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Seizure Disorders

Seizure disorders are a common problem in medicine, and the internist often plays an important role in the diagnosis, initiation of therapy, and long-term management. The physician must rely on behavioral manifestations to make the diagnosis, yet it is often difficult to distinguish epileptic from nonepileptic behavior. A seizure is defined as an "episodic and paroxysmal change in behavior" usually associated with an alteration in or loss of consciousness. It can be precipitated by a variety of systemic pathophysiological processes such as fever, or by metabolic derangements such as hypoglycemia or toxic reactions. Epilepsy is characterized by recurrent paroxysmal abnormalities in brain function associated with abnormal electrical discharges from neuronal aggregates. Epileptic seizures are usually brief and self-limited. In contrast to nonepileptic seizures, the source of an epileptic seizure.

In terms of both its physical and psychological effects and its associated social stigma, epilepsy can be extremely disabling. For example, seizures may prevent an epileptic patient from driving a car or piloting an aircraft and also present special problems during pregnancy. Management is often challenging, because an individual patient may require different types of treatment at different times, and because inappropriate therapy may actually worsen.

 Classification of epileptic seizures

Generalized seizures (convulsive or nonconvulsive)

Tonic-clonic seizures (grand real)

Absence secures (petit mal)

Minor motor seizures (myoclonic and atonic)

Partial seizures (focal, local)

Simple partial (without impairment of consciousness):

Focal motor seizures (Jacksonian)

Somatosensory and special sensory

Autonomic

Psychic

Complex partial (with impairment of consciousness):

These include motor symptoms (automatisms), sensory symptoms, affective symptoms, and psychic (cognitive) symptoms

 

In order to classify seizure disorders, the physician should carefully question the patient about his or her state of consciousness at the time of the seizure. If the patient remains conscious at the onset of the episode, the seizure is classified as "partial;" if the patient loses consciousness with no warning the seizure is "generalized," or "secondarily generalized" if an aura precedes.

Once the seizure has been classified, appropriate additional tests can be selected. For strictly generalized seizures, the physician should evaluate the patient for metabolic disorders, including hyponatremia, hypokalemia, hypocalcemia, and hypoglycemia, as well as withdrawal from alcohol or other drugs. In the adult population, de novo generalized seizures nearly always have a metabolic origin. Since some apparently generalized seizures are actually secondarily generalized, all adult patients should be evaluated.

The incidence of partial seizures is very high in adults. In such cases, the physician should rely on CT or MRI to detect the associated malformation, tumor, or other lesion.

Although it was once believed that patients should not be examined immediately after a seizure because the findings would be meaningless, in fact the opposite is true. Patients should always be examined after a seizure to detect any evidence of asymmetry--for example, weakness or twitching that is more pronounced in on arm than the other. Such evidence would indicate a focal rather than a generalized seizure.

Since patients often have preconceived notions about the type of epilepsy they have, the physician should always ask for a detailed description of the seizures rather than accepting the patient's reported "diagnosis" or accepting it at face value. Patients often mistakenly assume that "petit mal" simply means a relatively minor seizure and that "grand mal" means a major seizure.

Generalized Seizures

Although there are seven distinct types of generalized seizures, the events are usually classified into three major groups: major motor seizures, absence seizures, and minor motor seizures.

Grand Mal (Tonic-Clonic or Major Motor) Seizures

Grand mal seizures are the most common type of generalized seizure; they also occur when a partial seizure becomes secondarily generalized. In a purely generalized grand mal seizure, the first event is loss of consciousness; the patient will be unaware of what has happened.

The second event is the tonic stage, characterized by contraction of the skeletal muscles, extension of the axial musculature, upward deviation of the eyes, and paralysis of the respiratory muscles due to thoracoabdominal contractions. This stage is brief, ranging from only about 3 seconds to a maximum of 30 seconds, although it may seem longer because of its dramatic appearance.

The most striking feature is extension of the upper and lower extremities into a semi-opisthotonic posture. Sudden spasm of the respiratory muscles results in forced exhalation, which may sound like a scream--the so-called epileptic cry. Although contraction of the respiratory muscles causes the patient to stop breathing, it is not cause for concern, since the tonic stage lasts only a few seconds. As the muscles of mastication go into spasm, the patient may bite down hard.

Absence Seizures

The second group of generalized seizures, which includes petit real, is referred to as absence seizures. Absence seizures occur mainly during childhood and are rare after puberty. They are characterized by the arrest or suspension of consciousness for 5 to 10 seconds. Although a mother might say that her son appears healthy, and may not notice the typically brief seizures, the child's teacher will report that the child stares absently for short intervals throughout the day. Without treatment, petit mal seizures occur about 70 to 100 times per day, and such frequent blackouts.

Once you have seen a petit mal attack, you will never forget it. The child will seem to be looking straight through out. Other signs include rhythmic blinking (at a rate of three blinks per second) and rudimentary motor behaviors called automatisms, which also occur in adult temporal lobe epilepsy. Petit mal epilepsy is the easiest seizure disorder to diagnose because of its pathognomonic EEG--a spike-and-wave pattern.

Minor Motor Seizures

The most common types of minor motor seizures are myoclonic and akinetic seizures. Although these seizures usually occur in childhood, adults may sometimes experience them.

Myoclonic seizures are characterized by sudden, brief muscular contractions that may occur singly or repetitively. One type of myoclonic epilepsy of childhood is West Syndrome or infantile spasms, which typically appear at about 6 months of age and consist of sudden abduction of the upper extremity and flexion of the hip and knees. This disorder has a poor prognosis in terms of both intellectual development and long-term survival. Myoclonic seizures may also occur in adolescents with gray matter disease and in adults with viral infections such as encephalitis. Unfortunately, these seizures will probably become more common in the years ahead as a result of the increasing prevalence of infections due to the human immunodeficiency virus (HIV).

Unlike myoclonic seizures, akinetic seizures are characterized by a loss of muscle tone. The appearance depends on the muscles affected. "Head bobbing" occurs if the neck loses muscle tone, "bending seizures" occur if the upper extremities are affected, and "drop attacks" occur if the lower extremities are involved. However, it is much more common for children to faint than to have akinetic seizures. Although not diagnostic, the EEG is often helpful in identifying akinetic seizures.

Partial Seizures

As described above, partial seizures follow Jackson's focal model of epilepsy and are associated with brain lesions. These disorders are usually classified as either simple or complex, depending on whether or not consciousness is affected.

Simple Partial Seizures

In a simple partial seizure, consciousness is maintained. Since much of the motor cortex is devoted to controlling the face and hands, focal motor seizures most commonly affect these parts of the body. Motor movements may spread along the body, usually starting the hands and then affecting other areas, such as the face and upper half of the body. This is known as the "Jacksonian march." (There is almost never movement of the hip or trunk.) Motor seizures may also occur when the lesion (particularly a tumor).

Sylvian seizures are benign motor seizures that involve the tongue and may lead to aspiration. They are seen in adolescents, usually at night, and generally disappear once the child reaches adulthood. Although the seizure itself is benign, the potential for fatal aspiration makes it essential to diagnose and treat this condition appropriately. Fortunately, Sylvian seizures.

Simple partial seizures also include a large subgroup of sensory seizures that can sometimes be difficult to diagnose. The vertiginous seizure, originating in the temporal lobe, is probably the most common type of sensory seizure; unfortunately, dizziness has a broad differential diagnosis. Somatosensory seizures are usually described as a tingling feeling (paresthesia) or a sensation of heat or water running over the affected area; this sensation may spread rapidly from one body part to another. Rarely, a patient will report pain or a burning sensation as well as various auras.

Complex Partial Seizures

These are the most common types of seizures seen in adult medicine. They are characterized by an alteration of consciousness as well as other complex manifestations, and are also the most difficult to diagnose and treat. Patients may experience any or all of four symptom types: psychomotor, psychosensory, cognitive, and affective.

Psychomotor symptoms, or "automatisms," may take the form of simple vegetative movements or complex actions, such as disrobing. The most common automatisms are oral and buccal movements, such as lip smacking, licking, or chewing, and the picking behavior sometimes seen in patients with dementia. In some cases, these individuals may pick at their skin to the point of maceration. Walking is one of the most interesting automatisms that may occur during a complex partial seizure. The physician should not attempt to prevent such behavior during a seizure, because the patient may become violent if restrained. When questioned about their behavior, patients often say they have the urge to leave their present location, and some may drive off or go to the bus station or airport out of a desire to travel.

Epilepsy and Behavior

The issue of epilepsy and behavior presents two distinct complex and difficult management problems: (1) diagnosis and management of cognitive' and behavior changes in patients with different types of epilepsy, and (2) diagnosis and management of patients presenting with behavioral symptoms or symptom complexes akin to those seen in epileptic patients but without classical ictal or electroencephalographic (EEG) manifestations of seizures. The latter has been referred to as temporolimbic dysfunction, as the manifestations of these symptoms and symptom complexes are similar to those described in the literature as being associated with complex partial epilepsy and/or focal lesions in the temporal lobe, frontal lobe, the limbic system, and their connections. Although these problems have been recognized since antiquity, and have been the subject of numerous anecdotal reports and small and large prospective and retrospective studies, for a number of reasons.