Overview

Klüver-Bucy syndrome (KBS) is a neurological disorder caused by damage to the temporal lobe of the brain and is distinguished by a number of cognitive dysfunction symptoms. 

Patients with KBS often present the following symptoms:

• Hyperorality 
• Hypersexuality 
• Visual agnosia 
• Hypermetamorphosis (tendency to touch and explore everything around you, even if the objects are insignificant)
• Amnesia
• Reduced emotional responsiveness 

Hyperorality is a distinct symptom of KBS; it is characterised by compulsive eating and inappropriate object consumption.KBS is a very rare disorder as it is caused by damage to very specific regions of the brain. The specific regions affected are what result in hyperorality; understanding damage to this region of the brain raises questions about emotional regulation and impulse control. Understanding the pathology of this disorder allows us to understand the emotional and decision-making parts of the brain, and how, in KBS, the brain damage observed results in personality and behavioural changes.¹ 

While it is a very rare disorder, understanding further why this happens and its implications can help us improve our understanding of brain damage and KBS, supporting earlier diagnoses and helping us to implement tailored and more compassionate care approaches and improve the treatment of symptoms. 

In this article, we are going to discuss the implications of hyperorality in patients with KBS. 

What is klüver-bucy syndrome?

In Klüver-Bucy syndrome (KBS), damage in the form of lesions is found in the amygdalae and sometimes the hippocampus, which are structures found in the temporal lobe of the brain.¹ 

The amygdala is responsible for processing emotions; it controls our fear, anxiety and aggression responses. Damage to this part of the brain leads to symptoms such as abnormal emotional responses, patients showing a lack of emotion, fearlessness, being more docile and inappropriate social behaviours.² The hippocampus is involved in memory formation, which explains why damage to this region of the brain would result in symptoms such as amnesia.³

KBS can be caused by several pathologies that result in damage to the brain, the most noted is Herpes simplex encephalitis (HSE) caused by a viral infection that targets the brain, in particular, we often see it targeting the temporal lobes. Strokes, traumatic brain injuries, as well as neurodegenerative diseases such as Frontotemporal dementia (Pick's disease), Alzheimer’s and Huntington’s disease, can also all lead to the development of KBS, as they all can result in the degeneration of the temporal lobes.¹ KBS is distinct from these conditions; it results from the specific bilateral damage to the temporal lobes that these conditions can cause.⁴

What is the importance of the limbic system in KBS?

The limbic system is what allows us to process emotions and memories. It is also involved in motivation and behavioural responses and is linked to eating, social and sexual behaviours. The limbic system is essential for survival, and when it is dysregulated in disorders such a KBS, we see unusual patterns of behaviour, often a loss of the ability to identify what is considered safe and what is not.⁵ The amygdala and hippocampus are key components which allow our limbic system to function; we see damage to these specific regions in patients with KBS, and therefore, the symptoms that present themselves are a result of a dysfunction of the limbic system. 

What is hyperorality?

The amygdala is also involved in the development of compulsive behaviours, resulting in symptoms such as hyperorality and hypersexuality. Hyperorality is a distinct symptom of KBS; it is a strong compulsion to examine objects orally. Patients with hyperorality often impulsively place non-food objects in their mouths.¹ These compulsive tendencies can also present as impulsive and obsessive behaviours relating to food, such as bulimia and excessive eating.¹

These behaviours are driven by a dysfunction in the impulse control and sensory regulation regions of the brain, as these areas of the brain are damaged in KBS, the patient is unable to properly assess items. This can be particularly dangerous and disruptive to someone's everyday life; other than ingesting potentially harmful objects, hyperorality can result in negative social consequences. 

Why is hyperorality rare?

KBS is linked to bilateral brain damage, meaning lesions must be present in both sides of the brain for the disease to present itself.⁴ This kind of symmetrical damage is not common, and therefore, the condition is rare. The conditions and viral infections that often cause this type of bilateral damage are also themselves rare, and often do not target the amygdala specifically; therefore, it is unusual to have this pattern of damage to this specific region of the brain that would then present as KBS, and cause the patient to present the range of symptoms associated with this syndrome.⁶

Doctors previously used bilateral temporal lobectomies to treat seizures. It was noted that when the lobectomies were bilateral, symptoms such as those associated with KBS were observed. When the lobectomies were carried out unilaterally, and only caused lesions to one side of the brain, no such symptoms were observed. This tells us that it is important for both sides of the brain to be damaged for the syndrome to present itself.⁷

Why is hyperorality specifically linked to KBS?

Hyperorality is a very rare symptom; it is also seen in other disorders like Fronto-temporal dementia (FTD); a progressive brain disorder that is characterised by degeneration of the frontal and temporal lobes, resulting in personality and behavioural changes. As the disease progresses, it leads to prominent memory loss. As similar regions of the brain are being affected, like we see in KBS, we generally see similar symptoms arise; therefore, we can also see hyperorality present itself in these patients, even if they have not developed KBS as a result of their frontotemporal dementia.⁸

Hyperorality is often less severe in patients with FTD, and more often presents itself as altered food preferences, binge eating and overeating and a tendency to eat things that are non-food items. We see patients with FTD display a broader range of cognitive and behavioural symptoms as a larger area of the brain is affected.

Hyperorality is a more distinct symptom of KBS due to the pattern of damage to the brain. It is often described as bilateral damage to the amygdala, which means this region of the brain is damaged in both parts. In KBS, this damage to both sides of the brain is what results in the symptoms associated with KBS. Damage to this part of the brain on both sides prevents the normal functioning of the limbic system. This specific bilateral damage observed in patients with KBS, where both sides of this region of the brain sustain damage in the form of lesions, results in a dysregulation of the limbic system. This disconnect in the brain's circuits means the amygdala is no longer able to appropriately filter stimuli and regulate impulses and emotions.⁸ Similar to electrical circuits, the brain is composed of many components which all link together for a human to have normal functions and behaviours. Like when there is a disconnect or a wire is broken in an electrical circuit, we can see that it will stop working, much like circuits in the brain. When the wiring of the brain is disrupted due to damage, it can result in unusual behaviours and impaired cognitive abilities.

Treatment and management

KBS significantly impacts a patient's everyday life as it affects their ability to effectively judge the safety of situations and disrupts their normal social functioning abilities. Patients with KBS frequently require full-time care, close supervision and assistance with daily tasks; as they lose their ability to assess dangerous situations and things, they may put themselves at serious risk of harm. A patient may need supervision to limit the occurrence of them possibly putting harmful objects in their mouth, such as sharp objects and choking hazards, along with potentially toxic substances.

The primary form of management for patients with KBS is to treat their symptoms. For example, patients are prescribed antipsychotics, mood stabilisers, antidepressants and antiepileptics. Management of the symptoms can improve the patient's quality of life.⁹ 

Neurodegenerative diseases and traumas, which result in brain damage, can lead to the development of KBS. These underlying conditions should be treated quickly in order to prevent and minimise the damage to the brain. This therefore reduces the severity of the symptoms. For example, antiviral agents may be given to patients with HSE to reduce the damage done by the viral infection.¹⁰

Occupational therapy helps people with disabilities to live more independently, and can be useful for patients diagnosed with KBS. An occupational therapist can help a patient and carer adjust to their condition; they can set things in place to help them live more normal lives.

FAQs 

Can children get KBS?

Yes, children can develop KBS; however, it is less common than it is in adults.

Is there a cure for KBS?

No, there is no cure for KBS. Only its symptoms can be treated.

How is it diagnosed?

Diagnosis of KBS is primarily clinical and requires a doctor to identify the main characteristic symptoms of KBS in the patient. An MRI scan can then be used to assess the damage to the temporal lobes.

Summary 

Klüver-Bucy syndrome is a very rare condition, but it deeply affects the lives of those who have it. We have talked about the symptoms people with KBS present with, and that it can be dangerous, often requiring individuals to need constant care. This loss of independence is challenging for the patients and those close to them. The better we try to understand this condition, the better we will be able to support those affected.

Spreading awareness of such rare disorders is key to people receiving earlier diagnoses. Many rare conditions are often misunderstood, and people are often misdiagnosed or left without treatment or answers for long periods of time. This can leave people feeling isolated and with a lack of sufficient support. This article aims to contribute to the greater awareness of this rare but impactful condition.