Ganser Syndrome (Pseudodementia)

Synonyms: Prison psychosis, pseudodementia, hysterical pseudodementia.

This is a rare condition of uncertain or variable aetiology. It was first described by the psychiatrist Sigbert Ganser in 1898.¹ Ganser described the syndrome after studying the behaviour of three inmates of a prison and thus it has acquired the synonym "prison psychosis". He was of the opinion that the condition was hysterical or malingering in origin.

It is thought that people develop "Ganser's syndrome", either consciously or unconsciously, to avoid an unpleasant situation. There has been much debate over the years as to whether it is psychotic, hysterical or factitious in origin. Association with serious illness may suggest an aetiology similar to delirium. It is fairly common to find it associated with head injury.² There may be no one cause in all cases.

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) currently classifies Ganser syndrome as a dissociative disorder. It is often classified as a factitious disorder.

Ganser syndrome is said to be very rare with less than 100 cases in the literature. The precise incidence is not known as most of the recorded cases in the literature describe only individual patients and criteria are lax. Ganser syndrome is more common in men with a probable male to female ratio of 3 or 4:1. It is most frequently described in individuals between the ages of 15 and 40 but a wide range of ages have been reported. It has been described in children.³ Ganser syndrome is thought to be precipitated by episodes of severe stress, but has also been described in association with head injury.

The condition tends to occur against a background of head injury, serious illness or severe psycho-social stress. The 4 principle features are:

• Approximate answers
• Clouding of consciousness
• Somatic conversion symptoms such as hysterical paralysis
• Hallucinations, visual or auditory

The term approximate answers needs explanation. It is the most characteristic feature of the condition and German terms such as vorbeireden meaning talking past and vorbeigehen meaning to pass by or danebenreden meaning talking next to are used in the literature.

The essential feature of approximate answers is that whilst the patient gives an incorrect response, the nature of the response suggests that he understands the question. Thus he may say that grass is blue and that a dog has 3 legs. When asked the day of the week or month of the year he will give a day of the week or month of the year but the wrong one. This is in direct contrast to answers that are simply nonsensical, perseverative, or otherwise inappropriate.

Diagnostic criteria are not well established. Most authorities would want approximate answers and at least one other principle feature to make the diagnosis.

Other features include:

• A dreamy or perplexed appearance
• Memory or personal identity loss
• No recollection of the condition upon recovery
• Perseveration
• Echolalia
• Echopraxia
• Confusion
• Precipitating stress
• Loss of personal identity

There is no typical finding on examination. A full neurological examination should be performed and a mental state examination. There are now more sophisticated tests to assess exaggerated or fabricated cognitive dysfunction.⁴ Look for signs of self-inflicted injury.

• Acute psychotic illness such as schizophrenia
• Temporal lobe epilepsy
• Wernicke's encephalopathy
• Head injury
• Encephalitis
• Meningitis
• Munchausen's syndrome
• Drug intoxication

No investigation is diagnostic but a number may be performed to exclude other pathology. It is important to exclude an underlying organic cause.

• Mental state examination should be performed.
• FBC
• Urea and electrolytes
• Liver function tests
• Vitamin B12 levels
• Thyroid function tests
• Urine drug screen.
• CT scan or MRI scan to exclude structural pathology
• Lumbar puncture may be performed to exclude meningitis or encephalitis
• EEG does not usually show any specific disorder⁵

Admission to a psychiatric unit is required for assessment and to prevent self harm that is common in this condition.

Drug therapy is of limited value and not usually required. Evidence of benefit from benzodiazepines, antipsychotic medication or other treatments such as psychotherapy and ECT is very limited.

If the precipitating stress has been withdrawn, symptoms usually resolve spontaneously within days but there is usually no recollection of the illness. Sometimes severe depression follows.

Mortality and morbidity is related to the underlying cause, especially if organic.