Fundamentals of Minimally Invasive Radiofrequency Applications in Ear, Nose, and Throat Medicine

1.1.1

Submucous Coagulation

In the process of submucous coagulation, needle-shaped electrodes puncture the surface of the organ and are subsequently positioned inside it ( Fig. 42.1 ). When energy is applied, thermally induced coagulation builds up around the electrode, usually of ellipsoid shape, depending on the construction of the electrode. If positioning and energy dose are correct, the organ's surface is conserved and the application is almost entirely free of pain. The body's own decomposition and discharge of the necrotic tissue leads to a reduction in volume in the region treated.

1.1.2

Superficial Vaporization

The reduction in size of an organ (e.g. a tonsil) may also be accomplished by means of direct tissue ablation via vaporization (tissue vaporization) on the surface ( Fig. 42.2 ).

1.1.3

Submucous Vaporization

In the process of submucous vaporization, so-called channeling, channels are bored into the affected organ. For this purpose, a special bipolar electrode is necessary, at the tip of which a plasma ignition process takes place. When the tip comes into contact with tissue, the latter vaporizes immediately. A channel is generated by pushing the electrode forward in the tissue. More details on so-called plasma applications are to be found in the section “Plasma” Surgery.

1.1.4

Electrotomy

Electrotomy is also related to superficial vaporization methods. Contrary to plane vaporization at the surface, however, cuts are generated using fine needle–shaped electrodes with the objective of separating tissue ( Fig. 42.3 ).

1.2.1

Volume Shrinkage by the Body's Own Discharge of Coagulation Necrosis/Tissue Stabilization by Scar Formation After Coagulation Necrosis

Submucous coagulation shows two time-delayed effects: volume shrinkage caused by the body's own discharge of the coagulated tissue and stabilization of a region of tissue by the scarring process.

After thermocoagulation, several phases take effect in the volume of tissue involved.

• Tissue coagulation becomes apparent immediately after its production by a lighter color resulting from the induced protein denaturation.

• After 1 day, a clearly defined lesion is evident, bordered by a hyperemic edge surrounding the destroyed tissue.

• About 10 days after treatment, the lesion is surrounded with connective tissue.

• After approximately 3 weeks, the dead muscle tissue has been replaced completely by connective tissue (collagen deposits). The scarring process is complete; the region of tissue involved has decreased in size and hardened.

1.2.2

Tissue Ablation by Means of Vaporization

Superficial ablation of tissue at the surface is used, for example, in tonsillotomy to achieve the partial resection of hyperplastic tonsils. In this case, the tissue is removed by vaporization in layers using a special arrangement of electrodes.

1.2.3

Tissue Resection by Means of Electrotomy

In the process of electrotomy, a high current density is generated at the point where the tissue is touched by means of electrodes of small surface area in the form of needles or slings. The tissue is heated to well above 100°C in a very short period, leading to vaporization of the cell fluid and bursting of the cells concerned. If the electrode is moved through the tissue, a cut is the result. Depending on the cutting power and speed of the cut, a more or less deep coagulation seam is produced at the edges of the cut, with the result that bleeding is reduced or can be avoided.

1.3.1