Kluver-Bucy Syndrome

The original work was reported in 1937.¹ Heinrich Klüver and Paul Bucy removed the temporal lobe on both sides in rhesus monkeys to determine its function. The monkeys developed visual agnosia, emotional changes, altered sexual behaviour, hypermetamorphosis and oral tendencies.

The monkeys could see, but were unable to recognize familiar objects or their use. They would examine their surroundings with their mouths instead of their eyes ("oral tendencies") and developed a desire to explore everything ("hypermetamorphosis").

They showed a dramatic increase in overt sexual behaviour ("hypersexualism"), indulging in masturbation and both homosexual and heterosexual acts. They may even attempt copulation with inanimate objects.

Emotion was dulled and their 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".

The syndrome in humans is due to bilateral destruction of the amygdaloid body and inferior temporal cortex. The hypersexuality tends to be less gross than in the animal model, but possibly public and unacceptable. Other features include visual agnosia (inability to visually recognise objects), loss of normal fear and anger responses, loss of memory with dementia, distractibility and seizures.

It is a very rare disorder and much of the literature is about animal models rather than human cases. Many of the reports about humans are isolated case reports and few papers report more than a small number of cases. A report of 6 cases has reached the status of further reading for this article. Many of the reports originate from India. It may become commoner as more cases of herpes encephalitis survive due to treatment with antiviral agents.

The most common aetiology is herpes simplex encephalitis. It has been associated with other infections including tuberculous meningitis. Other causes include head injury , not necessarily very severe, dementia , especially fronto-temporal dementia (Pick's disease) but also Alzheimer's disease, surgical lesions, post-epilepsy or cerebrovascular disease.
It has occasionally been described in children.²

We rarely, if ever, see the full syndrome in humans.

• Emotional Blunting: There is a flat affect and poor response to emotional stimuli (placidity). Lesions in experimental animals allow them to approach danger with no anger or fear.
• Hyperphagia: There is a strong compulsion to place objects in the mouths. This is probably to gain oral stimulation and to explore the object to counteract the visual agnosia rather than 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". This may account for the oral compulsion.
• Inappropriate Sexual Behaviour: People with Kluver-Bucy syndrome lack social sexual restraint with profuse and inappropriate sexual activity. Monkeys with experimental lesions of the amygdala show abnormal sexual behaviour, mounting inanimate objects and members of the same sex.

Presentation in Children

The syndrome can occur in children and has been reported from India in 7 patients aged 2.5 to 6 years old.²

• They had all had herpes encephalitis and developed the syndrome on regaining consciousness and activity.
• Altered emotional behaviour, changes in dietary habits, hyperorality and hypersexuality were present in all, while psychic blindness and hypermetamorphosis occurred in only a few.
• All showed marked indifference and lack of emotional attachment towards their family.
• Apathy and easy distractibility were rare.
• Bulimia and a strong urge to put items other than food into the mouth were common.
• Hypersexuality presented 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 that they had been abused and their ignorance of sex led to a different pattern from adults.

The differential diagnosis usually relates to the actual site of the lesions whether caused by herpes encephalitis, trauma or vascular lesions.

Non-drug

Patients with Kluver-Bucy syndrome may need careful monitoring to prevent bulaemia and consequent obesity but also to prevent uninhibited and inappropriate sexual activity.

Drug

The SSRIs have been shown to be of value³ but carbamazepine may be better.⁴

Cognitive and behavioural disturbances after herpes encephalitis are often severe but improvement can occur over a long time and residual disabilities may be fairly mild.⁵ The loss of memory is consistent with the hypothesis that medial temporal lobe structures mediate memory consolidation.

A paper, also from India, looked at the clinical spectrum, pitfalls in diagnosis and therapeutic implications in herpes simplex encephalitis.⁶ It concluded that herpes simplex encephalitis is often misdiagnosed. Important factors influencing mortality and morbidity are early acyclovir therapy, age, immune status of patient, duration of illness, and consciousness level before initiation of therapy. They advised that acyclovir should be given to all patients as soon as the diagnosis is suspected, whilst awaiting confirmation of diagnosis.