Combined Lesions Of Temporal And Frontal Lobes

Some pathological processes tend to damage simultaneously multiple levels of neural circuitry critical to the regulation of aggression. The orbitofrontal surface and rostral temporal poles are particularly susceptible in closed head injuries, and conjoint lesions in the same patient are not uncommon. Temporolimbic epilepsy is a frequent sequel of both closed and open head injury.

Aggressive behavioral syndromes may result that have features associated with dysfunction of several brain regions. For example, as a result of brain trauma, a patient may, develop a temporolimbic epileptic focus as well as a contusion of the orbital frontal cortex. Such a patient can display the deepened emotions and anger associated with the interictal behavior syndrome as well as a failure to inhibit or modulate hostile responses typical of a frontal lesion. In one reported case, a young man suffered severe brain injury in a motor vehicle accident. Imaging studies demonstrated enlargement of the frontal and temporal horns of both lateral ventricles and EEG abnormalities were recorded over the right frontotemporal area. The patient displayed intermittent apathy suggestive of frontal lobe damage but also developed personality changes characteristic of the interictal behavior syndrome of temporal lobe epilepsy. He had outbursts of extremely violent behavior and eventually attempted to murder his parents and former girlfriend. When questioned regarding his aggression, the patient failed to appreciate that his behavior might be distressing to others. PET studies provide further evidence for frontal and temporolimbic dysfunction in psychiatric patients and in violent criminals. In one study of eight repeatedly violent psychiatric patients, low metabolic rates were noted in prefrontal and medial temporal cortices. Similarly, in a study of 41 murderers, reduced glucose metabolism was noted in the prefrontal cortex, superior parietal gyrus, left angular gyrus, and corpus callosum, and reduced left hemisphere activity compared with right hemisphere activity was noted in the amygdala, thalamus, and medial temporal lobe. These differences were particularly pronounced among individuals classified as having performed affective, impulsive violence compared with planned, predatory violence.

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