Laser interstitial Thermal Therapy (LiTT) is a relatively new lesion removal approach aiming to cure neurological disorders that cannot be successfully treated with drugs or other neuromodulation techniques. During the process, thermal doses in the form of laser beams are driven through a small hole in the skull to ablate tissue from precisely demarcated brain areas. LiTT is becoming more popular as it is much safer than the traditional open brain surgery alternatives.
Konstantinos Raktivan, September 2022
Initially, preoperative imaging is used to locate the malfunctioning brain circuit and plan the ablation process. Once the patient receives general anesthesia, a tiny hole is opened in the skull. Through that entry point a thin fiber is stereotactically guided to the target point at the desired depth, avoiding important structures like ventricles or large arteries. As low power laser beams warm up the surrounding tissue for a long period of time (usually 43°C for about 10 minutes), a focused therapeutic lesion is generated and intracranial volumes that occupy critical space are destroyed. MRI thermometry is utilized throughout the process to monitor temperature and the induced damage in real time.
LiTT is suggested when medication is nοt sufficient. It is approved for soft tissue removal and is preferred over other treatment methods in cases of well described, spherical or elongated, deep or otherwise difficult to reach cerebral structures. However, hypervascular or extensive lesions would require multiple ablation stages, with a higher risk of surgical complications.
Several neurological disorders can be cured with the utilization of LiTT, like movement disorders (essential tremor, Parkinson’s disease, dyskinesia, dystonia), psychiatric disorders (obsessive-compulsive disorder, major depressive disorder, addiction, anorexia nervosa, morbid obesity, aggressive and disruptive behavior, Tourette syndrome), chronic pain and brain tumors. Regarding drug-resistant epilepsy, applications are becoming more frequent, especially in cases of structures inaccessible to older techniques, such as hippocampus, amygdala or hypothalamic hamartoma (HH). Likewise, mesial temporal lobe epilepsy (MTLE) is more efficiently cured using this method than anterior temporal lobectomy. Practically, LiTT has been established in the treatment of MTLE and HH.
Absence of open craniotomy in this minimally invasive procedure results in reduced discomfort and shorter hospitalization, while increased reliability is achieved, owing to the real time control of the heat doses supply and the subsequent temperature change. Moreover, damage in the neighboring areas and the risk of postoperative complications in normal functionality are drastically reduced due to precise targeting. Nevertheless, despite the obvious and clear advantages, various complications have been observed, including motor weakness, cerebral edema, hemorrhage and seizures.
Other techniques related to LiTT that allow safer interventions compared to resections are radiofrequency thermoablation (RF), stereotactic radiosurgery (SRS) and the most recent magnetic resonance-guided focused ultrasound thermal ablation. RF and SRS are still in use as a result of long clinical experience.