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A longitudinal survey of adult spine and peripheral nerve case entries during neurosurgery residency training

Presented at the 2018 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Nitin Agarwal, Michael D. White, and D. Kojo Hamilton

OBJECTIVE

Currently, there is a lack of research assessing residents’ operative experience and caseload variability. The current study utilizes data from the Accreditation Council for Graduate Medical Education (ACGME) case log system to analyze national trends in neurosurgical residents’ exposure to adult spinal procedures.

METHODS

Prospectively populated ACGME resident case logs from 2013 to 2017 were retrospectively reviewed. The reported number of spinal procedures was compared to the ACGME minimum requirements for each surgical category pertaining to adult spine surgery. A linear regression analysis was conducted to identify changes in operative caseload by residents graduating during the study period, as well as a one-sample t-test using IBM SPSS software to compare the mean number of procedures in each surgical category to the ACGME required minimums.

RESULTS

A mean of 427.42 total spinal procedures were performed throughout residency training for each of the 877 residents graduating between 2013 and 2017. The mean number of procedures completed by graduating residents increased by 19.96 (r2 = 0.95) cases per year. The number of cases in every procedural subspecialty, besides peripheral nerve operations, significantly increased during this time. The two procedural categories with the largest changes were anterior and posterior cervical approaches for decompression/stabilization, which increased by 8.78% per year (r2 = 0.95) and 9.04% per year (r2 = 0.95), respectively. There was also a trend of increasing cases logged for lead resident surgeons and a decline in cases logged for senior resident surgeons. Residents’ mean caseloads during residency were found to be vastly greater than the ACGME required minimums: residents performed at least twice as many procedures as the required minimums in every surgical category.

CONCLUSIONS

Graduating neurosurgical residents reported increasing case volumes for adult spinal cases during this 5-year interval. An increase in logged cases for lead resident surgeons as opposed to senior resident surgeons indicates that residents were logging more cases in which they had a more critical role in the procedure. Moreover, the average resident was noted to perform more than twice the number of procedures required by the ACGME in every surgical category, indicating that neurosurgical residents are getting greater exposure to spine surgery than expected. Given the known correlation between case volume and improved surgical outcomes, this data demonstrates each graduating neurosurgical residency class experiences an augmented training in spine surgery.

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Jonathan Cohen, Nima Alan, James Zhou, and D. Kojo Hamilton

OBJECTIVE

Despite the growing neurosurgical literature, a subset of pioneering studies have significantly impacted the field of metastatic spine disease. The purpose of this study was to identify and analyze the 100 most frequently cited articles in the field.

METHODS

A keyword search using the Thomson Reuters Web of Science was conducted to identify articles relevant to the field of metastatic spine disease. The results were filtered based on title and abstract analysis to identify the 100 most cited articles. Statistical analysis was used to characterize journal frequency, past and current citations, citation distribution over time, and author frequency.

RESULTS

The total number of citations for the final 100 articles ranged from 74 to 1169. Articles selected for the final list were published between 1940 and 2009. The years in which the greatest numbers of top-100 studies were published were 1990 and 2005, and the greatest number of citations occurred in 2012. The majority of articles were published in the journals Spine (15), Cancer (11), and the Journal of Neurosurgery (9). Forty-four individuals were listed as authors on 2 articles, 9 were listed as authors on 3 articles, and 2 were listed as authors on 4 articles in the top 100 list. The most cited article was the work by Batson (1169 citations) that was published in 1940 and described the role of the vertebral veins in the spread of metastases. The second most cited article was Patchell's 2005 study (594 citations) discussing decompressive resection of spinal cord metastases. The third most cited article was the 1978 study by Gilbert that evaluated treatment of epidural spinal cord compression due to metastatic tumor (560 citations).

CONCLUSIONS

The field of metastatic spine disease has witnessed numerous milestones and so it is increasingly important to recognize studies that have influenced the field. In this bibliographic study the authors identified and analyzed the most influential articles in the field of metastatic spine disease.

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Nitin Agarwal, Michael D. White, Jonathan Cohen, L. Dade Lunsford, and D. Kojo Hamilton

OBJECTIVE

The purpose of this study was to analyze national trends in adult cranial cases performed by neurological surgery residents as logged into the Accreditation Council for Graduate Medical Education (ACGME) system.

METHODS

The ACGME resident case logs were retrospectively reviewed for the years 2009–2017. In these reports, the national average of cases performed by graduating residents is organized by year, type of procedure, and level of resident. These logs were analyzed in order to evaluate trends in residency experience with adult cranial procedures. The reported number of cranial procedures was compared to the ACGME neurosurgical minimum requirements for each surgical category. A linear regression analysis was conducted in order to identify changes in the average number of procedures performed by residents graduating during the study period. Additionally, a 1-sample t-test was performed to compare reported case volumes to the ACGME required minimums.

RESULTS

An average of 577 total cranial procedures were performed throughout residency training for each of the 1631 residents graduating between 2009 and 2017. The total caseload for graduating residents upon completion of training increased by an average of 26.59 cases each year (r2 = 0.99). Additionally, caseloads in most major procedural subspecialty categories increased; this excludes open vascular and extracranial vascular categories, which showed, respectively, a decrease and no change. The majority of cranial procedures performed throughout residency pertained to tumor (mean 158.38 operations), trauma (mean 102.17 operations), and CSF diversion (mean 76.12 operations). Cranial procedures pertaining to the subspecialties of trauma and functional neurosurgery showed the greatest rise in total procedures, increasing at 8.23 (r2 = 0.91) and 6.44 (r2 = 0.95) procedures per graduating year, respectively.

CONCLUSIONS

Neurosurgical residents reported increasing case volumes for most cranial procedures between 2009 and 2017. This increase was observed despite work hour limitations set forth in 2003 and 2011. Of note, an inverse relationship between open vascular and endovascular procedures was observed, with a decrease in open vascular procedures and an increase in endovascular procedures performed during the study period. When compared to the ACGME required minimums, neurosurgery residents gained much more exposure to cranial procedures than was expected. Additionally, a larger caseload throughout training suggests that residents are graduating with greater competency and experience in cranial neurosurgery.

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Jason Sheehan, Adina Ionescu, Nader Pouratian, D. Kojo Hamilton, David Schlesinger, Rod J. Oskouian Jr., and Charles Sansur

Object

Adjuvant treatment with radiation (radiation therapy or radiosurgery) is a mainstay of treatment for patients harboring glioblastomas multiforme (GBM). Hypoxic regions within the tumor make cells less sensitive to radiation therapy. Trans sodium crocetinate (TSC) has been shown to increase oxygen diffusion in the brain and elevate the partial brain oxygen level. The goal of this study was to evaluate the radiosensitizing effects of TSC on GBM tumors.

Methods

A rat C6 glioma model was used, in which C6 glioma cells were stereotactically injected into the rat brain to create a tumor. Following creation of a right frontal tumor, animals were randomized into 1 of 4 groups: 1) TSC alone (animal treated with moderate-dose TSC only); 2) radiation (animals receiving 8 Gy of cranial radiation); 3) radiation and low-dose TSC (animals receiving 8 Gy of radiation and 50 μg/kg of TSC); or 4) radiation and moderate-dose TSC (animals receiving 8 Gy of radiation and 100 μg/kg of TSC). Animals were observed clinically for 60 days or until death. Magnetic resonance (MR) imaging was performed at 2-week intervals on each animal and quantitatively evaluated for tumor response. Immunohistochemical analysis was performed on all brain tumors. Survival differences were also evaluated using the Kaplan–Meier method.

Results

On MR imaging, a statistically significant reduction in tumor size was seen in the group receiving moderate-dose TSC and radiation treatment compared with the group receiving radiation treatment alone. The rate of tumor growth was significantly less for the combination of TSC and radiation treatment compared with either modality alone. Median survival times for the TSC-only and the radiation therapy–only groups were 15 and 30 days, respectively. The 60-day median survival times for the groups receiving a combination of either low- or moderate-dose TSC with radiation therapy were statistically improved compared with those for the other treatment groups.

Conclusions

Use of TSC improves the extent of GBM tumor regression following radiation therapy and enhances survival. Radiosensitization of hypoxic tumors through increased oxygen diffusion may have clinical utility in patients with GBM tumors but must be explored in a clinical trial.

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D. Kojo Hamilton, Justin S. Smith, Charles A. Sansur, Aaron S. Dumont, and Christopher I. Shaffrey

Object

The originally described technique of atlantoaxial stabilization using C-1 lateral mass and C-2 pars screws includes a C-2 neurectomy to provide adequate hemostasis and visualization for screw placement, enable adequate joint decortication and arthrodesis, and prevent new-onset postoperative C-2 neuralgia. However, inclusion of a C-2 neurectomy for this procedure remains controversial, likely due in part to a lack of studies that have specifically addressed whether it affects patient outcome. The authors' objective was to assess the surgical and clinical impact of routine C-2 neurectomy performed with C1–2 segmental instrumented arthrodesis in a consecutive series of elderly patients with C1–2 instability.

Methods

Forty-four consecutive patients (mean age 71 years) underwent C1–2 instrumented fusion, including C-1 lateral mass screw insertion. Bilateral C-2 neurectomies were performed. Standardized clinical assessments were performed both pre- and postoperatively. Numbness or discomfort in a C-2 distribution was documented at follow-up. Fusion was assessed using the Lenke fusion grade.

Results

Among all 44 patients, mean blood loss was 200 ml (range 100–350 ml) and mean operative time was 129 minutes (range 87–240 minutes). There were no intraoperative complications, and no patients reported new postoperative onset or worsening of C-2 neuralgia postoperatively. Outcomes for the 30 patients with a minimum 13-month follow-up (range 13–72 months) were assessed. At a mean follow-up of 36 months, Nurick grade and pain numeric rating scale scores improved from 3.7 to 1.0 (p < 0.001) and 9.4 to 0.6 (p < 0.001), respectively. The mean postoperative Neck Disability Index score was 7.3%. The fusion rate was 97%, and the patient satisfaction rate was 93%. All 24 patients with preoperative occipital neuralgia reported relief. Seventeen patients noticed C-2 distribution numbness only during examination in the clinic, and 2 patients reported C-2 numbness, but it did not affect their daily function.

Conclusions

In this series of C1–2 instrumented arthrodesis in elderly patients, excellent fusion rates were achieved, and patient satisfaction was not negatively affected by C-2 neurectomy. In the authors' experience, C-2 neurectomy enhanced surgical exposure of the C1–2 joint, thereby facilitating hemostasis, placement of instrumentation, and decortication of the joint space for arthrodesis. Importantly, with C-2 neurectomy in the present series, no cases of new onset postoperative C-2 neuralgia occurred, in contrast to a growing number of reports in the literature documenting new-onset C-2 neuralgia without C-2 neurectomy. On the contrary, 80% of patients in the present series had preoperative occipital neuralgia and in all of these patients this neuralgia was relieved following C1–2 instrumented arthrodesis with C-2 neurectomy.

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Akil P. Patel, Michael T. Koltz, Charles A. Sansur, Mangla Gulati, and D. Kojo Hamilton

Object

Patients requiring neurosurgical intervention are known to be at increased risk for deep vein thrombosis (DVT) and attendant morbidity and mortality. Pulmonary embolism (PE) is the most catastrophic sequela of DVT and is the direct cause of death in 16% of all in-hospital mortalities. Protocols for DVT screening and early detection, as well as treatment paradigms to prevent PE in the acute postoperative period, are needed in neurosurgery. The authors analyzed the effectiveness of weekly lower-extremity venous duplex ultrasonography (LEVDU) in patients requiring surgical intervention for cranial or spinal pathology for detection of DVT and prevention of PE.

Methods

Data obtained in 1277 consecutive patients admitted to a major tertiary care center requiring neurosurgical intervention were retrospectively reviewed. All patients underwent admission (within 1 week of neurosurgical intervention) LEVDU as well as weekly LEVDU surveillance if the initial study was normal. Additional LEVDU was ordered in any patient in whom DVT was suspected on daily clinical physical examination or in patients in whom chest CT angiography confirmed a pulmonary embolus. An electronic database was created and statistical analyses performed.

Results

The overall incidence of acute DVT was 2.8% (36 patients). Of these cases of DVT, a statistically significant greater number (86%) were discovered on admission (within 1–7 days after admission) screening LEVDU (p < 0.05), whereas fewer were documented 8–14 days after admission (2.8%) or after 14 days (11.2%) postadmission. Additionally, for acute DVT detection in the present population, there were no underlying statistically significant risk factors regarding baseline physical examination, age, ambulatory status, or type of surgery.

The overall incidence of acute symptomatic PE was 0.3% and the mortality rate was 0%.

Conclusions

Performed within 1 week of admission in patients who will undergo neurosurgical intervention, LEVDU is effective in screening for acute DVT and initiating treatment to prevent PE, thereby decreasing the overall mortality rate. Routine LEVDU beyond this time point may not be needed to detect DVT and prevent PE unless a change in the patient's physical examination status is detected.

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Vincent C. Traynelis

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Ricky Medel, R. Webster Crowley, D. Kojo Hamilton, and Aaron S. Dumont

Pseudoaneurysms are rare lesions with a multitude of causes, including infectious, traumatic, and iatrogenic origins. In addition, there are a number of potential treatment options, all of which require consideration to determine the most appropriate management. Historically, surgical intervention has been the method of choice, but because the histopathological features of these lesions make them largely unsuitable for clipping, trapping or excision is often required. More recently endovascular methods have been used, including coil embolization, stent reconstruction, or parent artery occlusion. Although these methods are often successful, situations arise in which they are not technically feasible. The authors describe such a case in a pediatric patient with an iatrogenic pseudoaneurysm. Onyx was used to embolize the lesion and the results were excellent.

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D. Kojo Hamilton, Neal F. Kassell, Mary E. Jensen, and Aaron S. Dumont

✓This 34-year-old man with a 10-year history of HIV infection presented with an acute onset of severe headache, fever, nausea, vomiting, and left-sided weakness. Computed tomography (CT) scanning demonstrated diffuse subarachnoid hemorrhage (SAH), and subsequent CT angiography revealed multiple large and giant intracranial aneurysms with diffuse vasculopathy. The patient's CD4-positive cell count was low, although he had been receiving combination antiret-roviral therapy and his viral load was undetectable.

The preponderance of the literature on HIV-infected patients with intracranial vascular involvement has concerned children in whom there is a high viral load. In such children, appropriate antiretroviral therapy may result in the complete resolution of these vascular abnormalities. In the present study, the authors report on the unique case of an HIV-infected adult patient who presented with SAH, diffuse intracranial vasculopathy, and multiple giant and fusiform aneurysms, despite having received adequate antiretroviral treatment and demonstrating an undetectable viral load. Intracranial vascular involvement in these patients may become increasingly common as the management of HIV infection continues to improve and afflicted patients survive for longer periods.

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R. Webster Crowley, Rebecca M. Burke, M. Beatriz S. Lopes, D. Kojo Hamilton, and John A. Jane Sr.

High-grade spinal cord gliomas are rare and carry a poor prognosis. A number of treatment modalities exist for spinal cord gliomas, but no consensus exists regarding their management. Cordectomy represents a possible option for treating these lesions; however, few cases have been reported in adults, and none have been reported in the pediatric population. The authors describe the use of cordectomy for the treatment of a high-grade spinal glioma in a 9-year-old boy who remains cancer free 14 years following his initial presentation.