Kluver-Bucy Syndrome

Klüver-Bucy syndrome is a neurobehavioural syndrome associated with bilateral lesions in the anterior temporal horn or amygdala. Heinrich Klüver and Paul Bucy first described the syndrome in 1937¹ following experimental work where they removed rhesus monkeys' temporal lobes. They found that the monkeys developed:

1. Visual agnosia - they could see, but were unable to recognise familiar objects or their use.
2. Oral tendencies - they would examine their surroundings with their mouths instead of their eyes.
3. Hypermetamorphosis - a desire to explore everything.
4. 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".
5. Hypersexualism - a dramatic increase in overt sexual behaviour including masturbation, homosexual and heterosexual acts. 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.. 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 gross than with 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 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 with many of the reports originating from India.
• It is likely to become more common with greater survival of herpes encephalitis due to treatment with antiviral agents.

Risk factors

The most common cause is herpes simplex encephalitis, but it has also been associated with other infections such as tuberculous meningitis or primary cerebral Whipples disease.²

Other causes include:

• Head injury (not necessarily very severe)
• Dementia, especially fronto-temporal dementia (Pick's disease) but also Alzheimer's disease³
• Surgical lesions
• Post-epilepsy⁴
• Cerebrovascular disease

It has occasionally been described in children.⁵

• 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 pinpointing the actual site of the lesion(s) and to cause. Where psychiatric symptoms are predominant, the presence of Klüver-Bucy syndrome suggests a primarily organic cause.⁶

Non-drug

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

Drug

The SSRIs have been shown to be of value⁷ but carbamazepine may be better.⁸

Cognitive and behavioural disturbances after herpes encephalitis are often severe but improvement can occur over a long time and residual disabilities vary from major⁹ to fairly mild.¹⁰ 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.¹¹ It concluded that herpes simplex encephalitis is often misdiagnosed, leading to late treatment. 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.