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Sleep Disorders

Definition Sleep is an active state of decreased responsiveness during which multiple vital functions occur to promote higher cognitive functioning and overall good health. During this physiologic state, the brain restores several metabolic processes, clears waste products, and furthers synaptic reorganization to promote alertness, memory, and learning. To achieve these goals, the brain cycles through discrete stages of sleep that allow progressive revitalization to support neuronal…

Coma, Disorders of Consciousness, and Brain Death

Disorders of consciousness and limited responsiveness ( Table 373-1 ) encompass a range of conditions, from mild encephalopathy or confusion to coma and brain death. Although not all causes of encephalopathy lead to poor outcomes, the rapid and comprehensive evaluation of a patient with altered consciousness remains one of the most important goals in all of medicine. Depending on the cause, a patient with altered mental…

The Epilepsies

Definition A seizure is defined by transient focal or generalized signs or symptoms due to abnormal excessive or synchronous neuronal activity in the brain. Focal seizures, which originate within neuronal networks limited to one cerebral hemisphere, produce signs and symptoms corresponding to the specific region of the brain affected by the seizure. Generalized seizures rapidly affect extensive neuronal networks on both cerebral hemispheres, and their signs…

Cognitive Impairment and Dementia

The Spectrum of Mild Cognitive Impairment to Dementia Definition Dementia is a cognitive disorder that leads to interference with daily functioning and results in loss of independence ( Table 371-1 ). Dementia can range in severity from mild, when a patient may still be independent in a few activities, to severe, when total dependence occurs. Mild cognitive impairment is the term that describes the earlier phase…

Regional Cerebral Dysfunction: Higher Mental Functions

Definition Higher mental function is at the core of what defines competent, independent individuals. Impairment of higher mental function can be broadly classified into four categories. Intellectual developmental disorder is a form of cognitive impairment that is present from infancy. Acquired forms of cognitive impairment are delirium, dementia, and focal cognitive disorders. Delirium ( Chapter 361 ) is defined by its acute or subacute onset and…

Mechanical and Other Lesions of the Spine, Nerve Roots, and Spinal Cord

Disorders of the spine, nerve roots, and spinal cord are common and frequently disabling. At any one time, 1% of the U.S. population is chronically disabled by lower back pain and another 1% temporarily disabled. Lower back pain is the number one cause of years lived with disability in the United States, and neck pain is the number six cause. Low back and neck pain also…

Traumatic Brain Injury and Spinal Cord Injury

Acute Brain and Spinal Injury Epidemiology Traumatic brain injury and traumatic spinal cord injury are common preventable diseases. The majority of patients with traumatic brain and spinal cord injuries are young adult males. Hospitalization for traumatic brain injury is more common in urban areas, whereas brain injury-related deaths are more common in rural areas. An estimated 54 to 60 million people sustain a traumatic brain injury…

Headaches and Other Head Pain

Definition Headache, which is a very common symptom, can be secondary to an underlying abnormality but is usually a primary headache disorder such as migraine headache, tension-type headache, cluster headache, and paroxysmal hemicrania. Epidemiology About 90% of all adults experience headache at some time in their lives, and over 75% of children have complained of headaches by the age of 15 years. In the United States,…

Approach to the Patient with Neurologic Disease

Introduction Neurologic symptoms and diseases are encountered in all spheres of clinical practice. Many symptoms of nervous system diseases are a part of everyday experience for healthy people, whether it be slips of the tongue, headache, numbness, muscle twitches, tremors, or mood swings with feelings of elation and depression. The challenge is to decipher whether symptoms fall within the spectrum of normal health or warrant further…

Drug Use Disorders

Definition The term substance use disorder has replaced substance abuse and dependence in the diagnostic lexicon. As defined by the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders , “The essential feature of a substance use disorder is a cluster of cognitive, behavioral, and physiological symptoms indicating that the individual continues using the substance despite significant substance-related problems.” No single pathognomonic symptom is diagnostic…

Alcohol Use Disorders

Definition A variety of terms have been used to describe the spectrum of medical, psychological, behavioral, and social problems associated with excessive consumption of alcohol (alcohol problems) . The Diagnostic and Statistical Manual of Mental Disorders , 5th edition (DSM-5) replaced the terminology of alcohol abuse and alcohol dependence with the term alcohol use disorder ( Table 364-1 ) to describe more clearly the spectrum of…

Nicotine and Tobacco

Definitions Cigarette smoking is the most frequent (>90%) method of tobacco use, although other forms, including pipe tobacco, cigars, and smokeless tobacco, are common. Nicotine, which is the active ingredient in tobacco, acts as a reinforcer for the use of all forms of tobacco. In recent years, however, vaping of nicotine through electronic nicotine delivery systems (ENDS; e-cigarettes without tobacco) now constitutes more than 30% of…

Psychiatric Disorders in Medical Practice

Overview Disorders in Psychiatry Psychiatric disorders, also known as mental illnesses, are extraordinarily common and have a profound impact on well-being and functional status. Collectively, psychiatric disorders account for more aggregate disability than do disorders involving any other organ system, with depression alone being second only to cardiovascular disorders. Psychiatric disorders are defined as disorders of the psyche—that is, conditions that affect thoughts, feelings, or behaviors.…

Delirium and Changes in Mental Status

Evaluation of Change in Mental Status Evaluation of change in mental status requires simultaneous efforts towards (1) establishing a diagnosis; (2) identifying potential etiologies and addressing life-threatening contributors; and (3) managing symptoms to ensure patient safety. A careful history should be obtained, not only from the patient but also from a reliable informant who knows the patient’s baseline functional status and can describe the time course…

Retroviruses Other Than Human Immunodeficiency Virus

Definition The human T-lymphotropic virus (HTLV) family has four members: HTLV-1, HTLV-2, HTLV-3, and HTLV-4. HTLV-1 causes two distinct types of disease: adult T-cell leukemia/lymphoma and several chronic inflammatory conditions, most notably HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). HTLV-2 rarely causes neurologic symptoms and does not cause malignant disease. No disease associations have been established with HTLV-3 or HTLV-4. The Pathogens Within the taxa of RNA reverse-transcribing…

Systemic Manifestations of HIV/AIDS

With the advent of early, better tolerated, less toxic, antiretroviral therapy (ART), including fixed-dose combinations and single-tablet regimens, the life expectancy among people with HIV has come closer to that of the uninfected population. However, many complications may arise that are either unique to HIV infection or occur at a younger age or with greater frequency than in HIV-negative individuals. To some degree, these complications may…

Microbial Complications of HIV/AIDS

Microbial Complications Epidemiology Despite the widespread availability of effective antiretroviral regimens in the United States, opportunistic infections are still seen frequently at many health care facilities, especially those serving populations with poor access to health care. The annual incidence of new diagnoses of HIV in the United States was about 34,000 cases in 2019, representing about a 17% decline since 2016. Among the estimated 1.2 million…

Antiretroviral Treatment of Human Immunodeficiency Virus Infection

The development of effective antiretroviral therapy for human immunodeficiency virus (HIV) infection is one of the most notable achievements in modern medicine. Antiretroviral therapy should be administered and overseen by a clinician with experience and expertise whenever possible. Under such supervision, the life expectancy of an HIV-infected individual appropriately treated with antiretroviral therapy is now approaching that of the general population, in both developed , and…

Prevention of Human Immunodeficiency Virus Infection

At the end of 2020, approximately 37.6 million people worldwide were living with human immunodeficiency virus (HIV) infection and over 35 million people have died as a consequence of the acquired immunodeficiency syndrome (AIDS). Opportunities to prevent new HIV infection include behavioral modification, preexposure and postexposure prophylaxis, suppression of the viral load in already-infected individuals, and the hope for an effective vaccine ( Fig. 356-1 ). ,…

Acute Clinical Manifestations and Diagnosis of HIV

Clinical Manifestations Symptoms and Signs of Acute HIV Infection Different terms, including acute, recent, primary, and early HIV infection, have been used to describe initial exposure and infection with HIV. Regardless of the terminology, acute HIV infection is the period from the time of initial HIV infection until the stabilization of the viral load “set point” about 1 to 3 months later. The usual time from…