Neurosurgical Interventions in Psychiatric Disorders

Neurosurgical Interventions in Psychiatric Disorders: A Review

Abstract

Neurosurgical interventions are being considered for treatment-resistant psychiatric disorders.
These interventions include neuromodulation-based surgeries, such as deep brain stimulation (DBS), and ablative surgeries, such as cingulotomy.
Conditions treated include PTSD, depression, schizophrenia, OCD, anxiety and substance use disorder.
Psychosurgery has been controversial due to concerns about patient well-being.
Recent studies suggest symptom improvement and overall safety.
Neuromodulation techniques have become more sensitive and can target specific brain regions.
Side effects such as memory loss and seizures have been reported.
Ablative therapies are considered invasive.
These procedures are often a last resort, highlighting the need for continued research.
The review examines the history of neurosurgical interventions for psychiatric disorders and implications for clinical practice.

Introduction and Background

Psychosurgery involves physically altering the brain to alleviate mental disorders, dating back to the Stone Age.
Trephination, the earliest psychosurgical procedure, involved scalp incisions and drilling holes in the skull to release evil spirits.
Trephination was practiced from 5000 BC until the Renaissance.
The decline of trephination coincided with the development of antipsychotic medications during the 18th and 19th centuries.
Studies during this period by Wernicke and Broca, also saw the rise of the idea that distinct areas of the brain are responsible for specific functions of the body and laid the foundations of modern psychosurgery
Advancements in pharmacological treatments for psychiatric disorders like OCD, depression, anxiety, and schizophrenia have been made.
However, many patients remain resistant to treatment.
Neurosurgical interventions have grown in popularity, especially for patients with pharmaceutical treatment-resistant psychiatric disorders.
Modern psychosurgery includes:
- Ablative neurosurgery: targeted lesioning of neural circuits.
- Neuromodulation-based procedures: Deep brain stimulation (DBS), transcranial magnetic stimulation (TMS), and electroconvulsive therapy (ECT).
Neuromodulation techniques modulate dysfunctional neural pathways without causing permanent damage.
These techniques are considered safer and more effective, offering reversible and adjustable intervention.
Historically, neurosurgical interventions were frowned upon due to side effects, complications, and lack of research and oversight.
In the present era, neurosurgical interventions have been improving and transforming toward a more educated direction with consideration of patient safety.
This review discusses the relationship between neurosurgical interventions and their efficacy in symptom management of psychiatric disorders.
The objective is to share the latest findings, clinical objectives, and achievements in this topic.
The review also aims to identify gaps in current knowledge for improving psychiatric patient care and the potential use of neurosurgical interventions.

Review

Epidemiology

Psychiatric illnesses are a major challenge worldwide.
Approximately 25% of patients in the US are diagnosed with psychiatric illnesses.
About 20%-60% of patients with psychiatric disorders are battling with pharmaceutical treatment resistance.
In 2019, $106.5$ billion was spent to treat psychiatric disorders in adults aged 18 and older in the US.
These disorders affect daily living, interpersonal relationships, finances, and overall quality of life.
Medication and behavioral therapy fail to alleviate symptoms in around 10%-25% of people with mental illness.
20%-30% of people with schizophrenia would have healthy lives due to their resistance to antipsychotic medication.
One percent of young women suffer from anorexia nervosa (AN), which has the highest mortality rate of any mental illness.
About 10,000 leucotomies were carried out in the United States and the United Kingdom before psychiatric medications were available.
This number had increased significantly, and there were over 60,000 operations performed a few years later.
Within the first year of chlorpromazine's launch in 1954, the medicine was administered to almost two million patients.
The yearly number of ablative procedures performed in the United States has dropped below 15 in recent years.

Etiology

The understanding of mental disorders remains a challenge.
The origins of many mental health disorders are complex and involve both genetics and environmental factors.
Genetic factors may account for around 80% of schizophrenia cases.
Environmental variables linked to schizophrenia include maternal infection, malnutrition, and urbanization.
Structured narratives have been used to shed light on OCD, anxiety disorders, and depression.
The susceptibility of anorexia nervosa (AN) to hereditary factors is significant.

Pathology

New diagnostic tools and data combination have improved our understanding of brain anatomy and physiology.
Diagnostic methods include electroencephalography (EEG), functional magnetic resonance imaging (fMRI), transcranial magnetic stimulation, and positron emission tomography.
These methods provide a foundation for targeted neuromodulation surgery and a better understanding of brain processes in mental illnesses.
Abnormal connections between the brain's cortex, striatum, and thalamus are the cause of obsessive-compulsive disorder.
The corticostriatal pathway, crucial for motor control, habit formation, and cognitive functions, is dysregulated in OCD.
The striatum sends projections to the thalamus through the indirect pathway, involving structures such as the globus pallidus externus and subthalamic nucleus, which modulate thalamic output to the cortex.
These thalamocortical loops, which are important for integrating sensory and motor information, may be disrupted in OCD, contributing to the characteristic compulsive behaviors
Structural abnormalities, including reduced integrity in the genu of the corpus callosum, have been observed in both schizophrenia and depression, which disrupt interhemispheric communication between the frontal lobes.
These changes are linked to impaired cognitive and emotional regulation, with altered functional connectivity contributing to symptoms such as cognitive deficits in schizophrenia and emotional dysregulation in depression.
Anxiety disorders may have their roots in the medial cingulate cortex, a key region involved in emotional regulation and cognitive control.
Altered activity and connectivity in the mid-cingulate cortex (MCC), particularly in its role in threat detection and response inhibition, are thought to contribute to the heightened emotional sensitivity and impaired coping mechanisms seen in anxiety disorders.
An established target for neuromodulation in obsessive-compulsive personality disorder (OCPD) and depression is the inferior thalamic peduncle (ITP), which connects the thalamus to the orbitofrontal cortex.
Modulation of the ITP can help restore balance in neural circuits related to compulsive behaviors in OCPD and depressive symptoms.
Surgical intervention is considered for severe psychiatric disorders unresponsive to standard therapies such as psychotherapy, pharmacotherapy, and electroconvulsive therapy.
Common procedures such as cingulotomy, subcaudate tractotomy (SCT), capsulotomy, and limbic leucotomy (LL) show response rates ranging from 35% to 65%, with modern techniques reducing complications.
Conditions often targeted include treatment-refractory major affective disorders, obsessive-compulsive disorder, and chronic anxiety states.
Surgical intervention should be part of a comprehensive treatment plan and conducted by a specialized multidisciplinary team including neurologists, neurosurgeons, and psychiatrists.

Augmentation Strategies

Clinicians typically use a combination of therapies, including medication adjustment, psychotherapy, and somatic treatments like electroconvulsive therapy (ECT).
Augmentation strategies are considered when patients fail to respond adequately.
These strategies involve adding another medication or therapy to the existing regimen.
There is growing interest in early augmentation for faster symptom relief and functional recovery.
Early use of repetitive transcranial magnetic stimulation (rTMS) has shown promise in reducing depressive symptoms.
Electroconvulsive therapy (ECT) has been favored for augmenting pharmacotherapy in conditions such as schizophrenia.
Recent evidence suggests minimal cognitive impact and potential cognitive improvement with ECT.
Early intervention, including ECT, may improve outcomes in first-episode psychosis and shorten untreated illness duration in depression.
Neuromodulation techniques such as transcranial direct current stimulation (tDCS) have also shown efficacy as augmentation strategies, particularly in reducing symptom severity.
Early augmentation presents challenges such as increased costs and potential side effects but holds promise for hastening symptom relief and improving overall outcomes.
Extensive research is needed to better understand the role of early augmentation in psychiatric care.

Neurobiological Effects of ECT

ECT's neurobiological effects stem from its modulation of cortical activity, particularly in the prefrontal and temporal lobes.
Recent advances in imaging have made it possible to identify three distinct phases of ECT:
- Ictal phase: increased cortical blood flow, glucose metabolism, and oxygen intake.
- Post-ictal phase: brain glucose metabolism and blood flow decrease, connected with ECT's effectiveness in treating depression.
- Inter-ictal period
ECT increases neurogenesis in multiple subfields, including the dentate gyrus (granular and molecular cell layers), the subiculum, and the cornus ammonis.
The stronger the ECT dosage, the larger the volume rise

Patient Outcomes Following Neurosurgical Interventions

Treatment-Resistant Depression (TRD)

Neurosurgical interventions have led to a variety of results in patients facing various psychiatric pathologies.
Daily transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (DLPFC) has over a 50% improvement in their baseline when using the Hamilton Rating Scale for Depression scores.
TMS is used worldwide and is generally tolerated well by patients.
TMS requires multiple sessions over 3-6 weeks, making it difficult to implement.
A new protocol from Stanford University known as the SAINT protocol has been found to achieve faster remission following TMS therapy.
Epidural cortical stimulation (EpCS) has been explored as a potential TRD treatment option.
Patients had bilateral paddle leads placed epidurally over Brodmann area 10, which is the frontopolar prefrontal cortex, and area 46, which is the dorsolateral prefrontal cortex.
This method is potentially safer than DBS because DBS requires the insertion of leads directly into the brain tissue.
The study consisted of six participants originally, but one patient decided not to continue prior to implantation, so in total, there were only five participants.
All participants were unemployed, and three of them were on disability.
It had four women and one man; three women had MDD, and two had bipolar affective disorder I, depressed type.
Prior to the insertion of the leads, the patients scored 20 or more on the Hamilton Rating Scale for Depression and post the 2-3-week implantation time frame.
After the leads were inserted, the patients recovered for 2-3 weeks, and they received a 20-minute psychological screening prior to the leads being activated.
The patients had to follow up for seven months, and it was found that the patients had over 50% improvement on average in their depression compared to their status preimplantation, and 80% of the cohort obtained remission.
Remission for these patients was maintained at three and five years post-EpCS, which makes EpCS a great potential treatment modality.
Deep brain stimulation (DBS) is another treatment modality for TRD.
It is invasive and involves the insertion of intracranial leads stereotactically.
In DBS that targets the nucleus accumbens, approximately 40%-45% of the patients showed over a 50% decrease in their depression symptoms.
For patients who received ventral striatum/capsule DBS, studies at 12 months found a 53% response rate, and at around 37 months, a 71 % response rate.
Subcallosal cingulate (SCC) cortex DBS studies showed a response rate of over 60%.
There was a multicenter follow-up trial that demonstrated a 29% response rate at 12 months, while a follow-up single-blinded study showed a response rate of 98% and a rate of remission of 58%.
The difference in these follow-up trials could be due to a higher stimulation intensity of 6-10 mA, while the multicenter trial utilized an intensity of 5.2 mA.
These follow-up trial results then led to the BROADEN trial, which was a randomized SCC DBS multicenter trial.
The patients were divided into two groups, had bilateral SCC implantation, and received DBS treatment for six months or sham treatment.
At six months, no differences were noted, and the study was dismantled, but they did follow the participants for 2-8 years and found that the response rate rose to 81% and the remission rate rose to 54%.
These results thus demonstrate the potential of DBS and the need to possibly take an individualized approach due to the heterogeneity of psychiatric pathologies.
Although DBS has potential therapeutic use for TRD, its results have not been reproduced in randomized clinical trials.
In open-label investigations, DBS has shown some potentially promising results.
Some studies have tested magnetic resonance-guided focused ultrasound (MRgFUS) anterior capsulotomy (AC) on treatment-resistant depression.
There has been a reluctance to use invasive procedures such as anterior capsulotomy because of the potential damage to cognition.
The MRgFUS procedure uses ultrasonic waves to create lesions, which allows clinicians to perform anterior capsulotomy with a lower risk of infection and hemorrhage, with less ionizing radiation, thus making the procedure a lot safer.
They found that at six and 12 months, the memory, executive function, and processing of the patients improved.
Depressive symptoms in these patients were assessed using the Hamilton Rating Scale for Depression.
At six months, none of the patients showed a 50% or more increase from baseline.
At 12 months, only one patient showed a 50% or more increase from the baseline.
They also found that the patient's clinical symptoms improved when there was improvement in self-reported measures of disinhibition and apathy.
Overall, it was concluded that this treatment method is safe for these patients and does not have a dire impact on their cognition.

Alcohol Use Disorder (AUD)

Neurosurgical techniques have also been used to address alcohol use disorder.
Both invasive and non-invasive repetitive transcranial stimulation that focus on the prefrontal cortical areas as well as the basal ganglia systems are tolerated by patients and are deemed safe.
They also show positive potential in the management of alcohol craving and consumption in patients.
The best modality for severe life-threatening forms of AUD is invasive deep brain stimulation, while non-invasive DBS (rTMS and transcranial direct current stimulation (tDCS)) should be used for less severe forms.
To ensure that deep brain stimulation is efficient in the AUD patient population, it is important that the patients are characterized well in regard to their clinical characteristics such as their cravings and consumption levels, which will allow more reliable comparisons between studies.
Also, outcome measures and the criteria used in evaluation need to be made clear, and cravings for alcohol should be the criteria used to determine the efficacy of the trial.
Finding a method that is reliable to determine baseline cravings and post-treatment cravings is essential to make comparisons across studies.
It has been difficult to determine the main target in neuromodulation for AUD, so it is important to find a way to choose adequate targets such as the dorsolateral prefrontal cortex (DLPFC), the dorsal striatum, or another brain region.

Post-traumatic Stress Disorder (PTSD)

In patients suffering from PTSD, different studies have been conducted to see the therapeutic effects of different neuromodulation techniques on the pathology.
One of the techniques is transcranial magnetic stimulation, which is non-invasive, and studies have shown that it reduces PTSD symptoms, especially when a lower frequency stimulation of one or less is used.
The studies were conducted on patients with various types of trauma, such as sexual violence, vehicle accidents, and combat.
The patients were also mostly male, and their ages ranged from 18 to 75 years old.
Another method used to treat PTSD was the dorsolateral prefrontal cortex stimulation.
What researchers found was that patients had a larger therapeutic effect when treated with right DLPFC stimulation instead of left DLPFC, and no changes were observed when researchers compared right DLPFC to bilateral DLPFC.
When TMS was combined with psychotherapy, the patients experienced significant improvement.
The TMS patients also had very mild side effects such as insomnia, headache, and mood disturbances, which were addressed with pharmacotherapy.
Only in four instances, the patients experienced severe effects such as homicidal ideation, subconjunctival hemorrhage (the patient had a history of ocular disease), and generalized tonic-clonic seizures.
Transcranial direct current stimulation has also shown signs of clinical efficacy, but there are fewer studies that have focused on this technique's impact on PTSD.
A pilot study from 2015 found that tDCS has a positive impact on emotional and cognitive performance.
Another study assessed ventromedial prefrontal cortex tDCS and found it to be more effective in extinction consolidation than when combined with extinction learning.
With tDCS combined with DLPFC, it was found that patients experienced a reduction in their anxiety, depression, and PTSD symptoms after their treatment was over and when followed up one month later.
The tDCS studies recruited only patients who obtained PTSD from combat, and most of them were men between the ages of 20 and 69 who also had other comorbidities such as anxiety disorder and depression.
Deep brain stimulation, which has been used mainly for movement disorders, was used to treat combat-acquired PTSD in a 48-year-old male patient.
He received bilateral DBS to his basolateral amygdala, which resulted in a 35% symptomatic improvement after receiving this treatment for eight months.

Eating Disorders

Eating disorders such as anorexia nervosa have also been a target of neuromodulation studies.
It was found that DBS and other types of ablation demonstrate possible efficacy, but the current studies used small sample sizes and a short follow-up period.
Non-invasive methods such as tDCS and rTMS have shown a variety of results, which is due to the inability to generalize data since the studies had a range of methodologies such as case series and open-label studies.
These studies focused on different areas in the brain and used different intensities during the treatment regimen.
Patient characteristics varied across studies, such as their ages, previous treatment history, and illness duration.
In regard to weight changes, studies showed a large increase in weight with stereotactic radiofrequency (RF) ablation, but the issue is that these studies did not follow the standardized guidelines when they selected patients for neurosurgical procedures.
These studies utilized adolescents and young adults who did not have severe anorexia nervosa and who did not exhaust other psychosocial treatment modalities prior to them doing the neurosurgical option.
The studies did not document psychological symptom outcomes in these neurosurgical trials, despite the fact that patients with anorexia nervosa who pursue rapid weight loss also tend to have inhibition of their appetite and phobia related to anxiety.
More research is needed to obtain more reliable statistics for the use of these techniques in patients with anorexia.

Obsessive-Compulsive Disorder

Another pathology that has been targeted by neurosurgical modulation is obsessive-compulsive disorder (OCD).
Deep brain stimulation has been used in clinical studies to address OCD.
DBS is usually conducted in a continuous fashion, but it can be programmed to provide stimulation at certain intervals, which is the cyclic method.
A study explored the experiences of individuals with obsessive-compulsive disorder (OCD) following a positive response to deep brain stimulation (DBS).
By integrating preexisting cognitive models of self-constructs and dysfunctional beliefs, new insights into the rich, phenomenological nature of DBS-assisted OCD recovery were offered.
Additionally, caregivers provided their perspectives, and the challenges faced during the recovery process were discussed.
The findings highlighted the importance of considering patient education, DBS effectiveness evaluation, and complementary psychotherapy models.
A comprehensive, patient-specific, multidisciplinary adjunct program is essential for accurately assessing the effectiveness of DBS in treatment.
There was a study that observed the impact of capsulotomy, limbic leucotomy, and cingulotomy in treating OCD.
A review on observational studies that focused on the effect of capsulotomy on OCD at 12-month follow-up found that the average reduction in symptoms using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score and the full response rate (35% or more reduction on the Y-BOCS) were 37% and 41%.
A meta-analysis that focused on the impact of neuroablation on OCD showed that at the last follow-up, the response rate was 55%.
The observed response rates (35% or more reduction on the Y-BOCS) for cingulotomy, limbic leucotomy, and capsulotomy were 36%, 47%, and 59%, although there was some heterogeneity between the surgical groups, and the differences were not significant.
The most common adverse effects reported by the patients were cognitive deficits, behavioral problems, and postoperative headaches, although these were mild and transient.

Safety and Monitoring of Neurosurgical Interventions for Psychiatric Disorders

Patient safety and ethical consensus are crucial when considering surgical interventions for psychiatric disorders.
Obtaining informed consent is an important ethical consideration, especially for patients with psychosis or severe mental health issues who may have impaired capacity.
Special attention must be given to ensuring that patients are adequately informed, and the involvement of family members, caregivers, or mental health professionals may be necessary.
While medical management of psychiatric disorders through pharmaceuticals and psychotherapy has been relatively well studied, the role of neurosurgical management has been considered experimental.
Given the historical lack of precautions and high complication risk associated with psychosurgery, there is a need for robust research to solidify neurosurgery's reputation in the treatment of psychiatric disorders.
However, due to the limitations of certain drug compounds and psychiatric treatments, there is a rising consideration of surgical alternatives.

Safety Considerations

Two broad types of psychosurgical approaches to consider:
- Neuromodulation-based procedures (functional or stereotactic neurosurgery).
- Ablative neurosurgery.

Safety Considerations in Neuromodulation-Based Neurosurgical Procedures

Neuromodulation therapies, also known as stereotactic and functional neurosurgery, are minimally invasive surgical procedures that incorporate advanced neuroimaging techniques and technologies of the brain-computer interface.
Examples include deep brain stimulation, transcranial magnetic stimulation, and electroconvulsive therapy.
Given the technologically reliant nature of neuromodulation-based surgeries, these therapies have been of more recent development and continue to be optimized with the advancement of new imaging and surgical tools.

Deep Brain Stimulation

Deep brain stimulation (DBS) has been used in the treatment of a multitude of psychiatric disorders such as treatment-resistant depression, obsessive-compulsive disorder, and anxiety disorders.
DBS is considered minimally invasive and only requires a 10 cm incision in the skull, unlike other "open-skull" neurosurgical interventions.
Despite this seemingly low risk of complications, a study demonstrated that DBS procedures still carry the potential for both short- and long-term consequences.
- 0.5% faced asymptomatic intracerebral hemorrhage.
- 3.4% faced asymptomatic intraventricular hemorrhage.
- 1.7% had decreased consciousness.
- 1.1% of patients faced hardware discomfort.
- 1.4% had a decrease in the desired effect of the procedure.
Practicing neurosurgeons utilizing DBS procedures need to plan for potential complications and find ways to map the patient's neuroanatomy before surgical entry.
Advancements in Doppler and fMRI-based scanning tools have made this feasible.
It is integral to find ways to monitor patient outcomes after they have left the hospital back into their homes.
New passive technologies such as smartphone pupilometers are being introduced to bridge this gap in neurosurgery.
Virtual "telehealth" appointments also offer more accessible means of contacting patients post-surgery and allow for the evaluation of patient concerns and outcomes.

Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is a procedure that is commonly used in the treatment of severe obsessive-compulsive disorder, medication-resistant depression, aggression, and schizophrenia.
Since ECT was introduced as one of the first functional neurosurgical procedures, there have been a lot of optimizations that have drastically improved patient outcomes.
In a recent study, 804 different routine ECT procedures were studied, and there were no severe negative outcomes documented.
Minor side effects such as agitation and urinary stasis decreased significantly when the surgical team employed certain "pre-procedural maneuvers" such as manually holding the chin and closing the patient's mouth when delivering electrical stimuli.
ECT has shown to be a viable procedure in pregnant individuals who are negligent to take medications due to potential side effects.
Using similar ECT maneuvers in adolescent patients resulted in highly effective treatment of psychiatric disorders as well as a significant reduction in adverse effects.
The most commonly associated adverse effects of ECT were short-term memory loss, headaches, muscle aches, confusion, nausea, and cardiovascular fluctuations, especially without optimizations such as anesthesia.
It may also pose rare risks such as prolonged seizures.
Despite the common surgical risks associated with elderly patients, performing ECT on them (with comorbidities) has also shown to be relatively safe.
When compared with other procedures, there is no need for anesthesia.
ECT has shown to not only be effective at treating psychiatric disorders at a wide age range but has also evolved into a safe procedure with minimal to null risk of complications when performed correctly.

Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) uses electromagnetic forces to stimulate specific regions of the brain through a changing magnetic field.
TMS is the least invasive functional neurosurgical approach.
It has shown to be effective at treating epilepsy, depression, OCD, migraines, and smoking cessation.
Although TMS is a relatively recent innovation in the field of functional neurosurgery, there has been a growing amount of literature surrounding the safety and efficacy of the novel procedure.
TMS had negligent side effects and was safe for use in a wide age range like ECT.
Even with repeated and consistent TMS use in patients, the most common complications were relatively benign and rare, such as transient headaches, mild pain in the site of stimulation, and involuntary muscle contraction, which all resolved quickly.

Safety Considerations in Ablative Neurosurgical Procedures

Ablative techniques are primarily used to selectively excise lesions of dysfunctional brain tissue in the hopes of recovering the connectivity within healthy brain matter.
Various psychiatric illnesses have been approached through the lens of ablative neurosurgery, such as major depressive disorder (MDD), obsessive-compulsive disorder, and addiction.
Although ablative neurosurgical procedures were deemed "crude" and lost credibility during the mid-1900s, recent advances in neuroimaging technology have brought back interest in these procedures.

Anterior Capsulotomy

Anterior capsulotomy (AC) is primarily a well-established procedure in the treatment of severe OCD.
This procedure involves excising a lesion in the anterior limb of the brain's internal capsule, which is involved in the transmission of information to and from the cerebral cortex.
The use of AC as an OCD treatment plan projected a full response rate (measured by a clinically significant reduction in OCD symptoms after procedure) of 54%, with a transient and permanent rate of adverse event of 56.2% and 21.4%, respectively.
These adverse events were considered mild in nature and were characterized by headaches and pin-site swelling.
Another clinical outcome study also indicated AC to be more safe and effective when performed bilaterally on both sides of the brain.
The anterior limb of the internal capsule (ALIC) has an important function in the limbic system, which requires the involvement of both hemispheres of the brain
AC was indicated to be a viable, safe, and long-lasting operative procedure for patients with OCD as well as MDD.
Most recently, MRI guidance was used to safely perform AC in four patients with refractory OCD and in one patient with MDD, successfully controlling symptoms for both indications.
AC involves little to no risk to the patient.

Subcaudate Tractotomy

Subcaudate tractotomy is an ablative neurosurgical approach that involves selectively removing white matter tracts that connect the limbic structures and orbitofrontal cortex.
This procedure has changed significantly since its ideation due to the development and introduction of radiofrequency ablation procedures in medicine and neurosurgery.
After adopting the RF approach, SCT has become relatively free from complications.
For example, in a study by Patel et al., out of over 660 individual cases of SCT, one patient passed away due to unrelated factors and 1.6% of patients experienced mild episodes of epilepsy as the most common complication.
SCT is also a procedure that has been shown to have a higher level of safety when performed using image guidance.

Limbic Leucotomy

Limbic leucotomy is a neurosurgical technique that involves removing sections of the anterior cingulate cortex and the subcaudate area of the patient's brain.
It was originally the primary surgical treatment modality for MDD and OCD, and it continues to remain a treatment option when patients do not respond to anterior cingulotomy alone.
LL has had tremendous improvements in safety through the developments in neuroimaging, which have reduced the rate of complications substantially.
Adverse events associated with LL are transient hallucinations, amnesia, and mania, which are all, as expected, associated with signaling through the limbic pathway.
Although there are potential side effects associated with LL, most of these complications are quickly resolved and short-term.
The only complication that seems to be longer-term is abulia or the lack of motivation (although this is self-limited).
Patients with schizophrenia who underwent LL not only had a significant reduction in symptoms but had minimal side effects that transiently diminished postoperatively.
LL is a procedure that has faced tremendous growth in safety and monitoring measures, which has allowed for effective treatments and positive patient outcomes.
There has been tremendous growth in the safety considerations and efficacy of psychiatric neurosurgical procedures with vast improvements in ablative techniques and advancements in modulation techniques.
The success in utilization of these procedures is not only reliant on the experience of the clinician but also on ensuring that the respective patient is an excellent candidate to endure the recovery process associated with the operation.
Another important procedural consideration to ensure positive outcomes is following established standard-of-care approaches and avoiding risky techniques that may jeopardize the operation.

Future Directions

Neurosurgery for psychiatric disorders is gradually moving toward a safer and more educated direction, through research and technological advancements around the world.
An area of limited study is the lack of insufficient reliable neural biomarkers that have the potential to catch psychiatric disorders at an earlier time point and allow for more minimally invasive surgical options.
Potential electrochemical and physiological markers have been indicated by recent studies, and further research is warranted to validate the efficacy of using these markers in the clinical arena.
Scalp electroencephalography, stereo-EEG, magnetoencephalography, and electrocorticography are examples of local field potential data, which can be used in the comprehension of differences correlated to internal emotional states.
Artificial intelligence technologies are being developed and applied extensively to analyze this data at a more rapid pace.
There is a lot of research on invasive neuromodulation that has engaged in open-loop neurostimulation.
One of the examples is conventional DBS, which stimulates continuously.
Low-frequency signals will trigger only nucleus accumbens stimulation during craving periods and were proven by recent obesity trials.
Studies have also shown that closed-loop neurostimulation combats treatment-resistant depression by focusing on brain regions using machine learning analyses.
Private sector involvement has also participated in research for potential treatments for mental illness, with recent developments of brain-computer machines from companies such as Neuralink.

Conclusions

The two most prevalent disorders targeted with psychosurgery are OCD and MDD.
With advancements in neuroimaging techniques, knowledge of optimal targets in the brain for psychosurgery has greatly improved.
Stimulation techniques such as DBS, VNS, TMS, and others have gained traction due to the possibility of implanting closed-loop systems.
While neurosurgical management of psychiatric disorders is still considered experimental in many aspects, research and optimization of these procedures around the world have allowed them to gradually move toward a safer, more educated, and more effective direction.