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Catherine Miller and Ramachandra P. Tummala


External ventricular drains (EVDs) have an important role in the management of neurological disease, and their placement is a frequently performed neurosurgical procedure. Hemorrhage is a common complication of EVD placement and occurs more frequently than originally believed. There is also risk of hemorrhage with removal of an EVD, which has not been well described. The authors investigated the risk factors associated with placement and removal of EVDs at their institution.


A database was created including patients who required EVD placement from March 2008 to June 2014 at the University of Minnesota. A retrospective chart review was completed, and data were collected for each patient. All cranial imaging studies during the index hospitalization were reviewed to identify hemorrhages associated with either EVD placement or removal. The study was performed using a research protocol approved by the University of Minnesota's institutional review board.


Four hundred eighty-two EVDs were placed during the designated time period. Among the cases in which patients underwent imaging after the placement procedure, hemorrhage was found in 94 (21.6%). The hemorrhage volume ranged from 0.003 cm3 to 45.9 cm3 (mean [± SD] 1.96 ± 6.48 cm3). Two of these hemorrhages resulted in additional interventions: 1 surgical evacuation and 1 contralateral EVD. In 55 (22.5%) of the 244 cases in which imaging was performed after EVD removal, hemorrhage associated with removal was identified. The mean volume of these hemorrhages was 8.25 ± 20.34 cm3 (range 0.012–82.08 cm3). Two EVDs were replaced, and 1 patient died as a result of a large hemorrhage. Large hemorrhages (> 30 cm3) occurred in 2 patients on placement (0.46%) and in 5 patients on removal (2.0%). In this series, decreased platelet levels on admission and an increasing number of EVD placement attempts correlated with an increased risk of hemorrhage on placement. Only those with an EVD placed at bedside were more likely to have hemorrhage on EVD removal.


Multiple studies have reported varying EVD hemorrhage rates while very few studies have described hemorrhage secondary to EVD removal. This is the first reported analysis of risk factors associated with hemorrhage on EVD removal. Hemorrhages occur relatively frequently following EVD placement and removal, though clinical significance of these events seems to be low.

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Ramachandra P. Tummala, Ray M. Chu and Eric S. Nussbaum


The role of cerebral revascularization remains unclear in symptomatic occlusive cerebrovascular disease refractory to medical therapy. Despite the disappointing findings of the Cooperative Study on Extracranial–Intracranial Bypass, a subpopulation of patients with ischemic cerebrovascular disease and poor hemodynamic reserve may benefit from extracranial–intracranial (EC–IC) bypass. The authors reviewed the records of 65 patients who underwent 71 EC–IC bypass procedures at their institution over the past 6 years.


All patients except one presented with repeated transient ischemic attacks (TIAs) that were referable to the involved vascular region. Eight patients underwent EC–IC bypass urgently for “crescendo” TIAs refractory to anti-platelet and anticoagulation therapy. Indications for surgery included cervical internal carotid artery (ICA) occlusion in 28, supraclinoid ICA stenosis in two, middle cerebral artery stenosis or occlusion in 14, moyamoya disease in 18, and ICA dissection in three. Cerebral angiography demonstrated poor collateral flow to the involved region in each case. There were no postoperative strokes or deaths in this series. Following EC–IC bypass, the vast majority (95.4%) of patients experienced cessation of their ischemic events and stabilization of preexisting neurological dysfunction. Of the eight patients who underwent EC–IC bypass urgently for crescendo TIAs, two awoke with increased neurological deficits that improved rapidly within 24 hours of surgery.


Although the Cooperative Study failed to show benefit from this treatment modality, the authors have continued to perform EC–IC bypass in certain cases. Carefully selected individuals with occlusive cerebrovascular disease and persistent ischemic symptoms refractory to maximal medical therapy appear to benefit from cerebral revascularization.

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Ramachandra P. Tummala, Mustafa K. Bas ¸Kaya and Roberto C. Heros

The management of unruptured intracranial aneurysms has changed significantly in recent years and continues to evolve. The three main factors that have affected the management of unruptured intracranial aneurysms are as follows: 1) increased availability of noninvasive imaging technology, resulting in increased detection of incidental aneurysms; 2) improved understanding of the natural history of unruptured aneurysms; and 3) the advent of neuroendovascular therapy. In this report, the authors discuss the implications of these factors in the diagnosis and management of truly incidental, asymptomatic aneurysms and review the current practice patterns at their institution.

Historical and current articles regarding noninvasive neuroimaging, aneurysm screening, endovascular and surgical therapy, and the natural history of unruptured aneurysms were reviewed. Current practices used for diagnosis and management of incidental aneurysms at the authors' institution were also reviewed.

The management of incidental intracranial aneurysms has become an increasingly controversial subject in recent years. Improvements in noninvasive imaging resulting in detection of an increasing number of incidental aneurysms, the establishment of endovascular therapy as an attractive alternative to surgery, and studies indicating a more benign natural history for unruptured aneurysms than previously thought have led to significant changes in neurosurgical practice. Safety and long-term efficacy are the goals of treatment for unruptured aneurysms. Until conclusive studies are completed, the experience of the neurovascular team at each institution and the art of patient selection for treatment will continue to play a fundamental role in the management of these lesions.

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Ramachandra P. Tummala, Ernesto Coscarella and Jacques J. Morcos

Resection of the petrous temporal bone to various degrees provides different levels of access to lesions of the posterior fossa. Although their nomenclature can be confusing, the numerous variants of the transpetrosal approaches can be classified broadly into anterior and posterior groups. The posterior transpetrosal approaches include the retro-labyrinthine, translabyrinthine, and transcochlear, whereas the ones in the anterior group are extensions of the basic middle fossa approach. Both the anterior and posterior approaches have the potential of exposing the cerebellopontine angle and the petroclival region.

The posterior approaches are based on the standard mastoidectomy and involve resection of the petrous bone to various degrees. This results in progressively increased exposure anteriorly, but comes at the expense of hearing in the translabyrinthine approach and of hearing and facial strength in the transcochlear approach.

In contrast, the middle fossa approaches spare the lateral petrous bone and involve resection of the medial petrous bone to various degrees. All of the middle fossa approaches are designed to preserve hearing. Extensions of the middle fossa approaches involve resection of bone within the Kawase rhomboid and division of the tentorium to provide exposure of the posterior fossa.

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Qaisar A. Shah, Muhammad Zeeshan Memon, Ramachandra P. Tummala and Adnan I. Qureshi

Symptomatic occlusive lesions at the origins of the supra-aortic vessels pose challenges for treatment. Endovascular angioplasty and stent placement via the transfemoral approach is possible, but obtaining a stable position for the guide catheter via this approach is technically difficult. The authors describe the case of a 56-year-old man presenting with symptomatic occlusion of a previously placed stent at the origin of the left common carotid artery (CCA). An endovascular revascularization of the left CCA was planned. However, the absence of a lumen proximal to the stent prevented stable placement of a guide catheter via the transfemoral route. Consequently, the authors used a combined surgical and endovascular approach to gain access to the lesion. The left CCA was exposed surgically distal to the occlusion and clamped just proximal to its bifurcation to preserve flow from the external to the internal carotid artery (ICA) and to prevent embolism into the ICA. A wire was passed retrograde through the occlusive lesion and then was subsequently advanced proximally into the femoral sheath. This allowed transfemoral advancement of the appropriate endovascular devices to perform an angioplasty and placement of a stent. The patient remained neurologically stable, and postoperative studies showed improvement in cerebral perfusion. This case demonstrates the feasibility of distal-to-proximal stent delivery with a combined endovascular and surgical approach.

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Yoichi Watanabe, Divyajot Sandhu, Leighton Warmington, Sean Moen and Ramachandra Tummala


Arteriovenous malformation (AVM) is an intracranial vascular disorder. Gamma Knife radiosurgery (GKRS) is used in conjunction with intraarterial embolization to eradicate the nidus of AVMs. Clinical results indicate that patients with prior embolization tend to gain less benefit from GKRS. The authors hypothesized that this was partly caused by dosimetric deficiency. The actual dose delivered to the target may be smaller than the intended dose because of increased photon attenuation by high-density embolic materials. The authors performed a phantom-based study to quantitatively evaluate the 3D dosimetric effect of embolic material on GKRS.


A 16-cm-diameter and 12-cm-long cylindrical phantom with a 16-cm-diameter hemispherical dome was printed by a 3D printer. The phantom was filled with radiologically tissue-equivalent polymer gel. To simulate AVM treatment with embolization, phantoms contained Onyx 18. The material was injected into an AVM model, which was suspended in the polymer gel. The phantom was attached to a Leksell frame by standard GK fixation method, using aluminum screws, for imaging. The phantom was scanned by a Phillips CT scanner with the standard axial-scanning protocol (120 kV and 1.5-mm slice thickness). CT-based treatment planning was performed with the GammaPlan treatment planning system (version 10.1.1). The plan was created to cover a fictitious AVM target volume near the embolization areas with eleven 8-mm shots and a prescription dose of 20 Gy to 50% isodose level. Dose distributions were computed using both tissue maximum ratio (TMR) 10 and convolution dose-calculation algorithms. These two 3D dose distributions were compared using an in-house program. Additionally, the same analysis method was applied to evaluate the dosimetric effects for 2 patients previously treated by GKRS.


The phantom-based analyses showed that the mean dose difference between TMR 10 and convolution doses of the AVM target was no larger than 6%. The difference for GKRS cases was 5%. There were small areas where a large dose difference was observed on the isodose line plots, and those differences were mostly at or in the vicinity of the embolization materials.


The results of both the phantom and patient studies showed a dose reduction no larger than 5% due to the embolization material placed near the target. Although the comparison of 3D dose distributions indicated small local effects of the embolic material, the clinical impact on the obliteration rate is expected to be small.

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Robert D. Ecker, Ramachandra P. Tummala, Elad I. Levy and L. Nelson Hopkins

✓Both carotid endarterectomy and carotid artery stent placement with filter embolic protection present a higher risk for patients with internal carotid artery (ICA) lesions containing intraluminal thrombus. Despite the risk associated with intervention, patients with symptomatic intraluminal thrombus who were enrolled in the North American Symptomatic Endarterectomy Trial did better with surgical than medical treatment. We describe the novel use of an endovascular “internal cross-clamping” technique in two patients with symptomatic intraluminal thrombus in the ICA. A 57-year-old woman presented with a history of multiple episodes of left upper-extremity numbness, mild dysarthria, and agraphia occurring over the previous 24 hours. Cranial magnetic resonance imaging revealed a scattered watershed infarction of the right hemisphere and a critical stenosis of the right ICA. An 81-year-old man awoke with hemiplegia and inability to follow commands after undergoing a complicated carotid endarterectomy. Computed tomographic perfusion imaging demonstrated an increased time to peak in the left middle cerebral territory, and emergent angiography demonstrated both intimal flaps and thrombus in the endarterectomy bed. The lesions in both patients were treated with endovascular stent placement using both proximal and distal flow occlusion—a functional “internal cross-clamping”—for embolic protection. To our knowledge, this is the first report of internal trapping and stent placement for symptomatic carotid stenosis containing intraluminal thrombus. This treatment strategy should be added to the armamentarium of endovascular surgeons in selected patients with symptomatic carotid intraluminal thrombus.

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Bharathi D. Jagadeesan, Haralabos Zacharatos, David R. Nascene, Andrew W. Grande, Daniel J. Guillaume and Ramachandra P. Tummala

A 5-month-old infant was to be treated with elective transarterial embolization for a vein of Galen aneurysmal malformation (VGAM). A team of endovascular surgical neuroradiologists, pediatric interventional radiologists, and pediatric cardiologists attempted conventional femoral arterial access, which was unsuccessful given the small caliber of the femoral arteries and superimposed severe vasospasm. Thereafter, eventual arterial access was achieved by navigating from the venous to the arterial system across the patent foramen ovale following a right femoral venous access. Embolization was then successfully performed. At a later date, the child underwent successful transvenous balloon-assisted embolization and eventual arterial embolization with cure of the VGAM.

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Bharathi D. Jagadeesan, Andrew W. Grande, Daniel J. Guillaume, David R. Nascene and Ramachandra P. Tummala

Dural sinus malformations (DSMs) are rare congenital malformations that can be midline or lateral in location. Midline DSMs have been reported to have a worse prognosis than lateral DSMs and have traditionally been more difficult to manage. The authors report 2 unusual manifestations of midline DSMs and their management with percutaneous transfontanelle embolization. The first patient (Case 1) presented at 21 days of life with a large midline DSM and multiple highflow dural and pial arteriovenous shunts. The child developed congestive cardiac failure and venous congestion with intracranial hemorrhage and seizures within a few weeks. The second patient (Case 2) presented with a large midline DSM found on prenatal imaging that was determined to be a purely venous malformation on postnatal evaluation. This large malformation resulted in consumptive coagulopathy and apneic episodes from brainstem compression. The patient in Case 1 was treated initially with endovascular embolization and eventually with curative percutaneous-transfontanelle embolization. The patient in Case 2 was treated with percutaneous transfontanelle embolization in combination with posterior fossa decompression and cranial expansion surgery.

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Feng-Chi Chang, Ramachandra P. Tummala, Babak S. Jahromi, Rodney M. Samuelson, Adnan H. Siddiqui, Elad I. Levy and L. Nelson Hopkins

Inability to achieve vascular access is a common reason for failure to perform carotid artery angioplasty and stent placement. The authors report their experience with the use of an 8 Fr Simmons-2 catheter to gain carotid artery access in the setting of complex aortic arch anatomy. This guide catheter was used successfully to perform carotid artery angioplasty and stent placement in 10 patients with markedly tortuous aortic arches or supra-aortic branches. As the authors gained experience with this catheter, they used it as a first option in patients with the appropriate aortic arch anatomy.