Introduction

Klüver-Bucy Syndrome (KBS) is a rare disorder caused by changes to the temporal lobes that lead to behavioural changes. The common symptoms were discovered by two experimental neurologists (Brown and Sharpey-Schäfer), who described changes in behaviour among monkeys that had their temporal lobes surgically removed in 1888. However, the complete type of KBS was established in 1923 by Kluver and Bucy who described the same behavioural changes in a monkey three weeks after removal of their temporal lobes.¹

The temporal lobes are part of your brain and are found on both the left and right sides. They have a role in the formation of memories, controlling behaviour related to food and sex and processing emotions and senses. Damage to the temporal lobes, such as after a stroke or head trauma, leads to the common symptoms of KBS. It can also affect children, often after having a viral infection called herpes simplex encephalitis.

If either temporal lobe is damaged, it can cause KBS. Many diseases can cause KBS, but some examples include Alzheimer's disease, stroke, epilepsy, tuberculosis and Whipple's disease.¹

KBS does not have a cure, but management focuses on reducing symptoms. 

It is important to understand the symptoms of KBS so that diagnosis can be accurate, other conditions can be excluded, and treatment can be started early.

The main symptoms of KBS include:

• Hyperorality (excessively examining food and non-food objects with your mouth)
• Hypermetamorphosis (excessively noticing and reacting to everything you see)
• Hypersexuality (uncontrollable sexual fantasies or urges that can negatively affect your health or relationship)
• Hyperphagia (constant hunger and eating) and bulimia (bingeing and purging). This is not directly linked to bulimia nervosa.
• Placidity (State of calmness)
• Visual agnosia (not recognising information or people)
• Amnesia (significant memory loss)
  

Complete KBS is rare in humans as it requires extensive damage to or removal of both temporal lobes. If an individual presents with three or more, but not all of these symptoms, then they will be diagnosed with partial KBS.^1,5

Primary symptoms of Klüver-Bucy syndrome

Hyperorality

• This is when you feel the need to put objects (including non-edible objects) into your mouth
• It includes licking, biting, sucking or chewing to inspect them
• Needs close monitoring to prevent choking or ingestion of harmful substances
• Medication, including antidepressants or antipsychotics, may help with treatment²
  

Hypersexuality

• Hypersexuality is described as inappropriate, intense and regular sexual urges that can lead to negative consequences for the individual, such as pain
• These urges and desires are challenging to control/resist
• Examples include: public masturbation, sexual advances, fixation on sexual content, and frequent pelvic thrusting (including against objects)
• In some cases, it can lead to criminal charges due to non-consensual sexual acts or downloading child sexual abuse material¹
  

Visual agnosia (psychic blindness)

• This is when you are unable to recognise faces or objects despite having seen them before, despite having no issues with your vision
• Visual agnosia may be associated with hyperorality, in which an individual is unable to identify an object by looking at it; instead, they put it fully or partially into their mouth to identify it
• As you are unable to recognise faces, you use other traits, such as a person's voice, behaviour, and clothing, to identify people³

Additional symptoms and behavioural changes

Docility

• Presents as unusual and extreme levels of calmness in situations that would normally trigger fear or anger
• You lack aggression and respond less to things that would make someone else show emotion

Hypermetamorphosis

• Hypermetamorphosis is the need to react to everything you see
• This is more than just being curious; it’s being fascinated by and having an exaggerated response to the things around you
• Can lead to you being distracted as you are focusing on your environment rather than the task⁴

Amnesia/memory disturbances

• These can include impairments in short-term or long-term memory
• Often linked to damage in part of the brain called the hippocampus
• Anterograde amnesia: Unable to remember anything after the trigger
• Retrograde amnesia: Unable to remember anything from before the trigger
  

Emotional blunting

• This can involve a lack of emotional response and difficulty interpreting others’ emotions
  

Variability of Symptoms

Most cases of KBS do not present with all of the symptoms (partial KBS). Complete KBS requires damage to or removal of both temporal lobes. Differences in which symptoms you have can be affected by age or the cause of KBS.⁵ 

Age

The symptoms of KBS can vary between children. The table below summarises the typical symptoms experienced based on age.

The cause of KBS 

KBS can be caused by various conditions, including but not limited to infection (e.g., herpes simplex encephalitis), injury to the brain, stroke, tumours, or disease (Alzheimer's disease, Parkinson's disease). 

The part of the brain that is affected and the extent of brain damage can affect the severity of KBS, i.e, whether you’re having lots of symptoms or a few, and how responsive to treatment you are.

How is Kluver-Bucy syndrome diagnosed?

As KBS results from damage or changes to the brain, scans can help confirm where the damage is (the temporal lobes), which correlates with a diagnosis of KBS. 

Examples of scans include magnetic resonance imaging (MRI) or computed tomography (CT) to assess brain structure.

A person's behaviour can also suggest whether they have KBS. If they’re showing the main symptoms, it can contribute to a differential diagnosis and support scan results.

It would also be important to rule out other conditions that may have overlapping symptoms, such as psychosis, dementia, Korsakoff syndrome or Kleine-Levin syndrome.¹

Treatment and management

Treatment may require a specialist opinion as there is no cure available. This is because the brain's internal damage cannot be reversed. Treatment focuses on managing symptoms and may vary from person to person. 

Medication

Examples of medications prescribed include: 

1. Mood stabilisers
2. Antipsychotics, such as haloperidol, can treat behavioural abnormalities
3. Antidepressants, such as sertraline 
4. Antiepileptics, such as carbamazepine
5. Synthetic hormone such as leuprolide

Carbamazepine is often prescribed when the KBS is due to brain injury and can help to manage sexual behaviour, as can leuprolide. 

Therapy

• Behavioural therapy can help to either change or control behaviour
• Talking therapy can help provide coping mechanisms to deal with the stress caused
• Therapy can teach techniques that focus on the right things and can help you come to terms with the diagnosis

Supervision

If symptoms can’t be controlled, you may need a carer to help navigate social situations.

Coping mechanisms

Deep breathing, reducing clutter and noise can help manage hypermetamorphosis symptoms.

Summary

Kluver-Bucy syndrome can cause symptoms that significantly affect your behaviour. 

If you or someone close to you is feeling or acting differently, don’t be embarrassed to talk to your doctor about it. The sooner symptoms are investigated and a diagnosis is confirmed, the sooner treatment can start. A treatment and management plan may be agreed with different healthcare professionals, including doctors, psychiatrists or therapists, to help you manage the condition.