The term “brain death” implies permanent absence of cerebral and brainstem functions. US law equates brain death with cardiopulmonary death, but specific criteria need to be met for diagnosis of brain death or death by neurologic criteria (DBNC). There are established prerequisite criteria to consider a patient for brain death that include: (1) a cause of CNS catastrophe deemed irreversible; (2) no confounding metabolic abnormality; (3) no drug intoxication or CNS depressants; (4) a normothermic state; and (5) a normotensive state. If these criteria are met, then the patient can be formally considered for DBNC.

The goal of this chapter is to provide a concise summary of the most common emergencies in neuro-ophthalmology. The chapter’s focus is three main neuro-ophthalmic emergency topics: diplopia, pupil abnormalities, and acute loss of vision. The chapter concludes with other important topics that are not neurological in nature, but are important to diagnose immediately such as a retinal detachment or ruptured globe.

The evaluation of patients with the complaint of “dizziness” is a frequent occurrence in the ED. It accounts for 3.5–11% of ED visits. The word dizziness is a nonspecific term used by patients and healthcare professionals to describe a disturbed sense of wellbeing, usually perceived as an altered orientation in space. Vertigo is defined as an illusion of movement of oneself or one’s surroundings. It is usually experienced as a sensation of rotation or, less frequently, as undulation, linear displacement (pulsion), or tilt. Although vertigo usually suggests a vestibular disorder that can involve the inner ear or brain, this symptom itself cannot reliably localize the disorder. Dizziness or vertigo can result from numerous disorders of a complex human balance system. Despite the inherent complexities, the ED evaluation of dizziness or vertigo can be simplified by a systematic approach in history-taking, physical examination, and laboratory testing.

Central nervous system infections are typically transmitted hematologically or by contiguous spread. Frequently, there is colonization of the upper respiratory tract, invasion across the epithelium, and then activation of the complement cascade. Polymorphonuclear leukocytes and the cytokines reduce the blood–brain barrier (BBB) integrity and the host defenses. Pathogens invade the meninges, resulting in inflammation and an increased BBB permeability. A subsequent inflammatory response by neutrophils creates edema and increased intracranial pressure, CNS tissue ischemia, and hydrocephalus. Clinical features of meningitis depend upon the age and health status of the patient, the specific pathogen, and the duration of illness. Diagnosing a CNS infection in infants and young children or in patients with nonspecific signs and symptoms is a challenge in the emergency department (ED). A thorough history and physical examination should help lead to a clinical suspicion of a CNS infection.

Pain is one of the most common presenting complaints in the emergency department (ED), both acute pain and exacerbation of chronic pain syndromes. Acute pain is accompanied by anxiety and sympathetic hyperactivity, whereas chronic pain is often associated with affective symptoms of depression. Nociceptive (musculoskeletal, inflammatory, or somatic) pain involves activation of the peripheral receptors secondary to tissue damage from trauma or heat. Neuropathic pain involves direct activation of either sensory nerves or ganglia by nerve injury or disease. Differentiation between nociceptive and neuropathic pain in the ED can be difficult, but should be considered for successful management of the pain.

Hydrocephalus is an extremely common neurological condition encountered in the emergency department (ED). The condition is characterized by symptomatic inability to drain or resorb CSF, resulting in pressure build-up within the brain. Hydrocephalus can result from both congenital and acquired etiologies, many of which can respond to shunting. The symptoms of hydrocephalus are classically due to an increase in intracranial pressure (ICP); however, normal- or low-pressure variants can occur. Hydrocephalus can result from a blockage within the ventricular system (“obstructive”) or outside the ventricular system (“communicating”), thereby impairing CSF absorption into the cerebral venous sinuses. Hydrocephalus may also be caused by failure of CSF to be absorbed secondary to abnormalities in the brain parenchyma itself.

The electroencephalogram (EEG) is created by differential amplification of cortical postsynaptic excitatory and inhibitory potentials. As a neurophysiologic monitor, it can be used as a bedside tool to assess an unresponsive patient in an emergency setting, particularly in the case of a patient with a history of epilepsy or an unexplained coma. Use of EEG in the emergency department (ED) can be technically challenging; both obtaining and interpreting the study may pose difficulty in small community hospitals or remote settings.

Emergency medicine patients may present with a variety of symptoms secondary to the effects of drugs and toxins on the nervous system. A clear understanding of the unique susceptibilities and mechanisms of toxicity can aid in diagnosis and management. Observed effects may be secondary to alterations in neurologic function at any point in signal transmission or development. The number of xenobiotics resulting in disruptions to neurologic function can seem overwhelming, but many characteristics can be examined to inform the care of acutely poisoned patients.

Nearly half of all emergency department (ED) visits in the United States result in some type of imaging study, a large number of which are performed for neurological complaints. Common presenting neurological complaints include headache, weakness, stroke, and trauma. Often the initial study performed for the evaluation of these complaints is an unenhanced computed tomography (CT) of the brain. However, as will be discussed below, certain presentations and clinical history can warrant magnetic resonance imaging (MRI) as a superior first-line imaging test. This chapter seeks to provide guidance in imaging modality selection and to discuss imaging findings in common clinical presentations to the ED. When pertinent, alternative and recommended follow-up studies are also discussed

Guillain Barré syndrome (GBS) is an acquired neuromuscular disorder that presents as rapidly progressive weakness and numbness, usually in an ascending fashion. The underlying pathophysiology is monophasic inflammatory immune-mediated demyelinating polyneuropathy that in many cases is triggered by viral illnesses, usually a few weeks prior to the onset of syndrome. The majority of cases are in young adults, although it can occur in pediatric and elderly age groups. GBS should be considered in the differential diagnosis of new-onset rapidly progressing weakness in an otherwise healthy individual.

Movement disorders are rarely medical emergencies or reason for evaluation in the emergency department (ED). However, they may be seen, and range from the familiar parkinsonism and drug-induced dystonia to rare disabling hemiballism secondary to a stroke. Movement disorders are typically a sign of an underlying neurological or nonneurological disorder, rather than the primary diagnosis. They can be strange in appearance and are often misdiagnosed as being hysterical or psychiatric in origin. In the ED, movement disorders are diagnosed based on a history and physical examination, with relatively few contributions from laboratory and radiographic studies.

Weakness is often a very complicated ED presenting complaint. A detailed history and physical examination, and diligent search for etiology, are required. First, the clinician must elucidate true weakness versus fatigue. Fatigue is best defined as a decrease in the ability to perform motor functions. Fatigue may be the complaint for a broad differential diagnosis, including acute coronary syndrome, anemia, chronic inflammatory diseases, dehydration, hypoglycemia or other electrolyte derangements, adrenal insufficiency, a variety of infections, pulmonary disorders, medication side effects, and depression. These disorders are characterized by a lack of true muscular weakness on examination. True muscular weakness is not painful, and pain should guide the examiner to other etiologies such as fibromyalgia or polymyalgia rheumatica.

Traumatic brain injury (TBI) is an increasingly common cause of morbidity and mortality in the United States. Rates of emergency department visits for TBI rose 70% between 2001 and 2010, with an estimated 2.5 million patients/year seeking emergency care, highlighting the increased focus on early identification and treatment of brain injuries. Hospital admission rates for TBI rose 11% in this time frame while deaths decreased 7%. Despite improvements in the management of TBI, 50,000 people die each year from this trauma (30% of all trauma related deaths in the United States). Falls are the most common mechanism of TBI, followed by blunt trauma, motor vehicle collisions, and assault. Men are three times more likely to sustain a TBI than their female counterparts, whereas the very young (<4 years old) and older patients (>65 years old) are more likely to sustain head trauma than those of other ages.

The human nervous system contains more than 100 billion neurons. Each has a unique function enabling taste, smell, touch, sight, hearing, movement, respiration, cognition, and much more. In the setting of a neurologic emergency, patients may lose these unique capacities. It is the emergency physician’s responsibility to complete a neurologic history and examination to determine the type of deficit and the neuroanatomical location of the abnormality

The spectrum of neurologic emergencies in pregnancy extends from life-threatening eclamptic seizures to self-limiting paresthesias. Pregnancy markedly modifies human physiology, creating a unique and challenging physical and laboratory evaluation. In addition, pregnant patients may present with gestational and peripartum conditions resulting directly from pregnancy, but also a portent of future disease as well as exacerbation of pre-existing conditions changed by the patient’s gravid state. All of these issues can be complicated by the “second patient” (the fetus), which requires careful consideration.

The management of unresponsive post-cardiac arrest patients has been an area of much controversy and research. Interventions during the arrest, particularly no-pause cardiopulmonary resuscitation and the advent of the automated external defibrillator have placed patients in a better position to respond to post-resuscitative measures. The initiation of post-arrest therapeutic hypothermia protocols, now referred to as targeted temperature management (TTM), has resulted in significant improvement in the number of neurologically intact survivors. Post-arrest care is centered on TTM, but includes a series of protocolized steps that define the measures to be taken to optimize outcome in these patients. Post-arrest care is the fifth and final link in the American Heart Association’s out-of-hospital chain of survival.

Alterations in mental status are a frequently encountered chief complaint that the emergency physician is asked to evaluate. These changes vary from marked depression of mental status to extreme over-activation. The differential diagnosis of altered mental status (AMS) is perhaps one of the broadest encountered in medicine. Here we will discuss alterations in mental status, and a diagnostic approach to these types of patients.