Faculty Bibliography

In a previous study, when sub-threshold gastric distension (300ml) and a low dose of cholecystokinin octapeptide (CCK‑8) (112 ng/min for 21 min) were concurrently administered to human participants, intake of a test meal was significantly reduced. However, the supra-additive interaction of CCK-8 and gastric distension was not significant. The purpose of the present study was to determine whether a significant interaction would be obtained when CCK-8 and gastric distension were each increased by 50% above levels used in the previous study. Twelve normal-weight healthy participants were tested four times each with either CCK-8 (168ng/min for 30 min) or saline infusion crossed with gastric distension (450ml) or no distension. The combination of CCK-8 and gastric distension reduced food intake by a mean of 405 g ± 86 SE in comparison with the saline non-distension condition (p < 0.001), which is a 51% reduction. Although there were some differences in the protocols, the combined effect was double that seen in the previous study. Although the interactive effect was larger (118 g + 109 SE) than it was previously (73 + 86 SE), it was not significant (p = 0.29). There were also reports of a short-lived sick feeling after CCK-8, with and without, distension that were not observed in the previous study. Thus, the combination of CCK-8 at 1.5 times threshold and gastric distension at 450 ml (increased from 300 ml) resulted in a combined effect to reduce food intake, which was also 1.5 times its previous value, and thus appears linear.

Amiodarone (Cordarone^®, Pfizer Inc) is an antiarrhythmic medication with a well-known toxicity profile, including rare cases of hyponatremia as a result of syndrome of inappropriate antidiuretic hormone (SIADH). We report on such a case in which a patient was found to be hyponatremic after evaluation. An 88-year-old male who presented to the emergency department was found to be hyponatremic secondary to amiodarone-induced SIADH following a fall, with possible seizure and traumatic brain injury. He had a history of hypertension, paroxysmal atrial fibrillation, emphysema, myocardial infarction, benign prostatic hyperplasia, chronic kidney disease, Meniere's disease, anemia, and gastroesophageal reflux. Upon admission, his urine sodium level was elevated, and his serum sodium, urine osmolality, and anion gap were below normal. In the setting of hyponatremia, the patient's amiodarone was held: he had been taking amiodarone 200 mg once daily for nine months prior to admission. He was treated with intravenous (IV) normal saline over four days. He was fluid-restricted and his sodium levels were closely monitored every two hours. Within 19 hours, his serum sodium levels had improved. Amiodarone was restarted approximately three days later. Upon follow-up after discharge, the patient remained on amiodarone for the next two months. His serum sodium level ranged from 126 mEq/L to 131 mEq/L over a two-week period. He was supplemented with sodium chloride tablets and has been otherwise stable. Amiodarone may cause acute or chronic SIADH, with a wide range of symptoms. Seizures have not been reported in the literature but our patient had a witnessed seizure, although his electroencephalogram (EEG) was negative. Syndrome of inappropriate antidiuretic hormone can occur with any formulation of amiodarone in a dose-dependent fashion. Our patient's sodium levels stabilized within two weeks after amiodarone was resumed. The mechanism of amiodarone-induced SIADH remains unclear.

Neuropsychological assessment is critical for understanding the impact of seizures on cognition and informing treatment decisions. While focus is often placed on examining groups based on seizure type/epilepsy syndrome, an alternate approach emphasizes empirically derived groups based solely on cognitive performance. This approach has been used to identify cognitive phenotypes in temporal lobe epilepsy (TLE). The current study sought to replicate prior work by Hermann and colleagues (2007) and identify cognitive phenotypes in a separate, larger cohort of 185 patients with TLE (92 left TLE, 93 right TLE). Cluster analysis revealed 3- and 4-cluster solutions, with clusters differentiated primarily by overall level of performance in the 3-cluster solution (Low, Middle, and High performance) and by more varying cognitive phenotypes in the 4-cluster solution (Globally Low, Low Executive Functioning/Speed, Low Language/Memory, and Globally High). Differences in cognitive performance as well as demographic and clinical seizure variables are presented. A greater proportion of the patients with left TLE were captured by Cluster 3 (Low Language/Memory) than by the other 3 clusters, though this cluster captured only approximately one-third of the overall group with left TLE. Consistent with prior findings, executive functioning and speed emerged as additional domains of interest in this sample of patients with TLE. The current results extend prior work examining cognitive phenotypes in TLE and highlight the importance of identifying the comprehensive range of potential cognitive profiles in TLE.

Noninvasive transcranial brain stimulation has been widely used in experimental and clinical applications to perturb the brain activity, aiming at promoting synaptic plasticity or enhancing functional connectivity within targeted brain regions. However, there are different types of neurostimulations and various choices of stimulation parameters; how these choices influence the intermediate neurophysiological effects and brain connectivity remain incompletely understood. We propose several quantitative methods to investigate the brain connectivity of an epileptic patient before and after transcranial alternating/direct current stimulation (tACS/tDCS). The neuro-feedback derived from our analyses may provide useful cues for the effectiveness of neurostimulation.

Visuospatial attention is asymmetrically distributed with a leftward bias (i.e. pseudoneglect), while evidence for asymmetries in auditory spatial attention is still controversial. In the present study, we investigated putative asymmetries in the distribution of auditory spatial attention and the influence that visual information might have on its deployment. A modified version of the Posner task (i.e. the visuo-audio spatial task [VAST]) was used to investigate spatial processing of auditory targets when endogenous orientation of spatial attention was mediated by visual cues in healthy adults. A line bisection task (LBT) was also administered to assess the presence of a leftward bias in deployment of visuospatial attention. Overall, participants showed rightward and leftward biases in the VAST and the LBT, respectively. In the VAST, sound localization was enhanced by visual cues. Altogether, these findings support the existence of a facilitation effect for auditory targets originating from the right side of space and provide new evidence for crossmodal links in endogenous spatial attention between vision and audition.

BACKGROUND:Understanding the topographical organization of the cortico-basal ganglia circuitry is of pivotal importance because of the spreading of techniques such as DBS and, more recently, MR-guided focused ultrasound for the treatment of movement disorders. A growing body of evidence has described both direct cortico- and dento-pallidal connections, although the topographical organization in vivo of these pathways in the human brain has never been reported. OBJECTIVE:To investigate the topographical organization of cortico- and dento-pallidal pathways by means of diffusion MRI tractography and connectivity based parcellation. METHODS:High-quality data from 100 healthy subjects from the Human Connectome Project repository were utilized. Constrained spherical deconvolution-based tractography was used to reconstruct structural cortico- and dento-pallidal connectivity. Connectivity-based parcellation was performed with a hypothesis-driven approach at three different levels: functional regions (limbic, associative, sensorimotor, and other), lobes, and gyral subareas. RESULTS:External globus pallidus segregated into a ventral associative cluster, a dorsal sensorimotor cluster, and a caudal "other" cluster on the base of its cortical connectivity. Dento-pallidal connections clustered only in the internal globus pallidus, where also associative and sensorimotor clusters were identified. Lobar parcellation revealed the presence in the external globus pallidus of dissociable clusters for each cortical lobe (frontal, parietal, temporal, and occipital), whereas in internal globus pallidus only frontal and parietal clusters were found out. CONCLUSION/CONCLUSIONS:We mapped the topographical organization of both internal and external globus pallidus according to cortical and cerebellar connections. These anatomical data could be useful in DBS, radiosurgery and MR-guided focused ultrasound targeting for treating motor and nonmotor symptoms in movement disorders. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

BACKGROUND AND PURPOSE/OBJECTIVE:There is evidence suggesting that Los Angeles Motor Scale (LAMS) ≥ 4 predicts large vessel occlusion (LVO). We aim to determine whether atrial fibrillation (AF) can improve the ability of LAMS in predicting LVO. METHODS:We included consecutive patients with a discharge diagnosis of ischemic stroke admitted within 24 hours from last known normal time who underwent emergent vascular imaging using a computerized tomography angiography (CTA) of the head and neck. LVO was defined as intracranial internal carotid artery, proximal middle cerebral artery (M1 or proximal M2 segment), or basilar occlusion. LAMS was determined in the emergency department upon arrival. Univariate and multivariable models were performed to identify predictors of LVO and to determine whether AF improves the ability of LAMS to predict LVO. RESULTS:Among 1,234 patients admitted with ischemic stroke, 862 underwent emergent vascular imaging (69.8%) out of which 374 (43.4%) had evidence of LVO and 207 (24%) underwent mechanical thrombectomy. In multivariable models, predictors of LVO were LAMS (OR 1.42 per one point increase 95% CI 1.29-1.57) and AF (OR 1.95 95% CI 1.26-3.02, P < .001). We developed the LAMS-AF that includes the LAMS score and adds two points if AF is present. In this analysis, LAMS-AF (AUC .78) had improved prediction over LAMS (AUC .76) in predicting LVO and lead to reclassification of 8/68 patients (11.8%) with LAMS = 3 group into the high-risk LVO group. CONCLUSION/CONCLUSIONS:In patients with LAMS = 3, using the LAMS-AF score may improve the ability of LAMS in predicting LVO. Larger studies are needed to confirm our findings.

BACKGROUND AND PURPOSE/OBJECTIVE:The basal forebrain contains multiple structures of great interest to emerging functional neurosurgery applications, yet many neuroradiologists are unfamiliar with this neuroanatomy because it is not resolved with current clinical MR imaging. MATERIALS AND METHODS/METHODS:= 13) to demonstrate and characterize the detailed anatomy of the basal forebrain using a clinical 3T MR imaging scanner. We measured the size of selected internal myelinated pathways and measured subthalamic nucleus size, oblique orientation, and position relative to the intercommissural point. RESULTS:= .084 and .047, respectively). Individual variability for the subthalamic nucleus was greatest for angulation within the sagittal plane (range, 15°-37°), transverse dimension (range, 2-6.7 mm), and most inferior border (range, 4-7 mm below the intercommissural plane). CONCLUSIONS:Direct identification of basal forebrain structures in multiple planes using the TSE T2 sequence makes this challenging neuroanatomy more accessible to practicing neuroradiologists. This protocol can be used to better define individual variations relevant to functional neurosurgical targeting and validate/complement advanced MR imaging methods being developed for direct visualization of these structures in living patients.

Objectives: To demonstrate the development and use of an acute imaging protocol for the metabolic assessment of tissue viability during acute stroke.
Method(s): The DAWN and DEFUSE 3 trials (1,2) have demonstrated that there is much to gain from the use of physiologically based guidelines to extend the use of mechanical recanalization. Literature reports provide strong data supporting the use of brain tissue sodium concentration (TSC) as a biomarker for identifying physiologically non-viable tissue during evolving brain ischemia (3,4). Testing this hypothesis in vivo, in humans, have been previously hampered by acquisition times that were long for routine clinical use. Recent developments in MRI data acquisition and hardware make it possible to acquire the data to provide the aforementioned assessment in under 5 minutes at a level of signal-to-noise ratio (SNR) and spatial resolution compatible with physiologically driven MRI scans such as diffusion weighted imaging and perfusion imaging. This was achieved using an Ultra-Short-Echo Time sequence with optimal acquisition throughput (TPI, TE/TR 0.3/100 ms, p 0.2). Signal excitation/reception was performed using a patient-friendly double-tuned (¹H/²³Na) birdcage coil (Quality Electrodynamics Inc., Mayfield Heights, Ohio). The protocol was implemented on a MAGNETOM Skyra 3 Tesla scanner at NYU's Tisch hospital. The scanner is located adjacent (20 feet) to the neuro interventional suite where patients are recanalized. Subject's anesthesia was maintained (FabiusMRI, DraegerInc., Telford, PA) and physiological status continuously monitored using MRI-compatible equipment (Expression MR400, Phillips Healthcare, Andover, MA).
Result(s): After phantom validation and healthy volunteer studies to determine the quantitative performance of the data acquisition techniques the protocol was used on post-endovascular thrombectomy subjects (n 3), immediately upon procedure completion and under its own IRB approved protocol. During these studies, the use of the proposed methodology was found to be compatible with the clinical care of the subjects. Specifically, performing the required scans was not found to interfere with the subject's post-recanalization care. Tissue sodium concentration data were, likewise, found to meet the required levels of SNR to provide the quantitative assessment mentioned above. A representative data set from one of these sessions is shown in figure 1. This mechanically-recanalized patient had an area of non-salvaged tissue in the left parietal lobe that is clearly depicted on the ²³Na MRI scan. The TSC in this area was 76 mM at the time of the scan. (Figure presented)
Conclusion(s): This work demonstrates that state-of-the-art MRI methodology can be used to provide a clinically viable imaging protocol for evaluating the use of sodium MRI as a quantitative biomarker for identifying physiologically viable tissue during evolving brain ischemia