In this chapter, in contrast to Chapter 204, we consider the clinical occasions in which some of the symptoms of schizophrenia may be mistaken for those of epilepsy. In reality, there are very few situations in which this arises, and when they do, there are usually obvious causes for the confusion. We do not discuss the clinical phenomenology, investigations, and treatment of schizophrenia per se, and refer the interested reader to Chapter 270 by Jadresic in the first edition of this work.^9a

In contrast to disorders of affect, psychotic states, although they imply a severe disturbance of neurologic function, are less frequently encountered than disturbances of mood in neurologic practice. There are many reasons for this, not the least being that many people with neurologic disorders and reduced quality of life experience depression as a consequence, and, in general, a number of neurologic disorders influence areas of the brain that are linked to the regulation of mood, emphasizing the frontal-striatal axis.

The brain must allow the individual to interpret the world in which he or she lives in an orderly manner so that he or she can behave in a logical and adaptive way. The symptoms of psychosis, however, such as hallucinations and delusions, suggest deviant neurologic processing, and underlying this will be disturbances of neurologic function, often secondary to structural disease. The close association between some neurologic disorders and psychoses suggests neurochemical and or neuroanatomic bases for the abnormal mental states, for example, the psychoses associated with Parkinson disease and l-dopa therapies. There are biologic underpinnings to the psychotic disorders of epilepsy, and these are discussed in Chapter 204. It is interesting that, as noted, the discussions revolve around similar anatomic deviations as in schizophrenia in the absence of epilepsy and involve medial temporal structures, the amygdala and hippocampus in particular, and their efferent projections.¹⁷

The term psychosis generally refers to a condition in which there are hallucinations and delusions associated with abnormalities in behavior such as excitement and overactivity or psychomotor retardation, or catatonia, in which insight is diminished or lost.

A hallucination is a perception in the absence of an adequate sensory stimulus, and it must be distinguished from an illusion, which is due to a misinterpretation of perceptions. Pseudo-hallucinations are hallucinatory experiences that occur in subjective rather than objective space, are less clearly delineated, and thus lack the objectivity of hallucinations proper. The latter have concrete reality and are linked to a lack of insight into their nature.

Delusions are unshakable convictions that are manifestly incorrect. They have to be interpreted within the patients’ cultural setting, but it is the tenacity with which patients hold onto their beliefs against all logic that inevitably reveals the delusion. They need to be distinguished from overvalued ideas, which are strongly held beliefs that are not incorrigible.

Delusions are the hallmark of a paranoid illness and occur in a spectrum of psychiatric disorders, including schizophrenia. In the affective disorders, they are characteristically mood congruent, whereas mood-incongruent delusions are typical for schizophrenia. In the Capgras syndrome, a significant person in the patient’s life is replaced by a supposed identical double, and in the Fregoli syndrome, a supposed persecutor can change his or her appearance and appear as other people. These are referred to as misidentification syndromes.

Hallucinations that occur in clear consciousness for which there is no insight and that are mood incongruent are very suggestive of schizophrenia. In this condition, they are usually auditory, although patients may experience them in any modality. Specific auditory hallucinations noted in association with schizophrenia are referred to as being among the Schneiderian first-rank symptoms. These are listed in Table 1. When present in clear consciousness, they usually signify schizophrenia, although this is not diagnostic because they are sometimes noted in other psychotic disorders—for example, in mania. Furthermore, the diagnosis of schizophrenia can be made in their absence based on history and other observed abnormal behavior.

Olfactory hallucinations are reported in schizophrenia and in simple partial seizures of the uncinate variety. In epilepsy, these experiences are typically brief, unpleasant, hard to characterize, and consistent in their phenomenology. In schizophrenia, they are much more variable and may last for considerable periods of time, and they are usually accompanied by a delusional interpretation. In coenesthetic hallucinations, the body or part of the body feels altered or distorted, often in quite fantastic ways. Although often reported in schizophrenia, they may occur in migraine or following cerebrovascular accidents.

A characteristic feature of schizophrenia is alteration of thought and language. This may vary from a subtle flattening of the expression and concrete thinking to a florid schizaphasia. In the latter, neologisms (paraphasias) emerge, there are loose connections between thoughts and tangential thinking, and intrusive delusional content can lead to a veritable “word salad.”

The diagnosis of schizophrenia is usually not difficult to make in the advanced case, especially with knowledge of the patient’s history. However, by the time the patient has revealed his or her aberrant behavior and psychotic thinking, the underlying disorder will be well advanced. There is often evidence of difficult and unusual behavior going back to childhood, with comments about the person being different, a loner, and the like, and perhaps using unusual language or manifesting unusual thought processes for several years. A family history may be revealed (but is often concealed), and typically academic decline becomes apparent in the teenage years, often blamed on either stress or illicit drug taking.

Such cases usually first go to a psychiatrist for diagnostic evaluation, and if the diagnosis is clear, these patients may remain under psychiatric care for many years. In the early, uncertain stages of the disorder, however, patients with a developing schizophrenia may be referred to a neurologist, but usually on the grounds of academic failure and personality change, suggestive of a developing organic brain syndrome—the dementia praecox of Kraepelin. Such referrals, however, are not usually in reference to epilepsy.

The signs and symptoms of schizophrenia that are most likely to be confused with epilepsy are quite limited. They relate especially to the paroxysmal nature of the presentations and to the neurologic-soundingness of them. The signs are those of the motor disturbances of catatonia, and the symptoms are usually hallucinations, especially affecting the body image. Certain first-rank symptoms are also relevant, especially thought withdrawal and thought insertion.

The classic motor disorder of schizophrenia is catatonia, and for Kraepelin this deserved a separate nosologic category.¹⁰ It seems that catatonic forms are much less apparent now than 100 years ago; one reason may be the effective intervention of psychotic disorders with neuroleptic drugs. The original descriptions of these movement abnormalities revealed a wide range of motoric instability, from tics and dyskinesias to frank dystonia. Stereotypies, echophenomena, mannerisms, and special signs such as automatic obedience and negativism were reported, and such abnormal movements were thought to be integral to the condition. This was before the introduction of neuroleptic drugs and the later widespread reporting of tardive motor syndromes. It is estimated that around 50% of untreated schizophrenics display such motor abnormalities.^11,12