Epileptic seizure disorders can be grouped into two large families:
- generalized epilepsies, in which the epileptic activity involves the entire brain from the onset
- partial epilepsies or epilepsies of focal origin, in which the seizure activity originates from an identifiable cortical region
Psychiatric disorders have been recognized in patients with both generalized and partial epilepsies. Most of the psychiatric disorders have been associated with seizure disorders of focal origin, however, primarily those involving frontal and temporal structures.
Psychopathology in generalized epilepsies
Generalized epilepsies can be subdivided into two groups:
- Idiopathic or primary generalized epilepsies, of unknown cause
- Secondary generalized epilepsy (or Lennox-Gastaut syndrome), resulting from a severe insult to the brain, such as an infection of the brain or anoxia at birth
Psychopathology has been identified in patients with both types. For a long time, there was a false impression that patients with primary generalized epilepsies (including absence seizures, juvenile myoclonic epilepsy, or generalized tonic-clonic seizures on awakening) did not experience any psychopathology. In fact, these patients can present with problems of impulsive behavior, poor frustration tolerance, and short attention span.
The vast majority of patients with secondary generalized epilepsy suffer from cognitive developmental delay, which may range from mild to profound. The psychopathology identified in these patients is closely associated with these cognitive disturbances. The most frequent problems involve motor hyperactivity, impulsivity, aggression and agitation, and self-mutilation.
Psychopathology in partial (focal) epilepsies
Patients with seizure disorders of focal origin are more likely to present depressive, anxiety, and psychotic disorders, or attention deficit disorder in children.
Timing of symptoms in relation to seizures
Psychiatric symptoms may be classified according to when they occur in relation to seizures:
- pre-ictal symptoms, preceding a seizure
- ictal symptoms, an expression of the actual seizure
- postictal symptoms, following a seizure
- interictal symptoms, when patients are not having any seizures
Pre-ictal symptoms usually may be recognized several hours before the seizure, though it is not rare for them to be present 48 or even 72 hours before the occurrence of seizures. As the seizure onset nears, the intensity of these symptoms may increase. They consist typically of irritability, poor frustration tolerance, impulsivity, and a variety of symptoms of depression. Parents often can predict the occurrence of seizures as their child becomes more restless and impulsive.
Ictal psychiatric symptoms consist of symptoms of depression, fear, panic, or pleasurable sensations that are an expression of seizure activity involving certain structures in the temporal lobe (i.e., amygdala) or frontal lobe (i.e., cingulate gyrus). In contrast to pre-ictal symptoms, ictal symptoms are brief, lasting less than 30 seconds.
Postictal psychiatric symptoms can occur anytime within the 120 hours that follow a seizure or cluster of seizures. Frequently, patients are free of symptoms for 24 to 72 hours before any symptoms appear. Patients may experience isolated symptoms or a cluster of symptoms that may mimic depressive, anxiety, or psychotic episodes.
Symptoms of depression and anxiety are most frequently identified during the postictal period, but they have been the least investigated. Psychotic symptoms are more readily recognized and reported because of their negative impact on the patient's ability to function. Since the 1980s many reports of postictal psychosis have been published. Postictal psychosis occurs in approximately 5% to 10% of patients with poorly controlled seizures. Although postictal depressive and anxiety symptoms have been identified in up to 45% of patients with poorly controlled seizures, only a handful of studies have been published to date.
Postictal psychiatric symptoms may last only a few minutes or persist for several days. Often patients experience clusters of psychiatric symptoms that mimic depressive, anxiety, or psychotic disorders lasting several days or weeks. These symptoms often go unreported by patients and unrecognized by physicians, but they account to a significant degree for the negative impact that seizures have on the patient's quality of life.
Interictal psychiatric symptoms are those that occur when patients are not experiencing any seizures. These psychiatric symptoms are recognized more often. They may present as depressive, anxiety, or psychotic disorders, as behavioral disorders, or may mimic attention deficit disorders. Very often they may be indistinguishable from psychiatric disorders identified in people without epilepsy. Interictal symptoms often worsen during the postictal period.
Anatomic structures involved in the development of psychiatric symptoms
As already mentioned, psychiatric symptoms can be identified in patients suffering from both generalized epilepsies and epilepsies of focal origin. It is generally accepted that structures that are part of the limbic system mediate the development of these psychiatric symptoms, at least in part. Symptoms of depression and anxiety have been associated with seizures originating in the temporal lobe, frontal lobe, or both. Psychotic symptoms also have been identified in patients with seizures of focal origin, but are more likely when bilateral seizure foci are identified.
A localized seizure focus does not necessarily preclude other brain dysfunction at a distance from the seizure focus. For example, it is well known that patients with temporal lobe epilepsy may have dysfunction of the frontal lobes, evidenced by neuropsychological studies. Patients with temporal lobe epilepsy who have proven frontal lobe dysfunction are more likely to experience depressive episodes.
Impulsivity, poor frustration tolerance, and problems with attention-the most frequent symptoms of primary or idiopathic generalized epilepsies-suggest frontal lobe dysfunction. Up to one-third of children with partial epilepsy also may display oppositional and aggressive behavior, impulsivity, and poor frustration tolerance. While these behavioral problems are more common among children with seizures of frontal or temporal lobe origin, they also may be identified in children with seizures arising in the occipital or parietal lobes. Propagation of epileptic activity to frontal lobe structures may ultimately result in frontal lobe dysfunction facilitating the occurrence of these symptoms.
Adapted from: Holzer JC and Bear DM. Psychiatric considerations in patients with epilepsy. In: Schachter SC, Schomer DL, eds. The comprehensive evaluation and treatment of epilepsy. San Diego, CA: Academic Press; 1997. p. 131-148. With permission from Elsevier (www.elsevier.com).