About

Giridhar Kalamangalam, MD, DPhil, is a Wilder Family endowed professor and division chief of epilepsy at the University of Florida College of Medicine. He was recruited to UF Health in September 2017. Born and raised in India, he completed his medical education at the Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER) in Puducherri. He was a Rhodes scholar at Oxford University in England, where he earned a master’s degree in applied mathematics and a research doctorate in mathematical biology. His clinical training includes internal medicine rotations in the British National Health Service and a general neurology residency at the Institute of Neurological Sciences in Glasgow. He further specialized in epilepsy and EEG through fellowship training at the Cleveland Clinic. Dr. Kalamangalam's career is dedicated to the care of patients with epilepsy and research in the science surrounding epilepsy. His work has been published in peer-reviewed journals and funded by organizations such as the National Institute of Neurological Disorders and Stroke and the American Epilepsy Society. His research focuses on epilepsy imaging, cortical neurophysiology, brain dynamics, and neuroimaging methods, with particular interest in refractory epilepsy, brain mapping, and neurophysiology.

Research topics

• Computer Science
• Psychology
• Neuroscience
• Psychiatry
• Medicine
• Artificial Intelligence
• Family medicine
• Computer vision
• Data science

Selected publications

• COMPRESSIVE DATA STORAGE FOR LONG-TERM EEG: VALIDATION BY VISUAL ANALYSIS

  Clinical Neurophysiology Practice · 2025-01-01

  articleOpen access1st authorCorresponding

  Objectives: Long-term EEG monitoring (LTM) in acute neurology generates massive data volumes. We investigated whether data-analytic techniques could reduce LTM data size yet conserve their visual diagnostic features. Methods: LTM exemplars from 50 patients underwent singular value decomposition (SVD). High-variance SVD components were transformed using discrete cosine transform (DCT), and significant elements run-length encoded. Two regimes were tested: (I) SVD and DCT compression ratio (CR) of 1.7 and 12, and (II) CR of 3.7 and 5.7; each achieved an overall CR of ≈20. Compressed data were reconstructed alongside uncompressed originals, to create a total of 200 recordings that were scored by two blinded reviewers. Scores of original and reconstructed data were statistically analyzed. Results: Score differences between original recordings were smaller than comparisons involving reconstructions using the first regime but did not differ significantly from reconstructions using the second regime. Conclusions: Raw LTM EEG has sufficient redundancy to undergo extreme (20-fold) data compression without compromising visual diagnostic information. A balanced mix of SVD and DCT appears to be a suitable data-analytic pipeline for achieving such compression. Significance: Dimension reduction is a significant goal in managing big biomedical data. Our results suggest a pathway for archival of meaningful representations of entire LTM datasets. The latent space suggests new lines of data-scientific inquiry of the EEG in acute neurological illness.

  PublisherDOI

• Nontumoral Amygdalar Enlargement in Tumoral Epilepsy

  World Neurosurgery · 2025-03-31

  articleOpen accessSenior authorCorresponding

  An 18-year-old left-handed African American male presented with a year-long history of seizures characterized by episodic palpitations, sweating, and agitation. Brain magnetic resonance imaging revealed an enhancing tumor in the right anterior entorhinal cortex with adjacent amygdalar enlargement. Interictal magnetoencephalography and video-electroencephalogram -confirmed lesional right temporal lobe epilepsy. The patient underwent a partial right anterior temporal lobectomy, with histopathology revealing WHO Grade 2 pleomorphic xanthoastrocytoma with a BRAF V600 E mutation. The amygdala showed no tumor infiltration, confirming reactive hyperplasia rather than neoplastic involvement. This case underscores the importance of distinguishing tumor infiltration from benign seizure-related amygdalar enlargement in long-term epilepsy-associated tumors, usefully informing surgical strategy.

  PublisherDOI

• Gradients in signal complexity of sleep-wake intracerebral EEG

  PLoS ONE · 2025-03-31 · 1 citations

  articleOpen access1st authorCorresponding

  Spatial variation in the morphology of the electroencephalogram (EEG) over the head is classically described. Ultimately, location-dependent variation in EEG must arise from the cytoarchitectural and network structure of the portion of cortex sensed. In previous work, we demonstrated that over the lateral frontal lobe, sample entropy (SE) of intracerebral EEG (iEEG) over a subdural recording contact was predictive of that contact's connectivity to other contacts. In this work, we used a publicly available repository (the Montreal Neurological Institute Atlas; MNIA) of whole-brain normative iEEG to calculate SE over the entire cortical surface. SE was averaged region-wise and classified by the state of arousal (awake, N2, N3 and REM). SE averages were transformed to a linear scale between zero and unity, mapped to continuous color scale and overlaid on segmented cortical surface models, one for each sleep-wake state. Wake SE followed a rostro-caudal gradient (RCG), with high values anteriorly and a global minimum in the posterior cortex. Superimposed on the RCG were other gradients radiating away from primary somatic sensorimotor, visual and auditory regions to their association areas. All gradients were attenuated in deep (N3) sleep. In REM, the majority of the cortex exhibited wake-like SE, with the prominent exception of primary cortical sensory and motor areas. Normative human intracerebral EEG exhibits rich spatial structure - cortical gradients - in the distribution of SE. SE in the wake state tracks temporal processing hierarchies in cerebral cortex, concordant to the distribution of several other cortical attributes of structure (e.g., cortical thickness, myelin content). Sleep disrupts these gradients, with REM sleep bringing out unusual discordances between primary sensory and their association areas. Our results deepen the interpretation of EEG from conventional descriptors such as Berger bands to a spatial perspective related to cortical biology.

  PublisherOA PDFDOI

• Orbitofrontal Epilepsies: Intracranial Electroencephalography and Surgical Aspects

  Journal of Clinical Neurophysiology · 2025-10-08 · 1 citations

  article

  SUMMARY: Orbitofrontal epilepsies (OFE) produce variable clinical semiologies and nonspecific electrographic patterns thereby being challenging to localize. Furthermore, systematic studies of the surgical management and outcomes in OFE are sparse. The authors review the current literature and discuss the intracranial electroencephalography, microsurgical techniques, and surgical outcomes of patients in the context of a 20-year surgical experience in treating 24 patients with OFE. The authors distinguish between purely orbitofrontal resections (OF-focal, n = 10) and those in whom additional brain regions were concurrently resected (OF-plus, n = 14). These two cohorts were similar with respect to age, duration of epilepsy, and presence of an OF lesion on MRI. Patients frequently reported no auras (OF-focal: 7 [70%], OF-plus: 8 [57%]); generalized tonic-clonic seizures were common (OF-focal: 6 [60%], OF-plus: 7 [50%]); and seizures were often nocturnal (OF-focal: 5 [50%], OF-plus: 8 [57%]). Surgical extensions among the OF-plus group included the prefrontal or frontal pole (67%), temporal pole (11%), and mesial temporal lobe (22%). Durable Engel I to II outcomes at last follow-up (median: 4 years, interquartile range [IQR]: 2-7) were achieved in 5 patients (50%) with OF-focal epilepsies and 8 (57%) patients with OF-plus epilepsies. Among nonlesional cases, 4 of 11 patients (36%) achieved seizure freedom, of whom 3 (75%) underwent OF-plus resection. The most common etiology was malformation of cortical development (58%). Surgical resection of the OFE carries the same seizure-free rates as other neocortical epilepsies and can be done safely with minimal cognitive or functional decline.

  PublisherDOI

• Amygdalar volume asymmetry informs laterality in temporal lobe epilepsy: MRI-SEEG study

  Seizure · 2025-02-05 · 2 citations

  articleSenior author
  PublisherDOI

• Prognostic value of the 5-SENSE Score to predict focality of the seizure-onset zone as assessed by stereoelectroencephalography: a prospective international multicentre validation study

  BMJ Neurology Open · 2024-08-01 · 3 citations

  articleOpen access

  Introduction: Epilepsy surgery is the only curative treatment for patients with drug-resistant focal epilepsy. Stereoelectroencephalography (SEEG) is the gold standard to delineate the seizure-onset zone (SOZ). However, up to 40% of patients are subsequently not operated as no focal non-eloquent SOZ can be identified. The 5-SENSE Score is a 5-point score to predict whether a focal SOZ is likely to be identified by SEEG. This study aims to validate the 5-SENSE Score, improve score performance by incorporating auxiliary diagnostic methods and evaluate its concordance with expert decisions. Methods and analysis: Non-interventional, observational, multicentre, prospective study including 200 patients with drug-resistant epilepsy aged ≥15 years undergoing SEEG for identification of a focal SOZ and 200 controls at 22 epilepsy surgery centres worldwide. The primary objective is to assess the diagnostic accuracy and generalisability of the 5-SENSE in predicting focality in SEEG in a prospective cohort. Secondary objectives are to optimise score performance by incorporating auxiliary diagnostic methods and to analyse concordance of the 5-SENSE Score with the expert decisions made in the multidisciplinary team discussion. Ethics and dissemination: Prospective multicentre validation of the 5-SENSE score may lead to its implementation into clinical practice to assist clinicians in the difficult decision of whether to proceed with implantation. This study will be conducted in accordance with the Tri-Council Policy Statement: Ethical Conduct for Research Involving Humans (2014). We plan to publish the study results in a peer-reviewed full-length original article and present its findings at scientific conferences. Trial registration number: NCT06138808.

  PublisherOA PDFDOI

• Amygdalar Asymmetry and Enlargement (AA/AE) in Temporal Lobe Epilepsy: MRI-SEEG Study (P5-1.001)

  Neurology · 2024-04-09

  articleSenior author

  (i) To discover correlations between AE/AA and amygdalar epileptiform activity (ii) To examine the predictive value of AE/AA vis-à-vis SEEG-identified TLE lateralization.

  PublisherDOI

• Laser Ablation of Periventricular Nodular Heterotopia for Medically Refractory Epilepsy

  Annals of Neurology · 2024-09-19 · 10 citations

  article

  OBJECTIVE: Periventricular nodular heterotopia (PVNH) is the most common neuronal heterotopia, frequently resulting in pharmaco-resistant epilepsy. Here, we characterize variables that predict good epilepsy outcomes following surgical intervention using stereo-electroencephalography (SEEG) -informed magnetic resonance-guided laser interstitial thermal therapy (MRgLITT). METHODS: A retrospective review of consecutive cases from a single high-volume epilepsy referral center identified patients who underwent SEEG evaluation for PVNH to characterize the intervention and outcomes. RESULTS: Thirty-nine patients underwent SEEG-guided MRgLITT of the seizure onset zone (SoZ) in PVNH and associated epileptic tissue. PVNH and polymicrogyria (PMG) were densely sampled with a mean of 16.5 (SD = 2)/209.4 (SD = 36.9) SEEG probes/recording contacts per patient. Ablation principally targeted just the PVNH and cortex that was abnormal on imaging was ablated (5 patients) only if implicated in the SoZ. Volumetric analyses revealed a high percentage of PVNH SoZ ablation (96.6%, SD = 5.3%) in unilateral and bilateral (92.9%, SD = 7.2%) cases. Mean follow-up duration was 31.4 months (SD = 20.9). Seizure freedom (ILAE 1) was excellent: unilateral PVNH without other imaging abnormalities, 80%; PVNH with mesial temporal sclerosis (MTS) or PMG, 63%; bilateral PVNH, 50%. SoZ ablation percentage significantly impacted surgical outcomes (p < 0.001). INTERPRETATION: PVNH plays a central role in seizure genesis as revealed by dense recordings and selective targeting by LITT. MRgLITT represents a transformative technological advance in PVNH-associated epilepsy with seizure control outcomes consistent with those seen in focal lesional epilepsies. In localized unilateral cases and otherwise normal imaging, PVNH ablation without invasive recordings may be considered, and this approach deserves to be explored further. ANN NEUROL 2024;96:1174-1184.

  PublisherDOI

• The SEEG Wave

  Journal of Clinical Neurophysiology · 2024-06-27

  article1st authorCorresponding
  PublisherDOI

• Buna Joe “BJ” Wilder, MD (1929–2023)

  Neurology · 2024-03-21

  article1st authorCorresponding
  PublisherDOI

Recent grants

• Advancing Diagnosis and Functional Localization in Focal Epilepsy with Oxygen-Enh

  NIH · $982k · 2012–2019

Frequent coauthors

• Nitin Tandon

  Neurological Surgery

  40 shared

• Nicolas Gaspard

  Yale University

  27 shared

• Susan T. Herman

  Barrow Neurological Institute

  23 shared

• Stephan Schuele

  Northwestern Memorial Hospital

  19 shared

• Jeremy D. Slater

  18 shared

• Suzette M. LaRoche

  16 shared

• Brandon Foreman

  University of Cincinnati

  15 shared

• Lawrence J. Hirsch

  14 shared

Labs

• iBRAIN LabPI

Education

• M.D.

  Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER)

• Other, Mathematical Biology

  Oxford University

• M.S., Applied Mathematics

  Oxford University

Awards & honors

• American Epilepsy Society Fellow (2017)
• Top Doctor 2015-2016 Houstonia magazine
• American Clinical Neurophysiology Society Fellow (2013)
• Royal College of Physicians (London) Fellow (2011)
• Royal College of Physicians and Surgeons (Glasgow) Fellow (2…