Innovations, advances, and updates in neurosurgery

2.1 Neuroimaging

Structural imaging shows the anatomy of our neurological system reached from current image synthesizer, including computed tomography (CT) and magnetic resonance imaging (MRI). It is practical to distinguish lesions and design treatment plans perioperatively. Nowadays, CT-guide 3D modeling further investigates those obscure anatomical organizations. Recent literatures have also revealed its application in spinal surgery [7]. It can even be integrated with MRI in the management of head injury [8].

Functional imaging, which is mainly used in neuroscience and psychological research, is also gradually being widely used to diagnose certain neurological conditions. Positron emission tomography (PET) is performed to paint the cerebral network changes under metabolic continuity patterns in different neurological disorders [9]. Furthermore, multimodal PET/MRI or PET/CT could be an appropriate approach to jump off the limits of traditional image modalities [10, 11].

2.2 Fluorescence imaging technology

It is a challenging task to resect malignant brain tumors safely for neurosurgeons. They have to enable maximal tumor resection and to minimize surgery-induced neurological deficits simultaneously [12]. Thus, a large molecular weight dye is emerged and approved to visualize the boundary between tumor and normal tissue under intraoperative fluorescence imaging [13]. Ahmed Mansour et al. [14] even reported a technical note to clip an anterior spinal artery aneurysm with difficult endovascular embolization using a novel endoscopic fluorescence imaging system.

2.3 Augmented reality (AR) system

AR is considered to be the future of the gaming industry. The US Food and Drug Administration permitted the first AR image navigation system “Xvision” for surgical operations in 2019, and it is expected to bring significant changes. Through a head-mounted display headset, the position of the target is superimposed and displayed on the patient’s CT scan. This allows the surgeons to intraoperatively track the anatomies and surgical tools in real time as if they have acquired “see-through” capabilities [15, 16].

2.4 Brain multimodality monitoring

At present, a simple way to understand early neurological changes in neurosurgical patients is through intracranial pressure (ICP) monitoring. ICP-guided strategy has been the keystone for postoperative monitoring in severe traumatic brain injury and postoperative brain surgery before fatal neurological deteriorations happened. Modern technologies enable clinicians to detect brain hypoxia with swift corrective therapies in multimodal neurocritical monitoring [17, 18]. A growing body of literature demonstrated that the combination of ICP and partial pressure of brain tissue oxygen (PbtO2) monitoring can reduce the extent of brain tissue hypoxia in head injury victims to achieve more favorable outcomes [19].

2.5 Endovascular embolization technology

Endovascular embolization is considered to be one of the treatment options, where individuals may have high risk of intraoperative bleeding. Hybrid operating room is a suitable place for perioperative monitoring and treatment. Doctors may perform thrombectomy, coiling, and even clipping surgery at the same time in the same theater. An interesting study compared cerebral arteriovenous malformation patients with and without prior endovascular embolization. It showed a reduction in operation time and shorter hospitalization period [20]. Yet, Sophia F Shakur et al. [21] reported a large carotid body tumor treated by transarterial glue embolization with the liquid embolic agent N-BCA (N-butyl cyanoacrylate).

2.6 Minimally invasive three-dimensional (3D) endoscope

This fascinating tool removes the lesion through a small opening under the appropriate depth of field, in such a manner that the front and back distance are precisely anticipated. Compared with traditional surgery, 3D endoscopy can access various parts of the brain and spine without leaving conventional large scars. Endoscopy is widely used by clinicians in third ventriculostomy, pituitary surgery, as well as spinal surgery [22, 23, 24].

2.7 Surgical navigation system

Navigation technology uses perioperative real-time imaging to provide robotic guidance to surgical instruments. However, robotic control of the instruments may not be as experienced as a trained surgeon. Navigation in surgery has been proven to be used in minimally invasive spinal surgery to place pedicle screws during posterior lumbar fusion surgery to avoid screw misplacement, which can lead to catastrophic complications [25].

2.8 Telesurgical robotic system

This device involves a handheld control to operate from a remote command station, so that the surgery can be performed with an instrument directly operated by a robot. The main advantage is that the surgeon may operate elsewhere or even far away from the operating table [26].

2.9 Functional surgery using deep brain stimulation (DBS)

This method starts with creating a burr hole in the skull, followed by inserting tiny electrodes into the specific deep portion of the brain. The electrodes are subsequently connected to the battery, which then supply energy and stimulate the brain with electrical signals to relieve symptoms of diseases such as Parkinson’s disease (PD) and epilepsy. DBS opens up new treatment possibilities for neurological and psychiatric diseases, enabling neuroscientists to directly measure cell activity and probe the function of neural circuits [27].

2.10 Woundless stereotactic ablative radiotherapy (SABR)

SABR involves the non-surgical precise use of radiation therapy to the nidus part of a lesion. Some reformed equipments are frameless and the radiation dose may even be fractionated to minimize injuries to normal tissues. SABR has been used to treat intracranial tumors, trigeminal neuralgia, and refractory epilepsy, especially when the focuses are too deep in the brain, preventing a thorough removal with traditional craniotomies. The several advantages of SABR include its high accuracy, non-invasiveness, no loss of blood, and convenience in operation, as the task can be achieved at outpatient services [28].

2.11 Neural engineering

A brain-computer interface (BCI) allows the brain to communicate with the outside world without transmitting signals via the peripheral nerves and muscles. Jonathan Wolpaw proposed that BCI consists of the following three elements: signal acquisition, feature extraction, and translational algorithm [29]. Neuroprosthetics refers to an artificial implant that replaces the damaged part of the human nerve pathway using prostheses. Nerve prostheses use artificial electrical stimulation to excite the nerve tissue, thereby replacing damaged nerve functions. Specifically, sensory nerve prostheses convert external information into electrical stimulation signals to act on sensory nerve pathways, such as cochlear implants and visual prostheses [30].

2.12 Gene therapy

Gene therapy is a new management technique, which applies genes or short oligonucleotide sequences as therapeutic molecules, as an alternative for traditional drug compounds [31]. These methods include transgenes encoding therapeutic proteins, microRNAs, gene editing machinery like Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR), and anti-sense oligonucleotides (ASO’s) are classically utilized to treat those defective genes which contribute to disease development [32, 33, 34]. A critical issue in transgene delivery analysis is the immune reactivity to the transgene-encoded protein, and its influence on sustained gene expression. Moreover, literature reported using viral and non-viral vectors to deliver the oligonucleotide precisely and treat glioblastoma multiforme [35, 36].

3.1 Cellular and molecular neuroscience

Cellular and molecular neuroscience is a section of neuroscience that studies the biological mechanisms of neurons and supporting cells. The communications between neurons and the exploration of physiological functions of neurons are fundamentals in this field. Stem cells for the therapeutics of PD and spinal cord injury (SCI) have been applied in recent years [37, 38]. However, there are still unmet issues which need to be resolved, including ethical concerns and the possibility of malignant transformation of stem cells [39].

3.2 Behavioral and systems neuroscience

Behavioral neuroscience focuses on the use of biological principles to study psychological processes and behaviors. On the other hand, systems neuroscience focuses on the study of the cooperative work of neurons in a network and their relationship between mental and neurological diseases. Resultant developments of new drugs are possible because of the in-depth research conducted in both disciplines.

3.3 Cognitive and computational neuroscience

Cognitive and computational neuroscience describes the relationship between anatomy, thinking, and sensory process through mathematical models to evaluate the cognitive function. Control theory, quantitative psychology, machine learning, artificial intelligence, artificial neural network, and computational learning theory have shown rapid progress and development in recent years [40].

3.4 Biophysics of the brain

This module includes a new diverse spectrum of techniques, such as computational, structural, spectroscopical, or electrophysiological techniques, to investigate the components of the neural systems involved in physiological and pathophysiological conditions. Biophysical networks address a wide range of questions from gating at the channel level, exocytosis, long-term potentiation, to conformational states of proteins involved in problems such as Alzheimer’s disease [41].

3.5 Gut-brain connection

Gut-brain axis (GBA) is a complex bidirectional communication network that links the enteric with central nervous system (CNS). The gut communicates with the brain through vagus nerve that innervates the enteric nervous system, which is critical for the function of the gastrointestinal (GI) tract. Dysbiosis of gut microbiota plays a role in a number of neurological conditions, such as chronic pain, mood disorder, and neurodegenerative disease [42].

Recent literature has demonstrated the character of GBA connecting GI tract with CNS using molecular signals, hormone, and nerve transmission. Sangjune Kim et al. [43] showed a transneuronal propagation of pathologic $$-synuclein in PD GBA. Dong Seok Kim and colleagues even used glucagon-like peptide-1 receptor pathway as a new treatment strategy for PD through the axis [44]. Nevertheless, another report revealed fecal microbiota transplantation to downregulate IL-1$\beta$/NF-$\kappa$B signaling in spinal cord and NF-$\kappa$B signaling in gut following SCI in a mouse model, which eventually improve locomotion and GI functions of the mice that suffered from SCI [45]. Researchers should pay more attention to this extraordinary disease in future challenges (Fig. 2) [46, 47].

Fig. 2.Schematic diagram of gut-brain bidirectional communication (A) and microbiota-gut-brain communication (B).