Microsurgery Health Article

Definition

Microsurgery is surgery that is performed on very small structures, such as blood vessels and nerves, with specialized instruments under a microscope.

Purpose

Microsurgical procedures are performed on parts of the body that are best visualized under a microscope. Examples of such structures are small blood vessels, nerves, and tubes. Microsurgery uses techniques that have been performed by surgeons since the early twentieth century, such as blood vessel repair and organ transplantation, but under conditions that make traditional vascular surgery difficult or impossible.

The first microvascular surgery, using a microscope to aid in the repair of blood vessels, was described by Jules Jacobson of the University of Vermont in 1960. The first successful replantation (reattachment of an amputated body part) was reported in 1964 by Harry Bunke. This replantation of a rabbit's ear was significant because blood vessels smaller than 0.04 in (0.1 cm)—similar in size to the blood vessels found in a human hand—were successfully attached. Two years later, the successful replantation of a toe to the hand of a monkey was made possible using microsurgical techniques. Soon thereafter, microsurgery began being used in a number of clinical settings.

Numerous surgical specialties utilize the techniques of microsurgery. Otolaryngologists (ear, nose, and throat doctors) perform microsurgery on the small, delicate structures of the inner ear or the vocal cords. Cataracts are removed by ophthalmologists (eye doctors), who also perform corneal transplants and treat eye conditions like glaucoma. Urologists can reverse vasectomies (male sterilization), and gynecologists can reverse tubal ligations (female sterilization), giving people new choices about having children. Microsurgical techniques are used by plastic surgeons to reconstruct damaged or disfigured skin, muscles, or other tissues, or to transplant tissues from other parts of the body. And, importantly, a number of specialties can collaborate to treat patients who have limbs or other body parts; under certain circumstances, amputated parts can be reattached, or another body part can be replanted in the place of one lost (for example, a great toe replacing a lost or damaged thumb).

Today, microsurgery can be lifesaving. Neurosurgeons can treat vascular abnormalities found in the brain, and cancerous tumors can be removed.

Equipment

Microsurgical equipment magnifies the operating field, provide instrumentation precise enough to maneuver under high magnification, and allow the surgeon to operate on structures barely visible to the human eye. The most important tools used by the microsurgeon are the microscope, microsurgical instruments, and microsuture materials.

MICROSCOPE. While operating microscopes may differ according to their specific use, certain features are standard. The microscope may be floor- or ceilingmounted, with a moveable arm that allows the surgeon to manipulate the microscope's position. A view of the surgical site is afforded by a set of lenses and a high-intensity light source. This lighting is enhanced by maintaining a low level of light in the rest of the operating room. Two or more sets of lenses allow a surgeon and an assistant to view the operating field and focus and zoom independently. A video camera allows the rest of the surgical team to view the operating field on a display screen. Features that come on some microscopes include foot and/or mouth switch controls and motorized zoom and focus.

A magnification of five to forty times (5–40x) is generally required for microsurgery. A lower magnification may be used to identify and expose structures, while a higher magnification is most often used for microsurgical repair. Alternatively, surgical loupes (magnifying lenses mounted on a pair of eyeglasses) may be used for lower magnifications (2–6x).

INSTRUMENTS. Microsurgical instruments differ from conventional instruments in a number of ways. They must be capable of delicately manipulating structures barely visible to the naked eye, but with handles large enough to hold comfortably and securely. They must also take into account the tremor of the surgeon's hand, greatly amplified under magnification.

Some of the various instruments that are used in microsurgery include:

• forceps
• needle holders (for suturing)
• scissors
• vascular clamps (for controlling bleeding) and clamp applicators
• irrigators (for washing structures in the surgical field)
• vessel dilators (for opening up the cut end of a blood vessel)
• various standard surgical tools

SUTURE MATERIALS. Suturing, or stitching, is done by means of specialized thread and needles. The diameter (gauge) of suture thread ranges in size and depends on the procedure and tissue to be sutured. Conventional suturing usually requires gauges of 2-0 (0.3 mm) to 6-0 (0.07 mm). Conversely, gauges of 9-0 (0.03 mm) to 12-0 (0.001 mm) are generally used for microsurgery. Suture thread may be absorbable (able to be broken down in the body after a definite amount of time) or non-absorbable (retaining its strength indefinitely), natural (made of silk, gut, linen, or other natural material) or synthetic (made of nylon, polyester, wire, or other man-made material). The type of suture thread used depends on the procedure and tissue to be sutured.

The suture needle comes in various sizes (diameters and length) and shapes (straight or curved), and also with different point types (rounded, cutting, or blunt). It comes with suture thread preattached to one end; this is called the swage. As in the case of suture thread, the type of needle used depends on the procedure and tissue to be sutured; generally, needles with a diameter of less than 0.15 mm are used for microsurgery.