Aaron A. Cohen-Gadol

Intraoperative Fluorescence-Guided Resection of High-Grade Gliomas: A Comparison of the Present Techniques and Evolution of Future Strategies

OBJECTIVEnFluorescence guidance has a demonstrated potential in maximizing the extent of high-grade glioma resection. Different fluorophores (fluorescent biomarkers), including 5-aminolevulinic acid (5-ALA) and fluorescein, have been examined with the use of several imaging techniques. Our goal was to review the state of this technology and discuss strategies for more widespread adoption.nnnMETHODSnWe performed a Medline search using the key words fluorescence, intraoperative fluorescence-guided resection, intraoperative image-guided resection, and brain glioma for articles from 1960 until the present. This initial search revealed 267 articles. Each abstract and article was reviewed and the reference lists from select articles were further evaluated for relevance. A total of 64 articles included information about the role of fluorescence in resection of high-grade gliomas and therefore were selectively included for our analysis.nnnRESULTSn5-ALA and fluorescein sodium have shown promise as fluorescent markers in detecting residual tumor intraoperatively. These techniques have demonstrated a significant increase in the extent of tumor resection. Regulatory barriers have limited the use of 5-ALA and technological challenges have restricted the use of fluorescein and its derivatives in the United States. Limitations to this technology currently exist, such as the fact that fluorescence at tumor margins is not always reliable for identification of tumor-brain interface.nnnCONCLUSIONSnThese techniques are safe and effective for increasing gross total resection. The development of more tumor-specific fluorophores is needed to resolve problems with subjective interpretation of fluorescent signal at tumor margins. Techniques such as quantum dots and polymer or iron oxide-based nanoparticles have shown promise as potential future tools.

Vasovagal syncope in the Canon of Avicenna: The first mention of carotid artery hypersensitivity

Ibn Sina, known as Avicenna in the West, was a celebrated Persian thinker, philosopher, and physician who is remembered for his masterpiece, The Canon of Medicine. The Canon that served as an essential medical encyclopedia for scholars in the Islamic territories and Europe for almost a millennium consisted of 5 books. In the third book, Avicenna described patients with symptoms of carotid hypersensitivity syndrome. These patients, who had excessive yawning, fatigue, and flushing, dropped following pressure on their carotids. Based on such history, it seems that Avicenna was the first to note the carotid sinus hypersensitivity, which presents with vasovagal syncope following compression of the carotid artery. In this paper, we presented a brief account of Avicennas life and works and discuss his description of the so-called carotid hypersensitivity syncope. Notwithstanding his loyalty to the Greek theory of humoralism, Avicenna set forth his own version of theory of spirits to explain the mechanism of this disease. An account of the theory of spirits is also given.

Cavum velum interpositum, cavum septum pellucidum, and cavum vergae: a review

IntroductionAnterior midline intracranial cysts may be found most often in three forms: cavum septum pellucidum, cavum vergae, and cavum velum interpositum. A single offering that reviews these entities is difficult to find in the extant literature. Therefore, the present review was performed.Materials and methodsVarious search engines and germane texts were reviewed for the terms cavum septum pellucidum, cavum vergae, and cavum velum interpositum.ResultsWe report the findings of our search of the literature regarding these midline cystic structures.ConclusionsA better understanding of the associated anatomy, embryology, and pathology of these cysts will assist the clinician who treats such patients.

The intracranial arachnoid mater: A comprehensive review of its history, anatomy, imaging, and pathology

IntroductionThe arachnoid mater is a delicate and avascular layer that lies in direct contact with the dura and is separated from the pia mater by the cerebrospinal fluid-filled subarachnoid space. The subarachnoid space is divided into cisterns named according to surrounding brain structures.MethodsThe medical literature on this meningeal layer was reviewed in regard to historical aspects, etymology, embryology, histology, and anatomy with special emphasis on the arachnoid cisterns. Cerebrospinal fluid dynamics are discussed along with a section devoted to arachnoid cysts.ConclusionKnowledge on the arachnoid mater and cerebrospinal fluid dynamics has evolved over time and is of great significance to the neurosurgeon in clinical practice.

Anatomy and landmarks for branches of the brachial plexus: a vade mecum

Exploration and repair of the brachial plexus and its branches demands a good comprehension of its intricate anatomy. To this end, landmarks for identifying this anatomy may prove useful to the clinician and surgeon. As such, a specific collection is lacking in the literature. Therefore, the following review of salient surgical anatomy and regional landmarks of the brachial plexus and its branches is provided. Our hopes are that these data will be useful during clinical and surgical procedures of these regions and act as a single, concise source for such information.

Cranial roots of the accessory nerve exist in the majority of adult humans

The inclusion of a cranial root as a component of the accessory nerve is controversial with at least one recent study claiming that intracranial rootlets do not exist in humans. In response to this debate, the present study aimed to clarify this anatomy in a large cadaveric sample. In this study, 43 adult cadavers (86 sides) were dissected via a posterior approach to the craniocervical junction. Observations were made for the presence or absence of cranial roots of the accessory nerve, and when present, their lengths and diameters were measured. Relationships of these rootlets were documented. A cranial root of the accessory nerve was identified in 76% of sides. When identified, 1–6 cranial rootlets (mean 4.5) of the accessory nerve were observed. They ranged in diameter from 0.1 to 1.1 mm (mean 0.7 mm). The length of these nerves ranged from 8 to 24 mm with a mean of 17 mm. In general, the more superior rootlets were shorter and the more inferior rootlets were longer. Although there was a slight tendency for the cranial roots to be more numerous and larger on right sides and in males, this did not reach statistical significance. We believe this to be the largest study to date documenting the presence of a cranial root of the accessory nerve. Based on our findings, a cranial root exists in the majority of specimens. Neurosurgical procedures or high quality imaging of this area should enable the physician to see these structures. Clin. Anat. 27:102–107, 2014.

Three-dimensional morphometry of the A1 segment of the anterior cerebral artery with neurosurgical relevance.

BACKGROUND: Despite research in the anatomical sciences for the last 200 years, some structures of the human body remain controversial or incompletely described. One of these structures is the A1 segment of the anterior cerebral artery (ACA). OBJECTIVE: To analyze the A1 segment of the ACA using novel stereoscopic methods because the 3-dimensional morphometry of the ACA is important to neurosurgeons. METHODS: A digital-image computer-based system was used to analyze the A1 segment of 230 ACAs derived from computed tomography. Data analysis included the inner diameter, length, and volume and calculation of A1 symmetry, hypoplasia, and deviation, and tortuosity indexes. RESULTS: Hypoplasia of the A1 segment was found in 0.87% and only on the right sides, whereas asymmetry was found in 42.6% and was more common in female patients. Right A1 segments tended to be longer in male patients, and this reached significance. Also of significance was the correlation of an increased length with age. Right A1 segments tended to have greater volumes, and this was significant in a comparison of male and female patients. Tortuosity indexes tended to be greater for left sides, but deviation indexes tended to be greater on the right sides. CONCLUSION: Morphometric data of the A1 segment of the ACA as analyzed in the present study may be of utility to the neurosurgeon. Right A1 segments tend to be more tortuous, more deviated, longer, and narrower than left A1 segments.BACKGROUNDnDespite research in the anatomical sciences for the last 200 years, some structures of the human body remain controversial or incompletely described. One of these structures is the A1 segment of the anterior cerebral artery (ACA).nnnOBJECTIVEnTo analyze the A1 segment of the ACA using novel stereoscopic methods because the 3-dimensional morphometry of the ACA is important to neurosurgeons.nnnMETHODSnA digital-image computer-based system was used to analyze the A1 segment of 230 ACAs derived from computed tomography. Data analysis included the inner diameter, length, and volume and calculation of A1 symmetry, hypoplasia, and deviation, and tortuosity indexes.nnnRESULTSnHypoplasia of the A1 segment was found in 0.87% and only on the right sides, whereas asymmetry was found in 42.6% and was more common in female patients. Right A1 segments tended to be longer in male patients, and this reached significance. Also of significance was the correlation of an increased length with age. Right A1 segments tended to have greater volumes, and this was significant in a comparison of male and female patients. Tortuosity indexes tended to be greater for left sides, but deviation indexes tended to be greater on the right sides.nnnCONCLUSIONnMorphometric data of the A1 segment of the ACA as analyzed in the present study may be of utility to the neurosurgeon. Right A1 segments tend to be more tortuous, more deviated, longer, and narrower than left A1 segments.

The petrosal nerves: Anatomy, pathology, and surgical considerations

The literature lacks a comprehensive review of the petrosal nerves, which often have a complicated course and nomenclature. The medical literature was reviewed comprehensively for information regarding the anatomy, pathology, and surgery of the petrosal nerves. The terminology and anatomy of the petrosal nerves are often complicated. Our review found multiple nomenclatures used in the description of these structures. Information regarding the petrosal nerves may assist those who observe or operate at or near the skull base. To our knowledge, this is the first comprehensive review of these structures. Clin. Anat. 22:537–544, 2009.

Ossification of the petrosphenoidal ligament: unusual variation with the potential for abducens nerve entrapment in Dorello’s canal at the skull base

Variable bony anatomy at the skull base may result in compression or entrapment of exiting cranial nerves. The authors present an unusual variation of bilateral ossification of the roof of Dorello’s canal and review the germane literature. Clinicians might consider ossification of the petrosphenoidal ligament (also called Gruber’s ligament) in patients with unexplained cases of abducens nerve palsy.

The role of the renin--angiotensin system in the pathogenesis of intracranial aneurysms.

Introduction: Recent work has begun to elucidate the pathogenesis of intracranial aneurysms (IA) and has shown that many genes are involved in the risk for this condition. There has also been increasing research interest in the renin—angiotensin system (RAS) in the brain and its involvement in a range of cardiovascular and neurological disorders. The possibility that the RAS is implicated in the pathogenesis of IA merits further investigation. The aim of this article is to review the literature on the pathogenesis of IA and the pathophysiological significance of the brain RAS, and to identify directions for research into their association. Methods and results : A survey of the literature in these fields shows that although factors contributing to systemic hypertension predispose to IA, a large number of genes involved in endothelial cell adhesion, smooth muscle activity, extracellular matrix dynamics and the inflammatory and immune responses are also implicated. The brain RAS has a significant role in regulating blood pressure and in maintaining cerebrovascular autoregulation, but angiotensin II receptors are also involved in the maintenance of endothelial cell and vascular smooth muscle function and in the inflammatory response in the brain. Conclusions: There is strong, albeit largely circumstantial, evidence in the literature for a relationship between the brain RAS and the formation of IA. Research on the association between polymorphisms in RAS-related genes and the incidence of unruptured and ruptured IA is indicated.