Clinical Focus

  • Neurosurgery
  • Brain Tumors
  • Endoscopy
  • Skull-base surgery
  • Surgical Procedures, Minimally Invasive
  • Spinal Cord Tumors
  • Spinal Cord Injuries
  • TBI (Traumatic Brain Injury)
  • Spinal Fusion

Academic Appointments

Administrative Appointments

  • Advising Associate for Neurosurgery, Academic Advising Dean's Office, Stanford University School of Medicine (2012 - Present)
  • Assistant Professor of Neurosurgery, Stanford University School of Medicine (2010 - Present)

Boards, Advisory Committees, Professional Organizations

  • Secretary, American Association of South Asian Neurosurgeons (2014 - Present)
  • Editorial Board, Open Journal of Modern Neurosurgery (2013 - Present)
  • Education Committee Member, Congress of Neurological Surgeons (2013 - Present)
  • Editorial Board, CNS University - Tumor Section (2012 - Present)
  • Member at Large, American Association of South Asian Neurosurgeons (2012 - 2014)
  • Member, WW Keen Neurosurgical Society (2010 - Present)
  • Member, North American Skull Base Society (2010 - Present)
  • Member, American Association of Neurological Surgeons (2004 - Present)
  • Member, Congress of Neurological Surgeons (2004 - Present)

Professional Education

  • Fellowship, University of Washington - Harborview Medical Center, Complex Cerebrovascular and Skull base Surgery - Prof. Laligam N Sekhar (2016)
  • Fellowship, Weill Cornell Medical College, New York Presbyterian Hospital, Minimally Invasive Skull Base Surgery - Prof. Theodore H Schwartz (2015)
  • FACS, American College of Surgeons (ACS) - Fellow, Neurosurgery (2015)
  • FAANS, American Board of Neurological Surgery, Neurosurgery (2014)
  • Residency, Thomas Jefferson University Hospital - Philadelphia, Neurosurgery (2010)
  • Internship, Thomas Jefferson University Hospital - Philadelphia, General Surgery (2005)
  • MD, Tufts University School of Medicine, Boston, Medicine (2004)

Research & Scholarship

Current Research and Scholarly Interests

Robotics and the Brain-Machine Interface, Traumatic Brain Injury, Spinal Cord Injury


All Publications

  • Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide. Scientifica Singh, H., Vogel, R. W., Doan, A. T., Matsumoto, C. I., Kenning, T. J., Evans, J. J. 2016: 20

    View details for DOI 10.1155/1751245/

  • Impact of Early Leucocytosis and elevated hs-CRP on Delayed Cerebral Ischemia and Neurological Outcome following Subarachnoid Hemorrhage. World neurosurgery Srinivasan, A., Aggarwal, A., Gaudihalli, S., Mohanty, M., Dhandapani, M., Singh, H., Mukherjee, K. K., Dhandapani, S. 2016


    The role of inflammatory response in the pathophysiology of SAH is being increasingly recognized. This is a study to analyze the impact of cellular and biochemical markers of early inflammatory response to ictus on outcome following SAH.SAH patients were prospectively studied for markers of early cellular, biochemical, and cytotoxic inflammatory response such as total leucocyte count (TLC), high sensitive C-reactive protein (hs-CRP), and lactate dehydrogenase (LDH). The relationship of these markers on delayed cerebral ischemia (DCI), new infarct and Glasgow Outcome Scale (GOS) at 3 months was studied.A total of 246 patients were studied. Of these, 94 patients who developed DCI had significantly higher TLC (11.2 [+4.0] vs 9.4 [2.9]10(3)/mm(3), p=0.001) while 62 patients with new infarct had significantly higher TLC (11.0 [+3.6] vs 9.8 [+3.4]10(3)/mm(3), p=0.05).GOS had a significant inverse relationship to admission TLC. The mean TLC [+SD] was 12.7 [+4.2], 11.7 [+3.1], 10.2 [+3.4] & 9.3 [+2.8] among patients with GOS 1, 3, 4 & 5 respectively (p<0.001). hs-CRP showed trend of an inverse relationship to GOS in univariate analysis, while LDH had no relationship with any outcome parameter. In multivariate analysis, higher admission TLC had significant association with DCI (p=0.01) and poorer GOS (p<0.001), and higher hs-CRP had significant association with poorer GOS (p=0.05).Leukocytosis response to ictus seems to have significant independent association with both DCI and poor GOS, and hs-CRP levels had significant independent association with poor GOS, indicating preeminence of early cellular response in SAH pathophysiology.

    View details for DOI 10.1016/j.wneu.2016.02.049

    View details for PubMedID 26898490

  • Resection of pituitary tumors: endoscopic versus microscopic. Journal of neuro-oncology Singh, H., Essayed, W. I., Cohen-Gadol, A., Zada, G., Schwartz, T. H. 2016


    Transsphenoidal microscopic pituitary surgery has long been considered the gold standard in surgical treatment of pituitary tumors. Endonasal endoscopic pituitary surgery has come into prominence over the last two decades as an alternative to microscopic surgery. In this review, we use recent literature to discuss the advantages and disadvantages of each approach. Our review shows that for small intrasellar tumors, both approaches appear equally effective in experienced hands. For larger tumors with extrasellar extension, the endoscopic approach offers several advantages and may improve outcomes associated with the extent of resection and postoperative complications.

    View details for DOI 10.1007/s11060-016-2124-y

    View details for PubMedID 27161249

  • Endonasal endoscopic reoperation for residual or recurrent craniopharyngiomas. Journal of neurosurgery Dhandapani, S., Singh, H., Negm, H. M., Cohen, S., Souweidane, M. M., Greenfield, J. P., Anand, V. K., Schwartz, T. H. 2016: 1-13


    OBJECTIVE Craniopharyngiomas can be difficult to remove completely based on their intimate relationship with surrounding visual and endocrine structures. Reoperations are not uncommon but have been associated with higher rates of complications and lower extents of resection. So radiation is often offered as an alternative to reoperation. The endonasal endoscopic transsphenoidal approach has been used in recent years for craniopharyngiomas previously removed with craniotomy. The impact of this approach on reoperations has not been widely investigated. METHODS The authors reviewed a prospectively acquired database of endonasal endoscopic resections of craniopharyngiomas over 11 years at Weill Cornell Medical College, NewYork-Presbyterian Hospital, performed by the senior authors. Reoperations were separated from first operations. Pre- and postoperative visual and endocrine function, tumor size, body mass index (BMI), quality of life (QOL), extent of resection (EOR), impact of prior radiation, and complications were compared between groups. EOR was divided into gross-total resection (GTR, 100%), near-total resection (NTR, > 95%), and subtotal resection (STR, < 95%). Univariate and multivariate analyses were performed. RESULTS Of the total 57 endonasal surgical procedures, 22 (39%) were reoperations. First-time operations and reoperations did not differ in tumor volume, radiological configuration, or patients' BMI. Hypopituitarism and diabetes insipidus (DI) were more common before reoperations (82% and 55%, respectively) compared with first operations (60% and 8.6%, respectively; p < 0.001). For the 46 patients in whom GTR was intended, rates of GTR and GTR+NTR were not significantly different between first operations (90% and 97%, respectively) and reoperations (80% and 100%, respectively). For reoperations, prior radiation and larger tumor volume had lower rates of GTR. Vision improved equally in first operations (80%) compared with reoperations (73%). New anterior pituitary deficits were more common in first operations compared with reoperations (51% vs 23%, respectively; p = 0.08), while new DI was more common in reoperations compared with first-time operations (80% vs 47%, respectively; p = 0.08). Nonendocrine complications occurred in 2 (3.6%) first-time operations and no reoperations. Tumor regrowth occurred in 6 patients (11%) over a median follow-up of 46 months and was not different between first versus reoperations, but was associated with STR (33%) compared with GTR+NTR (4%; p = 0.02) and with not receiving radiation after STR (67% vs 22%; p = 0.08). The overall BMI increased significantly from 28.7 to 34.8 kg/m(2) over 10 years. Six months after surgery, there was a significant improvement in QOL, which was similar between first-time operations and reoperations, and negatively correlated with STR. CONCLUSIONS Endonasal endoscopic transsphenoidal reoperation results in similar EOR, visual outcome, and improvement in QOL as first-time operations, with no significant increase in complications. EOR is more impacted by tumor volume and prior radiation. Reoperations should be offered to patients with recurrent craniopharyngiomas and may be preferable to radiation in patients in whom GTR or NTR can be achieved.

    View details for DOI 10.3171/2016.1.JNS152238

    View details for PubMedID 27153172

  • Endonasal Access to the Upper Cervical Spine: Part 2Cadaveric Analysis JOURNAL OF NEUROLOGICAL SURGERY PART B-SKULL BASE Singh, H., Lober, R. M., Virdi, G. S., Lopez, H., Rosen, M., Evans, J. 2015; 76 (4): 262-265


    Objectives The study aims to determine factors that augment endonasal exposure of the cervical spine. Setting We used fluoroscopy and endoscopy to study endonasal visualization of the upper cervical spine. Participants Ten cadavers with normal anatomy were studied. Main Outcome Measures Endoscopic visualization was simulated with projected lines from an endoscope to the cervical spine in multiple positions. Results Neck position alone did not affect the extent of endonasal exposure of the upper cervical spine, although there was a trend correlating the extended neck position with more caudal exposure. The greatest impact was with concurrent use of a 30-degree endoscope and neck extension, and more caudal access was achieved by tilting the endoscope against the piriform aperture, using the posterior tip of the hard palate as the fulcrum. Conclusions Concurrent use of a 30-degree endoscope and neck extension increased the degree of exposure down the cervical spine. Maximum endonasal exposure of the upper cervical spine was obtained by maneuvering instruments at the fulcrum of the posterior hard palate and the nares, rather than changing the position of the neck alone. These results complement radiographic morphometric data in Part 1 of this study for preoperative assessment and surgical planning.

    View details for DOI 10.1055/s-0034-1395490

    View details for Web of Science ID 000358668800004

    View details for PubMedID 26225313

  • Endoscopic approaches to the cervical spine: analyzing the state of the evidence Minerva Ortopedica e Traumatologica Singh, H., Moraff, A., Evans, J. 2015; 66 (1): 63-70
  • History of simulation in medicine: from resusci annie to the ann myers medical center. Neurosurgery Singh, H., Kalani, M., Acosta-Torres, S., El Ahmadieh, T. Y., Loya, J., Ganju, A. 2013; 73: S9-S14


    Medical and surgical graduate medical education has historically used a halstedian approach of "see one, do one, teach one." Increased public demand for safety, quality, and accountability in the setting of regulated resident work hours and limited resources is driving the development of innovative educational tools. The use of simulation in nonmedical, medical, and neurosurgical disciplines is reviewed in this article. Simulation has been validated as an educational tool in nonmedical fields such as aviation and the military. Across most medical and surgical subspecialties, simulation is recognized as a valuable tool that will shape the next era of medical education, postgraduate training, and maintenance of certification.

    View details for DOI 10.1227/NEU.0000000000000093

    View details for PubMedID 24051890

  • Endonasal Access to the Upper Cervical Spine, Part One: Radiographic Morphometric Analysis JOURNAL OF NEUROLOGICAL SURGERY PART B-SKULL BASE Singh, H., Grobelny, B. T., Harrop, J., Rosen, M., Lober, R. M., Evans, J. 2013; 74 (3): 176-184
  • Brain tuberculoma in a non-endemic area. Infectious disease reports Lober, R. M., Veeravagu, A., Singh, H. 2013; 5 (1)


    Brain tuberculoma has previously accounted for up to a third of new intracranial lesions in areas endemic with tuberculosis, but is unexpected in the United States and other Western countries with improved disease control. Here we show the importance of considering this diagnosis in at-risk patients, even with no definitive pulmonary involvement. We describe a young man who presented with partial seizures and underwent craniotomy for resection of a frontoparietal tuberculoma. He subsequently completed six months of antituberculosis therapy and was doing well without neurological sequelae or evidence of recurrence five months after completion of therapy. With resurgence of tuberculosis cases in the United States and other Western countries, intracerebral tuberculoma should remain a diagnostic consideration in at-risk patients with new space occupying lesions. Mass lesions causing neurological sequelae can be safely addressed surgically and followed with antituberculosis therapy.

    View details for DOI 10.4081/idr.2013.e1

    View details for PubMedID 24470952

  • Traumatic epistaxis: Skull base defects, intracranial complications and neurosurgical considerations. International journal of surgery case reports Veeravagu, A., Joseph, R., Jiang, B., Lober, R. M., Ludwig, C., Torres, R., Singh, H. 2013; 4 (8): 656-661


    Endonasal procedures may be necessary during management of craniofacial trauma. When a skull base fracture is present, these procedures carry a high risk of violating the cranial vault and causing brain injury or central nervous system infection.A 52-year-old bicyclist was hit by an automobile at high speed. He sustained extensive maxillofacial fractures, including frontal and sphenoid sinus fractures (Fig. 1). He presented to the emergency room with brisk nasopharyngeal hemorrhage, and was intubated for airway protection. He underwent emergent stabilization of his nasal epistaxis by placement of a Foley catheter in his left nare and tamponade with the Foley balloon. A six-vessel angiogram showed no evidence of arterial dissection or laceration. Imaging revealed inadvertent insertion of the Foley catheter and deployment of the balloon in the frontal lobe (Fig. 2). The balloon was subsequently deflated and the Foley catheter removed. The patient underwent bifrontal craniotomy for dural repair of CSF leak. He also had placement of a ventriculoperitoneal shunt for development of post-traumatic hydrocephalus. Although the hospital course was a prolonged one, he did make a good neurological recovery.The authors review the literature involving violation of the intracranial compartment with medical devices in the settings of craniofacial trauma.Caution should be exercised while performing any endonasal procedure in the settings of trauma where disruption of the anterior cranial base is possible.

    View details for DOI 10.1016/j.ijscr.2013.04.033

    View details for PubMedID 23792475

  • Primary spinal germ cell tumors: a case analysis and review of treatment paradigms. Case reports in medicine Loya, J. J., Jung, H., Temmins, C., Cho, N., Singh, H. 2013; 2013: 798358-?


    Objective. Primary intramedullary spinal germ cell tumors are exceedingly rare. As such, there are no established treatment paradigms. We describe our management for spinal germ cell tumors and a review of the literature. Clinical Presentation. We describe the case of a 45-year-old man with progressive lower extremity weakness and sensory deficits. He was found to have enhancing intramedullary mass lesions in the thoracic spinal cord, and pathology was consistent with an intramedullary germ cell tumor. A video presentation of the case and surgical approach is provided. Conclusion. As spinal cord germinomas are highly sensitive to radiation and chemotherapy, a patient can be spared radical surgery. Diverse treatment approaches exist across institutions. We advocate biopsy followed by local radiation, with or without adjuvant chemotherapy, as the optimal treatment for these tumors. Histological findings have prognostic value if syncytiotrophoblastic giant cells (STGCs) are found, which are associated with a higher rate of recurrence. The recurrence rate in STGC-positive spinal germinomas is 33% (2/6), whereas it is only 8% in STGC-negative tumors (2/24). We advocate limited volume radiotherapy combined with systemic chemotherapy in patients with high risk of recurrence. To reduce endocrine and neurocognitive side effects, cranio-spinal radiation should be used as a last resort in patients with recurrence.

    View details for DOI 10.1155/2013/798358

    View details for PubMedID 24312128

  • High-resolution ultrasonography in the diagnosis and intraoperative management of peripheral nerve lesions Clinical article JOURNAL OF NEUROSURGERY Lee, F. C., Singh, H., Nazarian, L. N., Ratliff, J. K. 2011; 114 (1): 206-211


    The diagnosis of peripheral nerve lesions relies on clinical history, physical examination, electrodiagnostic studies, and radiography. Magnetic resonance neurography offers high-resolution visualization of structural peripheral nerve lesions. The availability of MR neurography may be limited, and the costs can be significant. By comparison, ultrasonography is a portable, dynamic, and economic technology. The authors explored the clinical applicability of high-resolution ultrasonography in the preoperative and intraoperative management of peripheral nerve lesions.The authors completed a retrospective analysis of 13 patients undergoing ultrasonographic evaluation and surgical treatment of nerve lesions at their institution (nerve entrapment [5], trauma [6], and tumor [2]). Ultrasonography was used for diagnostic (12 of 13 cases) and intraoperative management (6 of 13 cases). The authors examine the initial impact of ultrasonography on clinical management.Ultrasonography was an effective imaging modality that augmented electrophysiological and other neuroimaging studies. The modality provided immediate visualization of a sutured peroneal nerve after a basal cell excision, prompting urgent surgical exploration. Ultrasonography was used intraoperatively in 2 cases to identify postoperative neuromas after mastectomy, facilitating focused excision. Ultrasonography correctly diagnosed an inflamed lymph node in a patient in whom MR imaging studies had detected a schwannoma, and the modality correctly diagnosed a tendinopathy in another patient referred for ulnar neuropathy. Ultrasonography was used in 6 patients to guide the surgical approach and to aid in intraoperative localization; it was invaluable in localizing the proximal segment of a radial nerve sectioned by a humerus fracture. In all cases, ultrasonography demonstrated the correct lesion diagnosis and location (100%); in 7 (58%) of 12 cases, ultrasonography provided the correct diagnosis when other imaging and electrophysiological studies were inconclusive or inadequate.High-resolution ultrasonography may provide an economical and accurate imaging modality with utility in diagnosis and management of peripheral nerve lesions. Further research is required to assess the role of ultrasonography in evaluation of peripheral nerve pathology.

    View details for DOI 10.3171/2010.2.JNS091324

    View details for Web of Science ID 000285669500041

    View details for PubMedID 20225925

  • Dorsal Epidural Intervertebral Disk Herniation With Atypical Radiographic Findings: Case Report and Literature Review JOURNAL OF SPINAL CORD MEDICINE Teufack, S. G., Singh, H., Harrop, J., Ratliff, J. 2010; 33 (3): 268-271


    Intervertebral disk herniation is relatively common. Migration usually occurs in the ventral epidural space; rarely, disks migrate to the dorsal epidural space due to the natural anatomical barriers of the thecal sac.Case report.A 49-year-old man presented with 1 week of severe back pain with bilateral radiculopathy to the lateral aspect of his lower extremities and weakness of the ankle dorsiflexors and toe extensors. Lumbar spine magnetic resonance imaging with gadolinium revealed a peripheral enhancing dorsal epidural lesion with severe compression of the thecal sac. Initial differential diagnosis included spontaneous hematoma, synovial cyst, and epidural abscess. Posterior lumbar decompression was performed; intraoperatively, the lesion was identified as a large herniated disk fragment.Dorsal migration of a herniated intervertebral disk is rare and may be difficult to definitively diagnose preoperatively. Dorsal disk migration may present in a variety of clinical scenarios and, as in this case, may mimic other epidural lesions on magnetic resonance imaging.

    View details for Web of Science ID 000281007700011

    View details for PubMedID 20737802

  • Ventral surgical approaches to craniovertebral junction chordomas. Neurosurgery Singh, H., Harrop, J., Schiffmacher, P., Rosen, M., Evans, J. 2010; 66 (3): 96-103


    Chordomas are primarily malignant tumors encountered at either end of the neural axis; the craniovertebral junction and the sacrococcygeal junction. In this article, we discuss the surgical management of craniovertebral junction chordomas.In this paper, we discuss the surgical management of craniovertebral junction chordomas.The following approaches are illustrated: transoral-transpalatopharyngeal approach, high anterior cervical retropharyngeal approach, endoscopic transoral approach, and endoscopic transnasal approach. No single operative approach can be used for all craniovertebral chordomas. Therefore, the location of the tumor dictates which approach or approaches should be used.

    View details for DOI 10.1227/01.NEU.0000365855.12257.D1

    View details for PubMedID 20173533

  • Curvularia fungi presenting as a large cranial base meningioma: case report. Neurosurgery Singh, H., Irwin, S., Falowski, S., Rosen, M., Kenyon, L., Jungkind, D., Evans, J. 2008; 63 (1): E177-?


    Fungal infections are emerging as a growing threat to human health, especially in immunocompromised patients. Candida, Cryptococcus, and Aspergillus are a few of the commonly encountered organisms leading to brain abscesses. In this report, we describe Curvularia geniculata as the causative agent in central nervous system infection.Our review of the literature did not reveal a similar published case of central nervous system infection with this organism. A 35-year-old African-American man presented with obstructive hydrocephalus from a large cranial base lesion. Imaging characteristics on computed tomographic and magnetic resonance imaging scans were consistent with those of a cranial base meningioma.The patient underwent an endoscopic transnasal/transclival approach to the anterior middle cranial base for biopsy and decompression of this lesion. A spindle cell proliferation was observed on frozen section, which favored a diagnosis of meningioma. However, on permanent sections, we identified fungal hyphae with budding. Subsequent biopsies grew Curvularia in fungal cultures. Deoxyribonucleic acid sequencing was used to confirm the identification of the isolate as Curvularia geniculata.Limited data are available for in vitro susceptibility testing of Curvularia, and treatment modalities have not yet been standardized. The prognosis is usually poor. Despite being treated with voriconazole and intravenous amphotericin, this patient progressed to multiorgan failure and ultimately died. This is the first reported case of central nervous system infection by Curvularia geniculata.

    View details for DOI 10.1227/01.NEU.0000335086.77846.0A

    View details for PubMedID 18728558