Perspectives of neurosurgery for psychiatric disorders

Due to the abuse of psychosurgery in the past, often used indiscriminately and contraindicated (such as performing a lobotomy in a troubled child), it generated absurd rates of morbidity and mortality, causing a strong negative reaction in society [3]. In addition, from the emergence of effective psychotropic drugs, neurosurgical treatment for psychiatric disorders has been practically abandoned for a considerable period [1]. Currently, the procedures, when allowed, are under strict control of the committees of Neurosurgery for psychiatric diseases of referral hospitals and submitted to strict legislation in most countries [4].

Due to the abuse of psychosurgery in the past, often used indiscriminately and contraindicated (such as performing a lobotomy in a troubled child), it generated absurd rates of morbidity and mortality, causing a strong negative reaction in society [3]. In addition, from the emergence of effective psychotropic drugs, neurosurgical treatment for psychiatric disorders has been practically abandoned for a considerable period [1]. Currently, the procedures, when allowed, are under strict control of the committees of Neurosurgery for psychiatric diseases of referral hospitals and submitted to strict legislation in most countries [4].
In Brazil, for example, the legislation requires that all psychosurgeries can only occur with the authorization of the local medical council. This generally is a very time-consuming process, causing difficulty in assisting patients who need the procedure.
Of the ten most disabling diseases in the world, five belong to psychiatry: depression, alcoholism, bipolar disorder, schizophrenia and obsessive-compulsive disorder (OCD) [5]. Unfortunately, no matter how good the quality of care is, there is a group of very serious patients who are refractory to various treatment regimens. For these, the resource of the neurosurgical treatment fits [1].
The psychosurgery has been used primarily in refractory cases of OCD, schizophrenia, depression and aggressive behaviour. Although there are also reports of approaches to addiction disorders, anorexia, among others [3].
The evolution of treatments from grotesque and low discriminated lesions such as lobotomies to stereotactic approaches allowed a better selection of targets of interest with a much lower incidence of adverse effects [6].
In this way, capsulotomy, cingulotomy, subcaudal tractomy and limbic leucotomy are recommended as more usual and adequate approaches. The choice of the site of the brain to be approached is related to the symptomatology of the patient and to the experience of each center with a certain surgical technique [6].
Unfortunately, we have very few RCTs in this area, with the case series of each center predominating. Thus, the level of scientific evidence for the choice of each surgical target for a given disease is limited [7]. On the other hand, with better knowledge of the brain circuits through the advancement of imaging tests, in particular the tractography, it is already possible to carry out studies that allow for predictive results of response, which will make increasingly more based the choices of approach already in the near future from the customization of treatments [8,9]. Four modalities of psychosurgery are currently available: traditional radiofrequency surgery, DBS implantation, gamma knife radiosurgery and ultrasound surgery, the latter being still very restricted [10,11]. Each of these modalities presents advantages and disadvantages with respect to reversibility, onset of action, need for follow-up after the procedure and cost [10].
The DBS arose from the treatment of patients with movement disorders refractory to the usual drug therapy, allowing for very satisfactory improvements when properly indicated. These promising results motivated researchers to use this feature in psychiatric patients, especially with OCD and depression, which were also encouraged at first, but were not as effective after the publication of RCTs [12][13][14].
In fact, perhaps the greatest merit of the use of DBS in psychiatry, because it is a reversible and less stigmatizing procedure, has been to rekindle the interest of researchers and of society as a whole in the subject. Regrettably, we still pay the price for the mistakes of the past, which explains the control that currently exists on these approaches. Perhaps a neurosurgeon will never have as much autonomy to perform a psychosurgery as he has to operate a brain tumour. However, in the future, the "clock pendulum" may go down the middle, and legislation will be less bureaucratic, allowing this important treatment to be offered to a largest number of severely ill individuals.
We also hope that other forms of radiotherapy other than the gamma knife can be used to treat refractory psychiatric patients. Linear accelerator radiotherapy (LINAC), for instance, is already used to perform thalamotomies in patients with a contraindication to DBS or radiofrequency [15]. Because LINAC is much more available and has no further limitations of gamma knife devices, we believe that there is a very promising space in its use in psychosurgery [16].