SPELLS: Differential Diagnosis and Management Strategies

The patient who presents to the emergency department (ED) "having had a spell" represents a diagnostic challenge. For the purposes of this article, spells refer to events characterized by a transient loss of consciousness or alteration in mental status with a return to baseline by the time the patient is evaluated. Frequently, the patient cannot offer a good history or details concerning the event and the physician must rely on multiple sources including family, friends, witnesses, and Emergency Medical Services personnel. The physical examination is often completely normal. Despite these limitations, the history and physical examination remain the two most important factors in making the diagnosis, while laboratory tests and imaging studies are complimentary but rarely definitive. 3,4,13,15 The patient who has had a spell is approached with a vast differential diagnosis that is slowly narrowed as information is gathered (Table 1). There are four major categories of spells: seizures, syncope, psychiatric, and other. Although there are exceptions, metabolic, toxic, and infectious states do not generally result in transient alterations in consciousness, and these patients do not usually return to their baseline until the underlying cause is addressed; consequently, these groups of patients are not included in this discussion. Psychiatric diagnoses, such as psychogenic seizures and conversion disorders, can only be made after a comprehensive and multidisciplinary evaluation and thus, such diagnoses are almost never made in the ED. Syncope results from insufficient blood flow or oxygen to the central nervous system. The three major etiologic groups are cardiac, vagal, and vascular-mediated events. Cardiac-mediated syncope can result from decreased cardiac output as occurs with valve dysfunction, dysrhythmias, or impaired ejection. Vagal-mediated events result from parasympathetic stimulation resulting in bradycardias or asystole. Vascular-mediated events are due to either hypovolemia, or carotid or basilar artery insufficiency. Hypovolemia results in decreased cardiac output secondary to low-volume states, which can be primary, such as dehydration or blood loss, or secondary to vasodilation as from autonomic dysfunction, anaphylaxis, drugs, or toxins. Syncopal episodes account for an estimated 3% of ED visits. 3,13 The diagnosis is made by the history and physical examination in 45% to 85% of cases. 13–16 Syncope secondary to dysrhythmias carries the highest 1-year mortality versus the more common and relatively benign vasovagal episodes. Patients who experience a spell secondary to a cardiac dysrhythmia have a 1-year mortality of up to 30%, and an incidence of sudden death as high as 24% versus 3% to 4% in patients with noncardiac causes of syncope. Therefore, early identification is critical to ensure proper patient disposition. The patient who has had a spell owing to a seizure may have had either a motor or nonmotor event. Motor seizures, generally tonic-clonic, are usually brief, lasting less than 2 minutes, and are followed by a postictal period. Nonmotor seizures are classified as either focal, complex partial, or absense. 10 They may last for varying lengths of time and, because they are not associated with significant motor activity, a seizure origin is often overlooked. One other consideration is that of psychogenic seizures, though this entity is beyond the diagnostic capabilities of most EDs, as is discussed later in this article. Seizures and syncope explain the most spells; therefore, this article focuses on differentiating the two (Table 2). However, other less common causes of spells are always in the differential and include cerebral vascular accidents (CVAs), transient ischemic accidents (TIAs), subarachnoid hemmorhages (SAHs), basilar migraines, drop attacks, and transient global amnesia. These causes are rare but must be taken into consideration and are covered briefly in this article.