Postictal Lethargy

The postictal state is an ambiguous and poorly understood phenomenon. The means by which the various pathophysiological mechanisms produce differing postictal manifestations are still unknown. It is commonly assumed that various phenomena seen in the postictal state represent a manifestation of neuronal exhaustion in a selected neuronal pool. The clinical symptomatology of the postictal state is almost as diverse as the variations of ictal semiology. The postictal period correlates to a time in which neuronal, behavioral, and electroencephalographic return to the baseline is achieved. The clinical manifestation of the postictal period may vary with the seizure type as well as the intensity and duration of the seizure. These manifestations can vary even in the same patient from seizure to seizure.

The postictal state encompasses lethargy, confusion, psychosis, sleep, and coma. The elements of the postictal state have not been as well studied in a fashion that the ictal stages have been by historical data, physical examination, video electroencephalographic (EEG) monitoring, and functional neuroimaging. Family members often misinterpret the postictal period as a continuation of the ictus, leading to exaggerated estimates of the seizure duration. Many times it is even confusing to a trained clinician. The differentiation between these two states using EEG data can still remain ambiguous. The distinction is further blurred in conditions such as status epilepticus where certain EEG patterns such as periodic lateralized epileptiform discharges (PLEDs) are still debated as to whether they represent an ictal or a postictal phenomenon. Most postictal phenomena are ignored because they have poor lateralizing value. However, there are some postictal phenomena such as postictal aphasia and postictal hemiparesis (Todd's paralysis) that carry lateralizing value as to the ictal onset zone. This chapter focuses on various changes in cognition, behavior, alertness, and consciousness that occur after an epileptic seizure.

POSTICTAL DELIRIUM/PSYCHOSIS

There are patients who have a profoundly disturbed postictal recovery during which they display a delirious confusional state. At times, the reaction may appear violent, during which time the patient may appear hypervigilant. Postictal aggression usually occurs in the setting in which an attempt is made to restrain the patient (Delgado-Escueta, 1981; Fenwick, 1986). For this reason, the recovering patient should be surrounded by as little commotion as possible and not be restrained because this only tends to further agitate and confuse the individual.

These types of reactions are rare and are thought to be seen in patients with deteriorated or poorly controlled seizures. In some cases, postictal delirium may be accompanied by visual hallucinations (Niedermeyer, 1990). Some authors have found that directed violent behavior and suicidal attempts were more commonly a feature in patients with postictal psychosis instead of acute interic-tal psychosis or postictal confusion (Kanemoto et al., 1999).

Postictal psychosis, defined as a time-limited disturbance with diverse psychiatric symptoms that is temporally related to seizures or a flurry of seizures, has been described in patients with focal as well as generalized seizures. These cases are at times associated with abrupt anticonvulsant withdrawal (Savard et al., 1991; Kanner, 1996; Baumgartner, et al., 1995). The prevalence of this entity is unclear in patients with epilepsy, but has been reported as 6-10% (Kanner, 1996; Kanemoto et al., 1996). There is usually a lucid interval prior to the psychosis. The duration of the psychosis can last a few days or continue for up to 3 months (Lancman et al., 1994; Logsdail and Toone, 1988). Patients with postictal psychosis usually present with mood disorders and other positive psychiatric symptoms such as paranoid delusions, and auditory, visual, and sensory hallucinations (Logsdail and Toone, 1988; Mendez, 1991; So, 1991). Postictal psychosis has also been noted in cases following electroconvulsant therapy (Zwil, 1997). The speculated pathophysiological mechanisms of postictal psychosis vary from neuronal exhaustion after being hyperexcited by frequent epileptiform discharges, to dopaminergic hypersensitivity, to y-aminobu-tyric acid (GABA)-mediated mechanisms (Savard et al., 1991; Lancman, 1994; Ring et al., 1994; Szabo et al., 1996). Most patients have a benign prognosis, although as many as 15% of patients may develop chronic psychosis (Logsdail and Toone, 1988).

Occasionally patients with complex partial seizures may experience periods of aimless wandering (poriomania) that may represent a prolonged postictal automatism (Mayeux et al., 1979). The postictal EEG often shows either a generalized or a lateralized delta slow activity. The postictal lateralized slowing that patients may show on their EEGs may be a lateralizing sign of the ictal onset zone. The postictal EEG recording may also have a lack of interictal spikes that may have been evident as interictal activity prior to the seizure.

POSTICTAL LETHARGY/CONFUSION

It is often difficult to distinguish postictal confusion versus an impairment of comprehension. Differentiating postictal aphasia, abulia, and disorientation are also difficult. Care must be taken when diagnosing postictal confusion in patients with left temporal lobe epilepsy (TLE) because it may actually represent a postictal language dysfunction. In a study of patients with complex partial seizures of 32 patients with right TLE, 28 (88%) had initial postictal confusion with impaired comprehension and normal language function. In 33 patients with left TLE, 14 (42%) postictally had impaired comprehension with no paraphasia. These patients were much more likely to have paraphasic errors (36%) as compared with right TLE patients (6%). In this group of patients, a flattened effect and a prolonged disorientation for place was more commonly observed in patients with right TLE. (Devinsky et al., 1994).

Postictal confusion is often used to discern between typical absence seizures and complex partial seizures. There is no postictal period in typical absence

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