C-wire hand drill for small-hole stapedectomy

The Effect of CO(2) and KTP laser on the cat saccule and utricle

OBJECTIVES/HYPOTHESIS

To assess the potential carbon dioxide (CO(2)) and potassium-titanyl-phosphate (KTP) laser-related trauma to the saccule and utricle in a cat model.

STUDY DESIGN

Basic science experiment utilizing cat model.

METHODS

Twelve adult male cats were divided into two groups-CO(2) and KTP-to assess the potential saccule and/or utricle trauma with direct discharge of laser energy into the vestibule after the stapes was removed. Both groups were subdivided to assess the effects with acute sacrifice and three-month survival. Bone conduction auditory brain-stem response thresholds were used to monitor auditory function. Clinical observation was used to monitor vestibular function. The temporal bones were harvested, processed, and stained with hematoxylin and eosin (H&E) in all animals with the uninvolved side serving as the control.

RESULTS

None of the animals demonstrated changes in bone conduction auditory brain-stem responses. None of the animals in the survival group demonstrated clinical vestibular dysfunction. Saccular and utricular wall rupture was observed in all animals sacrificed acutely. None of the saccular and utricular wall ruptures were of a size and location that could be attributed to laser trauma, and none of the saccular and utricular wall ruptures were associated with neuroepithelial trauma.

CONCLUSIONS

There is no evidence of a difference between the CO(2) and KTP laser in potential laser-related trauma. Using bone-conducting auditory brain-stem response threshold and clinical monitoring of vestibular function, there was no evidence of clinical auditory or vestibular dysfunction. The histologic evidence of saccular and utricular wall rupture is more consistent with stapes extraction trauma than laser-related trauma.

Transtympanic electrode positioning: manubrium is a poor guide

BACKGROUND

Although a transtympanic electrode is commonly used for electrocochleography and electrically evoked auditory brainstem response, the variability of responses among healthy subjects is wide. The manubrium is the typical guidepost for electrode placement. This study addresses the hypothesis that electrode position relative to the round window niche is widely variable.

STUDY DESIGN

: Postmortem anatomic dissection of 41 bequeathed adult crania (82 temporal bones).

METHODS

Drill marks were made on the medial wall of the mesotympanum from 2 manubrium-based positions: 1.5 to 2 mm posterior to the umbo, and halfway between the umbo and the annulus posteroinferior.

RESULTS

Distances to the lip of the round window niche ranged from 0.8 to 3.5 mm and from 1.8 to 4.5 mm for the 2 electrode sites, respectively. The posteriorly determined site was uniform on the promontory, but the posteroinferior site was into hypotympanic trabeculations in 81% of ears and into the jugular plate in 6%. Distances from the electrode sites to round window niche were not obviously associated with either the orientation of the manubrium in the head or the mastoid size.

CONCLUSION

The location of a transtympanic positioned electrode using the manubrium as guidepost is not accurately predictable relative to the round window niche.

Methods of teaching stapedectomy

OBJECTIVES

Establish a better method of teaching residents stapes surgery, with the goal of improving surgical outcome.

STUDY DESIGN

A stapes surgery teaching module was developed with specific criteria to evaluate resident performance. A prospective study of stapes surgery performed by teaching module trained residents was compared with a retrospective review of stapes surgery performed by non-teaching module trained residents.

METHODS

Four residents naive to stapes surgery were assigned to a stapes surgery teaching module. Stapedectomy of 20 temporal bones per resident, with six 3-hour laboratory sessions, was performed. Laser (CO2 and argon) as well as mechanical techniques were used. Specific scoring criteria were applied to measure performance. Results of actual stapes surgery of teaching module trained residents were compared with those of a comparable group of non-teaching module trained residents.

RESULTS

Laser techniques in the laboratory resulted in statistically significantly better scores by defined criteria than mechanical techniques. Results of actual stapes surgery performed by teaching module trained residents demonstrated a trend toward better surgical results, although this was not statistically significant.

CONCLUSIONS

Graded operative experience and standard temporal bone surgery courses may not adequately prepare residents for stapes surgery. A teaching module with criteria to evaluate performance better prepares residents for this delicate procedure. Lasers provide a significant advantage in the laboratory model and should be used by residents at surgery. Residents not wishing to perform stapes surgery because of career pathway should be encouraged to turn over their cases to fellow residents.

Teflon-Wire Piston or Stainless-Steel Bucket Stapes Prosthesis: Does it Make a Difference?

The goal of this study was to determine whether postoperative (implantation of a stapes prosthesis) hearing gain and the amount of air-bone gap overclosure are more improved with the Teflon-wire piston or with the stainless-steel bucket prosthesis. We retrospectively reviewed the outcomes of 82 surgeries that had been performed by the primary author; 41 of these patients had received a Fisch Teflon-wire piston, and 41 had received a Bailey-modified Robinson stainless-steel bucket prosthesis.

The mean hearing gain for the patients who received the Teflon-wire piston was 23.3 dB after primary stapes surgery and 20.5 dB after revision surgery. Patients who received the stainless-steel bucket prosthesis experienced a mean hearing gain of 20.7 and 20.3 dB, respectively. Following primary stapes surgery, the air-bone gap overclosure was 4.4 dB with the Teflon-wire piston and 5.2 dB with the stainless-steel bucket prosthesis. There was no statistically significant difference in either hearing gain or air-bone gap overclosure between the two prostheses.

Stapedectomy for the home temporal bone dissection laboratory

During the last 15 years, there has been a steady decline in the number of stapedectomies performed. Suggestions have been made to limit the residents' training in stapes surgery as well as to determine who is qualified to perform stapedectomies. It is well recognized that the skills and precision required for a stapedectomy are different from those used in chronic ear surgery and, if these precise techniques are not used on a regular basis, one will lose the dexterity required for this operation. A technique has been developed that enables the resident or infrequent operator to improve his skills with stapedectomy in the laboratory, prior to being confronted with a patient. It should help to improve the residents' surgical experience as well as maintain the surgical skills required for this operation.