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. 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. There may be no one cause in all cases.

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

Epidemiology

Ganser's syndrome is said to be very rare with fewer than 100 cases in the literature.¹ The precise incidence is not known, as most of the recorded cases in the literature describe only individual patients and criteria are lax. Ganser's 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 has been reported. It has been described in children.² Ganser's syndrome is thought to be precipitated by episodes of severe stress but has also been described in association with head injury.

Presentation¹

The condition tends to occur against a background of head injury or serious illness. Severe psychosocial stress can also be a cause; psychosocial stresses accompanying immigration may have a catalytic effect in triggering the condition.³ The four principal 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 three 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.^4,5 Look for signs of self-inflicted injury.

Differential diagnosis¹

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

Associated diseases¹

Ganser's syndrome has been reported in the following:

• Neurosyphilis
• Epilepsy
• Post stroke
• Meningiomas
• Post anoxia
• Postpartum psychosis
• Traumatic brain injuries
• Infections
• Various dementias

Investigation¹

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.
• U&Es.
• LFTs.
• Vitamin B12 levels.
• TFTs.
• Urine drug screen
• CT scan or MRI scan. to exclude structural pathology.
• Lumbar puncture may be performed to exclude meningitis or encephalitis.
• Electroencephalograph (EEG) does not usually show any specific disorder⁶ but should be performed to rule out underlying causes such as delirium or seizure disorder.

One study reported that a man pursuing an insurance claim presented with Ganser's syndrome-like symptoms. Simple memory tests and the existence of symptoms not typical of the syndrome were used to exclude the syndrome.⁷

Management¹

Admission to a psychiatric unit in the acute phase is usually required for assessment and to prevent harm to self or to others. Simple psychotherapy is the mainstay of treatment. Drug therapy is of limited value and not usually required. Evidence of benefit from benzodiazepines, antipsychotic medication or other treatments, such as electroconvulsive therapy or hypnosis, is very limited.

Prognosis¹

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 are related to the underlying cause, especially if organic.

Document references

1. Schneider D et al, Ganser Syndrome, Medscape, Sep 2011
2. Miller P, Bramble D, Buxton N; Case study: Ganser syndrome in children and adolescents. J Am Acad Child Adolesc Psychiatry. 1997 Jan;36(1):112-5. [abstract]
3. Staniloiu A, Bender A, Smolewska K, et al; Ganser syndrome with work-related onset in a patient with a background of Cogn Neuropsychiatry. 2009 May;14(3):180-98. [abstract]
4. Slick DJ, Sherman EM, Iverson GL; Diagnostic criteria for malingered neurocognitive dysfunction: proposed standards for clinical practice and research. Clin Neuropsychol. 1999 Nov;13(4):545-61. [abstract]
5. Wisdom NM, Callahan JL, Shaw TG; Diagnostic utility of the structured inventory of malingered symptomatology to Arch Clin Neuropsychol. 2010 Mar;25(2):118-25. Epub 2010 Jan 28. [abstract]
6. Cocores JA, Schlesinger LB, Gold MS; A review of the EEG literature on Ganser's syndrome. Int J Psychiatry Med. 1986-1987;16(1):59-65. [abstract]
7. Merckelbach H, Peters M, Jelicic M, et al; Detecting malingering of Ganser-like symptoms with tests: a case study. Psychiatry Clin Neurosci. 2006 Oct;60(5):636-8. [abstract]

Internet and further reading

• Deibler MW, Hacker C, Rough J, et al; Ganser's syndrome in a man with AIDS. Psychosomatics. 2003 Jul-Aug;44(4):342-5.
• Sigbert Josef Maria Ganser, whonamedit.com; brief biography