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Sam Safavi-Abbasi, Leonardo B. C. Brasiliense, Ryan K. Workman, Melanie C. Talley, Iman Feiz-Erfan, Nicholas Theodore, Robert F. Spetzler and Mark C. Preul

✓In 25 years, the Mongolian army of Genghis Khan conquered more of the known world than the Roman Empire accomplished in 400 years of conquest. The recent revised view is that Genghis Khan and his descendants brought about “pax Mongolica” by securing trade routes across Eurasia. After the initial shock of destruction by an unknown barbaric tribe, almost every country conquered by the Mongols was transformed by a rise in cultural communication, expanded trade, and advances in civilization. Medicine, including techniques related to surgery and neurological surgery, became one of the many areas of life and culture that the Mongolian Empire influenced.

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Eric M. Horn, Michael Beaumont, Xiao Zheng Shu, Adrian Harvey, Glenn D. Prestwich, Kris M. Horn, Alan R. Gibson, Mark C. Preul and Alyssa Panitch

Object

Therapies that use bioactive materials as replacement extracellular matrices may hold the potential to mitigate the inhibition of regeneration observed after central nervous system trauma. Hyaluronic acid (HA), a nonsulfated glycosaminoglycan ubiquitous in all tissues, was investigated as a potential neural tissue engineering matrix.

Methods

Chick dorsal root ganglia were cultured in 3D hydrogel matrices composed of cross-linked thiol-modified HA or fibrin. Samples were cultured and images were acquired at 48-, 60-, and 192-hour time points. Images of all samples were analyzed at 48 hours of incubation to quantify the extent of neurite growth. Cultures in cross-linked thiolated HA exhibited more than a 50% increase in neurite length compared with fibrin samples. Furthermore, cross-linked thiolated HA supported neurites for the entire duration of the culture period, whereas fibrin cultures exhibited collapsed and degenerating extensions beyond 60 hours.

Two concentrations of the thiolated HA (0.5 and 1%) were then placed at the site of a complete thoracic spinal cord transection in rats. The ability of the polymer to promote regeneration was tested using motor evoked potentials, retrograde axonal labeling, and behavioral assessments. There were no differences in any of the parameters between rats treated with the polymer and controls.

Conclusions

The use of a cross-linked HA scaffold promoted robust neurite outgrowth. Although there was no benefit from the polymer in a rodent spinal cord injury model, the findings in this study represent an early step in the development of semisynthetic extracellular matrice scaffolds for the treatment of neuronal injury.

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Eberval Gadelha Figueiredo, Joseph M. Zabramski, Pushpa Deshmukh, Neil R. Crawford, Mark C. Preul and Robert F. Spetzler

Object

The management of wide-necked, giant, or unsuccessfully coil-treated basilar apex aneurysms requires a wide exposure, for both working area and linear visualization of the basilar artery (BA). Cranial-based approaches, such as the transcavernous approach, have been proposed to deal with such aneurysms; whether abbreviated forms of this approach might provide similar exposure remains controversial. The authors examine this issue quantitatively.

Methods

Four alcohol-preserved cadaveric heads injected with pigmented silicone were prepared for bilateral dissection. After completing an orbitozygomatic craniotomy, the surgeons worked in a reverse direction, performing the transcavernous approach in five steps: 1) posterior clinoidectomy; 2) cavernous sinus opening; 3) anterior clinoidectomy; 4) cutting of the distal dural ring; and 5) cutting of the proximal dural ring.

Performing the complete transcavernous approach significantly increased the working area and linear exposure of the BA compared with abbreviated forms of the approach (p < 0.05). Opening the roof of the cavernous sinus significantly increased the working area compared with posterior clinoidectomy alone (p = 0.014); however, additional gains in exposure required completing the transcavernous approach. Resection of the anterior clinoid process combined with opening of only the distal dural ring did not significantly increase the working area or linear exposure of the BA.

Conclusions

The complete transcavernous approach significantly increases the working area and linear exposure of the BA compared with the more conservative forms of approach.

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Cassius V. C. Reis, Sam Safavi-Abbasi, Joseph M. Zabramski, Sebastião N. S. Gusmão, Robert F. Spetzler and Mark C. Preul

✓ Almost 50 years of research on moyamoya disease (1957–2006) has led to the development of a variety of surgical and medical options for its management in affected patients. Some of these options have been abandoned, others have served as the basis for the development of better procedures, and many are still in use today. Investigators studying moyamoya disease during this period have concluded that the best treatment is planned after studying each patient's presenting symptoms and angiographic pattern.

The surgical procedures proposed for the treatment of moyamoya disease can be classified into three categories: direct arterial bypasses, indirect arterial bypasses, and other methods. Direct bypass methods that have been proposed are vein grafts and extracranial–intracranial anastomosis (superficial temporal artery–middle cerebral artery [STA–MCA] anastomosis and occipital artery–MCA anastomosis). Indirect techniques that have been proposed are the following: 1) encephaloduroarteriosynangiosis; 2) encephalomyosynangiosis; 3) encephalomyoarteriosynangiosis; 4) multiple cranial bur holes; and 5) transplantation of omentum. Other options such as cervical carotid sympathectomy and superior cervical ganglionectomy have also been proposed. In this paper the authors describe the history of the development of surgical techniques for treating moyamoya disease.

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Rudolf Ludwig Karl Virchow: pathologist, physician, anthropologist, and politician

Implications of his work for the understanding of cerebrovascular pathology and stroke

Sam Safavi-Abbasi, Cassius Reis, Melanie C. Talley, Nicholas Theodore, Peter Nakaji, Robert F. Spetzler and Mark C. Preul

✓ The history of apoplexy and descriptions of stroke symptoms date back to ancient times. It was not until the mid-nineteenth century, however, that the contributions of Rudolf Ludwig Karl Virchow, including his descriptions of the phenomena he called “embolism” and “thrombosis” as well as the origins of ischemia, changed the understanding of stroke. He suggested three main factors that conduce to venous thrombosis, which are now known as the Virchow triad. He also showed that portions of what he called a “thrombus” could detach and form an “embolus.” Thus, Virchow coined these terms to describe the pathogenesis of the disorder. It was also not until 1863 that Virchow recognized and differentiated almost all of the common types of intracranial malformations: telangiectatic venous malformations, arterial malformations, arteriovenous malformations, cystic angiomas (possibly what are now called hemangioblastomas), and transitional types of these lesions. This article is a review of the contributions of Rudolf Virchow to the current understanding of cerebrovascular pathology, and a summary of the life of this extraordinary personality in his many roles as physician, pathologist, anthropologist, ethnologist, and politician.

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Eric H. Sincoff and Johnny B. Delashaw

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Rungsak Siwanuwatn, Pushpa Deshmukh, Eberval Gadelha Figueiredo, Neil R. Crawford, Robert F. Spetzler and Mark C. Preul

Object

The authors quantitatively assessed the working areas and angles of attack associated with retrosigmoid (RS), combined petrosal (CP), and transcochlear (TC) craniotomies.

Methods

Four silicone-injected cadaveric heads were bilaterally dissected using three approaches progressing from the least to the most extensive. Working areas were determined using the Optotrak 3020 system on the upper and middle thirds of the petroclivus and brainstem. Angles of attack were studied using the Elekta SurgiScope at the Dorello canal and the origin of the anterior inferior cerebellar artery (AICA).

The TC approach provided significantly greater (p < 0.001) working areas at the petroclivus (755.6 ± 130.1 mm2) and brainstem (399.3 ± 68.2 mm2) than the CP (354.1 ± 60.3 and 289.7 ± 69.9 mm2) and RS approaches (292.4 ± 59.9, 177.2 ± 54.2 mm2, respectively). The brainstem working area associated with the CP approach was significantly larger (p < 0.001) than that associated with the RS route. There was no difference in the petroclival working area comparing the CP and RS approaches (p = 0.149). The horizontal and vertical angles of attack achieved using the TC approach were wider than those of the CP and RS at the Dorello canal and the origin of the AICA (p < 0.001).

Conclusions

The CP approach offers a more extensive working area than the RS for lesions involving the anterolateral surface of the brainstem, but not for petroclival lesions. The TC approach provides the widest corridor, improving the working area and angle of attack to both areas, but hearing must be sacrificed and the facial nerve is at risk.

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Nicholas C. Bambakidis, Nicholas Theodore, Peter Nakaji, Adrian Harvey, Volker K. H. Sonntag, Mark C. Preul and Robert H. Miller

The continuous regeneration of glial cells arising from endogenous stem cell populations in the central nervous system (CNS) occurs throughout life in mammals. In the ongoing research to apply stem cell therapy to neurological diseases, the capacity to harness the multipotential ability of endogenous stem cell populations has become apparent. Such cell populations proliferate in response to a variety of injury states in the CNS, but in the absence of a supportive microenvironment they contribute little to any significant behavioral recovery. In the authors' laboratory and elsewhere, recent research on the regenerative potential of these stem cells in disease states such as spinal cord injury has demonstrated that the cells' proliferative potential may be greatly upregulated in response to appropriate growth signals and exogenously applied trophic factors. Further understanding of the potential of such multipotent cells and the mechanisms responsible for creating a favorable microenvironment for them may lead to additional therapeutic alternatives in the setting of neurological diseases. These therapies would require no exogenous stem cell sources and thus would avoid the ethical and moral considerations regarding their use. In this review the authors provide a brief overview of the enhancement of endogenous stem cell proliferation following neurological insult.

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Mark C. Preul

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Attila Balogh, Mark C. Preul, Mark Schornak, Michael Hickman and Robert F. Spetzler

Object. The aim of this study was to acquire intraoperative images during neurosurgical procedures for later reconstruction into a stereoscopic image system (QuickTime Virtual Reality [QTVR]) that would improve visualization of complex neurosurgical procedures.

Methods. A robotic microscope and digital cameras were used to acquire left and right image pairs during cranial surgery; a grid system facilitated image acquisition with the microscope. The surgeon determined a field of interest and a target or pivot point for image acquisition. Images were processed with commercially available software and hardware. Two-dimensional (2D) or interlaced left and right 2D images were reconstructed into a standard or stereoscopic QTVR format. Standard QTVR images were produced if stereoscopy was not needed.

Intraoperative image sequences of regions of interest were captured in six patients. Relatively wide and deep dissections afford an opportunity for excellent QTVR production. Narrow or restricted surgical corridors can be reconstructed into the stereoscopic QTVR mode by using a keyhole mode of image acquisition. The stereoscopic effect is unimpressive with shallow or cortical surface dissections, which can be reconstructed into standard QTVR images.

Conclusions. The QTVR system depicts multiple views of the same anatomy from different angles. By tilting, panning, or rotating the reconstructed images, the user can view a virtual three-dimensional tour of a neurosurgical dissection, with images acquired intraoperatively. The stereoscopic QTVR format provides depth to the montage. The system recreates the dissection environment almost completely and provides a superior anatomical frame of reference compared with the images captured by still or video photography in the operating room.