bluuebunny/crossref_metadata_2025 huggingface dataset:
Dizziness While Traveling
Authors: Paulis Jacqueline
Published: December 2018

Dizziness has a broad differential diagnosis in any setting. As a result, history and physical examination are critical in assessing cardiovascular, metabolic, central nervous system, and other acute causes. In the setting of dehydration, oral rehydration therapy is generally a safe and effective method of treatment, especially in underresourced areas. This chapter examines a case in which a patient presents with dizziness following cramping, abdominal pain, nausea, and decreased oral intake. Results from a glucose test are normal. Given the symptoms and lack of availability of imaging services, the author address the diagnosis of dehydration and discusses oral rehydration therapy and oral rehydration salts.
Fever
Authors: Chaudhuri Rittik
Published: December 2018

The workup of fever is highly dependent on history and physical examination, especially in the setting or recent travel or insect bite. In the case of a definite tick bite, consider Lyme disease, erlichiosis, Spotty Rocky Mountain Fever, and anaplasmosis in the differential diagnosis. This chapter examines a case study of a man who presents to the emergency department with intermittent fever 2 weeks after returning from a hike in the woods. He found an embedded tick on his neck 3 days after returning from the hike. The author discusses patient history, physical exam and testing, and differential diagnoses. A thin smear was positive for Babesia parasitemia, which was confirmed by Babesia polymerase chain reaction.
Acute Mountain Sickness
Authors: Mann Nathaniel R.
Published: December 2018

Altitude-related illness takes many forms, including cerebral edema, pulmonary edema, mountain sickness, and other conditions. Fatigue, dehydration, carbon monoxide poisoning, infections, and other illnesses can mimic or confound these processes. This chapter discusses common symptoms and treatments for high altitude cerebral edema, with a focus on practical management in field environments.
Fall with Syncope
Authors: Fullagar Christopher J.
Published: December 2018

Syncope has a number of worrisome potential etiologies and often prompts a basic life support (BLS) emergency medical services (EMS) crew to call for advanced life support (ALS). Pain management may be another valid reason to call for ALS. EMS, and emergency medicine in general, is tasked with evaluating and mitigating the most worrisome causes of a patient’s presentations even if those causes are not necessarily the most likely. ALS is indicated for many patients who have suffered a syncopal episode although astute BLS assessment and intervention may be all that are indicated in certain cases. The importance of BLS care is often minimized or overlooked in EMS but can have a significant effect on patient care if well implemented. The case demonstrates how well-applied BLS effectively managed this patient presenting with syncope and a painful fracture.
Eye Pain
Authors: Saccary Abbie
Published: December 2018

Eye pain and eye redness are common complaints that frequently present to both emergency departments and primary care centers alike; however, quickly discerning the source of these nonspecific complaints is an essential and potentially vision-saving skill for any acute care practitioner. This case examines a common patient presentation to the emergency department for eye pain, redness, and diplopia and further delves into key differences between benign sources of infection and potentially vision-compromising postseptal (orbital) cellulitis. It discusses key physical exam findings and necessary imaging studies for this condition and addresses the immediate treatment, including specific antibiotic therapy and indications for ophthalmology consult and hospital admission.
Gastrointestinal Bleed
Authors: Hulland Oliver
Published: December 2018

The case illustrates how to approach the diagnosis and management of gastrointestinal bleeds. Principles of gastrointestinal anatomy are reviewed to discern the relative location of the bleed and the impact this has on management. This chapter reviews critical steps including early adequate access, anticoagulation, and the need for reversal agents, octreotide, early endoscopy, and empiric antibiotics for risk of infection. An illustration of the Sengstaken-Blakemore tube, which is placed in unstable and difficult to control upper gastrointestinal bleeds, is included.
Hypotension
Authors: Creditt Angela
Published: December 2018

Sepsis is a complex and potentially life-threatening sequela of infection that commonly occurs and can be difficult to identify. If unrecognized or undertreated, sepsis can progress to severe sepsis, septic shock, characterized by hypotension and multisystem organ failure, and ultimately death. This case illustrates classic signs and symptoms of sepsis and septic shock in a postoperative patient. Recognizing these symptoms, rapidly initiating resuscitation with intravenous fluids and broad-spectrum antibiotics and aggressive management of these patients is imperative to prevent further decompensation. In 2017, the Surviving Sepsis campaign published new guidelines to assist with the management of patients with sepsis and septic shock. Key points from these guidelines will be highlighted within this case.
Altered Mental Status
Authors: Oliva Cynthia
Published: December 2018

This case illustrates the diagnostic approach to evaluating an elderly person with altered mental status. It is important to maintain a broad differential of possible etiologies contributing to a decreased level of alertness. In this case, the patient suffers from hypercarbia due to hypoventilation. This patient is at increased risk of hypoventilation due to his history of chronic obstructive pulmonary disease and the administration of narcotic pain medication. Airway management is a top priority during the resuscitation of a patient suffering from hypercarbia. Methods of airway management include ensuring a patent airway, the administration of oxygen, initiating noninvasive positive pressure ventilation, and, if these measures fail, endotracheal intubation.
Agitation
Authors: Rashid Megan
Published: December 2018

The case illustrates a classic example of intensive care unit (ICU) delirium, which often goes unrecognized but can adversely affect both morbidity and mortality. The Confusion Assessment Method for the ICU (CAM-ICU) is a validated tool for diagnosing delirium, but it remains a diagnosis of exclusion, and it is important to rule out potentially life-threatening medical causes of altered mental status. Treatment is difficult even with the correct diagnosis, and prevention is key. The ABCDEF bundle (assessing and managing pain, both SAT and SBT, choice of analgesia/sedation, delirium, early mobility, and family engagement) is a tool that identifies high-risk populations, and can help mitigate the prevalence of ICU delirium.
Low Blood Pressure
Authors: Lee Scott
Published: December 2018

A brisk upper gastrointestinal bleed is a medical emergency that requires prompt recognition and early initiation of therapy. Patients may present with a variety of signs and symptoms including presyncope, syncope, tachycardia, hypotension, hematochezia, or hematemesis. An important distinction in the differential diagnosis is whether the source is variceal or nonvariceal. The initial goals of management include fluid resuscitation and stabilization. Intravenous proton pump inhibition should be initiated, and octreotide should be considered when liver disease is suspected. Initial investigations include complete blood count, type and screen, coagulation studies, and liver function. Early endoscopy is essential to management.
Rule out Sepsis in Infant
Authors: Waltuch Temima
Published: December 2018

This case reviews the workup and management of febrile infants less than 3 months of age. These infants are a unique population as their immune systems are immature, placing them at increased risk for serious bacterial infections. Most febrile infants have self-limited viral illnesses; however, it is important to identify those that have a coexisting or isolated bacterial illness. Febrile infants <28 days require a full sepsis workup and admission to the hospital for monitoring and parenteral empiric antibiotic treatment. Workup and management of febrile infants between 29 and 90 days present more of a controversy in the literature. At minimum, infants 1 to 2 months of age will have blood and urine cultures performed, while the lumbar puncture is dependent on their individual risk stratification. Workup for infants 2 to 3 months of age will be completely dependent on risk stratification.
Drowning
Authors: Pifko Elysha
Published: December 2018

This case illustrates how to approach a patient who presents after drowning in the setting of a new-onset seizure. Immediate attention should always be given to the airway, breathing, and circulation of any patient that presents after drowning. The majority of these patients recover without the need for further medical intervention. However, patients with significant rales, hypotension, or ventilatory failure will require admission to the intensive care unit. In patients that present with a first unprovoked seizure, laboratory tests and radiologic imaging should only be obtained in those with a concerning history. Antiepileptic drugs should also not be initiated in the majority of these patients. In general, management of seizures in the emergency department need to be catered toward each individual patient based on the circumstances of his or her presentation.
Abdominal Pain
Authors: Gutierrez Peter
Published: December 2018

This chapter is a review of the approach to pediatric abdominal pain, specifically the recognition, diagnosis, and management of appendicitis. Topics covered include red flag symptoms for abdominal pain in the pediatric patient, classic and nonclassic appendicitis presentations, and physical exam techniques that can help in the diagnosis of appendicitis. Also discussed is the Pediatric Appendicitis Score, which rates risk based on anorexia; nausea/emesis; migration of pain; fever (>38°C); pain with cough, percussion, or hopping; right lower quadrant tenderness; white blood cell count; and absolute band count. Middle risk assessment may require further imaging whereas high risk assessment can proceed immediately to surgery. The chapter also compares imaging modalities and reviews the literature for medical versus surgical management of appendicitis.
Shortness of Breath
Authors: Garcia Sylvia E.
Published: December 2018

This case illustrates the classic presentation of bronchiolitis, which is a clinical diagnosis. The pathophysiology is that of an upper respiratory infection, most commonly respiratory syncytial virus, progressing to involve the lower airways, with subsequent wheezing and respiratory distress. Supportive care is the focus of management in the majority of cases, as interventions including bronchodilators, nebulized racemic epinephrine, nebulized hypertonic saline (for nonhospitalized settings), steroids, and antibiotics all provide inconsistent or no benefit. Although a small subset of patients has shown to benefit from bronchodilator therapy, no study clearly defines this group. In severe cases, noninvasive respiratory support may be needed. Radiographic imaging and respiratory panel testing for infectious causes are not routinely recommended.
Rash
Authors: Cockrum Kara , Mills David
Published: December 2018

This case reviews the presentation of a pediatric patient with target lesions on the skin and mucous membrane involvement. Creating a focused differential diagnosis for patients with these symptoms is essential, as diagnoses range from self-limited illnesses treated with supportive care to life-threatening diseases requiring intensive care. Recognizing discriminating features of erythema multiforme (EM) minor, EM major, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) is critical when assessing a patient with concerning skin and mucosal findings. This case reviews the classic clinical features of EM and key features that differentiate it from conditions with high morbidity and mortality such as SJS and TEN. It focuses on the recognition of precipitating factors, the diagnostic workup, and the hallmarks of management for patients with EM.
Primary Blast Injury
Authors: Simon Leslie V.
Published: December 2018

This case illustrates the classic injury pattern seen in primary blast injury. Primary blast injury, caused only by high-order explosives, is the result of the blast wave’s compressive effect on tissue. Effects are greatest at the tissue-air interface. Ear damage is the most common and pulmonary injury is the most lethal. Gastrointestinal injury and brain injury are also common. Traumatic amputations due to primary blast injury were extremely rare in survivors prior to Operations Iraqi and Enduring Freedom. Primary blast injury is usually associated with secondary, tertiary, and quaternary blast injuries. Blast victims require a meticulous approach because the dramatic nature of the obvious soft tissue injuries may distract even experienced trauma providers from focusing on more lethal occult injuries.
Facial Disfiguration
Authors: Hofstetter Douglas , Austin Andrea , Maves Ryan
Published: December 2018

Leishmaniasis is a vector-borne protozoan disease that affects human populations across over 90 countries including areas in Latin America, Africa, and Asia bearing the brunt of the disease burden. Disease transmission occurs through the bite of infected female sandflies within the genera Phlebotomus (Old World) and Lutzomyia (New World). Depending on the host’s immune response and the infecting Leishmania species, clinical leishmaniasis can manifest as a cutaneous, mucocutaneous, or visceral disease. Overlap between the categories is common, as are asymptomatic infections. In cutaneous leishmaniasis, patients present with an array of skin findings at the site of inoculation that range from painless papules and nodules to deep, mutilating ulcerations. In mucocutaneous leishmaniasis, protozoa spread hematogenously or lymphatically from a cutaneous lesion to mucosal tissue. DNA polymerase chain reaction is therefore the best diagnostic test when available. Liposomal amphotericin B is the preferred treatment for visceral leishmaniasis in the United States.
Penetrating Chest Trauma
Authors: Biggs Katherine
Published: December 2018

This case describes the management of penetrating trauma to the abdomen and thorax caused by a rocket-propelled grenade. The patient presents with an open pneumothorax, which should be initially managed in the field with a 3-sided occlusive dressing or, ideally, with an Asherman chest seal. Definitive management includes placement of a chest tube drain and possibly surgical exploration and repair.
Central Cord Injury
Authors: Aarabi Bizhan , Sansur Charles A. , Ibrahimi David M. , Kole Mathew , Mushlin Harry
Published: December 2018

Acute traumatic central cord syndrome (ATCCS) is an incomplete spinal cord injury, originally described by Schneider in the early 1950s. The syndrome presents with disproportionate weakness of the upper extremities distally compared to the lower extremities, variable sensory loss, and decline in sphincter function. Although not unusual in fracture dislocations, ATCCS is typically observed in older patients with a background of degenerative spinal stenosis and suffering from a hyperextension injury of the cervical spine without instability. Many such patients to some extent recover clinically, and functional recovery might be helped with early spinal cord decompression. The timing of surgical decompression remains controversial.
Basilar Invagination and Cranial Settling
Authors: Elder Benjamin D. , Wolinsky Jean-Paul
Published: December 2018

Basilar impression represents the broader category of occipitocervical junction pathologies, including basilar impression, basilar invagination, and cranial settling. Basilar invagination results from migration of the entire spine into the skull base. Cranial settling is caused by C1–C2 instability, leading to upward migration and/or rotation of the C2 complex into the cranial vault. Platybasia results from deformation and flattening of the skull base. Many patients present with a combination of neck pain, myelopathy, and potentially lower cranial nerve dysfunction. Computed tomography and magnetic resonance imaging are used to clarify the complex osseous anatomy and compression of neural elements,. Patients with a reducible basilar invagination may be treated with posterior decompression and stabilization alone, while non-reducible or partially reducible invagination must be treated with anterior decompression and posterior stabilization. The goal of treatment is to prevent further neurological decline and provide adequate stabilization of the O-C junction.
Cervical Myelopathy
Authors: Ganau Mario , Kato So , Fehlings Michael G.
Published: December 2018

Patients with kyphotic deformity and degenerative cervical myelopathy are at elevated risk for traumatic and nontraumatic spinal cord injury and require comprehensive management entailing a careful clinical assessment with dedicated functional scales and radiological study of spinal balance. Surgical strategies to address this clinical scenario including anterior, posterior, and combined approaches. Whatever the choice, the surgical plan should always envisage spinal cord decompression and stabilization along with deformity correction. The surgical team should discuss pros and cons of the most appropriate surgical plan with the patient, anticipate possible complications, and propose alternate strategies. This chapter details the most important practical aspects of surgical management, ranging from technical advantages of multiple osteotomies and selection of implants for instrumented fusion, to the surgical and anesthesiological nuances to avoid intraoperative and postoperative complications. An overview is provided of scientific literature regarding the correction of kyphotic deformity and ongoing clinical trials.
Thoracolumbar Burst Fractures
Authors: Khanna Omaditya , Stricsek Geoffrey P. , Harrop James S.
Published: December 2018

Ten to twenty percent of all thoracolumbar spine fractures are burst fractures. Burst fractures are typically a result of an axial-loading mechanism, such as from jumping or a fall from height. In this chapter, the authors provide an overview of the different classification systems for thoracolumbar fractures, including the Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification system and Thoracolumbar Injury Classification and Severity (TLICS) score. The various treatment options, both surgical and nonsurgical, are discussed, including criteria for when surgical intervention is warranted. The authors discuss the various surgical approaches for treatment of these fractures and their relative efficacies and outcomes. Finally, the authors review the evidence, outcomes, and potential complications of the various treatment options in order to aid the surgeon in their decision-making when these fractures are encountered in their practice.
Thoracic Cord Compression
Authors: Azad Tej D. , Veeravagu Anand , Ratliff John K. , Desai Atman
Published: December 2018

The majority of extradural spinal tumors are metastatic. Magnetic resonance imaging (MRI) and computed tomography (CT) imaging are both useful for evaluation of epidural cord compression and biomechanical instability. For the patient with an extradural thoracic tumor, goals of therapy may include recovery or preservation of neurologic status, local oncologic control, recovery or maintenance of mechanical stability, and improvement of quality of life. This chapter discusses the key therapeutic decision-making criteria and surgical considerations in the management of patients with epidural cord compression due to an extradural thoracic tumor.
Spinal Cord Tumor
Authors: Galgano Michael A. , Fridley Jared , Gokaslan Ziya
Published: December 2018

Most intradural extramedullary tumors are histologically benign. The three most common intradural extramedullary tumors encountered are meningiomas, schwannomas, and neurofibromas. Excision of intradural meningiomas can be achieved via an en bloc fashion by utilizing a split-thickness durotomy or by ultrasonic aspiration and piecemeal removal. Patients often become symptomatic from spinal cord compression earlier than mass effect upon the brain. Therefore, surgical resection may be undertaken before pial penetration occurs. Neurofibromas commonly arise as a fusiform enlargement of the nerve, making it necessary to sacrifice the root during excision of the tumor. Schwannomas arise from the nerve root of origin, which is usually a nonfunctional dorsal sensory root that can be sacrificed; there is always a corresponding nerve root, which is typically a functional ventral motor root, that needs to be dissected off the tumor.
Radiation-Sensitive Spine Tumor
Authors: Robin Adam M. , Laufer Ilya
Published: December 2018

A decision-making framework called NOMS (neurologic, oncologic, mechanical and systemic) facilitates and guides therapeutic decisions for patients with spinal metastases. Patients should be evaluated for signs of myelopathy or cauda equina syndrome. The Epidural Spinal Cord Compression (ESCC) scale facilitates reporting of the degree of radiographic spinal cord compression. A determination of the expected histology-specific tumor response to conventionally fractionated external beam radiation (cEBRT) and systemic therapy should be made. Radiation therapy effectively treats biologic pain for radiosensitive tumors such as multiple myeloma. Patients should undergo a careful evaluation of movement-associated pain as tumor-induced spinal instability is an independent indication for surgery. Determination of tumor-associated mechanical instability can be facilitated by the Spinal Instability Neoplastic Score (SINS). Herein, the authors present a case of spinal multiple myeloma managed using the NOMS framework and in consideration of current evidence and treatment paradigms.
Cauda Equina Syndrome
Authors: Sieg Emily P. , Davanzo Justin R. , Kelleher John P.
Published: December 2018

Cauda equine syndrome arises secondary to compression of or injury to the cauda equine, a group of nerves in the lumbosacral spine that provide motor and sensory function to most of the lower extremities, pelvic floor musculature, and sphincters. Symptoms can include loss of bowel and bladder control, lower extremity motor and sensory deficits, and pain. Compressive etiologies such as a midline herniated disc are the most common cause of cauda equine syndrome. Any patient with the described constellation of symptoms should undergo magnetic resonance imaging of the lumbar spine. In the setting of acute loss of motor, sensory, or autonomic function and a disc herniation or other compressive lesion seen on a lumbar spine MRI, emergency decompression via laminectomy should be undertaken. Complications range from structural damage intraoperatively to more general postsurgical complications. Operating on cauda equine patients at the earliest opportunity seems the most appropriate clinical practice.
L4–L5 Degenerative Spondylolisthesis
Authors: Nasser Rani , Zuckerberg Scott , Cheng Joseph
Published: December 2018

When assessing a spondylolisthesis, the clinician should suspect an underlying pars interarticularis defect. Dynamic imaging may be beneficial to assess movement of the spondylolisthesis. This may guide management towards fusion as oppose to decompression alone. The initial management of patients presenting with axial back pain with radicular symptoms is largely conservative in the absence of neurological deficit. If the patient has persistent or progressive symptoms, surgical decompression and/or stabilization might be indicated. Patients with a symptomatic L4/L5 degenerative spondylolisthesis that are refractory to conservative management have been shown to have a beneficial treatment effect based on the SPORT trial.
Flat Back Deformity
Authors: Mosley Yusef I. , Harrop James S.
Published: December 2018

Flat back syndrome is a phenomenon that occurs when the patient has loss of lumbar lordosis, which can lead to pelvic incidence (PI) and lumbar lordosis (LL) mismatch. Patients can develop this syndrome after a prior lumbar fusion or develop loss of LL secondary to degenerative changes in the spine. This chapter discusses a case presentation of a patient who has developed flat back syndrome after undergoing a prior lumbar fusion. At the end of the presentation, the reader should be able to identify physical exam findings, order the appropriate imaging to evaluate the spinal malalignment, discuss the goals of surgery, and anticipate management complications associated with the surgery.
Epidural Abscess
Authors: Morales Hector G. Mejia , Singh Manish K.
Published: December 2018

There are several conditions that have similar symptoms as those seen in spine infections so it is important to apply imaging studies, labs, and patient history in the workup. In the case of a true spinal epidural abscess (SEA) there exists a tetrad of stages, as described by Heusner et al. These can be characterized with a spinal ache or pain that proceeds into the second stage of nerve root pain, which is followed by the third stage of weakness in the voluntary muscles that culminates at the fourth stage of paralysis. Due to the danger of rapid progression, most spinal epidural abscesses are considered to be a neurosurgical emergency.
Nonsurgical Spinal Diseases
Authors: Ranasinghe Lahiru , Aysenne Aimee M.
Published: December 2018

There are many disease processes which can have clinical manifestations similar to those produced by pathologies requiring surgical intervention. Demyelinating processes, such as multiple sclerosis, neurodegenerative disease such as amyotrophic lateral sclerosis, and infections such as HIV can all produce classic signs and symptoms of myelopathy. The spine surgeon much also be aware of nutrition deficiencies, such as B12 that can result in myelopathic symptoms. Extensive laboratory and neurodiagnostic imaging workups may be necessary to determine the etiology of a patient’s symptoms.
Principles of Invasive EEG
Authors: Lhatoo Samden D. , Lacuey Nuria , Ryvlin Philippe
Published: December 2018

The growing requirement for invasive EEG in presurgical evaluation of intractable focal epilepsy has been driven largely by the increasing complexity of epilepsy surgery cases. Extratemporal surgeries now exceed anterior temporal lobe resections for mesial temporal sclerosis, and the proportion of patients undergoing invasive EEGs has significantly increased. Half of all patients undergoing stereotactic EEG (SEEG) evaluations are MRI-negative (usually with focal cortical dysplasia type 1 or 2) and a third are reoperations for failed resective or palliative surgery. Certain principles guide the decision to use invasive EEG and the choice of invasive EEG technique. SEEG has distinct advantages, as do subdural grid evaluations and intraoperative corticography. The consequences of loose hypotheses in the decision to invasively evaluate a patient, and of inappropriate choice of technique, include poor seizure outcomes after surgery, morbidity, and mortality. This chapter discusses the guiding principles for invasive studies of the human epileptic brain.
Technical and Practical Aspects of Invasive Recordings and Brain Stimulation
Authors: Motamedi Gholam K. , Gotman Jean , Lesser Ronald P.
Published: December 2018

This chapter discusses the technical and practical issues involved in invasive recording and cortical stimulation mapping in patients with drug-resistant epilepsy. It reviews the way in which EEG signals are generated, circumstances when intracranial electrodes are needed, and how such electrodes operate. It also discusses the basic principles of cortical stimulation mapping and different methods of using intracranial electrodes for stimulation purposes, and relevant concepts involved in the process such as charge density and electrode surface area. It reviews different electrodes used for mapping including subdural surface electrodes and depth electrodes.
Depth Electrodes: Approaches and Complications
Authors: Ostergard Thomas , Miller Jonathan P.
Published: December 2018

Depth electrode placement is an invaluable technique in treating patients with refractory epilepsy. Like any neurosurgical operation, planning is the most important phase of the procedure. The seizure focus should first be grossly localized using data from scalp electrodes and seizure semiology. This gross localization will guide placement of invasive electrophysiological hardware. All electrode implantation methods rely on Talairach’s principles of stereotaxis. Traditional electrode implantation is performed with a stereotactic frame. Evolving techniques use frameless stereotaxy or neuroendoscopy for implantation. The most worrisome complication of electrode placement is electrode-associated intracranial haemorrhage. Electrode deviation is a much more common complication, which can be minimized by avoiding extreme insertion angles, minimizing intracranial electrode length, and maximizing entry point accuracy.
Physiological Activity and Artefacts in the Human Epileptic Brain Studied with Intracerebral Depth Electrode EEG
Authors: Frauscher Birgit , Dubeau François
Published: December 2018

‘Physiological activity and artefacts in the human epileptic brain studied with intracerebral depth EEG electrodes’ reviews (i) the various expressions of normal physiological EEG activity at different sites of the brain and (ii) provides an overview of the most common artefacts that can be observed with intracerebral electrodes. All physiological rhythms known from scalp EEG can be observed in intracerebral EEG recording, but their features may change depending on the sites of the brain investigated. A recent multicentre study analysed these differences in topographical distribution using a common stereotactic space. The data are available as an open web resource. The chapter further underlines the importance of artefact identification in intracerebral EEG: Although artefacts are less frequent than in scalp EEG, non-physiological artefacts in particular may still pose problems. This chapter is written for clinical neurophysiologists, epileptologists, and researchers interested in intracerebral EEG recording.
The Irritative, Epileptogenic, and Ictal Onset Zones in Depth EEG
Authors: Bartolomei Fabrice
Published: December 2018

‘Irritative, epileptogenic, and ictal onset zones in depth EEG’ reviews the three classical brain regions that are to be defined by epileptologists during invasive EEG recordings. It first reviews the concept of the epileptogenic zone (EZ) and the different historical definitions and then the patterns of ictal onset observed from depth EEG recordings. It then discusses the concept of irritative zone, which is related to the interictal spike distribution, and its relationship with the EZ. Finally, the concept of ‘epileptogenic networks’ is developed, offering a modern framework for the functional anatomy of focal epilepsies.
The Irritative Zone and Seizure Onset Zone in Acute ECOG: The Quest for Relevant Epileptogenic Tissue
Authors: Palmini André , Paglioli Eliseu
Published: December 2018

Acute intraoperative electrocorticography (ECoG) is a time-honoured technique to identify the relevant epileptogenic tissue (RET) and hence guide cortical resection to control medically refractory seizures. ECoG identifies the RET through careful analysis of pattern, morphology, frequency, and localization of interictal spikes recorded directly from the exposed cortical surface. Because the development and dissemination of chronic intracranial EEG recording techniques has put emphasis on ictal recordings (thus defining an ictal onset zone), acute ECoG is often considered unnecessary in surgical planning. The chapter describes limitations and advantages of acute ECoG to define the RET in comparison with more costly and risky procedures, particularly subdural grid and SEEG recording. Specifically, it shows how the integration of lesion type and sequentially recorded ECoG spikes during operation may provide a highly cost-effective approach to successful epilepsy surgery.
High-Frequency Oscillations (HFO)
Authors: Jacobs Julia
Published: December 2018

High-frequency oscillations (HFO) are new EEG biomarkers for epileptic tissue. These oscillations range in frequencies from 80 to 500 Hz and can be recorded with standard intracranial macroelectrodes. During the presurgical assessment of patients with refractory epilepsy, HFO have been found to occur mainly over seizure onset areas. HFO might co-occur with epileptic spikes, but are more specific to epileptic tissue than epileptic spikes. Several retrospective studies showed a correlation between the removal of brain areas generating HFO and postsurgical seizure freedom. In addition to demonstrating the clinical value of HFO analysis, this chapter provides a detailed introduction to the techniques for analysing HFO, including recording techniques and visual and automatic detection tools, and to interpretation of the results. It also reviews methodological challenges such as the occurrence of physiological HFO and the variability of HFO rates between patients and brain regions.
Invasive EEG in Tumoural Epilepsy
Authors: Chassoux Francine , Landré Elisabeth , Devaux Bertrand
Published: December 2018

Long-term epilepsy-associated tumours (LEATs) are usually dysembryoplastic neuroepithelial tumours (DNTs) and gangliogliomas. Both usually show childhood-onset intractable partial epilepsy, concordant focal EEG abnormalities, and predominant temporal location. Imaging showing typical pseudocystic pattern is suggestive of DNT. Gangliogliomas are characterized by association of a true cyst and nodular contrast enhancement. However, less typical patterns may also be seen, rendering differentiation between the two difficult. Stereo-EEG has demonstrated intrinsic epileptogenicity of both, the typical interictal pattern consisting of repetitive spikes on depressed background activity. Ictal onset discharges arise from tumour in all cases, spreading to peritumoural and secondarily distant areas. Intratumoural stimulations elicit seizures similar to spontaneous seizures. Hippocampus is involved early in most temporal tumours. Epileptogenic zone organization differs according to DNT subtypes, co-localized with tumour in simple and complex forms, and more extended in non-specific forms. In gangliogliomas, the epileptogenic zone is similar to that observed in non-specific DNTs.
Invasive EEG in Hypothalamic Hamartoma
Authors: Scholly Julia , Bartolomei Fabrice , Hirsch Edouard
Published: December 2018

This chapter reviews pathophysiological aspects of the epilepsy syndrome associated with hypothalamic hamartoma (HH), including the concept of secondary epileptogenesis, as well as indications, limits, and practical issues of intracranial EEG exploration and interpretation in this setting. It focuses on particularities of interictal and ictal intracerebral stereotactic EEG (SEEG) findings and demonstrates different patterns of SEEG seizure initiation, in both gelastic and other seizure types. It describes two challenging clinical cases supported by diagrams and original SEEG traces that illustrate complex relationships among the HH, the limbic system, and the neocortex arguing for network organization of the epileptogenic zone in HH-associated pharmacoresistant epilepsy. It also reviews surgical strategies and postsurgical prognosis after SEEG exploration and discusses SEEG-guided minimally invasive therapeutic options aiming at HH. It is written for both trainees and more experienced neurologists, neurophysiologists and neurosurgeons in continuing professional development.
Subdural EEG in Posterior Cortex Epilepsy
Authors: Sakamoto Americo C. , Velasco Tonicarlo R. , Gonzalez Martinez Jorge
Published: December 2018

Surgery for extratemporal epilepsy surgery provides seizure control or reduction, but its overall results are less rewarding than those for temporal lobe epilepsy. Strategies for planning extratemporal surgery are more challenging and complex. Completeness of resection of the epileptogenic zone (EZ) is the single most important predictor of postsurgical seizure outcome, and therefore precise spatial delimitation of the EZ is at least as important as its localization. Moreover, careful definition and mapping of the functional state of the cortex bordering the EZ is crucial to ensure more precise and less risky surgical procedures. Invasive studies play a central role in the presurgical evaluation of extratemporal pharmacoresistant epilepsies. This chapter describes the rationale supporting the use of subdural electrodes, their role and limitations in definition of the irritative and ictal onset zones, in functional mapping of the eloquent cortex, and especially in planning of the surgical strategy.
Human Brain Mapping Using Subdural Electrodes
Authors: Gollwitzer Stephanie , Hamer Hajo M.
Published: December 2018

Extraoperative cortical stimulation enables precise mapping of cortical function. The information gained is essential to plan resection and spare eloquent cortex. This chapter pictures typical stimulation responses evoked in primary and secondary motor areas, sensory areas, and language areas, and describes specific phenomena associated with electrical stimulation of the insula and angular gyrus. Simulation effects are put into anatomical context, with special attention to their interpretation in terms of operability. Differences between stimulation responses in indispensable cortex, such as primary motor areas, and in regions wherein resection does not cause permanent deficits, such as supplementary and negative motor areas, are thoroughly reviewed.
Intracranial Event-Related Potentials
Authors: Brázdil Milan , Jurák Pavel , Rektor Ivan
Published: December 2018

Human intracranial event-related potentials (ERPs) represent an extremely useful tool for investigating many higher-level brain functions. Direct measurements from cortical/subcortical structures and outstanding temporal resolution are the main advantages of this method, for which it is currently viewed as an important complement to modern neuroimaging techniques in the elucidation of cognitive and affective mechanisms and their neural substrates. In this chapter, basic methodological aspects of intracranial ERP recordings are described and the main invasively investigated components are reviewed. Two subgroups of ERPs are discussed in greater detail: the response-related Bereitschaftspotential and stimulus-related cognitive P3 potentials. Other brain functions less frequently investigated using intracranial recordings and briefly reviewed in this chapter are language, memory, emotions, error processing, and empathy. The clinical use of intracranial ERPs in the presurgical evaluation of individual patients is promising, but awaits further approval.
Cortico-Cortical Evoked Potential Mapping
Authors: Matsumoto Riki , Kunieda Takeharu
Published: December 2018

The utility of single-pulse electrical stimulation (SPES) for epilepsy surgery has been highlighted in the last decade. When applied at a frequency of about 1 Hz, it can probe cortico-cortical connections by averaging electrocorticographic signal time-locked to stimuli to record cortico-cortical evoked potentials (CCEPs) emanating from adjacent and remote cortices. Although limited to patients undergoing invasive presurgical evaluations, CCEPs provide a novel way to explore inter-regional connectivity in vivo in the living human brain to probe functional brain networks such as language and cognitive motor networks. In addition to its impact on basic systems neuroscience, this method, in combination with 50 Hz electrical cortical stimulation, can contribute clinically to the mapping of functional brain systems by tracking cortico-cortical connections among functional cortical regions in individual patients. This approach may help identify normal cortico-cortical networks in pathological brain, or plasticity of brain systems in conjunction with pathology. Because of its high practical value, it has been applied to intraoperative monitoring of functional brain networks in patients with brain tumours. With regard to epilepsy, SPES has been used to probe cortical excitability of the focus (epileptogenicity) and seizure networks. Both early (i.e. CCEP) and delayed responses are regarded as surrogate markers of epileptogenicity. With regard to its potential impact on human brain connectivity maps, worldwide collaboration is warranted to establish standardized CCEP connectivity maps as a solid reference for non-invasive connectome research.
Thermocoagulation of the Ictal Onset Zone Using SEEG (Thermo-SEEG)
Authors: Guénot Marc , Bourdillon Pierre
Published: December 2018

Stereo-EEG (SEEG)-guided radiofrequency thermocoagulation (thermo-SEEG), is a stereotactic lesioning procedure in which the SEEG electrodes are used to deliver a radiofrequency current. This technique offers drug-resistant epileptic patients undergoing phase 2 investigations the possibility to benefit from lesions of the ictal onset zone without any additional invasive stereotactic procedure. A SEEG recording site can be considered eligible for thermo-SEEG if bipolar recordings through two adjacent contacts of the same electrode, located in cortical grey matter, show evidence of either spike-wave discharges or low-amplitude fast pattern at the onset of seizures. Electrical stimulations are systematically performed during video-SEEG recording sessions to avoid possible side-effects of a lesion. After 1-year follow-up, 45.6% of patients show greater than 50% improvement in terms of seizure frequency and 11.9% are seizure-free. Moreover, thermo-SEEG is safer than conventional surgery, with only a 3.2% rate of side-effects, which are almost always transient, including the expected ones.
Fast Analytical Sensing Technology: Microelectrode-Based Recordings of Tonic and Phasic Neurotransmitter Signalling in the Mammalian Brain
Authors: Humeiden Michelle L. , Quintero Jorge E. , Slevin John T. , Gerhardt Greg A.
Published: December 2018

Communication in the nervous system is predominately chemical. However, understanding of neurotransmitter signalling in normal and diseased states remains lacking. Electrochemically based biosensors can detect chemical messengers on a near-real timescale, allowing exploration of neurotransmitter systems to bring into focus the functioning elements of this critical means of communication. Glutamate, the predominant excitatory neurotransmitter of the central nervous system, is an ideal candidate for measurement with biosensors. With biosensors, it has been found that spontaneous glutamate signals in the dentate gyrus are enhanced in kindled animals. Meanwhile, in a model of epilepsy, the utility of detecting and the dynamism of glutamate signalling become apparent as tonic glutamate levels and rapid, spontaneous phasic glutamate signals show a correlation with seizure activity in the CA1 region of rodents. The ability of these biosensors to detect neurotransmitters in the brain is promising for clinical applications to monitor and, eventually, treat epilepsy.
SEEG Recordings: From Signal Processing to Models of Epileptogenic Networks
Authors: Wendling Fabrice , Benquet Pascal , Bartolomei Fabrice
Published: December 2018

Signal processing methods may constitute a substantial complement to visual analysis of SEEG signals in providing quantified information on signals (e.g. morphological characteristics) and in computing meaningful quantities that are not accessible to visual inspection (e.g. spectral properties or synchrony). In addition, and complementary to signal processing, computational neuroscience aims at developing models of epileptogenic networks and ultimately explaining some mechanisms involved in the generation of epileptiform activity. This chapter reviews a number of signal processing methods (time–frequency analysis, epileptogenicity index, and nonlinear correlation analysis) and computational models (at micro- and mesoscopic levels). The methods and models described illustrate the insight that can be gained about the information conveyed by SEEG signals recorded from epileptogenic networks observed during interictal (spikes and high-frequency oscillations) and ictal (fast-onset discharges) periods. Provided examples show that appropriate processing/modelling methods applied to electrophysiological signals can considerably improve the interpretation of SEEG recordings.
Case 1.20
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

27-year-old man with ulcerative colitis and progressive back and abdominal discomfort

Axial fat-suppressed FSE T2-weighted (Figure 1.20.1) and SSFP (Figure 1.20.2) images demonstrate multiple mild-to-moderately hyperintense lesions in the periphery of the liver involving both hepatic lobes. There was no signal dropout from IP to OP T1-weighted 2D SPGR images (images not shown) to suggest intravoxel fat. Axial postgadolinium arterial, portal venous, equilibrium, and 5-minute delayed phase 3D SPGR images (...
Case 1.21
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

14-year-old boy with a 1-year history of episodic fever of unknown origin; he presents with new right-sided abdominal pain

Coronal SSFSE (Figure 1.21.1) and axial fat-suppressed FSE T2-weighted (Figure 1.21.2) images demonstrate a lobulated heterogeneous mass involving both the right and left hepatic lobes with regions of mildly increased signal intensity relative to adjacent liver. The mass is hypointense on axial IP and OP T1-weighted 2D SPGR images (...
Case 1.29
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

72-year-old man with probable alcoholic cirrhosis

Axial fat-suppressed FSE T2-weighted image (Figure 1.29.1) demonstrates a well-circumscribed mass in the medial left hepatic lobe, as well as some subtle, ill-defined, mildly increased signal intensity in the posterior right lobe. Axial IP and OP T1-weighted 2D SPGR images (...
Case 2.4
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

58-year-old man with a family history of colon cancer; noncontrast enhanced chest CT showed low-attenuation hepatic masses in the visualized liver

Axial T1-weighted IP and OP 2D SPGR images (Figure 2.4.1) demonstrate multiple low-signal-intensity nodules throughout the liver, visible only on the OP images. These nodules are not apparent on axial arterial and portal venous phase, postgadolinium 3D SPGR images (...
Case 2.7
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

52-year-old woman with elevated AST and ALT levels

Axial T1-weighted IP and OP 2D SPGR images (Figure 2.7.1) demonstrate diffuse, decreased signal intensity in the liver and spleen on IP images (which have the longer TE). The pancreas has normal signal intensity. Axial fat-suppressed T2-weighted image (...
Case 2.9
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

45-year-old man with history of vasculitis treated with prednisone and azathioprine, now with fever, chills, and daily sweats

Axial fat-suppressed T2-weighted FRFSE images (Figure 2.9.1) demonstrate multiple complex, hyperintense lesions in the liver and spleen. Axial pregadolinium and arterial, portal venous, and equilibrium phase postgadolinium 3D SPGR images (...
Case 2.13
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

54-year-old woman with elevated liver function test levels, abdominal distension, and telangiectasias and purpura on her face, upper chest, and extremities

Coronal SSFSE (Figure 2.13.1) and axial fat-suppressed FSE T2-weighted (Figure 2.13.2) images show hepatomegaly without focal abnormalities. However, axial postgadolinium arterial (...
Case 2.17
Authors: Lee Christine U. , Glockner James F.
Published: December 2018

19-year-old woman with midabdominal bloating and discomfort

Coronal SSFSE (Figure 2.17.1) and axial fat-suppressed T2-weighted FSE (Figure 2.17.2) images demonstrate marked hepatomegaly with subtle hypointensity of the caudate lobe compared with the remainder of the liver. Axial portal venous phase postgadolinium 3D SPGR images (...