Simon was born and raised in and around New York City. He moved to California to attend the University of California, Los Angeles (UCLA) where he obtained undergraduate degrees in both political theory and neuroscience. Simon continued his education at UCLA where he attended the David Geffen School of Medicine. While a medical student he worked under the mentorship of Dr. Carlos Cepeda to investigate the cellular mechanisms underlying pediatric epilepsy. Additionally, under the mentorship of Dr. Ausaf Bari he created an MRI based structural atlas of the human brainstem. Simon is currently undergoing clinical training in neurologic surgery at Stanford University. He is interested in understanding how neural networks function and contribute to disease and how they can aid in developing novel treatment therapies. Outside of medicine, Simon enjoys spending time with his wife, going for hikes with their dog, traveling, listening to audiobooks, and running.
Please see complete publication list on Google scholar profile: https://scholar.google.com/citations?view_op=list_works&hl=en&user=eEX91cwAAAAJ
- Cerebrovascular Disorders
BA, University of California, Los Angeles, Political Philosophy; Neuroscience (2017)
MD, University of California, Los Angeles David Geffen School of Medicine, Medicine (2021)
Modern Imaging of Aneurysmal Subarachnoid Hemorrhage.
Radiologic clinics of North America
2023; 61 (3): 457-465
In this review, we discuss the imaging of aneurysmal subarachnoid hemorrhage (SAH). We discuss emergency brain imaging, aneurysm detection techniques, and the management of CTA-negative SAH. We also review the concepts of cerebral vasospasm and delayed cerebral ischemia that occurs after aneurysm rupture and their impact on patient outcomes. These pathologies are distinct, and the use of multimodal imaging modalities is essential for prompt diagnosis and management to minimize morbidity from these conditions. Lastly, new advances in artificial intelligence and advanced imaging modalities such as PET and MR imaging scans have been shown to improve the detection of aneurysms and potentially predict outcomes early in the course of SAH.
View details for DOI 10.1016/j.rcl.2023.01.004
View details for PubMedID 36931762
Balamuthia mandrillaris brain infection: a rare cause of a ring-enhancing central nervous system lesion. Illustrative case.
Journal of neurosurgery. Case lessons
2022; 3 (15)
BACKGROUND: An 80-year-old man presented with subacute mental status change, dizziness, and left-sided vision loss. Magnetic resonance imaging demonstrated a ring-enhancing right parietooccipital lesion.OBSERVATIONS: Biopsy and laboratory testing demonstrated an amoebic Balamuthia mandrillaris infection. Fewer than 200 cases of this infection have been recognized in the United States, and no standardized treatment regimen currently exists.LESSONS: Rapid antimicrobial therapy with miltefosine, azithromycin, fluconazole, flucytosine, sulfadiazine, and albendazole was initiated. The pathophysiology, diagnosis, and management of this infection and the patient's course were reviewed. The importance of biopsy for pathologic and laboratory diagnosis and rapid treatment initiation with a multidisciplinary team was reinforced.
View details for DOI 10.3171/CASE2268
View details for PubMedID 36303497
A structural connectivity atlas of limbic brainstem nuclei.
Frontiers in neuroimaging
2022; 1: 1009399
Understanding the structural connectivity of key brainstem nuclei with limbic cortical regions is essential to the development of therapeutic neuromodulation for depression, chronic pain, addiction, anxiety and movement disorders. Several brainstem nuclei have been identified as the primary central nervous system (CNS) source of important monoaminergic ascending fibers including the noradrenergic locus coeruleus, serotonergic dorsal raphe nucleus, and dopaminergic ventral tegmental area. However, due to practical challenges to their study, there is limited data regarding their in vivo anatomic connectivity in humans.To evaluate the structural connectivity of the following brainstem nuclei with limbic cortical areas: locus coeruleus, ventral tegmental area, periaqueductal grey, dorsal raphe nucleus, and nucleus tractus solitarius. Additionally, to develop a group average atlas of these limbic brainstem structures to facilitate future analyses.Each nucleus was manually masked from 197 Human Connectome Project (HCP) structural MRI images using FSL software. Probabilistic tractography was performed using FSL's FMRIB Diffusion Toolbox. Connectivity with limbic cortical regions was calculated and compared between brainstem nuclei. Results were aggregated to produce a freely available MNI structural atlas of limbic brainstem structures.A general trend was observed for a high probability of connectivity to the amygdala, hippocampus and DLPFC with relatively lower connectivity to the orbitofrontal cortex, NAc, hippocampus and insula. The locus coeruleus and nucleus tractus solitarius demonstrated significantly greater connectivity to the DLPFC than amygdala while the periaqueductal grey, dorsal raphe nucleus, and ventral tegmental area did not demonstrate a significant difference between these two structures.Monoaminergic and other modulatory nuclei in the brainstem project widely to cortical limbic regions. We describe the structural connectivity across the several key brainstem nuclei theorized to influence emotion, reward, and cognitive functions. An increased understanding of the anatomic basis of the brainstem's role in emotion and other reward-related processing will support targeted neuromodulatary therapies aimed at alleviating the symptoms of neuropsychiatric disorders.
View details for DOI 10.3389/fnimg.2022.1009399
View details for PubMedID 37555163
View details for PubMedCentralID PMC10406319
A case series and review of the mononostril endoscopic transnasal transsphenoidal approach: Safe and effective in a low resource setting
CLINICAL NEUROLOGY AND NEUROSURGERY
2021; 202: 106499
A transnasal transsphenoidal (TNTS) approach can be performed through a binostril or mononostril technique. The binostril technique is generally preferred, however the mononostril may be an underutilized approach with significant benefits.All (n = 521) pituitary adenoma transsphenoidal surgeries performed from March 2008 until July 2017 at a university hospital in Indonesia were isolated. The majority (n = 512) were performed through a mononostril approach with no nasal speculum by a single experienced neurosurgeon. A PubMed literature review researching the differences in indications, techniques, and outcomes for both approaches supplements the case series. The mononostril surgical technique is described in detail.The average mononostril operating time was 105 min. The most prevalent surgical complications were CSF leak (4.1 %), diabetes insipidus (3.7 %) and cacosmia (2.1 %). Visual field deficits noted in 85 %, 89 % improved. Length of stay was less than 2 days for 90 %, with 13 ICU admissions (average one day). Recurrence rate was 8.2 % at follow up (1-10 years).Based on a literature review, binostril TNTS surgeries have longer operative time and a higher risk of epistaxis. According to our experience, post-operative patient comfort and satisfaction are higher with the monostril approach. Furthermore, this technique is easier to teach, ENT assistance unnecessary, and thus especially advantageous in low resource settings. Our CSF leak and tumor recurrence rates were lower than reported binostril rates in the literature. The mononostril technique is both safe and effective and should be strongly considered for an appropriately pre-selected subset of pituitary adenomas.
View details for DOI 10.1016/j.clineuro.2021.106499
View details for Web of Science ID 000632971000001
View details for PubMedID 33493882
Paroxysmal Discharges in Tissue Slices From Pediatric Epilepsy Surgery Patients: Critical Role of GABA(B) Receptors in the Generation of Ictal Activity
FRONTIERS IN CELLULAR NEUROSCIENCE
2020; 14: 54
In the present study, we characterized the effects of bath application of the proconvulsant drug 4-aminopyridine (4-AP) alone or in combination with GABAA and/or GABAB receptor antagonists, in cortical dysplasia (CD type I and CD type IIa/b), tuberous sclerosis complex (TSC), and non-CD cortical tissue samples from pediatric epilepsy surgery patients. Whole-cell patch clamp recordings in current and voltage clamp modes were obtained from cortical pyramidal neurons (CPNs), interneurons, and balloon/giant cells. In pyramidal neurons, bath application of 4-AP produced an increase in spontaneous synaptic activity as well as rhythmic membrane oscillations. In current clamp mode, these oscillations were generally depolarizing or biphasic and were accompanied by increased membrane conductance. In interneurons, membrane oscillations were consistently depolarizing and accompanied by bursts of action potentials. In a subset of balloon/giant cells from CD type IIb and TSC cases, respectively, 4-AP induced very low-amplitude, slow membrane oscillations that echoed the rhythmic oscillations from pyramidal neurons and interneurons. Bicuculline reduced the amplitude of membrane oscillations induced by 4-AP, indicating that they were mediated principally by GABAA receptors. 4-AP alone or in combination with bicuculline increased cortical excitability but did not induce seizure-like discharges. Ictal activity was observed in pyramidal neurons and interneurons from CD and TSC cases only when phaclofen, a GABAB receptor antagonist, was added to the 4-AP and bicuculline solution. These results emphasize the critical and permissive role of GABAB receptors in the transition to an ictal state in pediatric CD tissue and highlight the importance of these receptors as a potential therapeutic target in pediatric epilepsy.
View details for DOI 10.3389/fncel.2020.00054
View details for Web of Science ID 000523689500001
View details for PubMedID 32265658
View details for PubMedCentralID PMC7099654
- Structural correlates of emotional response to electrical stimulation of the amygdala in subjects with PTSD BRAIN STIMULATION 2020; 13 (2): 424-426
Pathological high frequency oscillations associate with increased GABA synaptic activity in pediatric epilepsy surgery patients
NEUROBIOLOGY OF DISEASE
2020; 134: 104618
Pathological high-frequency oscillations (HFOs), specifically fast ripples (FRs, >250 Hz), are pathognomonic of an active epileptogenic zone. However, the origin of FRs remains unknown. Here we explored the correlation between FRs recorded with intraoperative pre-resection electrocorticography (ECoG) and spontaneous synaptic activity recorded ex vivo from cortical tissue samples resected for the treatment of pharmacoresistant epilepsy. The cohort included 47 children (ages 0.22-9.99 yr) with focal cortical dysplasias (CD types I and II), tuberous sclerosis complex (TSC) and non-CD pathologies. Whole-cell patch clamp recordings were obtained from pyramidal neurons and interneurons in cortical regions that were positive or negative for pathological HFOs, defined as FR band oscillations (250-500 Hz) at ECoG. The frequency of spontaneous excitatory and inhibitory postsynaptic currents (sEPSCs and IPSCs, respectively) was compared between HFO+ and HFO- regions. Regardless of pathological substrate, regions positive for FRs displayed significantly increased frequencies of sIPSCs compared with regions negative for FRs. In contrast, the frequency of sEPSCs was similar in both regions. In about one third of cases (n = 17), pacemaker GABA synaptic activity (PGA) was observed. In the vast majority (n = 15), PGA occurred in HFO+ areas. Further, fast-spiking interneurons displayed signs of hyperexcitability exclusively in HFO+ areas. These results indicate that, in pediatric epilepsy patients, increased GABA synaptic activity is associated with interictal FRs in the epileptogenic zone and suggest an active role of GABAergic interneurons in the generation of pathological HFOs. Increased GABA synaptic activity could serve to dampen excessive excitability of cortical pyramidal neurons in the epileptogenic zone, but it could also promote neuronal network synchrony.
View details for DOI 10.1016/j.nbd.2019.104618
View details for Web of Science ID 000509818400010
View details for PubMedID 31629890
View details for PubMedCentralID PMC6980668
Cellular antiseizure mechanisms of everolimus in pediatric tuberous sclerosis complex, cortical dysplasia, and non-mTOR-mediated etiologies.
2018; 3 (Suppl Suppl 2): 180-190
The present study was designed to examine the potential cellular antiseizure mechanisms of everolimus, a mechanistic target of rapamycin (mTOR) pathway blocker, in pediatric epilepsy cases. Cortical tissue samples obtained from pediatric patients (n=11, ages 0.67-6.75years) undergoing surgical resections for the treatment of their pharmacoresistant epilepsy were examined electrophysiologically in exvivo slices. The cohort included mTOR-mediated pathologies (tuberous sclerosis complex [TSC] and severe cortical dysplasia [CD]) as well as non-mTOR-mediated pathologies (tumor and perinatal infarct). Bath application of everolimus (2mum) had practically no effect on spontaneous inhibitory postsynaptic activity. In contrast, long-term application of everolimus reduced spontaneous excitatory postsynaptic activity, burst discharges induced by blockade of gamma-aminobutyric acid A (GABAA) receptors, and epileptiform activity generated by 4-aminopyridine, a K+ channel blocker. The antiseizure effects were more pronounced in TSC and CD cases, whereas in non-mTOR-mediated pathologies, the effects were subtle at best. These results support further clinical trials of everolimus in mTOR pathway-mediated pathologies and emphasize that the effects require sustained exposure over time.
View details for DOI 10.1002/epi4.12253
View details for PubMedID 30564777