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Michael A. Horgan, Frank P. K. Hsu and Edmund H. Frank

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Joseph R. Keen, Allison Przekop, Joffre E. Olaya, Alexander Zouros and Frank P. K. Hsu


Deep brain stimulation (DBS) for dystonic cerebral palsy (CP) has rarely been reported, and its efficacy, though modest when compared with that for primary dystonia, remains unclear, especially in the pediatric population. The authors present a small series of children with dystonic CP who underwent bilateral pallidal DBS, to evaluate the treatment's efficacy and safety in the pediatric dystonic CP population.


The authors conducted a retrospective review of patients (under the age of 18 years) with dystonic CP who had undergone DBS of the bilateral globus pallidus internus between 2010 and 2012. Two of the authors independently assessed outcomes using the Barry-Albright Dystonia Scale (BADS) and the Burke-Fahn-Marsden Dystonia Rating Scale–movement (BFMDRS-M).


Five children were diagnosed with dystonic CP due to insults occurring before the age of 1 year. Mean age at surgery was 11 years (range 8–17 years), and the mean follow-up was 26.6 months (range 2–42 months). The mean target position was 20.6 mm lateral to the midcommissural point. The mean preoperative and postoperative BADS scores were 23.8 ± 4.9 (range 18.5–29.0) and 20.0 ± 5.5 (range 14.5–28.0), respectively, with a mean overall percent improvement of 16.0% (p = 0.14). The mean preoperative and postoperative BFMDRS-M scores were 73.3 ± 26.6 (range 38.5–102.0) and 52.4 ± 21.5 (range 34.0–80.0), respectively, with a mean overall percent improvement of 28.5% (p = 0.10). Those stimulated at least 23 months (4 patients) improved 18.3% (p = 0.14) on the BADS and 30.5% (p = 0.07) on the BFMDRS-M. The percentage improvement per body region yielded conflicting results between rating scales; however, BFMDRS-M scores for speech showed some of the greatest improvements. Two patients required hardware removal (1 complete system, 1 unilateral electrode) within 4 months after implantation because of infections that resolved with antibiotics.


All postoperative dystonia rating scale scores improved with pallidal stimulation, and the greatest improvements occurred in those stimulated the longest. The results were modest but comparable to findings in other similar series. Deep brain stimulation remains a viable treatment option for childhood dystonic CP, although young children may have an increased risk of infection. Of particular note, improvements in the BFMDRS-M subscores for speech were comparable to those for other muscle groups, a finding not previously reported.

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Vikram Jadhav, Gerald Matchett, Frank P. K. Hsu and John H. Zhang


Brain tissue at the periphery of a neurosurgical resection site is vulnerable to injury by a variety of mechanisms including direct trauma, edema, hemorrhage, retractor stretch, and electrocautery. The goal in the present study was to develop an in vivo model of surgically induced brain injury and to test an Src tyrosine kinase inhibitor for neuro-protective properties in this model.


The authors developed a new surgically induced brain injury model in rats. This model involves resection of part of the frontal lobe. Sprague–Dawley male rats weighing between 300 and 350 g were divided randomly into four groups: Group 1, surgical injury with vehicle treatment; Group 2, surgical injury after treatment with PP1 (an Src tyrosine kinase inhibitor with known neuroprotective properties); Group 3, sham surgery; and Group 4, control. Postoperative assessment included blood–brain barrier (BBB) permeability studies, and histological, immunohistochemical, and Western blot analyses. The authors found that surgical injury caused localized edema and disruption of the BBB compared with findings in the sham surgery group. Treatment with PP1 was associated with decreased edema, decreased breakdown of the BBB, decreased expression of both vascular endothelial growth factor and phosphorylated extracellular signal–regulated kinase 1 and 2, and preservation of ZO-1 expression.


In this study the authors describe a simple and reproducible in vivo animal model of surgically induced brain injury. Pretreatment with PP1 results in improved outcomes in this model, which suggests a possible role for Src tyrosine kinase inhibitors as preoperative therapy for planned neurosurgical procedures.

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Alvin Y. Chan, Diem Kieu T. Tran, Amandip S. Gill, Frank P. K. Hsu and Sumeet Vadera

Laser interstitial thermal therapy (LITT) is a minimally invasive procedure used to treat a variety of intracranial lesions. Utilization of robotic assistance with stereotactic procedures has gained attention due to potential for advantages over conventional techniques. The authors report the first case in which robot-assisted MRI-guided LITT was used to treat radiation necrosis in the posterior fossa, specifically within the cerebellar peduncle. The use of a stereotactic robot allowed the surgeon to perform LITT using a trajectory that would be extremely difficult with conventional arc-based techniques.

A 60-year-old man presented with facial weakness and brainstem symptoms consistent with radiation necrosis. He had a history of anaplastic astrocytoma that was treated with CyberKnife radiosurgery 1 year prior to presentation, and he did well for 11 months until his symptoms recurred. The location and form of the lesion precluded excision but made the patient a suitable candidate for LITT. The location and configuration of the lesion required a trajectory for LITT that was too low for arc-based stereotactic navigation, and thus the ROSA robot (Medtech) was used. Using preoperative MRI acquisitions, the lesion in the posterior fossa was targeted. Bone fiducials were used to improve accuracy in registration, and the authors obtained an intraoperative CT image that was then fused with the MR image by the ROSA robot. They placed the laser applicator and then ablated the lesion under real-time MR thermometry. There were no complications, and the patient tolerated the procedure well. Postoperative 2-month MRI showed complete resolution of the lesion, and the patient had some improvement in symptoms.

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Sumeet Vadera, Alvin Y. Chan, Lilit Mnatsankanyan, Mona Sazgar, Indranil Sen-Gupta, Jack Lin and Frank P. K. Hsu


Surgical treatment of patients with medically refractory focal epilepsy is underutilized. Patients may lack access to surgically proficient centers. The University of California, Irvine (UCI) entered strategic partnerships with 2 epilepsy centers with limited surgical capabilities. A formal memorandum of understanding (MOU) was created to provide epilepsy surgery to patients from these centers.


The authors analyzed UCI surgical and financial data associated with patients undergoing epilepsy surgery between September 2012 and June 2016, before and after institution of the MOU. Variables collected included the length of stay, patient age, seizure semiology, use of invasive monitoring, and site of surgery as well as the monthly number of single-surgery cases, complex cases (i.e., staged surgeries), and overall number of surgery cases.


Over the 46 months of the study, a total of 104 patients underwent a total of 200 operations; 71 operations were performed in 39 patients during the pre-MOU period (28 months) and 129 operations were performed in 200 patients during the post-MOU period (18 months). There was a significant difference in the use of invasive monitoring, the site of surgery, the final therapy, and the type of insurance. The number of single-surgery cases, complex-surgery cases, and the overall number of cases increased significantly.


Partnerships with outside epilepsy centers are a means to increase access to surgical care. These partnerships are likely reproducible, can be mutually beneficial to all centers involved, and ultimately improve patient access to care.

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Andreas Raabe, Peter Nakaji, Jürgen Beck, Louis J. Kim, Frank P. K. Hsu, Jonathan D. Kamerman, Volker Seifert and Robert F. Spetzler

Object. The authors prospectively compared a new technique of surgical microscope-based indocyanine green (ICG) videoangiography with intraoperative or postoperative digital subtraction (DS) angiography.

Method. The technique was performed during 187 surgical procedures in which 124 aneurysms in 114 patients were clipped. Using a newly developed setup, the ICG technique has been integrated into an operating microscope (Carl Zeiss Co., Oberkochen, Germany). A microscope-integrated light source containing infrared excitation light illuminates the operating field. The dye is injected intravenously into the patient, and intravascular fluorescence from within the blood vessels is imaged using a video camera attached to the microscope. The patency of parent, branching, and perforating arteries and documentation of clip occlusion of the aneurysm as shown by ICG videoangiography were compared with intraoperative or postoperative findings on DS angiography.

The results of ICG videoangiography corresponded with intra- or postoperative DS angiography in 90% of cases. The ICG technique missed mild but hemodynamically irrelevant stenosis that was evident on DS angiography in 7.3% of cases. The ICG technique missed angiographically relevant findings in three cases (one hemodynamically relevant stenosis and two residual aneurysm necks [2.7% of cases]). In two cases the missed findings were clinically and surgically inconsequential; in the third case, a 4-mm residual neck may require a second procedure. Indocyanine green videoangiography provided significant information for the surgeon in 9% of cases, most of which led to clip correction.

Conclusions. Microscope-based ICG videoangiography is simple and provides real-time information about the patency of vessels of all sizes and about the aneurysm sac. This technique may be useful during routine aneurysm surgery as an independent form of angiography or as an adjunct to intra- or postoperative DS angiography.

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Frank P. K. Hsu, Gregory J. Anderson, Aclan Dogan, Joseph Finizio, Akio Noguchi, Kenneth C. Liu, Sean O. McMenomey and Johnny B. Delashaw Jr.

Object. Conventional wisdom regarding skull base surgery says that more extensive bone removal equals greater exposure. Few researchers have quantitatively examined this assertion, however. In this study the authors used a frameless stereotactic system to measure quantitatively the area of petroclival exposure and surgical freedom for manipulation of instruments with successive steps of temporal bone removal.

Methods. With the aid of high-power magnification and a high-speed drill, 12 cadaveric specimens were dissected in four predetermined, successive bone removal steps: 1) removal of the Kawase triangle; 2) removal of the Glasscock triangle; 3) removal of the cochlea together with skeletonization of the anterior internal auditory canal; and 4) inferior displacement of the zygoma.

Step 1 offered 62 ± 43 mm2 of exposed petroclival area, with 84 ± 69 mm2 of surgical freedom; Step 2, 61 ± 22 and 76 ± 58 mm2; Step 3, 128 ± 47 and 109 ± 87 mm2; and Step 4, 135 ± 38 and 102 ± 69 mm2, respectively.

Conclusions. The middle fossa approach provided a means surgically to expose the petroclival area. When examined quantitatively by using a frameless stereotactic device, the authors determined that the removal of the cochlea and skeletonization of the anterior internal auditory canal (Step 3) provided the most significant increase in both exposure and surgical freedom. Removal of the zygoma improved neither exposure nor surgical freedom.

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Cheng-Mao Cheng, Akio Noguchi, Aclan Dogan, Gregory J. Anderson, Frank P. K. Hsu, Sean O. McMenomey and Johnny B. Delashaw Jr.


This study was designed to determine if the “keyhole concept,” proposed by Perneczky's group, can be verified quantitatively.


Fourteen (3 bilateral and 8 unilateral) sides of embalmed latex-injected cadaveric heads were dissected via 3 sequential craniotomy approaches: supraorbital keyhole, frontotemporal pterional, and supraorbital. Three-dimensional cartesian coordinates were recorded using a stereotactic localizer. The orthocenter of the ipsilateral anterior clinoid process, the posterior clinoid process, and the contralateral anterior clinoid process are expressed as a center point (the apex). Seven vectors project from the apex to their corresponding target points in a radiating manner on the parasellar skull base. Each 2 neighboring vectors border what could be considered a triangle, and the total area of the 7 triangles sharing the same apex was geometrically expressed as the area of exposure in the parasellar region.


Values are expressed as the mean ± SD (mm2). The total area of exposure was as follows: supraorbital keyhole 1733.1 ± 336.0, pterional 1699.3 ± 361.9, and supraorbital 1691.4 ± 342.4. The area of exposure on the contralateral side was as follows: supraorbital keyhole 602.2 ± 194.7, pterional 595.2 ± 228.0, and supraorbital 553.3 ± 227.2. The supraorbital keyhole skull flap was 2.0 cm2, and the skull flap size ratio was 1:5:6.5 (supraorbital keyhole/pterional/supraorbital).


The area of exposure of the parasellar region through the smaller supraorbital keyhole approach is as adequate as the larger pterional and supraorbital approaches. The keyhole concept can be verified quantitatively as follows: 1) a wide area of exposure on the skull base can be obtained through a small keyhole skull opening, and 2) the side opposite the opening can also be visualized.