Aggression and epilepsy

The relationship between epilepsy and aggressive behaviour is a particularly controversial issue (Geschwind, 1975). While in patients with episodic affective aggression, a history of epilepsy is reported to be more common (Bach-Y-Rita et al., 1971; Elliot, 1982) most of the community-based studies did not find an increased prevalence of aggressive behaviour in patients with epilepsy (Kligman and Goldberg, 1975; Lishman, 1998).

The prevalence of aggression in epilepsy in general, not regarding the specific epileptic subsyndrome, varies between 4.8% (Rodin, 1973) and 50% (Gastaut et al.,

1955). In a large survey of 666 patients with TLE, Currie et al. (1971) reported aggression in 7% of the patients. Falconer reviewed 100 patients from London's Maudsley Hospital referred for temporal lobectomy and found a prevalence of outbursts of aggressive behaviour in 27% of their patients (Falconer, 1973). However, these studies were hampered by selection bias and the real prevalence of aggressive behaviour in epilepsy remains controversial (Lishman, 1998).

In epilepsy three different types of aggressive behaviours should be distinguished on the basis of their relationship toward the seizures: ictal, postictal and interictal aggression. Ictal aggression occurs with extreme rarity (Gunn, 1971; Saver et al., 1996). In a large survey of several thousand seizures documented on video-telemetry an incidence of about 1/1000 seizures was found (Delgado-Escueta et al., 1981). In ictal aggression hostile and verbal or physical aggressive behaviour is often directed towards nearby objects or persons and may be provoked or not. The patients are usually amnestic for these aggressive episodes and express remorse for their behaviour (Devinsky and Bear, 1984; Fenwick, 1989).

Postictal aggression is more common than ictal aggression but it is still believed to be rare (Treiman, 1991). It often occurs following a cluster of complex partial seizures or very severe secondary generalized seizures. Ictal pain or dysphoria may predispose individuals to the development of postictal aggressive behaviour (Gerard, 1998). Postictal aggression is frequently observed in the context of postictal confusional states or postictal psychosis but it also occurs without any signs of delusion or hallucination (Kanemoto, 1999; Lancman, 1999; Szabo and Lancman, 1996). If postictal aggression is part of a postictal confusional state the disruptive behaviour immediately follows the seizure without a lucid interval. The violent behaviour tends to be resistive, poorly structured and patients usually are very aroused, angry and fearful (Kanemoto, 1999; Lancman, 1999).

Postictal psychosis follows a cluster of complex partial and secondary generalized seizures after a lucid interval, which might vary in duration between hours up to days (Fenwick, 1986; Kanemoto, 1996; Logsdail and Toone, 1988; Trimble, 1991). Aggressive behaviour in the context of a delusional state may be well-structured and goal-directed and even though patients often feel angry and aroused, they may appear calm and concentrated to the observer (Kanemoto, 1999; Szabo and Lancman, 1996). Kanemoto et al. (1999) recently pointed out that well-directed and self-destructive behaviour was not a feature of epileptic psychosis in general but the hallmark of postictal psychosis in particular.

Finally, interictal aggression can be seen in the context of an antisocial personality disorder which, in turn, might be the consequence of the sometimes difficult psychosocial background of patients with epilepsy. It might also be part of a psychotic episode (Logsdail and Toone, 1988) but as Kanemoto (1999) pointed out this is rare compared with postictal psychosis.

Interictal aggression is frequently seen in patients with epilepsy and mental handicap, but in these patients aggressive behaviour is often a result of poor social and communication competence in expressing personal needs, and very rarely results in severe violence (Gunn, 1977). Apart from that, an interictal syndrome of episodic affective aggression, independent of observable ictal activity, major psychiatric disorder or antisocial personality disorder, is well described and has been referred to as episodic dyscontrol (Bach-Y-Rita et al., 1971; Elliott, 1984; Leicester, 1982; Maletzky, 1973; Ratner and Shapiro, 1979; Stone et al., 1986).

Episodic dyscontrol is characterized by several discrete episodes of extreme unprovoked arousal and rage resulting in severe aggressive and violent behaviour. The behaviour is out of proportion to any precipitating psychosocial stressor and patients often feel remorse for their deeds. The phenomenological criteria are those of DSM-IV intermittent explosive disorder (IED) described above (Elliott, 1984). Because of the emotional arousal typically seen in episodic dyscontrol, this behavioural syndrome has to be classified as a subtype of affective, defensive aggression. The high level of arousal with signs of anxiety or fear is also the reason why amygdala pathology is thought to contribute to this behavioural syndrome (Elliot, 1992; Fenwick, 1986; Trimble et al., 1996).

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