Educational Limitations of ChatGPT in Neurosurgery Board Preparation

Objective This study evaluated the potential of Chat Generative Pre-trained Transformer (ChatGPT) as an educational tool for neurosurgery residents preparing for the American Board of Neurological Surgery (ABNS) primary examination. Methods Non-imaging questions from the Congress of Neurological Surgeons (CNS) Self-Assessment in Neurological Surgery (SANS) online question bank were input into ChatGPT. Accuracy was evaluated and compared to human performance across subcategories. To quantify ChatGPT's educational potential, the concordance and insight of explanations were assessed by multiple neurosurgical faculty. Associations among these metrics as well as question length were evaluated. Results ChatGPT had an accuracy of 50.4% (1,068/2,120), with the highest and lowest accuracies in the pharmacology (81.2%, 13/16) and vascular (32.9%, 91/277) subcategories, respectively. ChatGPT performed worse than humans overall, as well as in the functional, other, peripheral, radiology, spine, trauma, tumor, and vascular subcategories. There were no subjects in which ChatGPT performed better than humans and its accuracy was below that required to pass the exam. The mean concordance was 93.4% (198/212) and the mean insight score was 2.7. Accuracy was negatively associated with question length (R2=0.29, p=0.03) but positively associated with both concordance (p<0.001, q<0.001) and insight (p<0.001, q<0.001). Conclusions The current study provides the largest and most comprehensive assessment of the accuracy and explanatory quality of ChatGPT in answering ABNS primary exam questions. The findings demonstrate shortcomings regarding ChatGPT's ability to pass, let alone teach, the neurosurgical boards.

Surgery in octogenarians with intracranial meningiomas improves functional outcome at 1 year

PURPOSE

The population is aging, and age remains an important factor in deciding surgical candidacy for intracranial tumors. The natural history and surgical behavior of meningiomas in octogenarians are not well understood. We evaluated the surgical and functional outcomes, including survival, among octogenarians with intracranial meningiomas in a single institution.

METHODS

The Tumor Registry (2004-2021) was used to identify octogenarian patients (ages 80-89) diagnosed with intracranial meningioma. Primary endpoints were 1-year survival and functional outcome measured with mRS postsurgery. Kaplan-Meier, univariable Log-rank tests, and multivariable Cox hazards proportional regression models were used for assessing factors associated with overall survival (OS) in octogenarians with meningiomas who underwent surgery; logistic regression and McNemar's were used to further characterize risk factors affecting functional surgical outcome at 1 year.

RESULTS

Thirty octogenarians with intracranial meningioma who underwent surgery were identified. Median age was 82.5 years and 66.6% were female patients. The 1-year median postsurgical survival probability for all octogenarians with meningioma was 86.3% and no intraoperative mortality was observed. Frailty (mFI-5, p = 0.84), tumor grade (p = 0.11), tumor size (p = 0.22), extent of resection (p = 0.35), and Karnofsky scale on admission (p = 0.93) did not significantly affect the survival in octogenarians with meningiomas which were treated surgically. The 1-year postoperative functional status of octogenarian meningioma patients who underwent surgery was significantly improved compared to pre-op mRS (McNemar's chi-squared = 9.6, df = 1, p-value = 0.001946).

CONCLUSION

In octogenarians with meningiomas, surgical intervention significantly improves the pre-operative modified Rankin Scale at 1 year postsurgery in this cohort.

Flow diversion of a middle cerebral artery pseudoaneurysm secondary to a gunshot wound: A case report

Pseudoaneurysms are rare but devastating complications of penetrating head traumas. They require rapid surgical or endovascular intervention due to their high risk of rupture; however, complex presentations may limit treatment options. Our objective is to report a case of severe vasospasm, flow diversion, and in-stent stenosis complicating the treatment of a middle cerebral artery pseudoaneurysm following a gunshot wound. A 33-year-old woman presented with multiple calvarial and bullet fragments within the right frontotemporal lobes and a large right frontotemporal intraparenchymal hemorrhage with significant cerebral edema. She underwent an emergent right hemicraniectomy for decompression, removal of bullet fragments, and evacuation of hemorrhage. Once stable enough for diagnostic cerebral angiography, she was found to have an M1 pseudoaneurysm with severe vasospasm that precluded endovascular treatment until the vasospasm resolved. The pseudoaneurysm was treated with flow diversion and in-stent stenosis was found at 4-month follow-up angiography that resolved by 8 months post-embolization. We report the successful flow diversion of an middle cerebral artery (MCA) pseudoaneurysm complicated by severe vasospasm and later in-stent stenosis. The presence of asymptomatic stenosis is believed to be reversible intimal hyperplasia and a normal aspect of endothelial healing. We suggest careful observation and dual-antiplatelet therapy as a justified approach.

Lewy body disease as a potential negative outcome modifier of glioblastoma treatment: a case report

BACKGROUND

Elderly patients with glioblastoma are particularly susceptible to the adverse effects of ionizing radiation to the brain. This population also has an increasing prevalence of dementia in the successive seventh, eighth and nineth decade of life, and dementia with Lewy bodies is characterized by pathologic α-synucleins, proteins that take part in neuronal DNA damage repair.

CASE PRESENTATION

We report a 77-year-old man, with a history of coronary artery disease and mild cognitive impairment, who experienced subacute behavioral changes over 3 months with wording-finding difficulty, memory loss, confusion, perseveration, and irritable mood. Neuroimaging studies disclosed a 2.5 × 2.4 × 2.7 cm cystic enhancing mass with central necrosis in the left temporal lobe of the brain. Gross total resection of the tumor revealed IDH-1 wild-type glioblastoma. After treatment with radiation and temozolomide chemotherapy, his cognitive status deteriorated rapidly, and he died from unexpected sudden death 2 months after radiation. Autopsy of his brain revealed (i) tumor cells with atypical nuclei and small lymphocytes, (ii) neuronal cytoplasmic inclusions and Lewy bodies that were positive for α-synuclein in the midbrain, pons, amygdala, putamen and globus pallidus, and (iii) no amyloid plaques and only rare neurofibrillary tangles near the hippocampi.

CONCLUSIONS

This patient most likely had pre-clinical limbic subtype of dementia with Lewy bodies prior to his diagnosis of glioblastoma. The radiation and temozolomide that was used to treat his tumor may have accelerated neuronal damage due to induction of DNA breakage when his brain was already compromised by pathologic α-synucleins. α-Synucleinopathy could be a negative outcome modifier in glioblastoma patients.

Octogenarian Brain Tumor Registry: Single-Institution Surgical Outcomes and Mortality Study

BACKGROUND

Surgical intervention for brain tumor patients aged 80 to 89 years is controversial, as the comorbidities and physiology associated with aging are often thought to increase surgical risks. Surgical outcomes, however, are not well characterized for octogenarians. This review therefore assessed the outcomes and mortality risk associated with tumor removal in octogenarians at our academic institution.

METHODS

Retrospective review of patients aged 80 to 89 who underwent craniotomy for tumor resection (CTR) at our institution between 2004-2021 and who were diagnosed with meningioma, glioblastoma, or metastatic disease. Primary outcome was 30-day mortality.

RESULTS

Sixty-one CTRs were included in analysis. Median age was 83 (interquartile range 81-85) years, and the most common preoperative comorbidity was hypertension (n=44). Most patients (n=35) had a preoperative modified Rankin Scale (mRS) score between 0-2. Seventeen (27.9%) patients experienced postoperative complications (i.e., urinary tract infection, deep venous thrombosis, etc.), and 26.2% (n=16) experienced new-onset neurologic deficits postoperatively (i.e., aphasia, motor deficits, etc.). Upon discharge, most patients (n=43) had an mRS score of 3-4. Within 30 days of surgery, 14.8% (n=9) of patients were readmitted to the hospital and 8.2% (n=5) of patients died: 2 with meningioma, 1 with glioblastoma, and 2 with metastatic disease. The most common cause of death was intracranial hemorrhage (n=3). Three-month mortality was 23.0% (n=14). Mean survival after surgery was 33 months for meningioma patients, 6.9 months for glioblastoma patients, and 15 months for patients with metastatic lesions.

CONCLUSION

Our review found a 30-day mortality rate of 8.2% across all tumor types, and mean survival was similar to that previously reported for patients across all age groups. Surgical intervention for octogenarian tumor patients is therefore feasible, safe, and likely worthwhile for extending and improving lives.

Intracranial Metastasis of Extracranial Chondrosarcoma: Systematic Review With Illustrative Case

BACKGROUND

Cerebral chondrosarcoma metastases are rare and aggressive neoplasms. The rarity of presentation has precluded rigorous analysis of diagnosis, risk factors, treatment, and survival. We analyzed every reported case through exhaustive literature review. We further present the first case with Maffucci syndrome.

METHODS

Three databases, PubMed, Embase, and Google Scholar, and crossed references were queried for cerebral chondrosarcoma metastases. Extracted variables included demographics, risk factors, tumor characteristics, interventions, and outcomes. Univariate and multivariate analyses were performed.

RESULTS

Fifty-six patients were included from 1,489 literature results. The average age at brain metastasis was 46.6±17.6 years and occurred at a median of 24±2.8 months from primary diagnosis. Primary tumor histology (dedifferentiated 5.0±1.5 months, mesenchymal 24±3.0 months, conventional 41±7.4 months, p<0.05) and grade (low grade 54±16.7 months vs. high-grade 10±6.4 months, p<0.001) correlated with time interval until brain metastasis. A multiple enchondromatosis syndrome occurred in 13.2% of cases. At time of brain metastases diagnosis, extracranial metastases were identified in 76.2% of cases. Median survival after the development of brain metastasis was 2.0±0.78 months with a 1-year survival of 10.0%. On regression analysis, surgery reduced brain metastasis mortality risk and radiation trended towards reduced mortality risk (surgery: hazard ratio [HR] 0.22, 95% confidence interval [CI] 0.064-0.763, p=0.017; radiation: HR 0.31, 95% CI 0.091-1.072, p=0.064).

CONCLUSION

We present a systematic review of cerebral chondrosarcoma metastases. Primary tumor histology and grade correlate with time until cerebral metastasis. Following cerebral metastasis, these tumors have poor prognosis and modestly benefit from surgery.

Awake Craniotomy and Intraoperative Musical Performance for Brain Tumor Surgery: Case Report and Literature Review

Music experience and creation is a complex phenomenon that involves multiple brain structures. Music mapping during awake brain surgery, in addition to standard speech and motor mapping, remains a controversial topic. Music function can be impaired selectively, despite overlap with other neural networks commonly tested during direct cortical stimulation. We describe the case of a 34-year-old male patient presenting with a glioma located within eloquent cortex, who is also a professional musician and actor. We performed an awake craniotomy (AC) that mapped the standard motor and speech areas, while the patient played guitar intraoperatively and sang. Outcomes were remarkable with preservation of function and noted improvements in his musical abilities in outpatient follow-up. In addition, we performed a review of the literature in which awake craniotomies were performed for the removal of brain tumors in patients with some background in music (e.g., score reading, humming/singing). To date, only 4 patients have played a musical instrument intraoperatively during an AC for brain tumor resection. Using awake cortical mapping techniques and paradigms for preserving speech function during an intraoperative musical performance with singing is feasible and can yield a great result for patients. The use of standard brain mapping over music processing mapping did not yield a negative outcome. More experience is needed to understand and standardize this procedure as the field of brain mapping continues to grow for tumor resections.

Inhibition of the epigenetically activated miR-483-5p/IGF-2 pathway results in rapid loss of meningioma tumor cell viability

PURPOSE

Meningioma is the most common primary central nervous system tumor often causing serious complications, and presently no medical treatment is available. The goal of this study was to discover miRNAs dysregulated in meningioma, and explore miRNA-associated pathways amenable for therapeutic interventions.

METHODS

Small RNA sequencing was performed on meningioma tumor samples to study grade-dependent changes in microRNA expression. Gene expression was analyzed by chromatin marks, qRT-PCR and western blot. miRNA modulation, anti-IGF-2 neutralizing antibodies, and inhibitors against IGF1R were evaluated in a tumor-derived primary cultures of meningioma cells.

RESULTS

Meningioma tumor samples showed high, grade-dependent expression of miR-483-5p, associated with high mRNA and protein expression of its host gene IGF-2. Inhibition of miR-483-5p reduced the growth of cultured meningioma cells, whereas a miR-483 mimic increased cell proliferation. Similarly, inhibition of this pathway with anti-IGF-2 neutralizing antibodies reduced meningioma cell proliferation. Small molecule tyrosine kinase inhibitor blockade of the IGF-2 receptor (IGF1R) resulted in rapid loss of viability of cultured meningioma tumor-derived cells, suggesting that autocrine IGF-2 feedback is obligatory for meningioma tumor cell survival and growth. The observed IGF1R-inhibitory IC50 for GSK1838705A and ceritinib in cell-based assays along with the available pharmacokinetics data predicted that effective drug concentration could be achieved in vivo as a new medical treatment of meningioma.

CONCLUSION

Meningioma cell growth is critically dependent on autocrine miR-483/IGF-2 stimulation and the IGF-2 pathway provides a feasible meningioma treatment target.

Growth Analysis of Untreated Meningiomas under Observation

BACKGROUND

 When meningiomas are small or asymptomatic, the decision to observe rather than treat requires balancing the growth potential of the lesion with the outcome and side effects of treatment. The aim of this study is to characterize the growth patterns of untreated meningiomas to better inform the clinical decision-making process.

METHODS

 Patients with meningiomas were identified from 2005 to 2015. Those without treatment who had been followed for 1.5 years, with three magnetic resonance imaging (MRI) scans, were identified. Scans were measured with orthogonal diameters, geometric mean diameters, and volumes using the ABC/2 method. Regression modeling determined what growth pattern these parameters best approximated.

RESULTS

 Two hundred and fifteen MRI scans for 34 female (82.9%) and 7 male (17%) patients with 43 tumors were evaluated. Initial tumor volumes ranged from 0.13 to 9.98 mL. The mean and median initial volumes were 2.44 and 1.52 mL, respectively. Follow-up times ranged from 21 to 144 months, with a median of 70 months. There were 12 tumors (28%) whose growth rates were significantly greater than zero. For all tumors, use of a linear regression model allowed accurate prediction of the future size using prior data.

CONCLUSION

 Three-quarters of presumptive meningiomas managed conservatively do not grow significantly. The remainder have significant growth over time, and the behavior could be approximated with linear regression models.

Predictors of extended length of stay related to craniotomy for tumor resection

Background

Hospital length of stay (LOS) related to craniotomy for tumor resection (CTR) is a marker of neurosurgical quality of care. Limiting LOS benefits both patients and hospitals. This study examined which factors contribute to extended LOS (eLOS) at our academic center.

Methods

Retrospective medical record review of 139 consecutive CTRs performed between July 2020 and July 2021. Univariate and multivariable analyses determined which factors were associated with an eLOS (≥8 days).

Results

Median LOS was 6 days (IQR 3-9 days). Fifty-one subjects (36.7%) experienced an eLOS. Upon univariate analysis, potentially modifiable factors associated with eLOS included days to occupational therapy (OT), physical therapy (PT), and case management clearance (p < .001); and discharge disposition (p < .001). Multivariable analysis revealed that pre-operative anti-coagulant use (OR 10.74, 95% CI 2.64-43.63, p = .001), Medicare (OR 4.80, 95% CI 1.07-21.52, p = .04), ED admission (OR 26.21, 95% CI 5.17-132.99, p < .001), transfer to another service post-surgery (OR 30.00, 95% CI 1.56-577.35, p = .02), and time to post-operative imaging (OR 2.91, 95% CI 1.27-6.65, p = .01) were associated with eLOS. Extended LOS was not significantly associated with ED visits (p = .45) or unplanned readmissions within 30 days of surgery (p = .35), and both (p = .04; p = .04) were less likely following a short LOS (<5 days).

Conclusion

While some factors driving LOS related to CTR are uncontrollable, expedient pre- and post-operative management may reduce LOS without compromising care.

Telovelar versus transvermian approach to tumors of the fourth ventricle and their impact on postoperative neurological complications: A multicenter study

Background

Tumors of the fourth ventricle are exceedingly rare; however, such lesions are formidable due to the severe postoperative neurological complications (pNCs) which often occur. The adoption of the telovelar approach over the transvermian was created to supposedly mitigate the pNCs; however, there is a lack of sufficient data supporting this theory.

Methods

Records from six hospitals were reviewed for patients surgically treated for a single tumor within the 4^th ventricle from 2016 to 2022. The pNCs which had 10 or more occurrences among the patients were individually assessed as the dependent variable in a binary logistic regression model against covariates which included the surgical approach.

Results

This study of 67 patients confirms no significant differences in risk for pNCs between the transvermian and telovelar approach. Rather, multivariate analysis identified neurophysiological monitoring (IONM) as a protective factor for postoperative speech and swallowing defects (odds ratio [OR]: 0.076, 95% confidence interval [CI] 0.011-0.525). Furthermore, intraoperative external ventricular drainage (EVD) was a protective factor for postoperative gait and focal motor defects (OR: 0.075, 95% CI 0.009-0.648) and for postoperative hydrocephalus (OR: 0.020, 95% CI 0.002-0.233). A univariate meta-analysis pooling the present study's patients and an additional 304 patients from the three additional studies in the literature confirms no significant differences in risk between the transvermian and telovelar approach for pNCs.

Conclusion

Intraoperative adjuncts including IONM and EVD may play a significant role in the postoperative outcome. Despite the present study's sample size being a major limitation, the findings may provide great value to neurosurgeons given the scarcity of the current literature.

Reduced recurrence of chronic subdural hematomas treated with open surgery followed by middle meningeal artery embolization compared to open surgery alone: a propensity score-matched analysis

OBJECTIVE

Middle meningeal artery embolization (MMAE) is an emerging endovascular treatment technique with proven promising results for chronic subdural hematomas (cSDHs). MMAE as an adjunct to open surgery is being utilized with the goal of preventing the recurrence of cSDH. However, the efficacy of MMAE following surgical evacuation of cSDH has not been clearly demonstrated. The authors sought to compare the outcomes of open surgery followed by MMAE versus open surgery alone.

METHODS

Patients who underwent surgical evacuation alone (open surgery-alone group) or MMAE along with open surgery for cSDH (adjunctive MMAE group) were identified at the authors' institution. Two balanced groups were obtained through propensity score matching. Primary outcomes included recurrence risk and reintervention rate. Secondary outcomes included decrease in hematoma size and modified Rankin Scale (mRS) score at last follow-up. Variables in the two groups were compared by use of the Mann-Whitney U-test, paired-sample t-test, and Fisher's exact test.

RESULTS

A total of 345 cases of open surgery alone and 52 cases of open surgery with adjunctive MMAE were identified. After control for subjective confounders, 146 patients treated with open surgery alone and 41 with adjunctive MMAE following open surgery with drain placement were included in the analysis. Before matching, the rebleeding risk and reintervention rate for open surgery trended higher in the open surgery alone than the open surgery plus MMAE group (14.4% vs 7.3%, p = 0.18; and 11.6% vs 4.9%, p = 0.17, respectively). No significant differences were seen in duration of radiographic or clinical follow-ups or decreases in hematoma size and mRS score at last follow-up. After one-to-one nearest neighbor propensity score matching, 26 pairs of cases were compared for outcomes. Rates of recurrence (7.7% vs 30.8%, p = 0.038) and overall reintervention (3.8% vs 23.1%, p = 0.049) after open surgery were found to be significantly lower in the adjunctive MMAE group than the open surgery-alone group. With one-to-many propensity score matching, 76 versus 37 cases were compared for open surgery alone versus adjunctive MMAE following open surgery. Similarly, the adjunctive MMAE group had significantly lower rates of recurrence (5.4% vs 19.7%, p = 0.037) and overall reintervention (2.7% vs 14.5%, p = 0.049).

CONCLUSIONS

Adjunctive MMAE following open surgery can lower the recurrence risks and reintervention rates for cSDH.

Teaching through the screen: a toolbox for creating a virtual neurosurgical subinternship program

OBJECTIVE

The coronavirus disease 2019 (COVID-19) pandemic disrupted the landscape of traditional neurosurgical subinternships, ramifications of which persist to this day. The outright cancellation of in-person subinternships in 2020 presented not only a challenge to both applicants and programs, but also an opportunity to establish an effective and efficient platform for virtual neurosurgical training. To address this need, the authors designed and trialed a novel virtual neurosurgical subinternship (Virtual Sub-I).

METHODS

The weeklong, case-based Virtual Sub-I program combined flipped-classroom and active learning approaches. Students worked in small groups to discuss neurosurgical cases. Faculty and residents offered personalized mentorship sessions to participants. Surveys were used to assess students’ experience with the authors’ subinternship program, consistent with level 1 of the Kirkpatrick model.

RESULTS

A total of 132 students applied from both international and American medical schools. The final cohort comprised 27 students, of whom 8 (30%) were female and 19 (70%) were male. Students characterized the subinternship as “interactive,” “educational,” and “engaging.” One hundred percent of survey respondents were “very likely” to recommend the Virtual Sub-I to their peers. Faculty involved in the Virtual Sub-I stated that the program allowed them to determine the fit of participating medical students for their neurosurgery residency program, and that information gathered from the Virtual Sub-I had the potential to influence their ranking decisions.

CONCLUSIONS

The Virtual Sub-I recapitulates the educational and interpersonal benefits of the traditional subinternship experience and can serve as a prototype for future virtual surgical education endeavors. Furthermore, the Virtual Sub-I presents a more equitable platform for introducing medical students across the undergraduate medical education spectrum to neurosurgical education and mentorship.

Tumor-Derived Cell Culture Model for the Investigation of Meningioma Biology

Meningioma is the most common primary central nervous system tumor. Although mostly nonmalignant, meningioma can cause serious complications by mass effect and vasogenic edema. While surgery and radiation improve outcomes, not all cases can be treated due to eloquent location. Presently no medical treatment is available to slow meningioma growth owing to incomplete understanding of the underlying pathology, which in turn is due to the lack of high-fidelity tissue culture and animal models. We propose a simple and rapid method for the establishment of meningioma tumor-derived primary cultures. These cells can be maintained in culture for a limited time in serum-free media as spheres and form adherent cultures in the presence of 4% fetal calf serum. Many of the tissue samples show expression of the lineage marker PDG2S, which is typically retained in matched cultured cells, suggesting the presence of cells of arachnoid origin. Furthermore, nonarachnoid cells including vascular endothelial cells are also present in the cultures in addition to arachnoid cells, potentially providing a more accurate tumor cell microenvironment, and thus making the model more relevant for meningioma research and high-throughput drug screening.

Spinal laser interstitial thermal therapy: single-center experience and outcomes in the first 120 cases

OBJECTIVE

The objective of this study was to present the results of a consecutive series of 120 cases treated with spinal laser interstitial thermal therapy (sLITT) to manage epidural spinal cord compression (ESCC) from metastatic tumors.

METHODS

The electronic records of patients treated from 2013 to 2019 were analyzed retrospectively. Data collected included demographic, pathology, clinical, operative, and imaging findings; degree of epidural compression before and after sLITT; length of hospital stay; complications; and duration before subsequent oncological treatment. Independent-sample t-tests were used to compare means between pre- and post-sLITT treatments. Survival was estimated by the Kaplan-Meier method. Multivariate logistic regression was used to analyze predictive factors for local recurrence and neurological complications.

RESULTS

There were 110 patients who underwent 120 sLITT procedures. Spinal levels treated included 5 cervical, 8 lumbar, and 107 thoracic. The pre-sLITT Frankel grades were E (91.7%), D (6.7%), and C (1.7%). The preoperative ESCC grade was 1c or higher in 92% of cases. Metastases were most common from renal cell carcinoma (39%), followed by non-small cell lung carcinoma (10.8%) and other tumors (35%). The most common location of ESCC was in the vertebral body (88.3%), followed by paraspinal/foraminal (7.5%) and posterior elements (4.2%). Adjuvant radiotherapy (spinal stereotactic radiosurgery or conventional external beam radiation therapy) was performed in 87 cases (72.5%), whereas 33 procedures (27.5%) were performed as salvage after radiotherapy options were exhausted. sLITT was performed without need for spinal stabilization in 87 cases (72.5%). Post-sLITT Frankel grades were E (85%), D (10%), C (4.2%), and B (0.8%); treatment was associated with a median decrease of 2 ESCC grades. The local control rate at 1 year was 81.7%. Local control failure occurred in 25 cases (20.8%). The median progression-free survival was not reached, and overall survival was 14 months. Tumor location in the paraspinal region and salvage treatment were independent predictors of local recurrence, with hazard ratios of 6.3 and 3.3, respectively (p = 0.01). Complications were observed in 22 cases (18.3%). sLITT procedures performed in the lumbar and cervical spine had hazard ratios for neurological complications of 15.4 and 17.1 (p < 0.01), respectively, relative to the thoracic spine.

CONCLUSIONS

sLITT is safe and provides effective local control for high-grade ESCC from vertebral metastases in the thoracic spine, particularly when combined with adjuvant radiotherapy. The authors propose considering sLITT as an alternative to open surgery in selected patients with spinal metastases.

Minimally Invasive Separation Surgery for Metastases in the Vertebral Column: A Technical Report

BACKGROUND

Epidural spinal cord compression (ESCC) is a common and severe cause of morbidity in cancer patients. Minimally invasive surgical techniques may be utilized to preserve neurological function and permit the use of radiation to maximize local control. Minimally invasive techniques are associated with lower morbidity.

OBJECTIVE

To describe a novel, minimally invasive operative technique for the management of metastatic ESCC.

METHODS

A minimally invasive approach was used to cannulate the pedicles of the thoracic vertebrae, which were then held in place by Kirschner wires (K-wires). Following open decompression of the spinal cord, cannulated screws were placed percutaneously with stereotactic guidance through the pedicles followed by cement induction. Stereotactic radiosurgery is performed in the postoperative period for residual metastatic disease in the vertebral body.

RESULTS

The minimally invasive technique used in this case reduced tissue damage and optimized subsequent recovery without compromising the quality of decompression or the extent of metastatic tumor resection. Development of more minimally invasive techniques for the management of metastatic ESCC has the potential to facilitate healing and preserve quality of life in patients with systemic malignancy.

CONCLUSION

ESCC from vertebral metastases poses a challenge to treat in the context of minimizing potential risks to preserve quality of life. Percutaneous pedicle screw fixation with cement augmentation provides a minimally invasive alternative for definitive treatment of these patients.

Combined Surgical Resection and Laser Interstitial Thermal Therapy for Glioblastoma: Technical Note

Background Glioblastoma multiforme (GBM) is an aggressive intracranial malignancy that confers a poor prognosis despite maximum surgical resection and chemoradiotherapy. Survival decreases further with deep-seated lesions. Laser interstitial thermal therapy (LITT) is an emerging minimally invasive technique for tumor ablation shown to reduce tumor burden effectively, particularly in deep-seated locations less amenable to gross total resection. We describe our initial technical experience of using the combination of LITT followed by surgical resection in patients with GBMs that exhibit both an easily accessible and deep-seated component.

Materials and Methods Patients with GBM who received concurrent LITT and surgical resection at our institution were identified. Patient demographic and clinical information was procured from the University of Texas MD Anderson Cancer Center electronic medical record along with preoperative, postoperative, and 1-month follow-up magnetic resonance imaging (MRI).

Results Four patients (n = 2 male, n = 2 female) with IDH-wild type GBM who received combined LITT and surgical resection were identified and analyzed retrospectively. All patients received chemoradiotherapy before presentation. All but one patient (75%) received resection before presentation. Median age was 54 years (range: 44–56 years). Median length of hospital stay was 6.5 days (range: 2–47 days). Median extent of combined ablation/resection was 90.4%. One of the four patients experienced complications in the perioperative or immediate follow-up periods. Local recurrence was observed in one patient during the follow-up period.

Conclusion Malignant gliomas in deep-seated locations or in close proximity to white matter structures are challenging to manage. LITT followed by surgical resection may provide an alternative for tumor debulking that minimizes potential morbidities and extent of residual tumor. Further studies comparing this approach with standard resection techniques are warranted.

A comparison of spinal laser interstitial thermotherapy with open surgery for metastatic thoracic epidural spinal cord compression

OBJECTIVE

The proximity of the spinal cord to compressive metastatic lesions limits radiosurgical dosing. Open surgery is used to create safe margins around the spinal cord prior to spinal stereotactic radiosurgery (SSRS) but carries the risk of potential surgical morbidity and interruption of systemic oncological treatment. Spinal laser interstitial thermotherapy (SLITT) in conjunction with SSRS provides local control with less morbidity and a shorter interval to resume systemic treatment. The authors present a comparison between SLITT and open surgery in patients with metastatic thoracic epidural spinal cord compression to determine the advantages and disadvantages of each method.

METHODS

This is a matched-group design study comprising patients from a single institution with metastatic thoracic epidural spinal cord compression that was treated either with SLITT or open surgery. The two cohorts defined by the surgical treatment comprised patients with epidural spinal cord compression (ESCC) scores of 1c or higher and were deemed suitable for either treatment. Demographics, pre- and postoperative ESCC scores, histology, morbidity, hospital length of stay (LOS), complications, time to radiotherapy, time to resume systemic therapy, progression-free survival (PFS), and overall survival (OS) were compared between groups.

RESULTS

Eighty patients were included in this analysis, 40 in each group. Patients were treated between January 2010 and December 2016. There was no significant difference in demographics or clinical characteristics between the cohorts. The SLITT cohort had a smaller postoperative decrease in the extent of ESCC but a lower estimated blood loss (117 vs 1331 ml, p < 0.001), shorter LOS (3.4 vs 9 days, p < 0.001), lower overall complication rate (5% vs 35%, p = 0.003), fewer days until radiotherapy or SSRS (7.8 vs 35.9, p < 0.001), and systemic treatment (24.7 vs 59 days, p = 0.015). PFS and OS were similar between groups (p = 0.510 and p = 0.868, respectively).

CONCLUSIONS

The authors' results have shown that SLITT plus XRT is not inferior to open decompression surgery plus XRT in regard to local control, with a lower rate of complications and faster resumption of oncological treatment. A prospective randomized controlled study is needed to compare SLITT with open decompressive surgery for ESCC.

One hundred years of neurosurgery at the Medical College of Virginia/Virginia Commonwealth University (1919-2019)

The Department of Neurosurgery at the Medical College of Virginia/Virginia Commonwealth University (VCU) celebrates its 100th anniversary in 2019. It was founded by C. C. Coleman, who directed the US Army School of Brain Surgery during World War I and was one of the original members of the Society of Neurological Surgeons. Coleman began a residency program that was among the first four such programs in the United States and that produced such prominent graduates as Frank Mayfield, Gayle Crutchfield, and John Meredith. Neurosurgery at VCU later became a division under the medical school's surgery department. Division chairs included William Collins and Donald Becker. It was during the Becker years that VCU became a leading National Institutes of Health-funded neurotrauma research center. Harold Young oversaw the transition from division to department and expanded the practice base of the program. In 2015, Alex Valadka assumed leadership and established international collaborations for research and education. In its first 100 years, VCU Neurosurgery has distinguished itself as an innovator in clinical research and an incubator of compassionate and service-oriented physicians.

Traumatic lumbar spondylolisthesis resulting in complete thoracic spinal cord avulsion: an unusual presentation

Traumatic spondylolisthesis is a known occurrence in trauma, but complete cord transection is relatively rare. Moreover, complete cord transection at a site distant from the traumatic spondylolisthesis without spondyloptosis is exceedingly rare. In this report, authors describe the first case of thoracic cord avulsion following a traumatic grade II lumbar spondylolisthesis. The unusual presentation of this case highlights the importance of further evaluating patients with neurological symptoms out of proportion with the injuries seen on initial imaging. Magnetic resonance imaging performed after initial imaging studies demonstrated T11 cord transection with the distal cord herniating into the lumbar paraspinal soft tissues, thus allowing for preoperative planning to prepare for a more significant intervention including complex dural repair and lumbar drain placement, in addition to instrumented fusion to stabilize the traumatic spondylolisthesis.

Spatial regulation of gene expression in nonsyndromic sagittal craniosynostosis

OBJECTIVECranial suture patterning and development are highly regulated processes that are not entirely understood. While studies have investigated the differential gene expression for different sutures, little is known about gene expression changes during suture fusion. The aim of this study was to examine gene expression in patent, fusing, and fused regions along sagittal suture specimens in nonsyndromic craniosynostosis patients.METHODSSagittal sutures were collected from 7 patients (average age 4.5 months) who underwent minimally invasive craniotomies at the Children's Hospital of Richmond at VCU under IRB approval. The sutures were analyzed using micro-CT to evaluate patency. The areas were classified as open, fusing, or fused and were harvested, and mRNA was isolated. Gene expression for bone-related proteins, osteogenic and angiogenic factors, transforming growth factor-β (TGF-β) superfamily, and Wnt signaling was analyzed using quantitative polymerase chain reaction and compared with normal sutures collected from fetal demise tissue (control).RESULTSMicro-CT demonstrated that there are variable areas of closure along the length of the sagittal suture. When comparing control samples to surgical samples, there was a significant difference in genes for Wnt signaling, TGF-β, angiogenic and osteogenic factors, bone remodeling, and nuclear rigidity in mRNA isolated from the fusing and fused areas of the sagittal suture compared with patent areas (p < 0.05).CONCLUSIONSIn nonsyndromic sagittal craniosynostosis, the affected suture has variable areas of being open, fusing, and fused. These specific areas have different mRNA expression. The results suggest that BMP-2, FGFR3, and several other signaling pathways play a significant role in the regulation of suture fusion as well as in the maintenance of patency in the normal suture.

A systematic review of perioperative seizure prophylaxis during brain tumor resection: the case for a multicenter randomized clinical trial

OBJECTIVE

The majority of neurosurgeons administer antiepileptic drugs (AEDs) prophylactically for supratentorial tumor resection without clear evidence to support this practice. The putative benefit of perioperative seizure prophylaxis must be weighed against the risks of adverse effects and drug interactions in patients without a history of seizures. Consequently, the authors conducted a systematic review of prospective randomized controlled trials (RCTs) that have evaluated the efficacy of perioperative seizure prophylaxis among patients without a history of seizures.

METHODS

Five databases (PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, CINAHL/Academic Search Complete, Web of Science, and ScienceDirect) were searched for RCTs published before May 2017 and investigating perioperative seizure prophylaxis in brain tumor resection. Of the 496 unique research articles identified, 4 were selected for inclusion in this review.

RESULTS

This systematic review revealed a weighted average seizure rate of 10.65% for the control groups. There was no significant difference in seizure rates among the groups that received seizure prophylaxis and those that did not. Further, this expected incidence of new-onset postoperative seizures would require a total of 1258 patients to enroll in a RCT, as determined by a Farrington-Manning noninferiority test performed at the 0.05 level using a noninferiority difference of 5%.

CONCLUSIONS

According to a systematic review of major RCTs, the administration of prophylactic AEDs after brain tumor resection shows no significant reduction in the incidence of seizures compared with that in controls. A large multicenter randomized clinical trial would be required to assess whether perioperative seizure prophylaxis provides benefit for patients undergoing brain tumor resection.

Heterotopic Ossification of the Calvarium Following Bilateral Craniectomies in Traumatic Brain Injury

BACKGROUND

Heterotopic ossification (HO) is defined as ectopic bone formation following traumatic brain injury. Patients typically develop lesions in the hips, knees, and elbows that cause pain, restricted range of motion, nerve impingement, and pressure ulcers.

CASE REPORT

We report an unusual presentation of HO in an 18-year-old male who was involved in a motor vehicle accident and subsequently developed malignant intracranial pressure. His HO developed following bilateral craniectomies in which 2 different dural substitutes were used. Radiographic timing of ectopic bone formation and its continued growth varied.

CONCLUSION

We describe a case of HO in the cranium, a condition that is underreported in the literature. Of significance, despite sustaining multiple traumatic fractures that were managed conservatively, our patient failed to demonstrate any evidence of ectopic axial HO following his incident.

Hypophosphatemic rickets and craniosynostosis: a multicenter case series

OBJECTIVE This study examines a series of patients with hypophosphatemic rickets and craniosynostosis to characterize the clinical course and associated craniofacial anomalies. METHODS A 20-year retrospective review identified patients with hypophosphatemic rickets and secondary craniosynostosis at 3 major craniofacial centers. Parameters examined included sex, age at diagnosis of head shape anomaly, affected sutures, etiology of rickets, presenting symptoms, number and type of surgical interventions, and associated diagnoses. A review of the literature was performed to optimize treatment recommendations. RESULTS Ten patients were identified (8 males, 2 females). Age at presentation ranged from 1 to 9 years. The most commonly affected suture was the sagittal (6/10 patients). Etiologies included antacid-induced rickets, autosomal dominant hypophosphatemic rickets, and X-linked hypophosphatemic (XLH) rickets. Nine patients had undergone at least 1 cranial vault remodeling (CVR) surgery. Three patients underwent subsequent surgeries in later years. Four patients underwent formal intracranial pressure (ICP) monitoring, 3 of which revealed elevated ICP. Three patients were diagnosed with a Chiari Type I malformation. CONCLUSIONS Secondary craniosynostosis develops postnatally due to metabolic or mechanical factors. The most common metabolic cause is hypophosphatemic rickets, which has a variety of etiologies. Head shape changes occur later and with a more heterogeneous presentation compared with that of primary craniosynostosis. CVR may be required to prevent or relieve elevated ICP and abnormalities of the cranial vault. Children with hypophosphatemic rickets who develop head shape abnormalities should be promptly referred to a craniofacial specialist.

Delayed Collapse of a Pipeline Embolization Device

BACKGROUND

The Pipeline Embolization Device (PED) is a treatment modality for wide-neck complex intracranial aneurysms. There have been recent reports for the use of PEDs in dissecting pseudoaneurysms of the cervical carotid arteries. The use of this flow diversion technology has emerged as a promising alternative; however, there are various risks and complications that one should be aware of.

OBJECTIVE

To report a rare postoperative complication, identified during follow-up, in a patient initially treated for an internal carotid artery dissection with multiple overlapping PEDs.

METHODS

A 53-year-old male with unremarkable history presented with acute Horner's syndrome, and imaging findings revealing internal carotid artery dissection and pseudoaneurysm with significant flow-limiting stenosis. He underwent treatment with a PED.

RESULTS

At 3 months post-operation, a cerebral angiogram demonstrated that one of his pipeline stents in the posterior cavernous segment had collapsed at its central portion. Flow was preserved around the outside of the collapsed device. We performed 4 rounds of balloon angioplasty with modest, but not complete, re-expansion of the stent. The patient has been doing well in the postoperative period with no complications.

CONCLUSION

The PED's role in the management of aneurysms and other intra- and extra-cranial vascular pathologies continues to expand, and new complications are bound to be discovered, similar to our case. As the use of these devices becomes routine and widespread, the frequency of these complications will increase. The management of unforeseen complications of PEDs, such as a collapsed stent, will need to be determined on an individual basis.

Gene expression changes between patent and fused cranial sutures in a nonsyndromic craniosynostosis population

OBJECTIVE

Craniosynostosis is a premature fusion of 1 or more cranial sutures. It may occur with additional morphological abnormalities (syndromic) or in isolation. Studies suggest that dysregulation of normal cell proliferation, differentiation, and migration has a role in isolated or nonsyndromic craniosynostosis but the molecular mechanisms remain unknown. The aim of this research is to identify genes differentially expressed in prematurely fused human suture compared to patent suture in nonsyndromic craniosynostosis.

METHODS

Bone fragments from synostosed and patent sutures of 7 infants with nonsyndromic craniosynostosis were collected during surgical release of fused sutures. RNA was isolated from the fragments (7 patent and 7 fused) and global gene expression profiled using the Illumina WGE-DASL assay and HumanRef 8.0 Beadchip.

RESULTS

Comparison of mRNA expression in fused and patent suture identified 68 genes significantly differentially expressed and having fold changes ≤ -2.0 and ≥ 2.0 with a false discovery rate adjusted P value at .10 and 136 with adjusted P value of 0.15. SFRP2 (secreted frizzled-related protein 2) demonstrated the largest decrease in fused sutures. Analysis including only sagittal fused sutures revealed a set of 35 overlapping genes that may be involved in suture patency over all suture types. SPHKAP (sphingosine kinase type 1-interacting protein), a modulator of TGFβ signaling, was significant in the sagittal subset.

CONCLUSION

Differentially expressed genes were identified in fused suture relative to patent in a nonsyndromic craniosynostosis population. SFRP2 is likely important in suture patency. Genes having significant roles in osteoblastogenesis as negative regulators of canonical Wnt pathway were significantly downregulated.

Evaluation of glycerol-preserved bone allografts in cervical spine fusion: a prospective, randomized controlled trial

OBJECT

Bone allografts used for interbody spinal fusion are often preserved through either freeze drying or lowtemperature freezing, each having disadvantages related to graft preparation time and material properties. In response, a glycerol preservation treatment has been developed to maintain the biomechanical properties of allografts at ambient temperatures, requiring no thawing or rehydration and minimal rinsing prior to implantation. The authors conducted a prospective randomized study to compare the clinical results of glycerol-preserved Cloward dowels and those of freezedried Cloward dowels in anterior cervical discectomy and fusion. The primary outcome measures were evidence of fusion and graft subsidence, and the secondary outcome measures included adverse events, pain, and neck disability scores.

METHODS

Of 106 patients, 53 (113 levels of surgery) were randomly assigned to the glycerol-preserved graft group and 53 (114 levels of surgery) to the freeze-dried graft group. Subsidence was assessed at 3 and 6 months after implantation. Evidence of fusion was evaluated radiographically at 6 months postimplantation. Subsidence was quantitatively assessed based on physical measurements obtained from radiographs by using calibrated comparators, whereas fusion was also evaluated visually. Surgeons were blinded to treatment type during visual and physical assessments of the patients and the radiographs.

RESULTS

No one in either group had evidence of complete nonunion according to radiographic evaluation at the 6-month follow-up. Average subsidence for all graft-treated levels was 2.11 mm for the glycerol-preserved group and 2.73 mm for the freeze-dried group at the 3-month follow-up and 2.13 and 2.83 mm at the 6-month follow-up, respectively. The 2 treatment groups were statistically equivalent (p = 0.2127 and 0.1705 for the 3- and 6-month follow-up, respectively). No differences were noted between the graft types in terms of adverse event incidence or severity.

CONCLUSIONS

Glycerol-preserved bone allografts exhibit fusion results and subsidence values similar to those of their freeze-dried counterparts, potentially more favorable biomechanical properties, and significantly shorter preparation times.

Mechanical thrombectomy for pediatric stroke arising from an atrial myxoma: case report

Children experiencing severe neurological deficit due to acute ischemic stroke may benefit from endovascular intervention. The authors describe the use of mechanical thrombectomy in the treatment of embolic occlusion secondary to an atrial myxoma in a pediatric patient. This case involved an 11-year-old boy with a history notable for Raynaud syndrome and a distal extremity rash who presented to the emergency department with dense hemiparesis secondary to thromboembolic occlusion of the M1 segment of the middle cerebral artery. Following mechanical thrombectomy, the patient's pediatric National Institutes of Health Stroke Scale score improved from a 16 to a 7. In the setting of acute pediatric stroke due to atrial myxoma emboli, mechanical thrombectomy may be a first-line therapy.

Multiple unilateral traumatic carotid-cavernous sphenoid sinus fistulas with associated massive epistaxis: a consequence of parkour

BACKGROUND

Traumatic carotid-cavernous fistulas (CCFs) present the clinician with diagnostic and surgical challenges. Extension of a CCF into the sphenoid sinus presents additional management difficulties. Endovascular interventions using various thrombogenic materials such as balloons, coils, or liquids are effective treatment strategies. Ideally, these techniques are used to obliterate the fistula while maintaining the patency of the parent artery.

CASE REPORT

We present a rare case of traumatic carotid-cavernous sphenoid sinus fistulas complicated by multiple tears in the internal carotid artery with direct communication to the cavernous and sphenoid sinus. As a result, the patient developed massive epistaxis requiring emergent endovascular intervention. A total of 87 detachable coils were placed into the cavernous and sphenoid sinuses via transarterial and transvenous routes in a staged procedure, resulting in complete obliteration of the patient's multiple fistulas.

CONCLUSION

To our knowledge, this is the first reported case of multiple fistulous tears in the internal carotid artery with extension to the cavernous and sphenoid sinus. This report emphasizes the importance of early diagnosis and neurosurgical intervention.

Minimizing transfusion requirements for children undergoing craniosynostosis repair: the CHoR protocol

OBJECT

Children with craniosynostosis may require cranial vault remodeling to prevent or relieve elevated intracranial pressure and to correct the underlying craniofacial abnormalities. The procedure is typically associated with significant blood loss and high transfusion rates. The risks associated with transfusions are well documented and include transmission of infectious agents, bacterial contamination, acute hemolytic reactions, transfusion-related lung injury, and transfusion-related immune modulation. This study presents the Children's Hospital of Richmond (CHoR) protocol, which was developed to reduce the rate of blood transfusion in infants undergoing primary craniosynostosis repair.

METHODS

A retrospective chart review of pediatric patients treated between January 2003 and Febuary 2012 was performed. The CHoR protocol was instituted in November 2008, with the following 3 components; 1) the use of preoperative erythropoietin and iron therapy, 2) the use of an intraoperative blood recycling device, and 3) acceptance of a lower level of hemoglobin as a trigger for transfusion (< 7 g/dl). Patients who underwent surgery prior to the protocol implementation served as controls.

RESULTS

A total of 60 children were included in the study, 32 of whom were treated with the CHoR protocol. The control (C) and protocol (P) groups were comparable with respect to patient age (7 vs 8.4 months, p = 0.145). Recombinant erythropoietin effectively raised the mean preoperative hemoglobin level in the P group (12 vs 9.7 g/dl, p < 0.001). Although adoption of more aggressive surgical vault remodeling in 2008 resulted in a higher estimated blood loss (212 vs 114.5 ml, p = 0.004) and length of surgery (4 vs 2.8 hours, p < 0.001), transfusion was performed in significantly fewer cases in the P group (56% vs 96%, p < 0.001). The mean length of stay in the hospital was shorter for the P group (2.6 vs 3.4 days, p < 0.001).

CONCLUSIONS

A protocol that includes preoperative administration of recombinant erythropoietin, intraoperative autologous blood recycling, and accepting a lower transfusion trigger significantly decreased transfusion utilization (p < 0.001). A decreased length of stay (p < 0.001) was seen, although the authors did not investigate whether composite transfusion complication reductions led to better outcomes.

An unusual case of pediatric bow hunter's stroke

Background:

Bow Hunter's syndrome/stroke is defined as symptomatic, vertebrobasilar insufficiency provoked by physiologic head rotation. It is a diagnostically challenging cause of posterior circulation stroke in children. While there have been prior reports of this rare disorder, we describe an exceptional case of pediatric Bow Hunter's stroke resulting from a near complete occlusion the right vertebral artery (VA) secondary to an anomalous spur emanating from the right occipital condyle. Surgical and endovascular options and approaches are also detailed herein.

Case Description:

A 16-year-old male presented with multiple posterior circulation ischemic strokes. A dynamic computerized tomography angiogram performed with the patient's head in a rotated position revealed a near complete occlusion of the V3 segment of the right VA from a bone spur arising from his occipital condyle. The spur caused a focal dissection of the distal right VA with associated thrombus. He was initially managed with a cervical collar, antiplatelet therapy with aspirin 81 mg and anticoagulation with coumadin (INR goal 2-3) for 3 months. Despite the management plan, he had a subsequent thromboembolic event and a right VA sacrifice with coil embolization was then performed. At the 3-month follow-up, the patient was doing well with no reports of any subsequent strokes.

Conclusion:

We report the first reported pediatric case of Bow Hunter's stroke due to dynamic right VA occlusion from an occipital condylar bone spur. The vascular compression from this spur led to a right VA dissection and thrombus formation and ultimately caused multiple posterior circulation thromboembolic strokes. Endovascular treatment options including vessel sacrifice should be considered in cases that have failed maximal medical management.

Sonographic localization of a nonpalpable shunt: Ultrasound-assisted ventricular shunt tap

Background:

Patients frequently present to the emergency department (ED) for evaluation of cerebrospinal fluid (CSF) shunt malfunction, often requiring urgent management. A typical evaluation in the emergency room setting includes a thorough history and physical examination, noncontrasted head computed tomography (CT), shunt series, and occasionally a ventricular shunt tap.

Case Description:

We present the case of a 53-year-old male who initially presented to the ED in acute status epilepticus. His history was notable for seizures and multiple craniectomies and cranioplasties with subsequent placement of a ventriculoperitoneal shunt secondary to traumatic brain injury. Imaging in the ED suggested possible shunt failure. No previous imaging was available for comparison, and therefore a ventricular shunt tap was attempted. Initially, the tap could not be performed, as the shunt was not palpable secondary to the thickness of his scalp and location of the reservoir near his complex cranial reconstruction site. We report, for the first time, the utility of emergency ultrasound (EUS) to aid in such an encounter.

Conclusion:

EUS revealed the exact location of his shunt reservoir, and therefore enabled the shunt tap, which ultimately led to the discovery of the patient's proximal shunt failure in a setting that may have otherwise been missed. The patient underwent urgent shunt revision with a good outcome.

Intradiploic dermoid cyst of the lateral frontotemporal skull: case report and review of the literature

BACKGROUND

Intradiploic dermoid cysts represent 0.04-0.7% of cranial tumors. Fewer than 20 cases of dermoid cysts occurring in the lateral frontotemporal region with a sinus tract and bony involvement are described, only 7 with intracranial extension. We present the first report of such a lesion arising within the lateral coronal suture. As the literature on this topic grows, the matter of preoperative imaging for soft tissue and bony lesions of the lateral frontotemporal region is evolving, and this report offers a preliminary set of criteria for when imaging is a necessity.

CASE REPORT

A 2-year-old male presented with a bony lesion in the right frontotemporal region. Since birth the lesion had grown commensurately with the patient. Examination revealed an immobile hard mass overlying the right coronal suture with no discernable abnormality. Computed tomography demonstrated a cystic lesion without evidence of intracranial extension. Intraoperatively, the exophytic lesion was fully enclosed by bony matrix, interrupting the coronal suture as it approached the pterion. Following resection, pathology revealed an intradiploic dermoid cyst.

CONCLUSION

Intradiploic dermoid cysts occurring within patent cranial sutures away from the midline are rarely described lesions. Complete surgical resection with careful follow-up is the treatment of choice.

Electrically biased nanolithography with KOH-coated AFM tips

This letter provides the first study aimed at characterizing the desorption and nanolithographic processes for SAM-coated, gold-coated silicon substrates oxidatively patterned with an AFM with a tip under potential control. The process either results in recessed patterns where the monolayer has been removed or raised structures where the monolayer has been removed and silicon oxidation has taken place. Eleven different SAMs have been studied, and the type of pattern formed depends markedly upon SAM chain length, end functional group, and applied bias. We show how local pH and choice of monolayer can be used to very effectively control the type of pattern that is ultimately formed. Interestingly, we show that hydroxide anion accessibility to the substrate surface is one of the most significant factors in determining the pattern topography. Moreover, control over the pattern topography can be achieved by controlling the concentration of the KOH in the water meniscus formed at the point of contact between tip and surface in the context of a bias-controlled DPN experiment with a KOH-coated tip. The work provides important insight into the factors that control SAM desorption and also ways of controlling the topography of features made in a potential-controlled scanning probe nanolithographic process.

Nonenzymatic detection of bacterial genomic DNA using the bio bar code assay

The detection of bacterial genomic DNA through a nonenzymatic nanomaterials-based amplification method, the bio bar code assay, is reported. The assay utilizes oligonucleotide-functionalized magnetic microparticles to capture the target of interest from the sample. A critical step in the new assay involves the use of blocking oligonucleotides during heat denaturation of the double-stranded DNA. These blockers bind to specific regions of the target DNA upon cooling and prevent the duplex DNA from rehybridizing, which allows the particle probes to bind. Following target isolation using the magnetic particles, oligonucleotide-functionalized gold nanoparticles act as target recognition agents. The oligonucleotides on the nanoparticle (bar codes) act as amplification surrogates. The bar codes are then detected using the Scanometric method. The limit of detection for this assay was determined to be 2.5 fM, and this is the first demonstration of a bar code-type assay for the detection of double-stranded, genomic DNA.

A real-time PCR-based method for determining the surface coverage of thiol-capped oligonucleotides bound onto gold nanoparticles

Here we report a real-time PCR-based method for determining the surface coverage of dithiol-capped oligonucleotides bound onto gold nanoparticles alone and in tandem with antibody. The detection of gold nanoparticle-bound DNA is accomplished by targeting the oligonucleotide with primer and probe binding sites, amplification of the oligonucleotide by PCR, and real-time measurement of the fluorescence emitted during the reaction. This method offers a wide dynamic range and is not dependant on the dissociation of the oligonucleotide strands from the gold nanoparticle surface; the fluorophore is not highly quenched by the gold nanoparticles in solution during fluorescence measurements. We show that this method and a fluorescence-based method give equivalent results for determining the surface coverage of oligonucleotides bound onto 13 or 30 nm gold nanoparticles alone and in tandem with antibody. Quantifying the surface coverage of immobilized oligonucleotides on metallic nanoparticle surfaces is important for optimizing the sensitivity of gold nanoparticle-based detection methods and for better understanding the interactions between thiol-functionalized oligonucleotides and gold nanoparticles.