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Omar Tanweer, Rona Woldenberg, Sarah Zwany and Avi Setton

Aneurysms of the posterior spinal artery (PSA) are rare lesions. Isolated PSA aneurysms, not in the setting of a high-flow environment, are even more rare. In the few reported cases, these lesions have been predominantly resected or observed. The authors report an isolated pseudoaneurysm of the PSA at the T-11 level presenting with subarachnoid hemorrhage. The patient underwent successful endovascular obliteration. To the authors' knowledge, this is the first report of an endovascular repair of an isolated PSA aneurysm.

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Omar Tanweer, Akwasi Boah and Paul P. Huang

Object

Patients undergoing placement of an external ventricular drain (EVD) are at increased risk for development of venous thromboembolisms (VTEs). Early chemical prophylaxis has been shown to decrease rates of embolism formation, but the risks for bleeding and the optimal time to initiate prophylaxis have not been clearly defined for this patient population. The authors evaluated the safety and risks for bleeding when chemical prophylaxis for VTEs was started within 24 hours of EVD placement.

Methods

To compare rates of hemorrhage among patients who received prophylaxis within 24 hours and those who received it later than 24 hours after admission, the authors conducted an institutional review board–approved retrospective review. Patients were those who had had an EVD placed and postprocedural imaging conducted at Bellevue Hospital, New York, from January 2009 through April 2012. Data collected included demographics, diagnosis, coagulation panel results, time to VTE prophylaxis and imaging, and occurrence of VTEs. The EVD-associated hemorrhages were classified as Grade 0, no hemorrhage; Grade 1, petechial hyperdensity near the drain; Grade 2, hematoma of 1–15 ml; Grade 3, epidural or subdural hematoma greater than 15 ml; or Grade 4, intraventricular hemorrhage or hematoma requiring surgical intervention.

Results

Among 99 patients, 111 EVDs had been placed. Low-dose unfractionated heparin had been given within 24 hours of admission (early prophylaxis) to 56 patients and later than 24 hours after admission (delayed prophylaxis) to 55 patients. There were no statistical differences across all grades (0–4) among those who received early prophylaxis (n = 45, 5, 5, 1, and 0, respectively) and those who received delayed prophylaxis (n = 46, 4, 1, 1, and 3, respectively) (p = 0.731). In the early prophylaxis group, 3 VTEs were discovered among 32 of 56 patients screened for clinically suspected VTEs. In the delayed prophylaxis group, 5 VTEs were discovered among 33 of 55 patients screened for clinically suspected VTEs (p = 0.71).

Conclusions

Hemorrhagic complications did not increase when chemical prophylaxis was started within 24 hours of admission. Also, the incidence of VTEs did not differ between patients in the early and delayed prophylaxis groups. Larger randomized controlled trials are probably needed to assess decreases in VTEs with earlier prophylaxis.

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Donato Pacione, Omar Tanweer, Phillip Berman and David H. Harter

Utilizing advanced 3D printing techniques, a multimaterial model was created for the surgical planning of a complex deformity of the skull base and craniovertebral junction. The model contained bone anatomy as well as vasculature and the previously placed occipital cervical instrumentation. Careful evaluation allowed for a unique preoperative perspective of the craniovertebral deformity and instrumentation options. This patient-specific model was invaluable in choosing the most effective approach and correction strategy, which was not readily apparent from standard 2D imaging. Advanced 3D multimaterial printing provides a cost-effective method of presurgical planning, which can also be used for both patient and resident education.

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Conor Grady, Omar Tanweer, David Zagzag, Jafar J. Jafar, Paul P. Huang and Douglas Kondziolka

Stereotactic radiosurgery is widely used to treat cerebral arteriovenous malformations (AVMs), with the goal of complete angiographic obliteration. A number of case series have challenged the assumption that absence of residual AVM on follow-up angiograms is consistent with elimination of the risk of hemorrhage. The authors describe 3 cases in which patients who had angiographic evidence of AVM occlusion presented with late hemorrhage in the area of their prior lesions. They compare the radiographic, angiographic, and histological features of these patients with those previously described in the literature.

Delayed hemorrhage from the tissue of occluded AVMs has been reported as early as 4 and as late as 11 years after initial stereotactic radiosurgery. In all cases for which data are available, hemorrhage occurred in the area of persistent imaging findings despite negative findings on conventional angiography. The hemorrhagic lesions that were resected demonstrated a number of distinct histological findings.

While rare, delayed hemorrhage from the tissue of occluded AVMs may occur from a number of distinct, angiographically occult postirradiation changes. The hemorrhages in the authors' 3 cases were symptomatic and localized. The correlation of histological and imaging findings in delayed hemorrhage from occluded AVMs is an area requiring further investigation.

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Robert E. Elliott, Omar Tanweer, Akwasi Boah, Michael L. Smith and Anthony Frempong-Boadu

Object

Some centers report a lower incidence of vertebral artery (VA) injury with C-2 pars screws compared with pedicle screws without sacrificing construct stability, despite biomechanical studies suggesting greater load failures with C-2 pedicle screws. The authors reviewed published series describing C-2 pars and pedicle screw implantation and atlantoaxial fusions and compared the incidence of VA injury, screw malposition, and successful atlantoaxial fusion with each screw type.

Methods

Online databases were searched for English-language articles between 1994 and April of 2011 describing the clinical and radiographic outcomes following posterior atlantoaxial fusion with C-1 lateral mass and either C-2 pars interarticularis or pedicle screws. Thirty-three studies describing 2975 C-2 pedicle screws and 11 studies describing 405 C-2 pars screws met inclusion criteria for the safety analysis. Seven studies describing 113 patients treated with C-2 pars screws and 20 studies describing 918 patients treated with C-2 pedicle screws met inclusion criteria for fusion analysis. Standard and formal meta-analysis techniques were used to compare outcomes.

Results

All studies provided Class III evidence. Ten instances of VA injury occurred with C-2 pedicle screws (0.3%) and no VA injury occurred with pars screws. The point estimate of VA injury for C-2 pedicle screws was 1.09% (95% CI 0.73%–1.63%) and was similar to that of C-2 pars screws (1.48%, 95% CI 0.62%–3.52%). Similarly, there was no statistically significant difference in the rate of clinically significant screw malpositions (1.14% [95% CI 0.77%–1.69%) vs 1.69% [95% CI 0.73%–3.84%]). Radiographically identified screw malposition occurred in a higher proportion of C-2 pedicle screws compared with C-2 pars screws (6.0% [95% CI 3.7%–9.6%] vs 4.0% [95% CI 2.0%–7.6%], p < 0.0001). Pseudarthrosis occurred in a greater proportion of patients treated with C-2 pars screws (5 [4.4%] of 113) compared with those treated with C-2 pedicle screws (2 [0.22%] of 900). Point estimates with 95% confidence intervals show a slightly higher rate of successful atlantoaxial fusion in the pedicle screw cohort (97.8% [CI 96.0%–98.8%] vs 93.5% [CI 86.6%–97.0%]; p < 0.0001). Q-testing ruled out heterogeneity between the study groups.

Conclusions

With a thorough knowledge of axis anatomy, surgeons can place both C-2 pars and C-2 pedicle screws accurately with a small risk of VA injury or clinically significant malposition. There may be subtle trade-off of safety for rigidity when using axial pedicle instead of pars screws, and the decision to use either screw type must be made only after careful review of the preoperative CT imaging and must take into account the surgeon's expertise and the particular demands of the clinical scenario in any given case.

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Omar Tanweer, Taylor A. Wilson, Stephen P. Kalhorn, John G. Golfinos, Paul P. Huang and Douglas Kondziolka

OBJECT

Physicians are often solicited by patients or colleagues for clinical recommendations they would make for themselves if faced by a clinical situation. The act of making a recommendation can alter the clinical course being taken. The authors sought to understand this dynamic across different neurosurgical scenarios by examining how neurosurgeons value the procedures that they offer.

METHODS

The authors conducted an online survey using the Congress of Neurological Surgeons listserv in May 2013. Respondents were randomized to answer either as the surgeon or as the patient. Questions encompassed an array of distinct neurosurgical scenarios. Data on practice parameters and experience levels were also collected.

RESULTS

Of the 534 survey responses, 279 responded as the “neurosurgeon” and 255 as the “patient.” For both vestibular schwannoma and arteriovenous malformation management, more respondents chose resection for their patient but radiosurgery for themselves (p = 0.002 and p = 0.001, respectively). Aneurysm coiling was chosen more often than clipping, but those whose practice was ≥ 30% open cerebrovascular neurosurgery were less likely to choose coiling. Overall, neurosurgeons who focus predominantly on tumors were more aggressive in managing the glioma, vestibular schwannoma, arteriovenous malformation, and trauma. Neurosurgeons more than 10 years out of residency were less likely to recommend surgery for management of spinal pain, aneurysm, arteriovenous malformation, and trauma scenarios.

CONCLUSIONS

In the majority of cases, altering the role of the surgeon did not change the decision to pursue treatment. In certain clinical scenarios, however, neurosurgeons chose treatment options for themselves that were different from what they would have chosen for (or recommended to) their patients. For the management of vestibular schwannomas, arteriovenous malformations, intracranial aneurysms, and hypertensive hemorrhages, responses favored less invasive interventions when the surgeon was the patient. These findings are likely a result of cognitive biases, previous training, experience, areas of expertise, and personal values.

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Jan-Karl Burkhardt, Omar Tanweer, Peter Kim Nelson and Howard A. Riina

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Jan-Karl Burkhardt, Howard A. Riina, Omar Tanweer, Peyman Shirani, Eytan Raz, Maksim Shapiro and Peter Kim Nelson

The authors present the unusual case of a complex unruptured basilar artery terminus (BAT) aneurysm in a 42-year-old symptomatic female patient presenting with symptoms of mass effect. Due to the fusiform incorporation of both the BAT and left superior cerebellar artery (SCA) origin, simple surgical or endovascular treatment options were not feasible in this case. A 2-staged (combined deconstructive/reconstructive) procedure was successfully performed: first occluding the left SCA with a Pipeline embolization device (PED) coupled to a microvascular plug (MVP) in the absence of antiplatelet coverage, followed by reconstruction of the BAT by deploying a second PED from the right SCA into the basilar trunk. Six-month follow-up angiography confirmed uneventful aneurysm occlusion. The patient recovered well from her neurological symptoms. This case report illustrates the successful use of a combined staged deconstructive/reconstructive endovascular approach utilizing 2 endoluminal tools, PED and MVP, to reconstruct the BAT and occlude a complex aneurysm.

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Jan-Karl Burkhardt, Omar Tanweer, Miguel Litao, Pankaj Sharma, Eytan Raz, Maksim Shapiro, Peter Kim Nelson and Howard A. Riina

OBJECTIVE

A systematic analysis on the utility of prophylactic antibiotics for neuroendovascular procedures has not been performed. At the authors’ institution there is a unique setup to address this question, with some attending physicians using prophylactic antibiotics (cefazolin or vancomycin) for all of their neurointerventions while others generally do not.

METHODS

The authors performed a retrospective review of the last 549 neurointerventional procedures in 484 patients at Tisch Hospital, NYU Langone Medical Center. Clinical and radiological data were collected for analysis, including presence of prophylactic antibiotic use, local or systemic infection, infection laboratory values, and treatment. Overall, 306 aneurysms, 117 arteriovenous malformations/arteriovenous fistulas, 86 tumors, and 40 vessel stenosis/dissections were treated with coiling (n = 109), Pipeline embolization device (n = 197), embolization (n = 203), or stenting (n = 40).

RESULTS

Antibiotic prophylaxis was used in 265 of 549 cases (48%). There was no significant difference between patients with or without antibiotic prophylaxis in sex (p = 0.48), presence of multiple interventions (p = 0.67), diseases treated (p = 0.11), or intervention device placed (p = 0.55). The mean age of patients in the antibiotic prophylaxis group (53.4 years) was significantly lower than that of the patients without prophylaxis (57.1 years; p = 0.014). Two mild local groin infections (0.36%) and no systemic infections (0%) were identified in this cohort, with one case in each group (1/265 [0.38%] vs 1/284 [0.35%]). Both patients recovered completely with local drainage (n = 1) and oral antibiotic treatment (n = 1).

CONCLUSIONS

The risk of infection associated with endovascular neurointerventions with or without prophylactic antibiotic use was very low in this cohort. The data suggest that the routine use of antibiotic prophylaxis seems unnecessary and that to prevent antibiotic resistance and reduce costs antibiotic prophylaxis should be reserved for selected patients deemed to be at increased infection risk.