Practical Aspects and Avoidance of Complications
in Micro-Endoscopic Spine Surgeries

The use of endoscopic surgeries has increased in recent years, particularly for issues related to the head and spine, such as lumbar disk problems, colloid cysts, and tumors located deep within the brain.

Endoscopic techniques offer benefits such as excellent visualization and minimal invasiveness, resulting in reduced pain and a faster return to work. However, it is important to acknowledge potential obstacles and minimize complications when developing endoscopic skills.

General Principles in Micro-Endoscopic Spine Surgery

To ensure successful endoscopic surgery, precautions should be taken such as unobstructing the abdomen to prevent venous bleeding, securing cables for light, suction, and camera, careful handling of the endoscope to avoid damage, positioning the endoscope away from the surgical target, and attaching the holder securely to the table’s side rail.

The tissue should be displaced in one of four directions to avoid obstructing the view of vital structures and soiling the lens tip. Instruments should fit correctly in the endoscopic system’s working channel.

Proper Endoscopic Instruments

The appropriate selection of instruments is crucial in endoscopic surgery. Slim instruments with a single limb are preferred. The instruments should be functioning correctly before the surgery and have a slightly curved tip to enhance visibility.

Round shaft instruments are preferable, and precision grip is preferred over power grip. Straight instruments are preferred over those with a bayonet shape. Using instruments with a shorter length improves precision, and instruments that can perform multiple functions are useful in challenging situations with limited space.

Bimanual Dissection

A two-handed surgical technique is more effective than a one-handed procedure. Using both hands for dissection makes the process of cutting, retracting, achieving hemostasis, drilling, and dissecting tissue easier. In certain situations, it can be difficult to perform bimanual techniques, such as when the surgeon is holding the endoscope or when there is only one working channel in the endoscopic set. To overcome this limitation, the surgeon may utilize an endoscope holder or delegate the task of holding the endoscope to an assistant.

Proper Adjustment of the Operative Table Height and Use of a Platform

Even though most surgical tables can be adjusted for height, the use of a platform can be an additional option. Adjusting the height properly is essential to avoid shoulder abduction which can result in fatigue and physiological tremors during surgery. Lowering the table or using a platform enables the surgeon to observe the surgical site and facilitates the insertion of instruments into areas not directly visible when an endoscope holder is in use.

Differences between Endoscopic and Microsurgical Techniques

Endoscopy provides several advantages such as improved lighting, smaller incisions, and better visibility in hard-to-reach areas. However, it presents several difficulties compared to microscopy, including the need for straight instruments, keeping the surgical field in the corner instead of center, and limited space for the endoscope. In contrast, microscopic surgery has more space available for instrument manipulation.

Endoscopic surgery also has additional limitations like a blind area near the lens tip and potential disorientation from camera rotation. The surgeon must acquire the necessary skills to overcome these challenges and achieve better clinical outcomes in endoscopic surgeries.

Magnification

Most endoscopic surgeries require high magnification to achieve better visualization. To get a general idea of anatomy and orientation, lower magnification is preferred. Achieving lower magnification in endoscopic surgeries can be accomplished either by using the zoom function or by physically moving the scope away from the area of interest.

Before commencing the procedure, it is recommended to inspect the surrounding structures (including medial, lateral, anterior, and posterior relations) to identify the anatomy. Accurate understanding of anatomy is crucial because in many instances only a fraction of a structure can be observed. A neuronavigation system can be beneficial, particularly in cases where landmarks are not clearly visible, as in cases of redo surgery.

Orientation and Position of the Camera

Before the procedure, the camera’s orientation should be verified through movements in the anterior, posterior, and lateral directions. To ensure that the image orientation is consistent with open surgery, the camera head (buttons) should face the monitor. During surgery, it’s important to frequently check the camera orientation to avoid disorientation, as the camera may rotate inadvertently.

Straight versus Triangular Arrangement

To achieve good visualization during surgery, a triangular arrangement of instruments and endoscopes is recommended. When instruments are arranged in a straight line, distal instruments or surgical tissue may not be visible, but lateral movements of instruments and endoscopes can improve visualization. This point is practically useful and can be applied in various surgical situations.

For example, rotating the biopsy forceps can improve visualization of both the surgical target tissue and the distal limb of the forceps. Similarly, rotating the Kerrison punch can improve visualization of the cutting part of the foot plate and the lamina, which would be difficult to see if arranged in a straight line.

Proper Planning of the Size and Site of an Incision

At the start of spine endoscopic surgery, it is important to plan the size and location of the incision carefully. An unsupported large incision may result in instability, while excessive angulation can cause soft tissue to protrude and hinder the surgical process. A well-planned incision size can offer stability and minimize oozing during spine endoscopic surgery, and using a microscope may be a feasible option if the procedure becomes too challenging.

Proper Position of the Endoscope

Correct positioning of the endoscope is vital to avoid interference with the handling of instruments during spinal endoscopic surgery. It is preferable to have a triangular configuration between the endoscope, surgical target, and instrument during spine endoscopic surgery. Nevertheless, in narrow and deep spaces, it may not be possible to achieve a triangular arrangement, which can result in non-visualization of the distal instrument.

To address non-visualization caused by a straight arrangement in narrow and deep spaces, the distal instrument should be introduced first and kept in the blind area, followed by the introduction of the Kerrison punch. Instead, the instruments can be passed from either side of the scope when it is placed in the center.

Hand Support

Adequate support for the surgeon’s hands is important during micro-endoscopic surgery to ensure accurate movements and prevent fatigue, especially during long procedures. Long surgeries can cause fatigue, and unsupported hands can exacerbate physiological tremors. Micro-endoscopic surgery may not be compatible with standard hand support devices used in microsurgery. However, providing gentle hand support on the endoscopic sheath or surrounding structures can be beneficial.

Use of Precision Grip and Avoidance of Power Grip

In endoscopic surgery, the precision grip is more advantageous than the power grip as it allows for better control and hand support. The power grip in endoscopic surgery is less precise due to its lack of hand support and involvement of long muscles and multiple joints.

While a power grip may be necessary for certain instruments like the Kerrison punch, a precision grip should be added with the other hand to improve control. To reduce the number of motor units of the thumb and index finger in use and minimize the use of arm muscles, it is recommended to use a quiet hand technique and support the ulnar side of the hand.

Poor Visualization during Micro-endoscopic Surgery and How to Overcome This Limitation

The presence of blood, bone dust, fluid or tissue can cause poor vision during endoscopic surgery, as can high humidity, a damaged endoscope, or an out-of-focus camera. To clean the lens tip, mechanical cleaning, commercially available cleaners, saline irrigation and suctioning can be used. Correct positioning and angulation of the endoscope, along with removing unwanted tissue in front of the lens, is important. Using a larger diameter endoscope and intermittent irrigation can help prevent lens soiling.

Limited Space for Instrument Manipulation

In micro endoscopic surgery, limited space can make it challenging to manipulate instruments when using an endoscope. Using slender shaft instruments is preferable, and aligning the endoscope and instruments in the same direction is important to make the most of the limited space available. Suturing in micro-endoscopy can be difficult due to the narrow space, but it can be facilitated by using a rotation maneuver.

In situations where space is restricted, it is recommended to move the instrument towards the target area first and then follow with the endoscope. Angled-tip tools are more suitable for accessing the farthest corner of the surgical site.

Endoscopic Blind Spot

Endoscopic surgery offers better visualization and a wider view, but a drawback is the inability to see the area behind the endoscope tip. This can lead to potential damage to nearby structures by the instruments or the endoscope itself.

To mitigate this risk, surgeons should be trained to remove and reinsert the endoscope with each new instrument. To address the limitation of not being able to see the pathway proximal to the endoscope tip, one solution is to visually follow the instrument in the blind area until it becomes visible in the endoscopic view.

Control of Bleeding

During endoscopic surgery, managing bleeding can be difficult, particularly in a fluid environment where even small amounts of blood can disrupt visibility. To control bleeding during endoscopic surgery, applying gentle pressure on the hemorrhagic point with an existing instrument can be used as a solution, rather than removing the tool and using cautery forceps.

This creates a tamponade effect. A large amount of fluid irrigation and the intermittent blocking of fluid can aid in identifying the source of bleeding and controlling it. Transforming a liquid medium into an air medium by suctioning can help visualize and control bleeding. If attempts to control bleeding using other methods fail, cotton patties can be applied or the endoscope can be removed to control more severe bleeding by using a microscope or exoscope.

Prevention of Dural Tear

During severe spinal canal stenosis surgery, there is an increased risk of dural tear and cerebrospinal fluid leak. Proper case selection, keeping the ligamentum flavum intact until bony work is finished, and using a stepwise surgery approach for removal of the lamina by the Kerrison punch can prevent dural injury.

Using an eggshell drilling technique for lamina and proper drilling technique parallel to or away from the dura mater can also help avoid injury. Visualization during bone or ligament removal with the help of a rotation technique is recommended. Excision of the opposite-side protruded lumbar disk tissue from the contralateral side should be avoided to prevent dural injury.

Dural Repair

The confined space during endoscopic surgery presents difficulties for suturing the dura. It is better to use a rotating motion when manipulating the needle holder instead of moving it in a straight line. Time can be saved by placing the initial knot beforehand and forming a loop for suturing. Because of its large size, the Covidien endo-suturing instrument is not appropriate for use in neurosurgery.

Drilling

The recommended approach is to use a soft paint brush technique without applying any pressure, and to ensure that the drill is fully stopped before it is removed to avoid harm to important structures and the scope.

Learning Curve

The learning curve for these surgeries can be steep, and complications are more common early on. Techniques such as practicing on models and attending workshops can help shorten the learning curve. Well-trained surgeons are essential for better clinical outcomes, and a formal program with a peer-review board is recommended for achieving the minimum standard and technical skills in endoscopic spine surgery.

Training in Endoscopic Surgery

To avoid complications, simple cases should be selected in the beginning, and surgeons should spend more time in laboratories for training. Cadaveric dissection is the best method but often limited, and models and simulators can be costly. Inexpensive models using surgical gloves, papaya, silastic tubes, capsicum, and other easily available materials can be used for developing skills.

The article suggests that practicing with simple and inexpensive models can help surgeons gain the necessary skills for endoscopic surgeries. An exoscope system can also be used as a bridge for learning endoscopy.

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