Bilateral temporal lobe lesions (especially with hippocampal damage) cause recent memory impairment and behavioral disturbances. The etiology of temporal lesions may be diverse (eg, trauma, infarction, neoplasm, infection, inflammatory processes, and degenerative disorders such as Alzheimer's disease); however, the clinician needs to be especially cognizant of the possibility of herpes simplex encephalitis (HSE), which causes necrotic, hemorrhagic, and inflammatory changes, usually confined to the temporal region. Although computed tomography (CT), magnetic resonance imaging (MRI), and electroencephalography (EEG) show injury to the temporal region, definitive diagnosis is established only by the finding of the viral antigen in the brain (previously obtained only by biopsy) or by demonstration of viral DNA by the polymerase chain reaction technique. Other infectious (viral, bacterial, fungal, parasitic) and postinfectious encephalitic disorders may cause bitemporal lesions; however, it is crucial to recognize HSE, since this disorder responds to treatment with the antiviral agent, acyclovir. Persistent temporal lobe damage may result in neurologic and emotional disorders. One of the most unique clinical disorders due to bitemporal lesions is the Klüver-Bucy syndrome (KBS).
Klüver-Bucy syndrome was initially described in primates after experimental bilateral temporal lobectomy. The cardinal symptom is excessive oral tendencies in which the primate or patient grasps and brings to their mouth all types of objects (including inedible and dangerous objects). Other features include (1) irresistible impulse to touch objects, (2) placidity (absence of emotional response) in which the patient becomes apathetic and indifferent to emotional stimulus with loss of facial animation (sometimes simulating affective depressive state), and (3) marked increase in sexual activity, with no concern for social appropriateness. Amnesia and aphasia are invariably neurologic symptoms of KBS in humans. In my experience, KBS is not an uncommon disorder in clinical practice, especially after moderate to severe traumatic brain injury and in patients with HSE, especially those who were treated late with acyclovir or were previously treated with less effective antiviral agents. However, KBS frequently is not recognized or is misdiagnosed as a psychiatric disorder. Patients with the clinical features of KBS may be incorrectly diagnosed as having "organic psychoses" or "depression" and be treated with psychoactive medications, which may actually diminish brain recovery.
In this issue of the Journal (page 929), Salim et al report a unique case of KBS in a patient who had mild trauma to the brain (defined as a score of 13 to 15 on the Glasgow Coma Scale). Because the patient was neurologically asymptomatic before the injury, it seems unlikely that the KBS was due to intercurrent neoplasm, infectious-inflammatory disorder, or multiple sclerosis unmasked by the trauma. Since KBS is usually associated with significant pathologic temporal lobe injury, it is important to note that initial CT findings were reported to be normal. Computed tomography is the standard method for demonstrating macroscopic brain trauma, such as contusion or hemorrhage. However, CT is relatively insensitive for demonstrating microscopic disease such as diffuse axonal injury (DAI), which may be caused by rotational acceleration-deceleration head movements in which there is axonal stretching and shearing. Depending on the severity of the trauma, DAI may cause macroscopic or microscopic injury throughout the white matter of the cerebral hemispheres. Macroscopic injury may be detected by MRI, but rarely by CT.
Diffuse axonal injury is an important cause of posttraumatic neurologic disability. In the present case, MRI was done late, presumably because "results of neurologic evaluation were normal except for the odd behavior." Two points in this case need emphasis. First, brain injury may cause focal (as in hemiparesis) or diffuse (as in dementia) neurologic impairment, but behavioral, emotional, and personality change may also be important manifestations of brain disease. (2) In patients who are bilingual, language impairment in the most recently acquired language is an important clue to left hemispheric dysfunction. The patient's change in language should have initiated the need for more complete neuropsychologic testing. These two clues to structural brain injury should lead to early MRI, even when CT is normal.
Patients with the postconcussive syndrome may show both cognitive and behavioral-emotional disorders. This condition is due to physiologic and structural brain injury related to DAI. Clinicians now have the opportunity to demonstrate the anatomy and pathology of DAI using MRI and perhaps in the future will be able to learn about physiologic and biochemical substrates of DAI by using functional MRI, single photon emission CT, positron emission tomography, and MR spectroscopy. This case indicates how even mild trauma to the brain can cause significant neurologic and behavioral disorders.
Since KBS has most commonly been associated with severe brain injury, the clinical outcome has usually been poor. The case described herein shows that this is not invariably true. Although CT is an excellent imaging modality for severe traumatic injuries necessitating emergency intervention, in those patients who have neurobehavioral disturbances after mild brain trauma, we must move beyond CT and use MRI to search for structural brain lesions. This case has important implications for all physicians who treat patients with traumatic brain injury.
South Med J. 2002;95(8) © 2002 Lippincott Williams & Wilkins
Cite this: Klüver-Bucy Syndrome After Minor Brain Injury - Medscape - Aug 01, 2002.