Tympanic membrane healing in myringotomies performed with argon laser or microknife: an experimental study in rats

Laser-assisted myringotomy versus conventional myringotomy with ventilation tube insertion in treatment of otitis media with effusion: Long-term follow-up

BACKGROUND

Otitis media with effusion is the most common cause of conductive hearing loss in the pediatric population. Insertion of ventilation tubes with or without adenoidectomy is the accepted and standard surgical procedure. CO2 laser myringotomy without tube placement has been advocated as an alternative treatment.

AIM

To compare long-term follow-up results of laser versus classical myringotomy with ventilation tube insertion over five years.

MATERIALS AND METHODS

86 patients with bilateral otitis media with effusion were divided into two groups: laser myringotomy group and myringotomy with ventilation tube insertion group, with follow-up in hearing results and recurrence rates over five years.

RESULTS

The mean patency time of myringotomy in laser group was 23 days, while the mean patency time of the ventilation tubes ears was 4.0 months in myringotomy group. Twelve patients in laser group (13.9%) showed a recurrent otitis media with effusion compared to 9 patients in myringotomy group (10.4%).

CONCLUSION

Laser fenestration is a less effective alternative to myringotomy and tube placement. The recurrence rates after both procedures did not show statistical significance over long follow-up. It might be considered as an effective alternative to classical surgery and ideal for short-term ventilation.

Stapedectomy in sheep: an animal model for surgical training

HYPOTHESIS AND BACKGROUND

Stapedectomy is a surgical technique that requires progressive training. The external and middle ear of sheep have a close resemblance to the human and have been previously used as surgical training models. In our project we describe the anatomy of the middle and external ear in sheep focusing on surgical landmarks and technique in order to determine whether the sheep's ear is an adequate model for stapedectomy training.

MATERIALS AND METHODS

We reviewed the literature on sheep anatomy and use of sheep as an otologic surgical model. Macroscopic sections as well as temporal bone computed tomography were obtained. Stapedectomy was performed on 40 sheep, using 4 mm platinum piston prosthesis, by first year residents.

RESULTS

Most of the structures in the sheep's middle ear are similar to those in humans although their size is about two thirds smaller. Incus long process is shorter, thicker, and closer to the malleus body, making the piston insertion and adjustment more difficult. The median surgical time of stapedectomy was reduced from 70 (52.5-100.3) minutes to 39.5 (35.5-48) minutes after completing training. There was also a reduction in rate of complications (flap disruption, incus dislocation, and footplate mobilization).

CONCLUSION

Sheep ears constitute a cheap, easy to obtain and anatomically adequate model for stapedectomy training.

The early events in the healing of laser-produced tympanic membrane perforation

CONCLUSION

An immense keratinocyte activity with high cell turnover produced keratin that was delivered to span the perforation. The perforation size did not define the time to closure.

OBJECTIVES

Most tympanic membrane perforations heal spontaneously, whereas a fraction remains patent. A simple, nonsurgical cure for chronic perforations is required. Better understanding of the healing processes might enable the development of a simple medical cure. Therefore the structural events of the healing process were investigated, as well as its dynamics, by comparing perforation size with time to closure.

METHODS

Twenty-four Sprague-Dawley rats were myringotomized with a KTP laser. Different perforation sizes were produced. The 'early closing picture' was assessed with otomicroscopy and light and transmission electron microscopy at between 1 h and 2 weeks after myringotomy and perforation size was monitored until closure.

RESULTS

In all, 40% of the perforations were closed after 8 days and 89% at 12 days. The closing time did not directly correlate with perforation size. A wave of keratinocytes migrates towards the perforation site and disintegrates to form a keratin mass that eventually spans the perforation. A less intense activity is present near the annulus. The origin of the epithelial migration is probably regenerative centers.

Acute tympanic membrane perforations and the early immunological response in rats

CONCLUSIONS

This study showed that macrophages, B cells, and T cells occurred at different frequencies, localizations, and times after acute laser tympanic membrane perforation. Immunological cells were most prevalent in the proliferative mass adjacent to the annulus region. The cellular immunological response in freshly perforated eardrums was unexpectedly aggressive.

OBJECTIVES

To study the occurrence of immunocompetent cells during the healing process of fresh perforated tympanic membranes. The information could be used to develop alternative outpatient procedures in the cure of chronic perforations, replacing conventional surgery.

MATERIALS AND METHODS

A laser myringotomy was carried out in Sprague-Dawley rats, which were sacrificed at 3 and 6 days after the myringotomy. Tympanic membrane sections were stained immunohistochemically according to the avidin-biotin method, targeting macrophages, B cells, and T cells. Semi-quantification was performed; positive cells were counted and mean values were calculated.

RESULTS

Macrophages and B cells were most frequent at day 6 and T cells at day 3 after laser myringotomy. B cells were the most prevalent studied cell type. T cells peaked at day 3, after which they decreased in number. Most immunocompetent cells were observed in the proliferative mass at the edge of the perforation.