Magnetoencephalography

Background Pharmacological management of cervical dystonia (CD) is considered to be symptomatic in effect, rather than targeting the underlying pathophysiology of the disease. Magnetoencephalography (MEG), a direct measure of neuronal activity, while accepted as a modality for pre-surgical mapping in epilepsy, has never been used to explore the effect of pharmacotherapy in movement disorders. Methods Resting state MEG data were collected from patients with CD, pre- and post-botulinum toxin injections. All of these patients exhibited good clinical benefit with botulinum toxin. Resting state MEG data from four age- and gender-matched healthy controls with no neurological disorders were also collected. Results Our exploratory study reveals a difference in coherence between controls and patients in the following regions: fronto-striatal, occipito-striatal, parieto-striatal, and striato-temporal networks. In these regions there is an increase after botulinum toxin. Specifically, increased coherence in the left putamen and right superior parietal gyrus was noticeable. Both intrahemispheric and interhemispheric networks were affected. Discussion This is the first attempt to directly assess changes in functional connectivity with pharmacotherapy using MEG. Botulinum toxin might affect sensorimotor integration, leading to clinical benefit. The presence of increased interhemispheric coherence and intrahemispheric coherence points to the importance of global and local networks in the pathophysiology of dystonia.

Periodic Discharges: Insight from Magnetoencephalography

Purpose: This study used magnetoencephalography (MEG) dipole localization and coherence measurement to evaluate the magnetic fields associated with periodic discharges. The primary goal of the study was to evaluate whether MEG could consistently localize quasiperiodic discharges that were observed on the EEG portion of the recording. The secondary objective was to evaluate whether coherence measurements would correlate with topographic maxima of epileptiform activity. Methods: A total of 13 inpatients, whose electrographic records demonstrated lateralized periodic discharges (LPDs), were recruited from Henry Ford Hospital neurology and intensive care units. Nine patients were found clinically to be in status epilepticus before the EEG determination of LPDs. Spontaneous cortical brain activity was recorded with 148-channel MEG for 10 minutes. Data were sampled at 508 Hz and DC-100 Hz and filtered from 1 Hz to 40 Hz. Interictal events were imaged with single equivalent current dipole localization. Magnetoencephalography coherence source imaging analysis was performed and compared with the cortical topography of LPD patterns and with the focal lesions seen on the MRI (9 patients) or computed tomography (5 patients) imaging modalities. Results: The morphology of periodic waveforms was similar between EEG and MEG portions of the study. In patients with substrate positivity on imaging studies, coherence analysis revealed a tendency for LPDs to arise from the interface between the lesion and the surrounding, uncompromised cortex rather than from the lesion itself. In nonlesional patients with recent status epilepticus, the localization of maximal coherence was in the temporal lobes. Conclusions: This study demonstrated that MEG is able to detect and localize LPDs arising from damaged and adjacent cortex. The MEG coherence source imaging measurements also suggest the presence of epileptogenic networks perilesionally in cases with focal lesions on imaging. In patients without acute anatomic abnormality, the MEG coherence identified the epileptogenic networks in temporal lobe structures. Magnetoencephalography coherence source imaging may provide physicians with markers for differentiating between LPDs arising from acute injury currents versus LPDs arising from prolonged status epilepticus.

Multimodal Imaging in a Patient with Hemidystonia Responsive to GPi Deep Brain Stimulation

Background Dystonia is a syndrome with varied phenomenology but our understanding of its mechanisms is deficient. With neuroimaging techniques, such as fiber tractography (FT) and magnetoencephalography (MEG), pathway connectivity can be studied to that end. We present a hemidystonia patient treated with deep brain stimulation (DBS). Methods After 10 years of left axial hemidystonia, a 45-year-old male underwent unilateral right globus pallidus internus (GPi) DBS. Whole brain MEG before and after anticholinergic medication was performed prior to surgery. 26-direction diffusion tensor imaging (DTI) was obtained in a 3 T MRI machine along with FT. The patient was assessed before and one year after surgery by using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Results In the eyes-closed MEG study there was an increase in brain coherence in the gamma band after medication in the middle and inferior frontal region. FT demonstrated over 50% more intense ipsilateral connectivity in the right hemisphere compared to the left. After DBS, BFMDRS motor and disability scores both dropped by 71%. Conclusion Multimodal neuroimaging techniques can offer insights into the pathophysiology of dystonia and can direct choices for developing therapeutics. Unilateral pallidal DBS can provide significant symptom control in axial hemidystonia poorly responsive to medication.

Application of MEG coherence in lateralization of mTLE

Magnetoencephalography (MEG) is a noninvasive imaging method for localization of focal epileptiform activity in patients with epilepsy. This study investigates the cerebral functional abnormalities quantified by MEG coherence laterality in mesial temporal lobe epilepsy (mTLE). Resting state MEG data was analyzed using MEG coherence source imaging (MEG-CSI) method to determine the coherence in 54 anatomical sites in 12 adult mTLE patients and 12 age- and gender-matched controls. MEG coherence laterality, after Bonferroni adjustment, showed significant differences for right versus left mTLE in insular cortex and both lateral orbitofrontal and superior temporal gyri (p<;0.025). None of these anatomical sites showed statistically significant differences in coherence laterality between right and left sides of controls. Coherence laterality was in agreement with the declared side of epileptogenicity in insular cortex (in 75% of patients) and both lateral orbitofrontal (83%) and superior temporal gyri (84%). Combining all significant laterality indices improved the lateralization accuracy to 92%. The proposed methodology for using MEG to investigate the abnormalities related to focal epileptogenicity and propagation can provide a further means of noninvasive lateralization.

Application of DTI connectivity in lateralization of mTLE

Diffusion tensor imaging (DTI) is a noninvasive imaging method for measuring the diffusion properties of the underlying white matter tracts through which epileptiform activity is propagated. This study investigates the structural abnormalities quantified by DTI in mesial temporal lobe epilepsy (mTLE). Fiber tracts passing through 54 anatomical sites in 12 adult mTLE patients and 12 age- and gender-matched controls were identified using DTI tractography. DTI nodal degree (ND) and laterality index were then calculated. ND laterality, after Bonferroni adjustment, showed significant differences for right versus left mTLE in gyrus rectus, insular cortex, precuneus and superior temporal gyrus (p<;0.025). None of these anatomical sites showed statistically significant differences in ND laterality between right and left sides of the controls. Laterality models determined by logistic regression on the ND laterality data agreed with the side of epileptogenicity as it pertained to the gyrus rectus, insular cortex, precuneus and superior temporal gyrus for 89%, 72%, 83% and 92% of the patients, respectively. Combining the laterality measures in these four anatomical sites improved the results further with correct lateralization of 100% for all patients. The proposed methodology for using DTI connectivity to investigate diffusion abnormalities related to focal epileptogenicity and propagation can provide a further means of noninvasive lateralization.