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Srinivas Chivukula, Ramesh Grandhi and Robert M. Friedlander

Two key discoveries in the 19th century—infection control and the development of general anesthesia—provided an impetus for the rapid advancement of surgery, especially within the field of neurosurgery. Improvements in anesthesia and perioperative care, in particular, fostered the development of meticulous surgical technique conducive to the refinement of neuroanatomical understanding and optimization of neurosurgical procedures and outcomes. Yet, even dating back to the earliest times, some form of anesthesia or perioperative pain management was used during neurosurgical procedures. Despite a few reports on anesthesia published around the time of William Morton's now-famous public demonstration of ether anesthesia in 1846, relatively little is known or written of early anesthetics in neurosurgery. In the present article the authors discuss the history of anesthesia pertaining to neurosurgical procedures and draw parallels between the refinements and developments in anesthesia care over time with some of the concomitant advances in neurosurgery.

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Robert M. Friedlander and Christopher S. Ogilvy

✓ Fenestration of the proximal anterior cerebral artery (A1 segment) is a rare occurrence. This vascular anomaly is often associated with aneurysms and other abnormalities. The current article describes the case of a 33-year-old man who presented with a subarachnoid hemorrhage secondary to a ruptured aneurysm originating from the proximal end of an A1 fenestration. This patient also had a contralateral A1 fenestration as well as an azygos anterior cerebral artery. This is the first report of such an unusual vascular anatomy. The literature is reviewed and possible embryological mechanisms are discussed.

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Vallabh Janardhan, Robert Friedlander, Howard Riina and Philip Edwin Stieg

Object

A decision to treat incidental intracranial aneurysms (IIAs) relies on understanding the risks of treatment and weighing them against the those of aneurysm rupture. Whereas the natural history of IIAs is currently being studied, the risks associated with treating IIAs and factors associated with poor outcome need to be clearly established.

Methods

In a consecutive series of 125 patients, 160 IIAs were treated either surgically (152 cases) or endovascularly (eight cases). Postprocedural morbidity was defined as a new neurological deficit associated with a score greater than or equal to 3 on the modified Rankin Scale or a score of less than 24 on the Mini-Mental Status Examination. Logistic regression analysis was used to identify predictors of postprocedural morbidity from retrospectively collected data on demographic, clinical, and radiographic characteristics.

Treatment of IIAs was not associated with any mortality and was associated with postprocedural morbidity in 17 (13.6%) of 125 patients (early outcome) and eight (6.4%) of patients (late outcome). In the logistic-regression model, treatment of aneurysms (≥13 mm) and posterior circulation aneurysms were independently associated with postprocedural morbidity. In patients in whom postprocedural neurological deficits developed, 12 (70.6%) of 17 and four (23.5%) of 17 patients harbored aneurysms with broad or calcified necks, respectively. Age, comorbidities, multiple aneurysms, specific aneurysm location, and history of subarachnoid hemorrhage related to a different aneurysm were not significantly associated with poor outcome.

Conclusions

The authors found that IIAs can be safely and effectively treated without causing mortality and with a lower morbidity rate than previously reported. A combination of radiographic variables may be helpful in identifying patients at risk for postprocedural morbidity.

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Kai U. Frerichs, Philip E. Stieg and Robert M. Friedlander

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Ezequiel Goldschmidt, Amir H. Faraji, Brian T. Jankowitz, Paul Gardner and Robert M. Friedlander

Near-infrared (NIR) light is commonly used to map venous anatomy in the upper extremities to gain intravenous access for line placement. In this report, the authors describe the use of a common and commercially available NIR vein finder to delineate the cortical venous anatomy prior to dural opening.

During a variety of cranial approaches, the dura was directly visualized using an NIR vein finder. The NIR light source allowed for recognition of the underlying cortical venous anatomy, dural sinuses, and underlying pathology before the dura was opened. This information was considered when tailoring the dural opening. When the dura was illuminated with the NIR vein finder, the underlying cortical and sinus venous anatomy was evident and correlated with the observed cortical anatomy. The vein finder was also accurate in locating superficial lesions and pathological dural veins. A complete accordance in the findings on the pre– and post–dural opening images was observed in all cases.

This simple, inexpensive procedure is readily compatible with operative room workflow, necessitates no head fixation, and offers a real-time image independent of brain shift.

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Jason Sheehan, Dale Ding and Robert M. Starke

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Yoshiaki Takamiya, Robert M. Friedlander, Harold Brem, Amy Malick and Robert L. Martuza

✓ The effectiveness of AGM-1470, a potent, fungal-derived inhibitor of angiogenesis, in suppressing the neovascularization and growth of human Schwann cell tumors was tested in six schwannomas, seven neurofibromas, and one neurofibrosarcoma. Tumor fragments from surgical specimens were implanted into the subrenal capsule of 348 nude mice (nu/nu). Seven days after implantation, the tumors were measured and vascularity was graded. The animals were then randomly assigned to one of two groups, to receive either saline (control group) or systemic AGM-1470 treatment. After 2 to 6 weeks of treatment, tumor size and degree of vascularity were recorded. In the six different schwannomas implanted into 138 mice, the average vascular grade in the control group after 2 weeks of treatment increased from 2.2 to 3.2 (+1.0), while in the AGM-1470-treated group it decreased from 2.2 to 1.7 (−0.5) (p < 0.01). In the seven different neurofibromas implanted into 158 mice, the change in the average vascular grade in control and AGM-1470-treated animals was +0.5 and −1.0, respectively (p < 0.01). In the one neurofibrosarcoma implanted into 52 mice, the change in average vascular grade in each group during the 6-week treatment period was +1.9 and −1.0, respectively (p < 0.01). Neurofibrosarcoma growth after 6 weeks of AGM-1470 treatment was only 8.5% of the growth found in the control animals (p < 0.01). This study determined that AGM-1470 is effective in inhibiting angiogenesis and the growth of human nerve-sheath tumors.

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Nitin Agarwal, Ahmed Kashkoush, Michael M. McDowell, William R. Lariviere, Naveed Ismail and Robert M. Friedlander

OBJECTIVE

Ventricular shunt (VS) durability has been well studied in the pediatric population and in patients with normal pressure hydrocephalus; however, further evaluation in a more heterogeneous adult population is needed. This study aims to evaluate the effect of diagnosis and valve type—fixed versus programmable—on shunt durability and cost for placement of shunts in adult patients.

METHODS

The authors retrospectively reviewed the medical records of all patients who underwent implantation of a VS for hydrocephalus at their institution over a 3-year period between August 2013 and October 2016 with a minimum postoperative follow-up of 6 months. The primary outcome was shunt revision, which was defined as reoperation for any indication after the initial procedure. Supply costs, shunt durability, and hydrocephalus etiologies were compared between fixed and programmable valves.

RESULTS

A total of 417 patients underwent shunt placement during the index time frame, consisting of 62 fixed shunts (15%) and 355 programmable shunts (85%). The mean follow-up was 30 ± 12 (SD) months. The shunt revision rate was 22% for programmable pressure valves and 21% for fixed pressure valves (HR 1.1 [95% CI 0.6–1.8]). Shunt complications, such as valve failure, infection, and overdrainage, occurred with similar frequency across valve types. Kaplan-Meier survival curve analysis showed no difference in durability between fixed (mean 39 months) and programmable (mean 40 months) shunts (p = 0.980, log-rank test). The median shunt supply cost per index case and accounting for subsequent revisions was $3438 (interquartile range $2938–$3876) and $1504 (interquartile range $753–$1584) for programmable and fixed shunts, respectively (p < 0.001, Wilcoxon rank-sum test). Of all hydrocephalus etiologies, pseudotumor cerebri (HR 1.9 [95% CI 1.2–3.1]) and previous shunt malfunction (HR 1.8 [95% CI 1.2–2.7]) were found to significantly increase the risk of shunt revision. Within each diagnosis, there were no significant differences in revision rates between shunts with a fixed valve and shunts with a programmable valve.

CONCLUSIONS

Long-term shunt revision rates are similar for fixed and programmable shunt pressure valves in adult patients. Hydrocephalus etiology may play a significant role in predicting shunt revision, although programmable valves incur higher supply costs regardless of initial diagnosis. Utilization of fixed pressure valves versus programmable pressure valves may reduce supply costs while maintaining similar revision rates. Given the importance of developing cost-effective management protocols, this study highlights the critical need for large-scale prospective observational studies and randomized clinical trials of ventricular shunt valve revisions and additional patient-centered outcomes.

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Georgios Andrea Zenonos, David Fernandes-Cabral, Maximiliano Nunez, Stefan Lieber, Juan Carlos Fernandez-Miranda and Robert Max Friedlander

OBJECTIVE

Surgical approaches to the ventrolateral pons pose a significant challenge. In this report, the authors describe a safe entry zone to the brainstem located just above the trigeminal entry zone which they refer to as the “epitrigeminal entry zone.”

METHODS

The approach is presented in the context of an illustrative case of a cavernous malformation and is compared with the other commonly described approaches to the ventrolateral pons. The anatomical nuances were analyzed in detail with the aid of surgical images and video, anatomical dissections, and high-definition fiber tractography (HDFT). In addition, using the HDFT maps obtained in 77 normal subjects (154 sides), the authors performed a detailed anatomical study of the surgically relevant distances between the trigeminal entry zone and the corticospinal tracts.

RESULTS

The patient treated with this approach had a complete resection of his cavernous malformation, and improvement of his symptoms. With regard to the HDFT anatomical study, the average direct distance of the corticospinal tracts from the trigeminal entry zone was 12.6 mm (range 8.7–17 mm). The average vertical distance was 3.6 mm (range −2.3 to 8.7 mm). The mean distances did not differ significantly from side to side, or across any of the groups studied (right-handed, left-handed, and ambidextrous).

CONCLUSIONS

The epitrigeminal entry zone to the brainstem appears to be safe and effective for treating intrinsic ventrolateral pontine pathological entities. A possible advantage of this approach is increased versatility in the rostrocaudal axis, providing access both above and below the trigeminal nerve. Familiarity with the subtemporal transtentorial approach, and the reliable surgical landmark of the trigeminal entry zone, should make this a straightforward approach.

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Nitin Agarwal, Phillip A. Choi, David O. Okonkwo, Daniel L. Barrow and Robert M. Friedlander

OBJECTIVE

Application for a residency position in neurosurgery is a highly competitive process. Visiting subinternships and interviews are integral parts of the application process that provide applicants and programs with important information, often influencing rank list decisions. However, the process is an expensive one that places significant financial burden on applicants. In this study, the authors aimed to quantify expenses incurred by 1st-year neurosurgery residents who matched into a neurosurgery residency program in 2014 and uncover potential trends in expenses.

METHODS

A 10-question survey was distributed in partnership with the Society of Neurological Surgeons to all 1st-year neurosurgery residents in the United States. The survey asked respondents about the number of subinternships, interviews, and second looks (after the interview) attended and the resultant costs, the type of program match, preferences for subinternship interviews, and suggestions for changes they would like to see in the application process. In addition to compiling overall results, also examined were the data for differences in cost when stratifying for region of the medical school or whether the respondent had contact with the program they matched to prior to the interview process (matched to home or subinternship program).

RESULTS

The survey had a 64.4% response rate. The mean total expenses for all components of the application process were US $10,255, with interview costs comprising the majority of the expenses (69.0%). No difference in number of subinternships, interviews, or second looks attended, or their individual and total costs, was seen for applicants from different regions of the United States. Respondents who matched to their home or subinternship program attended fewer interviews than respondents who had no prior contact with their matched program (13.5 vs 16.4, respectively, p = 0.0023) but incurred the same overall costs (mean $9774 vs $10,566; p = 0.58).

CONCLUSIONS

Securing a residency position in neurosurgery is a costly process for applicants. No differences are seen when stratifying by region of medical school attended or contact with a program prior to interviewing. Interview costs comprise the majority of expenses for applicants, and changes to the application process are needed to control costs incurred by applicants.