Minimally Invasive Brain Surgery offers patients safer procedures, faster recovery, and reduced risks. Using advanced techniques like neuroendoscopy, surgeons can treat complex brain conditions with precision and minimal disruption.
Ask any surgeon what the hardest organ to treat through surgery is, and most will answer the human brain. Not only do scientists have yet to fully understand how it facilitates complex thoughts and actions, but it’s also a labyrinth of blood vessels, grey matter, and neurons. The slightest trauma can lead to lasting damage, if not life-threatening.
In light of this, one of medical science’s priorities hinges on lowering the risk of collateral damage during surgery. For the brain, there’s minimally invasive brain surgery, scientifically referred to as neuroendoscopy or neuroendoscopic surgery.
Although not a substitute for traditional brain surgery, its efficacy in treating certain brain disorders has been proven time and again through multiple clinical trials.
Precise Treatment
Organs are delicate in their own right, but none are as delicate as the brain. Neurosurgeons know they can’t afford to hurt healthy tissue while removing tumour or repairing an aneurysm. However, even when performed by the most careful and experienced pair of hands, brain surgery remains a high-risk operation.
Some of the worst-case scenarios include:
- Short or long-term impairment of functions (depending on the affected region)
- Brain or cranial (skull bone) infection
- Cerebral thrombosis or blood clotting
- Coma caused by surgery complications
- Costly follow-up surgery
Roger Harti, professor of neurosurgery at Weill Cornell Medicine Neurological Surgery, says neurosurgeons save complex brain surgery for last because of such scenarios. High-risk patients like the elderly or anyone with a condition that makes anaesthesia dangerous are prone to more severe complications.
Minimally invasive brain surgery lowers the chances of post-surgery complications by restricting the corridor to the malady to no larger than a U.S. dime. Some variants use an existing opening such as the nostrils or mouth to access hard-to-reach parts of the brain.
Key to this kind of surgery is a modern instrument known as a neuroendoscope. Attached to manual or robotic arms and linked to computerised surgical imaging systems, a neuroendoscope handles a wide range of tasks from real-time video feed to housing specialised instruments.
The main advantage is similar to that of other related procedures: precise treatment. It can be broken down into four benefits.
1. Reduced Surgical Tissue Damage
While the procedure still requires cutting through healthy brain tissue, the amount it disturbs is nowhere as much as in open surgery. The result is a lower risk of surgical complications like post-surgery haemorrhage and movement disorders.
2. Real-Time View of the Brain Interior
Using high-definition cameras and light sources built into the neuroendoscope, neurosurgeons receive a clear live feed of the tumour or anomaly in the patient’s brain. There would be little to zero need to cut a swathe deep into the target region.
3. Faster Recovery Times
Between the minimal incision and lower risk of complications, patients can expect a quicker recovery. Although neuroendoscopy still involves a hospital stay, most patients can be discharged after a shorter time than conventional brain surgery.
4. Better Post-Op Cosmetic Outcomes
Neurosurgeons skilled at the surgical procedure can hide the scar to maintain the head’s appearance prior to the operation. Then again, the incision is small enough to be hidden from plain sight without attempting to hide it.
Neuroendoscopy enjoys a relatively high success rate. A 2023 study of over 130 patients in a hospital in Switzerland recorded a success rate of 90.5% for under-18 individuals and 92.1% for those 18 and over. However, keep in mind that “success” in this case refers to either an improvement or no major change in their condition after the operation.
The same study also recorded a minimal risk of permanent complications (0% and 1.2%, respectively) but a low to moderate risk of transient complications (23.4% and 18.8%, respectively). Under-18 patients are more than twice as likely to undergo a second surgery as their 18-and-above counterparts.
Different Approaches to Minimally Invasive Brain Surgery
Minimally invasive brain surgery can be performed in various ways based on the neuroendoscope’s entry point, a few of which don’t warrant creating incisions. Some common avenues are through the head, via the nostrils, and via the eye socket. Here’s a quick look at each approach.
Method | Entry Point | Description | Target Area |
Endoscopic neurosurgery | Cranium or skull | An endoscopic version of craniotomy, this approach creates a small incision at the top of a patient’s skull. | The majority of the cerebrum, mainly the topside lobes |
Retro-sigmoid craniotomy | Back of the ear | Often known as keyhole craniotomy, this approach targets tumours and other problems at the back of a patient’s head. | Cerebellum, brainstem, and lobes within the posterior fossa |
Endonasal neurosurgery | Nostrils or the sinus cavity | This approach inserts the neuroendoscope through the nose area to reach the skull base. | Base regions of the brain |
Transorbital neurosurgery | Eye socket | A rarely used approach until recently, it passes the neuroendoscope via an incision in the corner of the eye socket interior. | Base regions of the brain, mainly those close to the optical nerve |
Despite their differences, all types of neuroendoscopy share the primary purpose of tumour removal.
Where Can Brain Tumours Develop?
Brain tumours can fester in any part of the brain, the most common locations being:
- Meninges – a protective tri-layer lining wrapped around the brain and spinal cord
- Pituitary canal – a duct connecting the pituitary gland to the nasopharynx
- Frontal lobe – the largest part of the cerebrum responsible for multiple functions
- Cerebellum – a region below the cerebrum that handles motor balance and coordination
- Brainstem – the main connection between the brain and spinal cord responsible for vital functions
Neuroendoscopy is suitable for removing brain tumours no bigger than 5.5 cm (2.17 in) in diameter. Considering the average tumor grows to around 5 cm (1.97 in), minimally invasive brain surgery becomes viable for a wide range of cases.
However, it’s worth noting that some tumours can grow aggressively over a short timeframe. These mostly consist of malignant Grade 3 and 4 tumours (according to the World Health Organization’s tumour grading system), which can grow too large for neuroendoscopy to safely remove. But whatever the grade, late detection of the tumour increases the likelihood of the procedure becoming an unviable solution.
Besides tumour removal, the surgery can treat cerebrospinal fluid (CSF) circulation disorder. This refers to a set of abnormalities that impede the normal flow of CSF, which serves in a similar capacity as blood. One example is hydrocephalus, though surgeons may elect for shunt surgery before neuroendoscopy (or a combination of both).
Who Is Eligible for Minimally Invasive Brain Surgery?
Neuroendoscopy more or less follows the same steps as open brain surgery, starting with getting an accurate diagnosis. While children and adults are eligible, doctors also need to be informed of other conditions that can jeopardise the surgery’s chances of success.
The Pre-Surgical Assessment Process
A neurological exam is the starting point where the doctor performs a series of tests aimed at finding out the patient’s physical and mental state. A common method involves evaluating the state of the patient’s cranial nerves, of which there are a dozen.
The Cranial Nerves
Cranial Nerve (CN) | Function | Testing Method |
CN I – Olfactory | Smell | Identify various scents with eyes closed |
CN II – Optic | Sight | Visual test using a special kind of lighting |
CN III – Oculomotor* | Sight | Have the eye follow the doctor’s light or finger |
CN IV – Trochlear* | Sight | Have the eye follow the doctor’s light or finger |
CN V – Trigeminal | Chewing | Observe how the patient bites or chews |
CN VI – Abducens* | Sight | Have the eye follow the doctor’s light or finger |
CN VII – Facial | Looks | Various facial movements (e.g., smiling) |
CN VIII – Acoustic | Hearing | Any hearing test (e.g., audiometry, tuning fork) |
CN IX – Glossopharyngeal | Taste | Identify tastes using the back of the tongue |
CN X – Vagus | Eating | Swallowing and testing for gag reflex |
CN XI – Accessory | Motion | Head and shoulder movement tests |
CN XII – Hypoglossal | Speech | Speaking with the tongue sticking out |
*CN III, IV, and VI are consolidated as a single test
The exam also involves mental tests, during which the doctor converses with the patient to gauge the latter’s abilities such as attention and emotion, and checking for motor reflexes.
Further Testing
A comprehensive neurological exam doesn’t confirm the presence of a tumour or any brain malady but rather justifies further testing. Such a task is left to exams that use state-of-the-art equipment, mainly magnetic resonance imaging (MRI) and biopsy.
Both tests work in tandem. A brain MRI is a non-invasive procedure that scans an area of the brain for a tumour but can’t determine whether it’s benign or malignant. For that, a neurosurgeon must perform a biopsy, taking a sample of brain tissue from the suspected area and studying it under a microscope.
Even if the brain tumor diagnosis returns positive, it won’t automatically mandate brain surgery. Neurosurgeons prefer exploring non-surgical options like prescription meds and radiation therapy before resorting to the scalpel.
The Minimally Invasive Brain Surgery Process
Pre-surgery
For cases that warrant minimally invasive brain surgery, the neurosurgeon will instruct the patient on how to get ready. Certain ongoing medications may need to be stopped for the time being to mitigate the risk of adverse events during surgery. They may also set a fasting period of several hours before the scheduled surgery to mitigate the risk of vomiting while under the anaesthetic’s effects.
Surgery
On the day of the neuroendoscopy, the patient will be administered anaesthesia to reduce pain (especially for those with a low pain threshold). An anaesthesiologist reviews the patient’s medical history and determines the proper anaesthetic and dosage for the case. The anaesthetic is delivered through a cannula placed at either the forearm or the back of the hand.
With the patient numbed and on the operating table, the neurosurgeon can proceed with the surgery proper. Standard endoscopic neurosurgery requires drilling what’s known as a burr hole through the skull. It also has the benefit of relieving pain and pressure caused by fluid buildup between the brain tissues. No cutting or drilling is required if the neuroendoscope will pass through an existing orifice, such as the nostril or mouth.
As soon as a straight path toward the affected part of the brain is made, the next step is to insert the neuroendoscope and the instrument to be used. The long shaft protects healthy brain tissue from coming into contact with the instrument, reducing the risk of accidental damage. The neuroendoscope is hooked onto a display for a real-time video feed of the surgical area.
The length of a typical neuroendoscopy depends on factors like the patient’s condition and the location of the surgical area. The shortest possible time is one hour, whereas open brain surgery can take two hours minimum.
Post-surgery
After the procedure, the patient needs to stay at the hospital for at least a day or two to be closely monitored for adverse events. The doctor may perform several rounds of tests to ensure the patient’s faculties are working as intended despite the disturbance from the surgery.
How Does Neuroendoscopy Compare to Microsurgery?
As stated previously, neuroendoscopy isn’t a substitute for open brain surgery (also called microsurgery). Multiple factors like the tumor growth rate, the tumour or anomaly’s location within the brain, and the patient’s condition determine the most effective surgical treatment.
Nevertheless, neuroendoscopy has the numbers to prove that it’s more effective and less risky. Below is the average data from a study of roughly 50 patients at a hospital in China.
Criteria | Neuroendoscopy (D – tumor diameter in cm) | Microsurgery (D – tumor diameter in cm) |
Length of hospital stay | 11.2 days | 16.8 days |
Total hospitalization cost* | RMB 75,000 (USD$10,302) | RMB 104,000 (USD$14,287) |
Operation time | 221.8 minutes (D<5) 406.5 minutes (D>5) | 305.8 minutes (D<5) 332.6 minutes (D>5) |
Blood loss during surgery | 84.4 ml (D<5) 110.0 ml (D>5) | 459.5 ml (D<5) 675.0 ml (D>5) |
Post-op complications | 2 cases | 16 cases |
*Conversion to USD$ based on the exchange rate as of this writing
Another study a year before reviewed data from 4 randomised controlled trials (RCTs) and 10 non-RCT studies done between 2006 and 2018, involving a total of more than 1,600 patients. It compares neuroendoscopy with conventional (not endoscopic) craniotomy.
Criteria | Neuroendoscopy | Craniotomy |
Re-bleeding rate* | 3.20% | 8.94% |
Average evacuation rate** | 88.74% | 80.80% |
Average operation time** | 102.89 minutes | 219.9 minutes |
Good recovery case rate* | 65.21% | 46.59% |
Mortality rate* | 9.84% | 20.40% |
*Calculated by dividing the number of events by the total number of cases included
**Calculated by getting the average of the mean values specified by the studies
The consensus among the medical community is that neuroendoscopy is in a position to gain popularity as endoscopic technology progresses. Given a few more years, it may develop workarounds for current limitations like the ability to remove tumours larger than 5.5 cm.
Conclusion
Minimally invasive brain surgery is showing promise as a lower-risk alternative to open brain surgery. Using advanced imaging techniques and medical technology, this procedure offers minimal disruption to healthy tissue and shorter hospital stays. It is poised to grow popular in the future, though not designed to phase out traditional surgery entirely.
