Myringotomy

In cases of otitis media or chronic otitis, the middle ear should be fully evaluated. Otitis media is an important perpetuating cause of recurrent otitis externa.¹⁹ The evaluation should include radiography of the bulla, which may be accomplished with conventional radiology or with intraoral dental films.

After these imaging studies have been performed, the ear should be fully evalu­ated with the video otoscope. In order to evaluate the middle ear, a myringotomy must be performed. Both the diode laser and the CO₂ laser can be used for this proce­dure (Figure 19-22). The goal is to provide sufficient laser energy to ablate the tympanic membrane without damaging the underlying structures. This can be accomplished with the CO₂ laser by using a series of single pulses through a waveguide placed in the operating channel of the video otoscope aimed at the periphery of the pars tensa of the eardrum. The beam diameter of these guides usually ranges from 0.4 to 1.0 mm. In general a diameter of more than 0.5 mm and a power setting of 3 to 6 watts should be used. The higher power is usually necessary in cases with chronic disease. The diode laser is very useful in this procedure. A 600- to 1000-micron fiber is intro­duced into the video otoscope, and a myringotomy is performed in the contact mode. A setting of 4 to 7 watts is appropriate. This is performed while irrigating with ster­ile saline solution. This keeps the fiber cool, and peripheral damage is not an issue. In addition, any hemorrhage that occurs can be rapidly identified and controlled with

Figure 19-22

Diode laser myringotomy.

Figure 19-23

Normal middle ear after myringotomy.

this laser. Irrigation markedly increases visualization and allows for the removal of any matter within the bulla.

After the myringotomy has been performed, the middle ear should be carefully evaluated for any masses (Figure 19-23). These masses should be biopsied and then can be ablated with CO₂ or diode laser energy as described previously in this chapter.