Bio

Clinical Focus


  • Pediatric Neurosurgery
  • Brain Tumors
  • Surgical epilepsy
  • Neuroendoscopy
  • Arnold-Chiari Malformation
  • Minimally invasive craniosynostosis
  • Moya-moya disease

Academic Appointments


Administrative Appointments


  • Division Chief, Pediatric Neurosurgery (2014 - Present)

Boards, Advisory Committees, Professional Organizations


  • Section Editor, Neurosurgery (2014 - Present)
  • Education Chair, American Society of Pediatric Neurosurgery (2013 - Present)
  • Committee on Trauma, American College of Surgeons (2012 - Present)
  • Member at Large, Executive Commitee, Section of Pediatric Neurosurgery (2014 - Present)
  • Executive Committee, Congress of Neurological Surgeons (2014 - Present)

Professional Education


  • Board Certification: Pediatric Neurological Surgery, American Board of Pediatric Neurological Surgery (2008)
  • Fellowship:University of Washington (2002) WA
  • Residency:University of Washington (2001) WA
  • Internship:University of Washington (1995) WA
  • Board Certification: Neurological Surgery, American Board of Neurological Surgery (2005)
  • Medical Education:Stanford University School of Medicine (1994) CA
  • Bachelor of Sciences, Duke University, Neurosciences (1989)

Community and International Work


  • Stanford Neurosurgery in Uganda, Mulago Hospital

    Topic

    Pediatric Neurosurgery/Endoscopy

    Partnering Organization(s)

    Duke University

    Populations Served

    Uganda

    Location

    International

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    Yes

Research & Scholarship

Current Research and Scholarly Interests


Dr. Grant directs a Blood-brain Barrier Translational Laboratory focusing on enhancing drug delivery to brain tumors in children.

Teaching

2015-16 Courses


Publications

All Publications


  • New tools for studying microglia in the mouse and human CNS. Proceedings of the National Academy of Sciences of the United States of America Bennett, M. L., Bennett, F. C., Liddelow, S. A., Ajami, B., Zamanian, J. L., Fernhoff, N. B., Mulinyawe, S. B., Bohlen, C. J., Adil, A., Tucker, A., Weissman, I. L., Chang, E. F., Li, G., Grant, G. A., Hayden Gephart, M. G., Barres, B. A. 2016; 113 (12): E1738-46

    Abstract

    The specific function of microglia, the tissue resident macrophages of the brain and spinal cord, has been difficult to ascertain because of a lack of tools to distinguish microglia from other immune cells, thereby limiting specific immunostaining, purification, and manipulation. Because of their unique developmental origins and predicted functions, the distinction of microglia from other myeloid cells is critically important for understanding brain development and disease; better tools would greatly facilitate studies of microglia function in the developing, adult, and injured CNS. Here, we identify transmembrane protein 119 (Tmem119), a cell-surface protein of unknown function, as a highly expressed microglia-specific marker in both mouse and human. We developed monoclonal antibodies to its intracellular and extracellular domains that enable the immunostaining of microglia in histological sections in healthy and diseased brains, as well as isolation of pure nonactivated microglia by FACS. Using our antibodies, we provide, to our knowledge, the first RNAseq profiles of highly pure mouse microglia during development and after an immune challenge. We used these to demonstrate that mouse microglia mature by the second postnatal week and to predict novel microglial functions. Together, we anticipate these resources will be valuable for the future study and understanding of microglia in health and disease.

    View details for DOI 10.1073/pnas.1525528113

    View details for PubMedID 26884166

  • Purification and Characterization of Progenitor and Mature Human Astrocytes Reveals Transcriptional and Functional Differences with Mouse. Neuron Zhang, Y., Sloan, S. A., Clarke, L. E., Caneda, C., Plaza, C. A., Blumenthal, P. D., Vogel, H., Steinberg, G. K., Edwards, M. S., Li, G., Duncan, J. A., Cheshier, S. H., Shuer, L. M., Chang, E. F., Grant, G. A., Gephart, M. G., Barres, B. A. 2016; 89 (1): 37-53

    Abstract

    The functional and molecular similarities and distinctions between human and murine astrocytes are poorly understood. Here, we report the development of an immunopanning method to acutely purify astrocytes from fetal, juvenile, and adult human brains and to maintain these cells in serum-free cultures. We found that human astrocytes have abilities similar to those of murine astrocytes in promoting neuronal survival, inducing functional synapse formation, and engulfing synaptosomes. In contrast to existing observations in mice, we found that mature human astrocytes respond robustly to glutamate. Next, we performed RNA sequencing of healthy human astrocytes along with astrocytes from epileptic and tumor foci and compared these to human neurons, oligodendrocytes, microglia, and endothelial cells (available at http://www.brainrnaseq.org). With these profiles, we identified novel human-specific astrocyte genes and discovered a transcriptome-wide transformation between astrocyte precursor cells and mature post-mitotic astrocytes. These data represent some of the first cell-type-specific molecular profiles of the healthy and diseased human brain.

    View details for DOI 10.1016/j.neuron.2015.11.013

    View details for PubMedID 26687838

  • Pediatric Central Nervous System Tumors in Nepal: Retrospective Analysis and Literature Review of Low- and Middle-Income Countries WORLD NEUROSURGERY Azad, T. D., Shrestha, R. K., Vaca, S., Niyaf, A., Pradhananga, A., Sedain, G., Sharma, M. R., Shilpakar, S. K., Grant, G. A. 2015; 84 (6): 1832-1837

    Abstract

    Central nervous system (CNS) tumors are the most common cause of cancer-related death in children. Very little is known about the demographics and treatment of pediatric brain tumors in the low and middle-income countries (LMIC).We performed a retrospective chart review of all pediatric patients who presented to the neurosurgical service at Tribhuvan University Teaching Hospital in Kathmandu, Nepal from 2009-2014 and collected information on patients <18 years old who received a diagnosis of a CNS tumor. We analyzed age, gender, clinical presentation, extent of surgical resection, histopathology, and length of hospital stay. We also conducted a literature review using specific terminology to capture studies of pediatric neuro-oncologic epidemiology conducted in LMIC. Study location, length of study, sample size, study type, and occurrence of four common pediatric brain tumors were extracted RESULTS: We identified 39 cases of pediatric CNS tumors, with 62.5% observed in male children. We found that male children (median = 13 years) presented later than female children (median = 8 years). The most frequently observed pediatric brain tumor type was ependymoma (17.5%), followed by astrocytoma (15%) and medulloblastoma (15%). Surgical resection was performed for 80% of cases and gross total resection reported in 62.9% of all surgeries. 54.1% of patients had symptoms for more than 28 days prior to seeking treatment. Symptomatic hydrocephalus was noted in 57.1% of children who presented with CNS tumors. The literature review yielded studies from 18 countries. Study length ranged from 2-20 years and sample sizes varied from 35-1948. Overall, we found more pronounced variation in the relative frequencies of the most common pediatric brain tumors, compared to high-income countries.We present the first operative series of childhood CNS tumors in Nepal. Children often had delayed diagnosis and treatment of a tumor, despite symptoms.. More comprehensive data is required to develop improved treatment and management algorithms in the context of a given country's demographics and medical capabilities for childhood CNS tumors.

    View details for DOI 10.1016/j.wneu.2015.07.074

    View details for Web of Science ID 000366286300060

    View details for PubMedID 26283488

  • Evolution of cranioplasty techniques in neurosurgery: historical review, pediatric considerations, and current trends. Journal of neurosurgery Feroze, A. H., Walmsley, G. G., Choudhri, O., Lorenz, H. P., Grant, G. A., Edwards, M. S. 2015; 123 (4): 1098-1107

    Abstract

    Cranial bone repair is one of the oldest neurosurgical practices. Reconstructing the natural contours of the skull has challenged the ingenuity of surgeons from antiquity to the present day. Given the continuous improvement of neurosurgical and emergency care over the past century, more patients survive such head injuries, thus necessitating more than ever before a simple, safe, and durable means of correcting skull defects. In response, numerous techniques and materials have been devised as the art of cranioplasty has progressed. Although the goals of cranioplasty remain the same, the evolution of techniques and diversity of materials used serves as testimony to the complexity of this task. This paper highlights the evolution of these materials and techniques, with a particular focus on the implications for managing pediatric calvarial repair and emerging trends within the field.

    View details for DOI 10.3171/2014.11.JNS14622

    View details for PubMedID 25699411

  • Gorlin syndrome and desmoplastic medulloblastoma: Report of 3 cases with unfavorable clinical course and novel mutations PEDIATRIC BLOOD & CANCER Gururangan, S., Robinson, G., Ellison, D. W., Wu, G., He, X., Lu, Q. R., McLendon, R., Grant, G., Driscoll, T., Neuberg, R. 2015; 62 (10): 1855-1858

    Abstract

    We present three cases of genetically confirmed Gorlin syndrome with desmoplastic medulloblastoma (DMB) in whom tumor recurred despite standard therapy. One patient was found to have a novel germline missense PTCH1 mutation. Molecular analysis of recurrent tumor using fluorescent in situ hybridization (FISH) revealed PTEN and/ or PTCH1 loss in 2 patients. Whole exome sequencing (WES) of tumor in one patient revealed loss of heterozygosity of PTCH1 and a mutation of GNAS gene in its non-coding 3' -untranslated region (UTR) with corresponding decreased protein expression. While one patient died despite high-dose chemotherapy (HDC) plus stem cell rescue (ASCR) and palliative radiotherapy, two patients are currently alive for 18+ and 120+ months respectively following retrieval therapy that did not include irradiation. Infants with DMB and GS should be treated aggressively with chemotherapy at diagnosis to prevent relapse but radiotherapy should be avoided. The use of molecular prognostic markers for DMB should be routinely used to identify the subset of tumors that might have an aggressive course. Pediatr Blood Cancer 2015;62:1855-1858. © 2015 Wiley Periodicals, Inc.

    View details for DOI 10.1002/pbc.25560

    View details for Web of Science ID 000360228000027

    View details for PubMedID 25940061

  • Ex vivo generation of dendritic cells from cryopreserved, post-induction chemotherapy, mobilized leukapheresis from pediatric patients with medulloblastoma JOURNAL OF NEURO-ONCOLOGY Nair, S. K., Driscoll, T., Boczkowski, D., Schmittling, R., Reynolds, R., Johnson, L. A., Grant, G., Fuchs, H., Bigner, D. D., Sampson, J. H., Gururangan, S., Mitchell, D. A. 2015; 125 (1): 65-74

    Abstract

    Generation of patient-derived, autologous dendritic cells (DCs) is a critical component of cancer immunotherapy with ex vivo-generated, tumor antigen-loaded DCs. An important factor in the ability to generate DCs is the potential impact of prior therapies on DC phenotype and function. We investigated the ability to generate DCs using cells harvested from pediatric patients with medulloblastoma for potential evaluation of DC-RNA based vaccination approach in this patient population. Cells harvested from medulloblastoma patient leukapheresis following induction chemotherapy and granulocyte colony stimulating factor mobilization were cryopreserved prior to use in DC generation. DCs were generated from the adherent CD14+ monocytes using standard procedures and analyzed for cell recovery, phenotype and function. To summarize, 4 out of 5 patients (80 %) had sufficient monocyte recovery to permit DC generation, and we were able to generate DCs from 3 out of these 4 patient samples (75 %). Overall, we successfully generated DCs that met phenotypic requisites for DC-based cancer therapy from 3 out of 5 (60 %) patient samples and met both phenotypic and functional requisites from 2 out of 5 (40 %) patient samples. This study highlights the potential to generate functional DCs for further clinical treatments from refractory patients that have been heavily pretreated with myelosuppressive chemotherapy. Here we demonstrate the utility of evaluating the effect of the currently employed standard-of-care therapies on the ex vivo generation of DCs for DC-based clinical studies in cancer patients.

    View details for DOI 10.1007/s11060-015-1890-2

    View details for Web of Science ID 000362334800007

  • Preface to Clinical Neurosurgery Volume 62, Proceedings of the Congress of Neurological Surgeons 2014 Annual Meeting. Neurosurgery Grant, G. A., Tomei, K. L., Hankinson, T. C., Muh, C. R., Dumont, A. S., Cheshier, S. H., Upadhyaya, C., Choudhri, O. 2015; 62: N1-?

    View details for DOI 10.1227/NEU.0000000000000822

    View details for PubMedID 26182050

  • Six Degree-of-Freedom Measurements of Human Mild Traumatic Brain Injury ANNALS OF BIOMEDICAL ENGINEERING Hernandez, F., Wu, L. C., Yip, M. C., Laksari, K., Hoffman, A. R., Lopez, J. R., Grant, G. A., Kleiven, S., Camarillo, D. B. 2015; 43 (8): 1918-1934

    Abstract

    This preliminary study investigated whether direct measurement of head rotation improves prediction of mild traumatic brain injury (mTBI). Although many studies have implicated rotation as a primary cause of mTBI, regulatory safety standards use 3 degree-of-freedom (3DOF) translation-only kinematic criteria to predict injury. Direct 6DOF measurements of human head rotation (3DOF) and translation (3DOF) have not been previously available to examine whether additional DOFs improve injury prediction. We measured head impacts in American football, boxing, and mixed martial arts using 6DOF instrumented mouthguards, and predicted clinician-diagnosed injury using 12 existing kinematic criteria and 6 existing brain finite element (FE) criteria. Among 513 measured impacts were the first two 6DOF measurements of clinically diagnosed mTBI. For this dataset, 6DOF criteria were the most predictive of injury, more than 3DOF translation-only and 3DOF rotation-only criteria. Peak principal strain in the corpus callosum, a 6DOF FE criteria, was the strongest predictor, followed by two criteria that included rotation measurements, peak rotational acceleration magnitude and Head Impact Power (HIP). These results suggest head rotation measurements may improve injury prediction. However, more 6DOF data is needed to confirm this evaluation of existing injury criteria, and to develop new criteria that considers directional sensitivity to injury.

    View details for DOI 10.1007/s10439-014-1212-4

    View details for Web of Science ID 000358249800018

    View details for PubMedID 25533767

  • Therapeutic strategies to improve drug delivery across the blood-brain barrier. Neurosurgical focus Azad, T. D., Pan, J., Connolly, I. D., Remington, A., Wilson, C. M., Grant, G. A. 2015; 38 (3): E9-?

    Abstract

    Resection of brain tumors is followed by chemotherapy and radiation to ablate remaining malignant cell populations. Targeting these populations stands to reduce tumor recurrence and offer the promise of more complete therapy. Thus, improving access to the tumor, while leaving normal brain tissue unscathed, is a critical pursuit. A central challenge in this endeavor lies in the limited delivery of therapeutics to the tumor itself. The blood-brain barrier (BBB) is responsible for much of this difficulty but also provides an essential separation from systemic circulation. Due to the BBB's physical and chemical constraints, many current therapies, from cytotoxic drugs to antibody-based proteins, cannot gain access to the tumor. This review describes the characteristics of the BBB and associated changes wrought by the presence of a tumor. Current strategies for enhancing the delivery of therapies across the BBB to the tumor will be discussed, with a distinction made between strategies that seek to disrupt the BBB and those that aim to circumvent it.

    View details for DOI 10.3171/2014.12.FOCUS14758

    View details for PubMedID 25727231

  • Sertraline-induced potentiation of the CYP3A4-dependent neurotoxicity of carbamazepine: An in vitro study EPILEPSIA Ghosh, C., Hossain, M., Spriggs, A., Ghosh, A., Grant, G. A., Marchi, N., Perucca, E., Janigro, D. 2015; 56 (3): 439-449

    Abstract

    Drug toxicity is a hurdle to drug development and to clinical translation of basic research. Antiepileptic drugs such as carbamazepine (CBZ) and selective serotonin reuptake inhibitors such as sertraline (SRT) are commonly co-prescribed to patients with epilepsy and comorbid depression. Because SRT may interfere with cytochrome P450 (CYP) enzyme activity and CYPs have been implicated in the conversion of CBZ to reactive cytotoxic metabolites, we investigated in vitro models to determine whether SRT affects the neurotoxic potential of CBZ and the mechanisms involved.Human fetal brain-derived dopaminergic neurons, human brain microvascular endothelial cells (HBMECs), and embryonic kidney (HEK) cells were used to evaluate cytotoxicity of CBZ and SRT individually and in combination. Nitrite and glutathione (GSH) levels were measured with drug exposure. To validate the role of CYP3A4 in causing neurotoxicity, drug metabolism was compared to cell death in HEK CYP3A4 overexpressed and cells pretreated with the CYP3A4 inhibitor ketoconazole.In all cellular systems tested, exposure to CBZ (127 μm) or SRT (5 μm) alone caused negligible cytotoxicity. By contrast CBZ, tested at a much lower concentration (17 μm) in combination with SRT (5 μm), produced prominent cytotoxicity within 15 min exposure. In neurons and HBMECs, cytotoxicity was associated with increased nitrite levels, suggesting involvement of free radicals as a pathogenetic mechanism. Pretreatment of HBMECs with reduced GSH or with the GSH precursor N-acetyl-l-cysteine prevented cytotoxic response. In HEK cells, the cytotoxic response to the CBZ + SRT combination correlated with the rate of CBZ biotransformation and production of 2-hydroxy CBZ, further suggesting a causative role of reactive metabolites. In the same system, cytotoxicity was potentiated by overexpression of CYP3A4, and prevented by CYP3A4 inhibitor.These results demonstrate an unexpected neurotoxic interaction between CBZ and SRT, apparently related to increased CYP3A4-mediated production of reactive CBZ metabolites. The potential clinical implications of these findings are discussed.

    View details for DOI 10.1111/epi.12923

    View details for Web of Science ID 000351240300016

    View details for PubMedID 25656284

  • Therapeutic strategies to improve drug delivery across the blood-brain barrier NEUROSURGICAL FOCUS Azad, T. D., Pan, J., Connolly, I. D., Remington, A., Wilson, C. M., Grant, G. A. 2015; 38 (3)
  • Joint eQTL assessment of whole blood and dura mater tissue from individuals with Chiari type I malformation BMC GENOMICS Lock, E. F., Soldano, K. L., Garrett, M. E., Cope, H., Markunas, C. A., Fuchs, H., Grant, G., Dunson, D. B., Gregory, S. G., Ashley-Koch, A. E. 2015; 16
  • Is there a role for decompressive craniectomy in children after stroke? World neurosurgery Grant, G. A. 2015; 83 (1): 44-45

    View details for DOI 10.1016/j.wneu.2013.08.049

    View details for PubMedID 24012655

  • Preface to clinical neurosurgery volume 61, proceedings of the congress of neurological surgeons 2013 annual meeting. Neurosurgery Grant, G. A., Hankinson, T., Muh, C., Dumont, A., Cheshier, S. 2014; 61: N1-?

    View details for DOI 10.1227/NEU.0000000000000442

    View details for PubMedID 25032656

  • Identification of Chiari Type I Malformation subtypes using whole genome expression profiles and cranial base morphometrics BMC MEDICAL GENOMICS Markunas, C. A., Lock, E., Soldano, K., Cope, H., Ding, C. C., Enterline, D. S., Grant, G., Fuchs, H., Ashley-Koch, A. E., Gregory, S. G. 2014; 7
  • Genome Sequencing of SHH Medulloblastoma Predicts Genotype-Related Response to Smoothened Inhibition CANCER CELL Kool, M., Jones, D. T., Jaeger, N., Northcott, P. A., Pugh, T. J., Hovestadt, V., Piro, R. M., Esparza, L. A., Markant, S. L., Remke, M., Milde, T., Bourdeaut, F., Ryzhova, M., Sturm, D., Pfaff, E., Stark, S., Hutter, S., Seker-Cin, H., Johann, P., Bender, S., Schmidt, C., Rausch, T., Shih, D., Reimand, J., Sieber, L., Wittmann, A., Linke, L., Witt, H., Weber, U. D., Zapatka, M., Koenig, R., Beroukhim, R., Bergthold, G., Van Sluis, P., Volckmann, R., Koster, J., Versteeg, R., Schmidt, S., Wolf, S., Lawerenz, C., Bartholomae, C. C., von Kalle, C., Unterberg, A., Herold-Mende, C., Hofer, S., Kulozik, A. E., von Deimling, A., Scheurlen, W., Felsberg, J., Reifenberger, G., Hasselblatt, M., Crawford, J. R., Grant, G. A., Jabado, N., Perry, A., Cowdrey, C., Croul, S., Zadeh, G., Korbel, J. O., Doz, F., Delattre, O., Bader, G. D., McCabe, M. G., Collins, V. P., Kieran, M. W., Cho, Y., Pomeroy, S. L., Witt, O., Brors, B., Taylor, M. D., Schueller, U., Korshunov, A., Eils, R., Wechsler-Reya, R. J., Lichter, P., Pfister, S. M. 2014; 25 (3): 393-405

    Abstract

    Smoothened (SMO) inhibitors recently entered clinical trials for sonic-hedgehog-driven medulloblastoma (SHH-MB). Clinical response is highly variable. To understand the mechanism(s) of primary resistance and identify pathways cooperating with aberrant SHH signaling, we sequenced and profiled a large cohort of SHH-MBs (n = 133). SHH pathway mutations involved PTCH1 (across all age groups), SUFU (infants, including germline), and SMO (adults). Children >3 years old harbored an excess of downstream MYCN and GLI2 amplifications and frequent TP53 mutations, often in the germline, all of which were rare in infants and adults. Functional assays in different SHH-MB xenograft models demonstrated that SHH-MBs harboring a PTCH1 mutation were responsive to SMO inhibition, whereas tumors harboring an SUFU mutation or MYCN amplification were primarily resistant.

    View details for DOI 10.1016/j.ccr.2014.02.004

    View details for Web of Science ID 000333233400015

    View details for PubMedID 24651015

  • Reorganization and stability for motor and language areas using cortical stimulation: case example and review of the literature. Brain sciences Serafini, S., Komisarow, J. M., Gallentine, W., Mikati, M. A., Bonner, M. J., Kranz, P. G., Haglund, M. M., Grant, G. 2013; 3 (4): 1597-1614

    Abstract

    The cerebral organization of language in epilepsy patients has been studied with invasive procedures such as Wada testing and electrical cortical stimulation mapping and more recently with noninvasive neuroimaging techniques, such as functional MRI. In the setting of a chronic seizure disorder, clinical variables have been shown to contribute to cerebral language reorganization underscoring the need for language lateralization and localization procedures. We present a 14-year-old pediatric patient with a refractory epilepsy disorder who underwent two neurosurgical resections of a left frontal epileptic focus separated by a year. He was mapped extraoperatively through a subdural grid using cortical stimulation to preserve motor and language functions. The clinical history and extensive workup prior to surgery is discussed as well as the opportunity to compare the cortical maps for language, motor, and sensory function before each resection. Reorganization in cortical tongue sensory areas was seen concomitant with a new zone of ictal and interictal activity in the previous tongue sensory area. Detailed neuropsychological data is presented before and after any surgical intervention to hypothesize about the extent of reorganization between epochs. We conclude that intrahemispheric cortical plasticity does occur following frontal lobe resective surgery in a teenager with medically refractory seizures.

    View details for DOI 10.3390/brainsci3041597

    View details for PubMedID 24961623