Search Results

There is a long history of the association of cerebral blood flow changes during epileptic seizures. The advent of radiopharmaceutical agents to measure cerebral perfusion during seizures has enabled a clinically feasible way to measure ictal cerebral blood flow changes. Studies show that ictal SPECT findings, especially with the use subtraction ictal SPECT techniques, correlate well with other measures of seizure onset and the epileptogenic zone. Ictal SPECT studies are also helpful in predicting outcome after epilepsy surgery. Applications of parametric mapping using ictal SPECT studies have helped to further define regions of perfusion changes in groups of patients with specific regions of seizure onset. Application of parametric mapping techniques in subjects with temporal lobe epilepsy has yielded interesting common patterns of ictal hyperperfusion and hypoperfusion. These studies help define expected patterns of ictal perfusion changes in TLE, as well as shed light on the associated pathophysiology of aspects of ictal semiology, such as the associated changes in consciousness during temporal lobe epileptic seizures.

Chapter 4 discusses the feasibility and pitfalls of using brain imaging and recording technologies such as fMRI, PET and SPECT scans, magnetoencephalography, transcranial magnetic stimulation and event-related potentials in neurodevelopmental disorders. While such techniques are useful in assessing the typically developing brain, their full potential is yet to be realized in disorders that result in atypical brain development. Nevertheless, brain imaging and recording techniques can offer some clues to the underlying causes of attention deficits. For example, research in children with ADHD offers promising insights into how the atypical brain processes information in the attention domain. However, issues such as degree of intellectual impairment, anxiety levels, and attention difficulties pose significant problems in obtaining reliable imaging neuropsychological data in some neurodevelopmental disorders. The authors propose that the next decade will see such challenges evaporate as brain imaging and recording technologies become more refined and accessible to a wider range of neurodevelopmental disorders.

Functional brain imaging has been widely used to describe regional abnormalities in cerebral blood flow and metabolism in Parkinson’s disease (PD) patients scanned in the rest state with PET, SPECT, or perfusion MRI techniques. This general brain mapping approach has also been used to identify PD-related functional changes occurring at the network level. This chapter summarizes recent advances in the use of disease-related spatial covariance patterns (metabolic brain networks) to study disease progression and to identify robust imaging biomarkers with which to assess therapeutic outcome in PD patients. Specific attention is given to clinical applications of network-based techniques in the study of dopaminergic pharmacotherapy and stereotaxic surgical interventions for the disorder.

Disturbances of cognition are frequent in Parkinson’s disease (PD), with an increasing prevalence of dementia with longer disease duration. The pathological hallmark of parkinsonian dementia is the presence of extra-nigral Lewy body pathology associated with dysfunction of multiple subcortical neurochemical projection systems. Unlike the severe loss of dopaminergic function that typifies early stage PD, more severe and extensive cholinergic deficits are consistently evident in more advanced patients with comorbid dementia. Indeed, PET and SPECT imaging studies indicate that cortical cholinergic deficits may be more extensive in PD patients with dementia relative to their non-parkinsonian demented counterparts with Alzheimer’s disease. This chapter discusses the relevance of cholinergic dysfunction in PD patients, particularly its correlation with impaired performance on tests of working memory and executive functioning. Recent imaging findings suggesting an increase in the deposition of cortical protein aggregates in cognitively impaired PD patients are also discussed.

This chapter summarizes the contribution of imaging to the current understanding of the mechanisms underlying surgical interventions for PD. Structural imaging studies using MRI techniques have served to improve the accuracy of stereotaxic targeting. That said, functional imaging with positron emission tomography (PET), single photon emission tomography (SPECT), and fMRI have provided an in vivo method to assess changes in brain function in the vicinity of the surgical target and in remote, interconnected brain regions within a spatially distributed neural network. This chapter provides an overview of functional/anatomical models of basal ganglia circuitry, followed by a discussion of the changes mediated by surgery at both the regional and network levels. Specific attention is dedicated to the effects of deep brain stimulation (DBS) on network organization and on disease progression.

This chapter reviews the role of neuroimaging in PD clinical trials to investigate both symptomatic and potential disease-modifying therapies. While clinical ratings are typically used as the primary measures of therapeutic response, these descriptors have inherent limitations. Imaging methods including FDOPA PET and beta-CIT SPECT have been used to provide objective and potentially less variable indicators of treatment outcome. The chapter describes the relevance of imaging biomarkers to trial design, including confirmation of diagnosis prior to randomization and as an adjunctive means for assessing efficacy. This chapter reviews the use of functional brain imaging in prior clinical trials of PD and discusses novel applications of these tools in the evaluation of new therapies for the disorder.

Doctors often prescribe drugs for fibromyalgia patients with distinct manifestations associated with the disorder such as tension headache, chronic fatigue, or bladder spasms. Few of the preparations discussed in this chapter have been shown to be specifically effective in fibromyalgia, but nearly all of them are widely prescribed by doctors who treat fibromyalgia patients. In an April 1982 bulletin, the Food and Drug Administration specifically allowed physicians to use approved drugs for “off-label” purposes. This chapter reviews our clinical experience with these drugs for fibromyalgia-related manifestations and presents a personalized, critical evaluation of them. One of the most commonly employed interventions in fibromyalgia is the tender point injection. Controlled studies have clearly demonstrated its usefulness in patients with myofascial pain syndrome. When a patient comes to our office and reports that a specific point—for example, in the upper back or neck area—hurts, we try to ascertain how severe this discomfort is in relation to their overall pain. If we are told that at least 30 percent (and preferably more than 50 percent) of their pain at the moment is from a specific tender area, this is an indication for a local injection. Patients who “hurt all over” rarely respond to tender point injections for more than a few days. Once we have decided to give a local injection or injections (usually limiting the number of injections to three per visit, with visits spaced several weeks apart), what preparations are used? The drugs of choice always include a local pain deadener, or anesthetic, usually xylocaine, novocaine, or marcaine. After the painful area is sprayed with a coolant anesthetic such as ethyl chloride or florimethane, the anesthetic in the shots usually works immediately. Sometimes a steroid is added to the anesthetic in the same syringe. Not all doctors use steroids for tender point injections. However, the doses we use are very low, and systemic effects are uncommon.

Diagnoses in psychiatry are based entirely on behavioral, not biological, criteria: though a small number of practitioners use functional brain imaging as a diagnostic tool, most psychiatrists believe that imaging has no role beyond potential medically apparent causes of a patient’s condition and make no use of this resource for routine clinical care. Although biological psychiatry has had a huge impact on the overall field since the 1960s, some tools are privileged over others. This chapter considers the plausibility and potential of imaging techniques as an aid for diagnosing, categorizing, and treating psychiatric illness by considering SPECT clinics, DSM classifications (and limitations), patient receptiveness, and other current developments. It evaluates to what extent neuroimaging can act as diagnostic agent, predictor of incipient illness, and even cure unto itself.

The term “neuroimaging” includes the use of various technologies to either directly or indirectly image the structure or function of the brain and its response to normal and abnormal processes. Structural neuroimaging attempts to noninvasively visualize gross pathology in the brain and can be used for the diagnosis of gross (large-scale) intracranial diseases, such as tumors. The most common structural imaging techniques are X-ray, computed tomography (CT), and magnetic resonance imaging (MRI). Functional neuroimaging techniques are primarily based on regional cerebral blood flow, regional cerebral metabolic rate of glucose consumption, or neuroreceptor signaling. They are most commonly used to quantify neuroreceptor status, diagnose diseases that cause metabolic derangement, and study the neurobiology and cognitive psychology associated with various neurological and neuropsychiatric disorders, such as major depression. The most common functional neuroimaging techniques are positron emission tomography (PET), single-photon emission tomography (SPECT), and functional magnetic resonance imaging (fMRI).