Loss of Consciousness

Loss of consciousness—syncope—may result from cardiovascular or neurologic causes. The cardiovascular causes are discussed in Chapter 14, The Heart, and Chapter 15, The Peripheral Vascular System. The term blackout is commonly used, but it may mean different conditions to the patient and the interviewer. Any patient who uses this term should be asked to clarify its meaning. The patient may be referring to an actual loss of consciousness, a dimming of vision, or a decreased awareness of the environment without an actual loss of consciousness.

A useful way to clarify the symptom of loss of consciousness is to ask the patient, ''Have you ever lost consciousness, fainted, or felt that you were not aware of your surroundings?'' If the patient answers in the affirmative, identify the cause of the loss of consciousness. Ask the following questions:

''Can you describe the attack to me—every event as it occurred until you lost consciousness?'' ''Did anyone witness the attack?''* ''Were there any symptoms that preceded the attack?'' ''Were you told that there were body movements?'' Can you describe everything you remember after the attack until you felt completely normal?'' ''Was there a period of sleepiness that followed?'' If yes, ' 'For how long did this period last?'' ''How did you feel after the attack? Were you confused?''

Did you notice afterward that you had urinated or had a bowel movement during the attack?''

Epileptic seizures may produce a loss of consciousness and are caused by the sudden, excessive, disorderly discharge of neurons. The first step in approaching the symptom of seizure is to identify its type. If the discharge is focal, the clinical seizure reflects the effect of the excessive discharge in that area of the body. For example, if the discharge is located in the inferior precentral gyrus, involved with hand and arm motion, the seizure is characterized by involuntary motion of the hand and arm. A generalized seizure results from a discharge in the subcortical structures, such as the thalamocortical radiations. These have widespread bilateral cortical connections. There are three main types of generalized seizures:

Petit mal (absence seizure) Grand mal (generalized tonic-clonic) # Myoclonic

A petit mal seizure is characterized by a sudden attack of unconsciousness lasting only about 10 seconds, usually without any warning. During the petit mal seizure, the patient appears to be staring or daydreaming. There is no associated falling or involuntary limb motion. The patient rapidly returns to normal activity without being aware of the attack. These seizures are most common in children 5 to 15 years of age. On occasion, they may persist into adulthood.

A grand mal seizure is a generalized major motor convulsion. Affected patients lose consciousness, and many fall down rigidly. In 50% of patients with grand mal seizures, there is an aura of giddiness, involuntary twitching, change in mood, confusion, or epigastric discomfort as the seizure begins. Some patients may cry out initially. During this tonic phase, there is an increase in muscle tone, resulting in a rigid, flexed posture and then a rigid, extended posture. The patient may become apneic and cyanotic. The eyes may open and stare or may be deviated to one side. The clonic phase follows, with involuntary movements of the body. These are often associated with salivation, eye rolling, and incontinence. Biting the tongue is common.

*Document a history with an observer, if possible.

After the clonic phase, the individual passes into a phase resembling sleep from which she or he cannot be easily awakened. Postictally, or after the seizure, the patient may be confused and often falls into a deep sleep that lasts for hours. Accompanying muscle pain and headache are common.

A myoclonic seizure is a minor motor seizure characterized by sudden muscle contractions of the face and upper extremities. The eyelids and forearms are commonly affected. There is no detectable loss of consciousness.

Febrile convulsions are common in children from 6 months to 6 years of age and are similar to grand mal seizures. When a child has a high fever, a seizure lasting less than 10 minutes may occur. The younger the child is at the time of the first febrile seizure, the greater is the likelihood that seizures will recur.

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