Warren W. Boling

α-[11C]-Methyl-l-tryptophan PET identifies the epileptogenic tuber and correlates with interictal spike frequency

Epilepsy surgery has been successfully performed in patients with tuberous sclerosis complex (TSC) and seizures arising from a restricted epileptogenic area. The outcome of cortical excision depends on accurate pre-surgical identification of the epileptogenic tuber. [11C] alpha-methyl-L-tryptophan (alpha-MTrp) was originally developed to measure serotonin synthesis in vivo with positron emission tomography (PET). However in pathologic conditions its uptake may also depend on the synthesis of quinolinic or kynurenic acid via the kynurenine pathway. Increased levels of serotonin and quinolinic acid have been observed in epileptogenic lesions, raising the possibility that alpha-MTrp PET may localize the epileptogenic area. The aim of this study was to correlate alpha-MTrp PET uptake with the localization of the epileptogenic area and with interictal spike frequency in patients with TSC. alpha-MTrp uptake was measured in 8 patients (2 males, mean age 29.6+/-14.9 years, range 3-50 years) with intractable partial epilepsy due to TSC. All patients underwent scalp EEG monitoring during the PET scan. In four (50%), increased uptake of alpha-MTrp occurred in the epileptogenic area alone. Two (25%) patients showed multifocal abnormalities and the remaining two (25%) did not show focal changes. PET localization was mostly seen in patients with frequent interictal abnormalities on the EEG. Furthermore, there was a significant correlation between alpha-MTrp uptake and the frequency of interictal spikes (r=0.6; P<0.05). alpha-MTrp PET is a promising diagnostic tool in the localization of the epileptogenic area in patients with TSC.

Historical Contributions to the Modern Understanding of Function in the Central Area

OBJECTIVE To review the historical developments leading to the modern understanding of central area physiological features. METHODS Important scientific writings related to stimulation and function of the central area were studied, beginning with the first electrolytic battery description. RESULTS Volta’s description of the electrolytic battery provided a reliable tool for mapping cortical function. However, 70 years elapsed before Fritsch and Hitzig convincingly demonstrated an excitable cortex and challenged Flourens’ theories of cerebral function. The localization of sensory and motor cortical representations was hampered by difficulties in interpreting responses to stimulation in animals and in relating animal data to the human brain. Nevertheless, by the beginning of the 20th century, the evidence for a separate sensory and motor gyrus within the central area was overwhelming. Pioneering surgeons such as Keen, Krause, Foerster, Frazier, and Cushing demonstrated the motor and sensory areas in human subjects during the course of surgery. CONCLUSION The interpretation of central area function has evolved from the 19th century view that diffuse areas of the cortex and the limbic system serve motor and sensory functions to the theories of Grünbaum, Sherrington, Campbell, and others at the beginning of the 20th century, who suggested segregated functional regions defined by sulcal and architectonic anatomic features. Subsequently, Penfield and Rasmussen supported the idea of a sensorimotor area in which central area function is not strictly separated by the central sulcus. Modern research using microelectrode recordings and functional imaging indicates localized primary sensory and motor functions defined by architectonic anatomic features.

Techniques in Epilepsy Surgery: Index

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Techniques in Epilepsy Surgery: Frontmatter

techniques in epilepsy surgery the mni approach cambridge medicine. Book lovers, when you need a new book to read, find the book here. Never worry not to find what you need. Is the techniques in epilepsy surgery the mni approach cambridge medicine your needed book now? Thats true; you are really a good reader. This is a perfect book that comes from great author to share with you. The book offers the best experience and lesson to take, not only take, but also learn.

Anatomy of Important Functioning Cortex

Important functioning cortex includes the language areas (Anterior, Posterior, and Superior), primary sensorimotor, and primary visual cortex.

Techniques in Epilepsy Surgery: Endopial resection (intervascular endopial gyral emptying)

Introduction This chapter is of crucial importance, because it deals with the fundamental approach to the surgery of epilepsy which is the actual selective removal of the epileptogenic brain tissue while leaving in situ the sulci with their content formed by a supportive pia-arachnoid envelope containing the vascular elements. These supportive and vascular elements of the brain do not participate directly in the seizure process, and their resection will result in interference with bypassing blood vessels that is in large part related to postoperative deficits. Indeed, when considering neurological complications in epilepsy surgery, deficits are either due to the actual resection of functional tissue or to the secondary damage to functional areas resulting from the occlusion or damage to blood vessels. Traditionally, epileptic foci were treated by “en bloc” resections where a lobe or a region of the brain is removed leaving behind a large cavity. During these procedures, the surgeon coagulates and divides numerous blood vessels that terminate within or traverse the resected area. Side effects and complications with this procedure are in large part related to the occlusion and resection of arteries and veins, which in turn may cause edema and operative bleeding. The classical examples are the so-called “temporal lobectomy” and the anterior temporal resection where the actual removal entails the division of several opercular arteries and, at times,of veins running over the cortex. There are usually no side effects or complications if the resection is restricted to a rather “silent area” or because the potential post-occlusion swelling is compensated by a relatively large removal cavity. There are many instances where an “en bloc” resection cannot be carried out for fear of causing infarction in a more distal territory. Typically these are resections in the opercular, central, frontal, and parietal areas, that is to say, where a neocortical removal is often contemplated.

Techniques in Epilepsy Surgery: History of epilepsy surgery

Introduction The purpose of this chapter is not to present an exhaustive review of the history of surgery of epilepsy from the beginning until today but rather to present a gallery of portraits of individual neurosurgeons who have contributed significantly in developing the field. The period covered extends from the late nineteenth century to the advent of magnetic resonance imaging (MRI) around 1984. This single event was to cause a revolution in the field and led to the creation of numerous comprehensive epilepsy centers as well as the advent of important international conferences such as the historical Palm Desert symposium organized by P. Engel in 1986. From that time onward, numerous workers from all branches of neurosciences have contributed to the development of this subspecialty that has had no equivalent in other fields of neurosurgery over the last 30 years. The reader will also note and forgive the strong emphasis on the role played by the Montreal Neurological Institute (MNI) in the development of epilepsy surgery and the creation of a diaspora that has had a widespread and continuous effect over the years.

Techniques in Epilepsy Surgery: The search for the epileptic focus: investigation of the surgical candidate

Introduction The investigation of the surgical patient is essentially the search for the epileptic focus. The neurosurgeon must understand that the clinical manifestations of a seizure result from activation of a brain region, the so-called symptomatic zone, which may be distant from the actual epileptic focus, the so-called ictal zone. EEG, as well, must be interpreted carefully for its localization value since the abnormal activity first detected by the electrode may in fact have originated from a distant brain site that may not be sampled adequately with an EEG recording electrode. Much effort is put into the search for an imaging abnormality since a lesion seen on MRI has considerable value in the localization of the seizure focus. In surgery for epilepsy, it is the true epileptic focus or ictal zone that is essential to recognize and target with treatment to realize the best results in seizure control. Rasmussen has developed a useful concept of localization to orient the investigation, determine the modalities of resection, and explain success or failure of resective surgery. It is based on three levels of localization that constitute the surgical hypothesis or the deinition of the epileptogenic zones and the area of resection that is likely to abolish the seizures.