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Cerebral Vascular Biology in Health and Disease

Key Points Cerebral artery tone is substantially modulated under physiologic conditions by endothelium-derived nitric oxide, by reactive oxygen species, and through hyperpolarization mediated by several types of K + channels. Cerebral vascular function is very sensitive to endothelial dysfunction that occurs during chronic disease, resulting in impairment of vasodilator mechanisms. Oxidative stress and inflammation occur in the cerebral circulation in response to cardiovascular risk factors present…

Answers

Chapter 1 A1. C In this question, the eye lead electrodes are very helpful. By convention the LOC electrode is placed on the left lower outer canthus and the ROC electrode is placed on the right upper outer canthus. With eye closure, the corneas (positively charged) deflect upwards, making the LOC electrode more electronegative at the same moment that the ROC becomes more electropositive. Thus, with…

Questions

Chapter 1 Q1. The thin and thick arrows point to what findings on the EEG? ( Fig. 1Q1 ) A. They both indicate frontal slowing, which is worse in B. B. They both indicate eye movements, which are slower in B. C. The thin arrow points to eye flutter and the thick arrow points to frontally predominant generalized rhythmic delta activity (GRDA). D. The thin arrow…

Influence of common drugs on the EEG and on seizure threshold

Many common medications have effects on the brain and thus on the EEG. Although these effects are not specific, it is important for our readers to be familiar with them in order to avoid an erroneous diagnosis of intrinsic brain pathology. Anti-Depressants Tricyclic anti-depressants such as imipramine, amitriptyline, doxepin, desipramine, and nortriptyline usually increase the amount of beta activity, as well as theta activity in the…

The EEG: Tips on indications, reading, and reporting

Indications Routine EEG Initial assessment for patients with possible epilepsy or after a seizure. If normal, depending on the level of suspicion, a repeat routine EEG, a sleep-deprived study, or a long-term EEG may be indicated. Follow-up assessment after the introduction of AEDs. Follow-up assessment after the cessation of AEDs. You’re Reading a Preview Become a Clinical Tree membership for Full access and enjoy Unlimited articles…

The EEG in other neurological and medical conditions and in status epilepticus

The Dementias There are many subtypes of dementias, and EEGs are nonspecific, often showing slowing of the PDR, loss of the usual anterior beta activity, and a gradual increase in diffuse slowing. Nevertheless, certain EEG features can help with our understanding of the problem. For example, focal slowing is most prominent in the anterior regions in frontotemporal dementia. In its early stages, Alzheimer's disease may display…

The EEG and epilepsy

When evaluating a new patient, the first line of inquiry for the clinician is, “is this a seizure?” There are many seizure mimics including parasomnias, syncope, transient ischemic attacks and psychogenic non-epileptic attacks (PNEA). A seizure is defined by the International League against Epilepsy (ILAE) to be “a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.” If…

The abnormal EEG

Background Abnormalities Organization In the awake state, in a well-organized EEG, there is a well-formed posterior dominant rhythm (PDR) occipitally, which attenuates with eye opening. Anteriorly, the frequencies are faster and lower in amplitude. This is sometimes referred to as the normal anterior-posterior (A-P) gradient. In sleep, there are distinct sleep states with sleep structures (e.g., K-complexes, vertex waves) specific to each state. If these elements…

The normal EEG from neonates to adolescents

Neonates Neonatal EEGs are perhaps the most challenging for the student and even for the experienced electroencephalographer. In the neonatal period, the brain is developing rapidly. Within the first 24 weeks of gestation, the cortical layers of the brain form with migration of neurons and glial cells from the periventricular germinal zone to the cortex. From 24 weeks to term, the brain goes from having a…

The normal adult EEG

The Normal EEG Understanding the elements of the normal EEG is a prerequisite for developing expertise in interpreting the abnormal record. In the following discussion, the frequency bands and individual waveforms found in the normal adult EEG are described for both the waking and sleeping states. Alpha Activity Hans Berger, the Berlin psychiatrist who in 1929 recorded the first EEG in humans, described a rhythm in…

Origin and technical aspects of the EEG

Origin of the EEG The EEG records electrical activity from the cerebral cortex. Inasmuch as electrocortical activity is measured in microvolts (µV), it must be amplified by a factor of 1,000,000 in order to be displayed on a computer screen. Most of what we record is felt to originate from neurons, and there are a number of possible sources including action potentials, post-synaptic potentials (PSPs), and…

Functional (psychogenic) movement disorders: Phenomenology, diagnosis, and treatment

Introduction The terminology for functional movement disorders (FMDs) has changed over the years. Originally called hysteria, Freud called them conversion disorders based on his view of the cause. In recent years, the term psychogenic movement disorder (PMD) was most common, based on the idea that they are caused by psychological factors rather than by an organic cause. Psychogenic was the preferred term in the second edition…

Peripheral movement disorders

Introduction Abnormal involuntary movements (dyskinesias) usually are caused by brain damage or dysfunction. Occasionally, however, lesions of the spinal cord, spinal roots, cervical or lumbar plexus, or even peripheral nerves appear to cause a variety of dyskinesias ( Table 26.1 ). Sometimes the relationship between the trauma and the movement disorder is not definite, and there are no proven rules to relate them. Jankovic and colleagues…

Restless legs syndrome

Restless legs syndrome and periodic movements of sleep Clinical features The term “restless legs” has been applied to a number of conditions. originally applied this term to unpleasant crawling sensations in the legs, particularly when sitting and relaxing in the evening, which disappeared on walking. The syndrome was probably first described by Thomas Willis in 1685. In honor of these two physicians, and to indicate that…

Paroxysmal dyskinesias

Introduction Paroxysmal dyskinesia refers to a group of diverse disorders that have as a salient clinical feature the occurrence of episodes of abnormal movements lasting variable periods of time that may or may not be triggered by a stimulus. The episodes are often separated by intervals of normal neurologic function, although in some of these disorders there may be baseline deficits that persist. Other paroxysmal neurologic…

Autoimmune movement disorders

Acknowledgment The contribution of Fidel Baizabal-Carvallo, MD, the coauthor of the recent review of the topic (Reproduced with permission from Baizabal-Carvallo JF, Jankovic J. Autoimmune and paraneoplastic movement disorders: An update. J Neurol Sci. 2018;385:175–184) is acknowledged with appreciation. References available on Expert Consult: www.expertconsult.com Introduction Advances in immunology over the past few decades have led to the discovery of a variety of new antibodies and…

Wilson disease

Wilson disease Wilson disease is an inborn error of copper metabolism manifested by hepatic cirrhosis and damage to the basal ganglia, brainstem, and other subcortical and cortical regions ( ). Wilson disease is one of the few curable movement disorders, but the good outcome is critically dependent on early diagnosis. It presents in so many guises that any patient younger than 50 years of age with…

Stiffness syndromes

Introduction Muscle stiffness may be the presenting symptom in many disorders of the motor nervous system and muscles ( Table 21.1 ). Spasticity is the most common, and the others must be distinguished from it. In this chapter, therefore, spasticity is the primary topic and considered first. The pathophysiologic process of rigidity, muscle stiffness in parkinsonism, is discussed in Chapter 2 . The important entities of…

Ataxia: Pathophysiology and clinical syndromes

Introduction Ataxia is the type of clumsiness produced by dysfunction of the cerebellum or cerebellar pathways. The pathophysiology of the signs and symptoms has been detailed in the earlier chapter on motor control ( Chapter 2 ) and have been reviewed ( ; ). The core symptoms are difficulty with balance and gait, clumsiness of the hands, and dysarthria. The differential diagnosis is very long and…