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Klüver-Bucy syndrome is a neuro-behavioural syndrome associated with bilateral lesions in the anterior temporal horn or amygdala. Heinrich Klüver and Paul Bucy first described the syndrome in 1937 after experimental work where they removed rhesus monkeys' temporal lobes.[1] They found that the monkeys developed:

  • Visual agnosia - they could see, but were unable to recognise familiar objects or their use.
  • Oral tendencies - they would examine their surroundings with their mouths instead of their eyes.
  • Hypermetamorphosis - a desire to explore everything.
  • Emotional changes - emotion was dulled and facial movements and vocalisations were far less expressive. They lost fear where it would normally occur. Even after being attacked by a snake, they would casually approach it again. This was called 'placidity'.
  • Hypersexuality - a dramatic increase in overt sexual behaviour, including masturbation. They may even attempt copulation with inanimate objects.

The syndrome in humans is due to bilateral destruction of the amygdaloid body and inferior temporal cortex, most commonly due to herpes simplex encephalitis (HSE). It shares visual agnosia and loss of normal fear and anger responses in common with the monkey model but one also sees loss of memory with dementia, distractibility and seizures. The hypersexuality tends to be less overt than in the monkeys but may be public and unacceptable.

It is a very rare disorder and most of the literature relates to animal models rather than human cases:

  • Most literature relating to humans is isolated case reports and few papers report more than a small number of cases.
  • A report of six cases is included in the 'Further reading & references' section, below. Many of the reports originate from India.
  • It is likely to become more common as a consequence of greater survival following HSE, as antiviral agents improve and are readily available.

Risk factors

The most common cause is HSE but it has also been associated with other infections such as:

  • Tuberculous meningitis.
  • Listerial meningoencephalitis.[2]
  • Primary cerebral Whipple's disease.[3]

Other causes include:

  • Head injury (not necessarily very severe).
  • Dementia, especially frontotemporal dementia (Pick's disease) but also Alzheimer's disease.[4]
  • Surgical lesions.
  • Post-epilepsy.[5]
  • Cerebrovascular disease.

It has occasionally been described in children.[6]

NB: we rarely, if ever, see the full syndrome in humans.

In adults

  • Emotional blunting: there is a flat affect and poor response to emotional stimuli (placidity).
  • Hyperphagia: there is a strong compulsion to place objects in the mouth, probably to gain oral stimulation and to explore the object to counteract the visual agnosia, rather than due to hunger. Nevertheless, there is bulimia and there will be marked weight gain unless diet is restricted. Actions may include socially inappropriate licking or touching.
  • Visual agnosia: there is an inability to recognise objects or faces visually. This is also called 'psychic blindness' ands may account for the oral compulsion.
  • Increased sexual behaviour: individuals with Klüver-Bucy syndrome lack social sexual restraint with profuse and inappropriate sexual activity.

In children[6]

  • It usually follows HSE and develops on regaining consciousness and activity.
  • Altered emotional behaviour, changes in dietary habits, hyperorality and hypersexuality have been reported as present in all, while psychic blindness and hypermetamorphosis occurred in only a few.
  • Marked indifference and lack of emotional attachment towards their family.
  • Apathy and easy distractibility are rare.
  • Bulimia and a strong urge to put items other than food into the mouth are common.
  • Hypersexuality presents as frequent holding of genitals, intermittent pelvic thrusting movements and rubbing of genitals to the bed on lying prone. Usually sexually inappropriate behaviour in children is taken as indicative of sexual abuse. There was no suggestion reported that they had been abused and it is thought that their ignorance of sex led to a different pattern from adults.

The differential diagnosis usually relates to pinpointing the actual site of the lesion(s) and to cause.[7]Where psychiatric symptoms are predominant, the presence of Klüver-Bucy syndrome suggests a primarily organic cause.

General points

  • Patients need careful monitoring to prevent bulimia and consequent obesity but also to prevent uninhibited and inappropriate sexual activity, which has been reported as leading to criminal conviction for at least one patient.[8]
  • Sudden behavioural or emotional changes after HSE treatment may be indicative of a relapse and should prompt a longer course of aciclovir.[9]


Selective serotonin reuptake inhibitors (SSRIs) have been shown to be of value but carbamazepine may be better.[6]

Cognitive and behavioural disturbances after HSE are often severe but improvement can occur over a long time and residual disabilities vary from major to fairly mild.[10, 11]The loss of memory is consistent with the hypothesis that medial temporal lobe structures mediate memory consolidation.

A paper from India concluded that HSE is often misdiagnosed, leading to late treatment.[12] Important factors influencing mortality and morbidity are early aciclovir therapy, age, the immune status of the patient, duration of illness and consciousness level before initiation of therapy.

Further reading and references

  1. Kluver H, Bucy PC; Psychic blindness and other symptoms following bilateral temporal lobectomy in rhesus monkeys. Am J Physiol 1937119:352-3

  2. Cohen MJ, Park YD, Kim H, et al; Long-term neuropsychological follow-up of a child with Kluver-Bucy syndrome. Epilepsy Behav. 2010 Dec19(4):643-6.

  3. Leesch W, Fischer I, Staudinger R, et al; Primary cerebral Whipple disease presenting as Kluver-Bucy syndrome. Arch Neurol. 2009 Jan66(1):130-1.

  4. Kile SJ, Ellis WG, Olichney JM, et al; Alzheimer abnormalities of the amygdala with Kluver-Bucy syndrome symptoms: an amygdaloid variant of Alzheimer disease. Arch Neurol. 2009 Jan66(1):125-9.

  5. Naito K, Hashimoto T, Ikeda S; Kluver-Bucy syndrome following status epilepticus associated with hepatic encephalopathy. Epilepsy Behav. 2008 Feb12(2):337-9. Epub 2007 Nov 5.

  6. Jha S, Patel R; Kluver-Bucy syndrome -- an experience with six cases. Neurol India. 2004 Sep52(3):369-71.

  7. Lippe S, Gonin-Flambois C, Jambaque I; The neuropsychology of the Kluver-Bucy syndrome in children. Handb Clin Neurol. 2013112:1285-8. doi: 10.1016/B978-0-444-52910-7.00051-9.

  8. Devinsky J, Sacks O, Devinsky O; Kluver-Bucy syndrome, hypersexuality, and the law. Neurocase. 2010 Apr16(2):140-5. Epub 2009 Nov 18.

  9. D Ku B, Sang Yoon S; Relapsing herpes simplex encephalitis resulting in kluver-bucy syndrome. Intern Med. 201150(7):763-6. Epub 2011 Apr 1.

  10. Pascual-Castroviejo I, Pascual-Pascual SI, Viano J; Kluver-Bucy syndrome. Seven year follow-up of one patient. Neurologia. 2008 Mar23(2):114-8.

  11. Raschilas F, Wolff M, Delatour F, et al; Outcome of and prognostic factors for herpes simplex encephalitis in adult patients: results of a multicenter study. Clin Infect Dis. 2002 Aug 135(3):254-60. Epub 2002 Jul 10.

  12. Jha S, Patel R, Yadav RK, et al; Clinical spectrum, pitfalls in diagnosis and therapeutic implications in herpes simplex encephalitis. J Assoc Physicians India. 2004 Jan52:24-6.