Kluver-Bucy syndrome
Kluver-Bucy syndrome is a rare behavioral disorder primarily affecting the brain's temporal lobes and amygdala, resulting in significant changes in emotional responses and behavior. It is characterized by symptoms such as visual agnosia (difficulty recognizing objects), hyperorality (examining objects by mouth), a lack of aggression, and altered sexual behavior. These symptoms often arise after damage to the amygdala or disruptions in communication between the brain's hemispheres, typically due to conditions like encephalitis, strokes, or dementia.
The syndrome was first identified in monkeys in the late 1930s and later observed in humans in the 1950s following brain surgery for epilepsy. Diagnosis requires the presence of three or more associated symptoms. Although no definitive cure exists, treatments may include medications such as anticholinergics and selective serotonin reuptake inhibitors (SSRIs), which aim to alleviate some symptoms. While Kluver-Bucy syndrome is considered rare and primarily involves behavioral issues rather than life-threatening conditions, understanding and managing the underlying causes remains crucial to preventing its onset.
Kluver-Bucy syndrome
ANATOMY OR SYSTEM AFFECTED: Brain, eyes, genitals
DEFINITION: A behavioral disorder characterized by lack of emotional activity or responses similar to that often observed in patients with Alzheimer disease
CAUSES: Malfunction in communication between left and right temporal lobes or damage to amygdala
SYMPTOMS: Unusual fear response, use of mouth for examining objects, inability to recognize objects
DURATION: Lifelong
TREATMENTS: Symptomatic
Causes and Symptoms
Kluver-Bucy syndrome was first observed in 1937 when German neuroanatomist Heinrich Kluver, working with American neuropathologist Paul Bucy at Northwestern University, observed that the removal of the temporal lobes, including the amygdala, of a rhesus monkey resulted in significant behavioral changes in the animal. More specifically, the monkey displayed visual agnosia, the inability to recognize objects while at the same time displaying excessive responses to visual stimulation (hypermetamorphosis). The animals also demonstrated a significantly increased tendency to orally examine objects (hyperorality) and heightened sexual responses.
The syndrome was first described in humans in 1955 by Sergio Dalle Ore and a colleague following a temporal lobectomy in a male being treated for epilepsy. Symptoms largely followed those previously observed by Kluver and Bucy in monkeys and are still considered valid for the diagnosis of the illness. Specific characteristics of the syndrome in humans include auditory, tactile, or visual agnosia; the inability to recognize familiar objects including other persons (psychic blindness); hyperorality; the examination of objects orally rather than visually; docility; complete lack of aggressiveness sometimes termed as placidity; and changes in diet that can include either overeating or the eating of inappropriate objects (hyperphasia). Hyperphasia has been reported to take the form of not only placing in the mouth unusual foods but also placing in the mouth dangerous objects such as cigarettes, razors, and nails or even excrement. Altered sexuality, attempting to achieve sexual satisfaction not through intercourse or masturbation but through comments or touching, has also been observed in persons diagnosed with Kluver-Bucy syndrome. Humans generally do not exhibit all the characteristics of the syndrome, with diagnosis based upon manifestation of three or more of these symptoms.
The underlying basis for the syndrome remains unclear. Kluver-Bucy syndrome may be triggered by damage either to the or within the amygdala, the frontal portion of the temporal lobes. The function of the cells that constitute the includes production of a variety of neurotransmitters; the initial studies carried out by Kluver and Bucy that resulted in the description of the condition had involved investigation of the effect of mescaline on this region of the brain. Kluver-Bucy syndrome has been triggered by pathological conditions associated with, or secondary to, more than fifty different conditions, including encephalitis, strokes, tumors, and dementias such as Alzheimer disease or Pick’s disease.
Specific diagnosis beyond the appearance of behavioral changes has been difficult and controversial. Radioimaging studies as well as positron emission tomography (PET) scans have shown the presence of damage to neural connections within the amygdala as well as other regions in the temporal lobes. The issue has been controversial, however, since not all patients diagnosed with the syndrome exhibit such changes or the presence of lesions.
Treatment and Therapy
Few effective treatments have been described. However, the use of anticholinergics, drugs that inhibit the activity of the acetylcholine, have shown some success in causing of the syndrome. Several studies have reported that treatment of patients with carbamazepine, an and prescribed for treatment of seizures that have their origin in the trigeminal ganglia region, has had some success, particularly in adults.
Treatments have also been directed toward the functioning of the amygdala directly. The region is associated with cognitive recognition and social behaviors, the result of its interconnections with other regions of the of the brain. The amygdala is characterized by neural interactions involving the neurotransmitter serotonin. Inhibitors of uptake have shown some success in addressing the syndrome. This class of drugs has been categorized as selective serotonin reuptake inhibitors (SSRI) and includes at least eight major categories of drugs. SSRIs are frequently prescribed as antidepressants, and they function to increase serotonin levels within the nerve synapse, with the result that neurotransmitter action on nerves is increased.
Perspective and Prospects
No cure for Kluver-Bucy syndrome currently exists; fortunately, the syndrome is a relatively rare disorder with no more than several hundred cases being reported since it was first described in humans in 1955. Furthermore, Kluver-Bucy syndrome manifests itself in behavior difficulties rather than in life-threatening conditions. Therefore, management of the problem is the primary means of dealing with the condition. Since the syndrome most commonly manifests itself in the aftermath of other diseases or difficulties, prevention of the condition is indirect, reflecting the elimination or prevention of other underlying causes. They include recognition and rapid treatment of the causes of or intervention during birth to address conditions that may result in oxygen deprivation (hypoxia).
Rare cases may evolve into Korsakow syndrome, a disorder characterized by significant encephalopathy. Korsakow syndrome is generally observed only among alcoholics.
Bibliography
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