Epilepsy and music: practical notes.

Music processing occurs via a complex network of activity far beyond the auditory cortices. This network may become sensitised to music or may be recruited as part of a temporal lobe seizure, manifesting as either musicogenic epilepsy or ictal musical phenomena. The idea that sound waves may directly affect brain waves has led researchers to explore music as therapy for epilepsy. There is limited and low quality evidence of an antiepileptic effect with the Mozart Sonata K.448. We do not have a pathophysiological explanation for the apparent dichotomous effect of music on seizures. However, clinicians should consider musicality when treating patients with antiepileptic medication or preparing patients for epilepsy surgery. Carbamazepine and oxcarbazepine each may cause a reversible altered appreciation of pitch. Surgical cohort studies suggest that musical memory and perception may be affected, particularly following right temporal lobe surgery, and discussion of this risk should form part of presurgical counselling.

Working memory network plasticity after anterior temporal lobe resection: a longitudinal functional magnetic resonance imaging study.

Working memory is a crucial cognitive function that is disrupted in temporal lobe epilepsy. It is unclear whether this impairment is a consequence of temporal lobe involvement in working memory processes or due to seizure spread to extratemporal eloquent cortex. Anterior temporal lobe resection controls seizures in 50-80% of patients with drug-resistant temporal lobe epilepsy and the effect of surgery on working memory are poorly understood both at a behavioural and neural level. We investigated the impact of temporal lobe resection on the efficiency and functional anatomy of working memory networks. We studied 33 patients with unilateral medial temporal lobe epilepsy (16 left) before, 3 and 12 months after anterior temporal lobe resection. Fifteen healthy control subjects were also assessed in parallel. All subjects had neuropsychological testing and performed a visuospatial working memory functional magnetic resonance imaging paradigm on these three separate occasions. Changes in activation and deactivation patterns were modelled individually and compared between groups. Changes in task performance were included as regressors of interest to assess the efficiency of changes in the networks. Left and right temporal lobe epilepsy patients were impaired on preoperative measures of working memory compared to controls. Working memory performance did not decline following left or right temporal lobe resection, but improved at 3 and 12 months following left and, to a lesser extent, following right anterior temporal lobe resection. After left anterior temporal lobe resection, improved performance correlated with greater deactivation of the left hippocampal remnant and the contralateral right hippocampus. There was a failure of increased deactivation of the left hippocampal remnant at 3 months after left temporal lobe resection compared to control subjects, which had normalized 12 months after surgery. Following right anterior temporal lobe resection there was a progressive increase of activation in the right superior parietal lobe at 3 and 12 months after surgery. There was greater deactivation of the right hippocampal remnant compared to controls between 3 and 12 months after right anterior temporal lobe resection that was associated with lesser improvement in task performance. Working memory improved after anterior temporal lobe resection, particularly following left-sided resections. Postoperative working memory was reliant on the functional capacity of the hippocampal remnant and, following left resections, the functional reserve of the right hippocampus. These data suggest that working memory following temporal lobe resection is dependent on the engagement of the posterior medial temporal lobes and eloquent cortex.

Psychiatric outcomes after temporal lobe surgery in patients with temporal lobe epilepsy and comorbid psychiatric illness: A systematic review and meta-analysis.

BACKGROUND: The currently available evidence is unclear in regard to psychiatric outcomes of temporal lobe epilepsy (TLE) in patients with comorbid psychiatric disorders (PD). AIM: To identify and synthesize psychiatric outcomes in patients with TLE and comorbid psychiatric illnesses before and after TLE surgery. METHODS: Studies were included if participants were adults and/or children with temporal epilepsy and comorbid psychiatric illness. Surgical interventions included focal resection (e.g., lobectomy, selective amygdalohippocampectomy) or stereotactic laser ablation. Included studies reported on pre- and post- surgery data of comorbid psychiatric illness (e.g., mood and anxiety disorders, depression, psychosis, adjustment disorders, non-epileptic seizures, and personality disorders). RESULTS: Ten studies were included in the review. The proportion of patients achieving PD resolution or improvements after surgery varied widely between studies, ranging from 15 % to 57 % at the reported follow-up time. Three studies reported on PD symptom worsening after surgery, with considerable variations of patient proportions across studies. Meta-analysis suggests that 43 % of patients demonstrated improvement and 33 % of patients showed a worsening in psychiatric scores across all studies. Preliminary data from three studies suggest that seizure control may be associated with favourable psychiatric outcomes. CONCLUSION: A considerable proportion of reported TLE patients with comorbid psychiatric illnesses have improvement in their psychiatric symptoms after temporal lobe epilepsy surgery. There is scarcity of detailed outcome reporting including symptom scores, and to date, predictive factors for favourable vs unfavourable outcomes in this patient population are not clear. Further research on the topic is warranted.

Artery of Uchimura: origin and evolution of identification of the vascular supply to the hippocampus.

In 1928, neuroscientist Yushi Uchimura (1897-1980) published a landmark study detailing the hippocampal vasculature. Working in Walther Spielmeyer's Munich laboratory (1925-1927), Uchimura sought evidence for a vascular theory of Ammon's horn sclerosis (AHS). He described an artery supplying the vulnerable sector of the hippocampus, where pathognomonic changes of AHS were noted, and characterized the artery as particularly susceptible to circulatory disturbances. Discovery of this artery led to new concepts and new terminology pertaining to the hippocampus. In addition to having a distinguished career in psychiatry and academia (including a position as University of Tokyo dean), Uchimura was, before attending medical school, one of Japan's best baseball pitchers; he was eventually named Nippon Professional Baseball Organization commissioner and inducted into the Japan Baseball Hall of Fame. Uchimura's description of hippocampal vasculature, which is still subject to debate after nearly a century, brought international attention to AHS and epilepsy and showed the hippocampal vasculature to be variable and vulnerable; important considerations for later neurosurgeons in the development of selective mesial temporal surgery. Prominent figures in neurosurgery have since developed classification systems for the hippocampal vasculature in which the artery of Uchimura remains central. Perhaps no other brain artery has been the nexus for such intense investigation and debate about its association to structure, function, disease, and treatment methodology.

Robotic Surgical Approach to the Mesial Temporal Region: A Preliminary Three-Dimensional Cadaveric Study of Technical Feasibility.

OBJECTIVE: Robotic surgical systems are used worldwide in various fields. In this study, we present the advantages and disadvantages of the most common robotic surgical system, the da Vinci Xi system, in the supracerebellar transtentorial approach to the mesial temporal region and discuss options for its integration into neurosurgery. METHODS: Our study was conducted at the Advanced Simulation and Applied Endoscopic Surgery Training and Research Center and Anatomy Laboratory. Four formalin-fixed human cadaveric head specimens with red silicone dye injected into their arterial structures and blue silicone dye injected into their venous structures were used in the study. Dissections were performed in microscopic and robotic stages. All phases were photographed using a three-dimensional photographic technique. RESULTS: The mesial temporal lobe could be accessed via the supracerebellar transtentorial route with the use of the robotic system. We show that the robotic system can be used in difficult approaches and narrow regions with a wider exposure and superior image quality than with the microscopic approach, improving the ergonomics for the surgeon. The shortcomings of robotic systems are examined and innovative solutions are offered. CONCLUSIONS: This study shows the advantages and disadvantages of the robotic surgical approach to the mesial temporal region via the supracerebellar transtentorial route. Robotic surgical systems can play a major role in neurosurgical practices with the tools designed and the innovative solutions determined in this study. Nevertheless, further research and development of these systems and related instruments are necessary to ensure their wider implementation in neurosurgery.

Characterization of a Factual Knowledge-Associated Brain Memory Area by Functional Magnetic Resonance Imaging and Implementation in Tumor and Epilepsy Brain Surgery.

BACKGROUND: The role of the dominant hippocampus in verbal and episodic memory recall has been extensively investigated. However, there are categories of memory estimated independent of hippocampal function. In particular, factual knowledge is solely constituted from written or spoken input independent on undertaken experience, but the temporal structures involved are not well defined. METHODS: In this retrospective study, we mapped the activity of factual knowledge recall using functional magnetic resonance imaging (fMRI) in 60 patients scheduled for tumor or epilepsy surgery and in 18 patients resected within or close to the left mesial temporal lobe. Memory tests were performed preoperatively and postoperatively to investigate deficit symptoms in factual knowledge retrieval. RESULTS: We found a highly reproducible localized brain area within the parahippocampal gyrus, in the depth of the dorsal collateral sulcus, which was constantly involved in factual knowledge retrieval during fMRI tasks in 93% of patients (56/60) during recall of capital cities or multiplication tasks, in two thirds of the patients mainly on the dominant side. In addition, all 18 patients after surgery within this area showed postoperative factual knowledge deficits (56% permanent, 44% transitory), memory prognosis significantly correlating with the first day's factual knowledge retrieval task results. CONCLUSIONS: Using fMRI, we visualized a circumscribed brain area within the parahippocampal gyrus during factual knowledge retrieval, the lesioning of which led to factual knowledge deficits. Thus, impairment of factual knowledge retrieval may occur if resection is extended into the parahippocampal gyrus. Preoperative fMRI memory maps may contribute to avoiding such deficits.

Surgical Approaches to the Temporal Horn: An Anatomic Analysis of White Matter Tract Interruption.

BACKGROUND: Surgical access to the temporal horn is necessary to treat tumors and vascular lesions, but is used mainly in patients with mediobasal temporal epilepsy. The surgical approaches to this cavity fall into 3 primary categories: lateral, inferior, and transsylvian. The current neurosurgical literature has underestimated the interruption of involved fiber bundles and the correlated clinical manifestations. OBJECTIVE: To delineate the interruption of fiber bundles during the different approaches to the temporal horn. METHODS: We simulated the lateral (trans-middle temporal gyrus), inferior (transparahippocampal gyrus), and transsylvian approaches in 20 previously frozen, formalin-fixed human brains (40 hemispheres). Fiber dissection was then done along the lateral and inferior aspects under the operating microscope. Each stage of dissection and its respective fiber tract interruption were defined. RESULTS: The lateral (trans-middle temporal gyrus) approach interrupted "U" fibers, the superior longitudinal fasciculus (inferior arm), occipitofrontal fasciculus (ventral segment), uncinate fasciculus (dorsolateral segment), anterior commissure (posterior segment), temporopontine, inferior thalamic peduncle (posterior fibers), posterior thalamic peduncle (anterior portion), and tapetum fibers. The inferior (transparahippocampal gyrus) approach interrupted "U" fibers, the cingulum (inferior arm), and fimbria, and transected the hippocampal formation. The transsylvian approach interrupted "U" fibers (anterobasal region of the extreme capsule), the uncinate fasciculus (ventromedial segment), and anterior commissure (anterior segment), and transected the anterosuperior aspect of the amygdala. CONCLUSION: White matter dissection improves our knowledge of the complex anatomy surrounding the temporal horn. Identifying the fiber bundles at risk during each surgical approach adds important information for choosing the appropriate surgical strategy.

Neuroimaging for patient selection for medial temporal lobe epilepsy surgery: Part 1 Structural neuroimaging.

The objective of part one of this review is to present the structural neuroimaging techniques that are currently used to evaluate patients with temporal lobe epilepsy (TLE), and to discuss their potential to define patient eligibility for medial temporal lobe surgery. A PubMed query, using Medline and Embase, and subsequent review, was performed for all English language studies published after 1990, reporting neuroimaging methods for the evaluation of patients with TLE. The extracted data included demographic variables, population and study design, imaging methods, gold standard methods, imaging findings, surgical outcomes and conclusions. Overall, 56 papers were reviewed, including a total of 1517 patients. This review highlights the following structural neuroimaging techniques: MRI, diffusion-weighted imaging, tractography, electroencephalography and magnetoencephalography. The developments in neuroimaging during the last decades have led to remarkable improvements in surgical precision, postsurgical outcome, prognosis, and the rate of seizure control in patients with TLE. The use of multiple imaging methods provides improved outcomes, and further improvements will be possible with future studies of larger patient cohorts.

Neuroimaging for patient selection for medial temporal lobe epilepsy surgery: Part 2 functional neuroimaging.

We evaluate and discuss the various functional imaging techniques that are currently in use to assess the eligibility of a refractory temporal lobe epilepsy (TLE) patient for treatment with medial temporal lobe surgery. The assessment of eligibility for treatment is challenging and relies heavily on functional imaging modalities that provide physiological information, in addition to structural data acquired by different imaging techniques. This review is the final segment of a two part study, the first of which focused on the structural and anatomical imaging modalities that are in use for the surgical treatment of TLE. The authors performed a comprehensive query of PubMed, Embase and Medline databases in search of all relevant English language studies that were published between 1990 and 2013. Overall, 56 papers were reviewed (50% of them covering primarily functional neuroimaging), including a total of 1517 patients. The extracted data included the general study identification, demographics, population, study design, neuroimaging methods, reference standard imaging method used (gold standard), outcomes, and conclusions. As the majority of the studies investigated functional MRI, single photon emission computed tomography and positron emission tomography, the authors focus the review on these specific modalities.

Functional MRI, resting state fMRI, and DTI for predicting verbal fluency outcome following resective surgery for temporal lobe epilepsy.

OBJECTIVE: Predicting cognitive function following resective surgery remains an important clinical goal. Each MRI neuroimaging technique can potentially provide unique and distinct insight into changes that occur in the structural or functional organization of "at-risk" cognitive functions. The authors tested for the singular and combined power of 3 imaging techniques (functional MRI [fMRI], resting state fMRI, diffusion tensor imaging) to predict cognitive outcome following left (dominant) anterior temporal lobectomy for intractable epilepsy. METHODS; The authors calculated the degree of deviation from normal, determined the rate of change in this measure across the pre- and postsurgical imaging sessions, and then compared these measures for their ability to predict verbal fluency changes following surgery. RESULTS: The data show that the 3 neuroimaging techniques, in a combined model, can reliably predict cognitive outcome following anterior temporal lobectomy for medically intractable temporal lobe epilepsy. CONCLUSIONS: These findings suggest that these 3 imaging modalities can be used effectively, in an additive fashion, to predict functional reorganization and cognitive outcome following anterior temporal lobectomy.

Planning for selective amygdalohippocampectomy involving less neuronal fiber damage based on brain connectivity using tractography.

Temporal lobe resection is an important treatment option for epilepsy that involves removal of potentially essential brain regions. Selective amygdalohippocampectomy is a widely performed temporal lobe surgery. We suggest starting the incision for selective amygdalohippocampectomy at the inferior temporal gyrus based on diffusion magnetic resonance imaging (MRI) tractography. Diffusion MRI data from 20 normal participants were obtained from Parkinson's Progression Markers Initiative (PPMI) database (www.ppmi-info.org). A tractography algorithm was applied to extract neuronal fiber information for the temporal lobe, hippocampus, and amygdala. Fiber information was analyzed in terms of the number of fibers and betweenness centrality. Distances between starting incisions and surgical target regions were also considered to explore the length of the surgical path. Middle temporal and superior temporal gyrus regions have higher connectivity values than the inferior temporal gyrus and thus are not good candidates for starting the incision. The distances between inferior temporal gyrus and surgical target regions were shorter than those between middle temporal gyrus and target regions. Thus, the inferior temporal gyrus is a good candidate for starting the incision. Starting the incision from the inferior temporal gyrus would spare the important (in terms of betweenness centrality values) middle region and shorten the distance to the target regions of the hippocampus and amygdala.