and Peng Li1
(1)
West China Hospital of Sichuan University, Chengdu, China
The etiology of human aggressive behavior has not been elucidated. In clinical practice, the definition of aggressive behavior is as follows: attack to property, others, or oneself with the deliberate intention of destruction. Organic psychosis, schizophrenia, mental retardation, emotional disorders, and personality disorders can be associated with aggressive behavior, and most frequently occur in the acute phase of mental illness [1]. In 1990, a regional epidemiological investigation for violent psychosis in the United States showed that the incidence of aggressive behavior in patients with psychiatric disorders was five times that of normal people. Moreover, 50 % of the patients with psychiatric disorders and 10 % of patients with schizophrenia have histories of making threats, agitation, and aggressive behavior [2]. This aggressive behavior causes serious threat to the safety of medical staff, the whole society, and even to patients themselves.
A variety of drugs have been recommended for the treatment of aggressive behavior , including typical and atypical antipsychotic drugs such as benzodiazepines, mood stabilizing drugs, beta blockers, selective 5-HT re-uptake inhibitors, etc. These drugs have different effects on brain neurotransmitter systems . At present, the knowledge of the etiology of aggressive behavior is limited. Several chemical compounds are supposed to have influence to the aggressive behavior such as 5-HT, dopamine, y-aminobutyric acid (GABA), norepinephrine and other neurotransmitters [1]. However, the detailed mechanism underlying aggressive behavior is still unclear. Current neurophysiological research on the management of large numbers of patients with schizophrenia accompanied by agitated and aggressive behaviors is limited. Although improvement of aggressive behaviors with medication can be observed, the efficacy is still not ideal in many cases. Thus, surgical management may be a possible choice for carefully selected patients.
From 1935 to 1937, Moniz and Lima first reported successful results of bilateral frontal lobe lobotomies for the treatment of mental disorders. The main purpose of the treatment was to improve impulse, violence, and difficultly controlled behaviors. Based on their results, they proposed the “psychosurgical method” for treating certain cases of mental disorders [3, 4]. In 1947, with the help of the stereotactic technique, the mediodorsal thalamotomy was successfully completed by Wycis and Spiegel to treat patients with serious mental disorders. This new surgical approach resulted in smaller regions of damage, which helped to reduce the side effects of surgery. Moreover, patient disabilities and the number of mortalities were significantly reduced. In recent years, along with the development of clinical psychiatry, neurophysiology, neuroanatomy , imaging techniques, and functional neurosurgery, more attention has been paid to psychosurgery by clinicians [5].
Mental and behavioral disorders associated with aggressive behavior can be observed in patients with schizophrenia, schizoaffective disorder , mental retardation, personality disorders, and other psychiatric illnesses. For serious medically refractive patients with aggressive behavior, inclusion criterion for surgical management may be suggested as: (1) confirmed diagnosis by more than two psychiatrists, (2) at least 6 weeks of failed medication with more than three kinds of drugs with normalized psychological management that cannot relieve symptoms, (3) more than 5 years of disease history, (4) patients between 18 and 75 years old (for stereotactic surgery or radiosurgery treatment). However, for patients with severe mental retardation, considering the serious influence on daily life and with behavioral training being conducted soon after the operation, surgery can be carefully considered when the patient is more than 10 years old. (5) Behavior has seriously influenced the patient’s ability to lead a normal life and does harm to the patient and his/her family members, (6) families and patients can accept the risk of operation, and can keep up subsequent treatment and long-term follow-up.
The following patients should be excluded from receiving psychosurgery: (1) patients whose age does not conform to the inclusion criteria, (2) those with disease duration of less than 5 years, (3) those with lack of normative medication, psychological treatment, and/or hospitalization, (4) patients with some accompanying bodily disease such as: infectious disease, metabolic disease, frailness, seriously high blood pressure, heart disease, and/or severe pathological brain disease, (5) patients whose psychosurgical targets have been damaged, (6) those with other bodily reason that impedes proper implementation of the surgery, (7) those refusing treatment (with the exception of mental disorder without self-knowledge), (8) lack of good family support, since postoperative follow-up would not be guaranteed and post-surgical management would be difficult, (9) conflicts with the law, ethics, politics, and/or religion [6, 7].
For patients that meet the standards of psychosurgery, psychiatrists and neurological surgeons should again carefully evaluate the condition of the patients before the operation. This should include assessments of a patient’s diagnosis and previous drug and psychological behavior treatment, judgment of patient and family expectations, status of support and supervision, and whether the procedure would comply with the country’s ethics and laws. Relevant preoperative examination, neural electrophysiological, image and psychological measurement are also important for preparation of the operation. Good cooperation between doctors, patients, and their families helps to have better disease improvement.
The theoretical basis of modern psychosurgery considers that human mental processes are extremely complex. Although the specific anatomical structure related to mental disorders is yet to be clarified, the limbic system and its connected structures are thought to have close relationship with a human’s mental activities. The anatomy and theoretical basis of modern psychosurgery mainly concentrate on three circuits of the human limbic system: the internal and lateral circuits, and the defense reaction circuit. These structures have complex connections to the basal ganglia and frontal lobe, which are closely related to mental activities such as emotion and motivation [8].
(1)
The internal circuit of the limbic system, which was first reported by Papez in 1937, begins at the septal area and passes through the cingulate gyrus to the hippocampus, via the mammillary body. It then runs again from the mammillary body-thalamus access to the anterior nucleus of the thalamus, and then back to the cingulate gyrus.
(2)
The lateral circuit of the limbic system, which was first reported by Yakovlev in 1948, contains fiber tracts that originate in the orbitofrontal cortex, the insular lobe, frontal temporal lobe, and amygdala. These fiber tracts project to the mediodorsal thalamic nucleus, and then run back to the orbitofrontal cortex.
(3)
The defense reaction circuit of the limbic system, which was reported by Kelly, originates from the hypothalamus via the stria terminalis and runs from the septal area to the amygdala before returning to the hypothalamus [5].
Lesions to the structures of these three circuits and related structures may change brain neurotransmitters, thus achieving the purpose of improving and controlling psychiatric disorders . Operations can be completed under local or general anesthesia. Stereotactic radiofrequency thermocoagulation , stereotactic radiosurgery , and deep brain stimulation are the most popular surgical procedures used to treat psychiatric disorders.
Common surgical targets include the anterior limb of the internal capsule, amygdaloid nucleus, and medial septal area [8–10].
(1)
The anterior limb of the internal capsule contains the efferent fiber tracts of the anterior nucleus of the thalamus and frontal lobe, the frontopontine tract, and the tracts between the orbitofrontal cortex and hypothalamus. Lesions to the anterior limb of the internal capsule aim to cut off the fiber tracts between the thalamus and the prefrontal cortex, which serve to partially interrupt communication between the nucleus medialis thalami and the frontal lobe. An anterior internal capsulotomy has been reported to be an effective treatment option for obsessive-compulsive disorder , anxiety, and phobia in selected patients.
(2)
The amygdaloid nucleus, also known as the amygdala complex, receives afferent fibers from the olfactory bulb and anterior olfactory nucleus, via the lateral olfactory stria. The fibers from the piriform area and diencephalon end in the basolateral amygdaloid nucleus. In addition, the amygdaloid nucleus receives fibers from the hypothalamus, thalamus, brainstem reticular formation, and neocortex. The afferent fibers of the amygdaloid nucleus pass through the terminal stria and septal area, medial preoptic nucleus, anterior part of the hypothalamus, preoptic area, and the anterior commissure. Thus, a portion of the fibers end in the hypothalamus, dorsomedial nucleus of the thalamus, and the midbrain reticular formation, while the other fibers end in the rein nuclear via the stria terminalis. The amygdaloid nucleus still has complex connection to the prefrontal cortex, cingulate gyrus, anterior part of the temporal lobe, and ventral insula. Thus, lesions to the amygdaloid nucleus result in behavior that is mild and calm, with lack of initiative and will. Obvious improvement has been reported following amygdalohippocampectomy for the treatment of mania, aggressive and destructive behavior, and impulsive mood.
(3)
Medial septal area: The nucleus accumbens is located in the septal area, which is divided into interior and lateral part. The interior part is located anterior to the anterior commissure and the lateral part is located posterior to the anterior commissure. The nucleus accumbens is a key part of the Papez circuit and comprises the lateral circuit of the basal limbic system. It is considered by many researchers to be a “relay station” of the limbic system, and has close fiber connections with many structures such as the hypothalamus, mammillary bodies, cingulate gyrus, amygdala, and hippocampus. Lesions to the interior part of the nucleus accumbens have been used to treat behaviors associated with vandalism, associability tension, irritability, and other symptoms. The optimal targets for patients with psychiatric disorders associated with mania, impulsiveness, aggression, self-injury, compulsion , and destruction, are the amygdaloid nucleus, anterior limb of the internal capsule, and medial septal area. Additionally, for the above target behaviors, the nucleus accumbens , cingulate gyrus, and caudate nucleus can be targeted in select patients.
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