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Psychiatric Consequences of Epilepsy
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Epilepsy is a common neurological disorder having a prevalence of around 1%. It is estimated that between 30-50% of epileptics have significant psychiatric difficulties. The incidence of psychosis and mood disorders is high in this population and personality disturbance is also more common than in the general population. Epileptics are at greater risk of developing schizophrenia particularly those with temporal lobe epilepsy. Personality disturbance is also more common in the group with focal temporal lobe seizures. Aggressiveness of an explosive nature is characteristic and libido is often reduced. Impulsiveness, moodiness and suspiciousness have been described but these findings are open to criticism.
Psychiatric complications of epilepsy (you may wish to review the classification of epilepsy at this point) will be divided into :
- Peri-ictal
- Inter-ictal
- Schizophreniform psychosis
- Affective psychosis
- Non Epileptic Attack Disorder (previously pseudoseizures)
- Cognitive impairment
- Personality
Peri-ictal.
The period surrounding the seizure.
Precipitation of seizures
Precipitants can be external (reflex epilepsy; photic epilepsy) or internal (stress; anxiety, hyperventilation; fatigue; sleep loss; withdrawal from drugs such as benzodiazepines, antiepileptics, alcohol; drugs which lower the seizure threshold such as antidepressants, neuroleptics).
Prodrome
Changes in mood (particularly dysphoria and irritability) may appear minutes to days before a seizure and are not directly related to seizure activity.
Auras
These represent the initial focal onset of the seizure, last only seconds to a few minutes and typically have a stereotyped form. In temporal lobe epilepsy (TLE) these may include hallucinations in any modality, epigastric sensations, deja or jamais vu. These can comprise the sole feature of a complex partial seizure.
Ictal
Automatisms can occur when the seizure starts in the periamygdaloid region and spreads bilaterally. 80% last less than 5 minutes and ictal automatisms never last more than 1 hour. More protracted automatisms can occur due to complex partial status.
Post-ictal
Some degree of post-ictal confusion is common after any generalised seizure. Examination would reveal confusion, reduced attention, disorientation and impaired co-ordination.
Inter-ictal.
The period between seizures.
Schizophreniform psychosis
This has been described as a psychosis with characteristic features of schizophrenia, on average starting some 14 years after the onset of epilepsy. Visual hallucinations appear more common than in schizophrenia. Incidence may be around 2% of epileptics, the majority having left temporal lesions. It appears to be a non-specific effect of underlying brain damage rather than directly due to seizure activity.
Affective psychosis
In epilepsy overall there is a 5-fold increase in the risk of suicide, but in TLE this figure rises to 25-fold.
Non Epileptic Attack Disorder
Previously known as pseudoseizures, these are attacks which may be mistaken for epilepsy but are not of epileptic origin. Most patients have or have had epilepsy. Clinical pictures include atypical pattern of the attacks, rarity of injuries or incontinence (note these do happen in this disorder). Aetiologies include previous sexual abuse, hyperventilation syndrome etc.
Cognitive impairment
This can be temporary, due to continuing seizures plus/minus the effects of antiepileptic medication, or progressive, probably due to brain injury from continuing seizure activity.
Personality
Whilst an "epileptic personality" has been described in older literature this construct appears to have little actual validity. Irritability and impulsive behaviour (including aggression and violence) may be part of an episodic dyscontrol syndrome secondary to complex partial seizures.
Classification of Epilepsy
Definition.
Epilepsy is a brain disorder characterised by recurring excessive neuronal discharge, manifested by transient episodes of motor, sensory or psychological dysfunction, with or without loss of consciousness or convulsive movements. The seizure is associated with marked electoencephalographic (EEG) changes.
Classification.
Current classification follows the following structure:
Generalised seizures
These involve all brain structures and may be primary (generalised from the outset) or secondary (arising secondary to a partial seizure).
- Tonic-clonic (grand mal)- either phase can occur alone. In the tonic phase respiratory arrest, tongue-biting and bladder emptying can occur.
- Absence (petit mal) - transient loss of consciousness with retention of postural tone, lasting a few seconds, More common in childhood. Automatic movements in 80% of patients.
- Myoclonic
- Atonic
Partial seizures
The seizure originates in a focal area of cortex or sub-cortex. They may become secondary generalised seizures.
- Simple partial seizures - marked by simple motor or sensory symptoms without impairment of consciousness.
- Complex partial seizures - there is disturbance of consciousness. Most commonly temporal lobe in origin (TLE) but may be frontal. Two types of onset; simple partial onset or impaired consciousness at onset. Automatisms may be present.
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