Effects of Sacrificing Tensor Tympani Muscle Tendon When Manubrium of Malleus Is Foreshortened in Type I Tympanoplasty

The current study aims at observing effects of sacrificing the tensor tympani tendon when manubrium of malleus is foreshortened or retracted on graft uptake, hearing improvement, and occurrence of complications if any during type I tympanoplasty surgery for central perforations. 42 patients were included in group A where the tensor tendon was sectioned and 42 patients were included in group B where the tensor tympani tendon was retained and kept intact. Graft uptake rates are very good in both groups but hearing improvement was found significantly better in group A than group B. No unusual or undesired complications were seen in any of the cases. Sectioning of tensor tympani tendon is safe and effective procedure in cases where manubrium is foreshortened.


Introduction
It is not unusual to find medially retracted or foreshortened handle of malleus (manubrium) during tympanoplasty. Apart from posing difficulties in placement of graft during underlay technique, it can affect orientation during surgery as the manubrium is one of the important landmarks in middle ear. Sectioning of the tensor tympani tendon near the neck of malleus would lateralize the manubrium to a significant extent and add to mobility of malleus as well. Arviso and Todd Jr. [1] have studied adult crania without clinical otitis and concluded that foreshortened malleus is an anatomic variant, not a sign of pathology. The current study aims at evaluating results of type I tympanoplasty for central perforations where manubrium was found foreshortened preoperatively or during surgery and the tensor tympani tendon (TT) was cut during surgery and comparing these results with those cases where manubrium was foreshortened and TT was kept intact.

Material and Methods
A total of 84 cases were included in the study with inclusion criteria being a dry central perforation where the manubrium of malleus was found to be medially rotated and touching the medial wall of the middle ear. Cases with perforation size more than 4 mm (measured by placing graph paper on the perforation) are included. Cases where all the three ossicles were intact and mobile and where a type I tympanoplasty was performed were included. Cases with ossicular erosion or with cholesteatoma or with a marginal perforation were excluded. All subjects with mucosal chronic otitis media were clinically evaluated thoroughly including tuning fork tests and otoendoscopy done when ear is dry for more than 2 weeks. A pure tone audiogram was done for all the subjects. In some of them, a medially rotated malleus could be found during otoendoscopy (Figure 1) whereas, in many others, it was found during surgery. Odd numbered patients were included in group A where TT was cut during surgery ( Figure 2). Even numbered patients were included in group B where TT was not cut. All cases were operated on under general anesthesia. Postauricular skin incision was used in all the cases in both groups. Vascular strip incision was used for canal wall skin and after middle ear contents were observed and after necessary disease removal, malleus was carefully made free of all attachments from remnant of tympanic membrane (TM). Ossicular mobility and intactness were also checked. If the subject met the inclusion criteria, decision of 2 International Journal of Otolaryngology  sectioning of TT was taken if the patient is in group A and TT was kept intact in patients of group B. Temporalis fascia was used as the graft material and kept lateral to the handle of malleus and medial to the annulus [2,3]. Anterior tucking was done in all the cases in both groups. It was made sure during surgery that the annulus at the anterior canal wall is reposited back in the original position in the sulcus. Plenty of gelfoam was kept in middle ear, around ossicles especially medial to manubrium and also in the external ear canal in all cases. Cases were followed up regularly for the next 6 months minimum and audiometry results were recorded at 6 months postoperatively. Otoendoscopy picture at 6 months was taken into consideration. The same Amplaid A177 dual channel audiometer with standard calibration was used in all the cases to avoid errors. Parameters compared include graft uptake, medialisation suggested by graft touching the medial wall of middle ear, lateralisation suggested by blunting of anterior angle, air bone gap (ABG) at 6 months, and occurrence of squamous pearls.

Discussion
Handle of malleus is longer than the long process of incus and this provides additional impedance matching function of middle ear and adds to improved conduction of sound through middle ear. When the handle is retracted severely, this should affect conduction of sound as well. Hol et al. [4] have used autologous interposition of incus to overcome severely retracted handle of malleus and stated that patients presenting with COM (chronic otitis media), a (central) perforation, a medially rotated malleus, and intact ossicular Table 2: Comparison of graft uptake rates of different authors.

Author
Graft material Take-up (%) Dabholkar et al. [7] Temporalis fascia 84 Dornhoffer [8] Perichondrium 85 Indorewala [9] Fascia lata 95 Indorewala [9] Temporalis fascia 66 Batni and Goyal [10] Temporalis chain are a treatment challenge. Lateralizing the malleus handle may require disconnection of the ossicular chain and an autologous incus interposition to bring back the reconstructed tympanic membrane in its original position and improve the hearing. According to Todd [5], orientation of manubrium is inexplicably widely variable. Deng et al. [6] have concluded that the section of the tensor tympani muscle tendon in canal wall-down tympanoplasty with ossiculoplasty had no statistically significant influence on sound transmission and can be a safe maneuver in middle ear surgery. It is well known, and we can see it in our cases; after cutting the tensor tympani tendon, the anterior tympanic membrane remnant becomes pleated, so we need to completely separate it from the manubrium. It will also make it easy to place the graft. The manubrium will support the graft from medial side, so the chances of medialisation should also be reduced. By cutting the tensor tympani tendon, the graft is more lateral thus increasing the middle ear volume. This will also help the ossicles to move more freely and it should improve hearing as adequate volume of middle ear is an important consideration for successful conduction of sound.
The current study aims to evaluate effect of sectioning the tensor tympani tendon in type I tympanoplasty surgery without mastoidectomy where the canal wall was preserved and the results are compared. Table 2 shows comparison of graft uptake rates of different authors.

Conclusion
Graft uptake rates are adequate if tensor tympani is cut or preserved, whereas hearing improvements are better in patients where tensor tendon was cut and the difference is statistically significant. No other complications were observed in the current study in both groups. Sectioning of tensor tympani tendon is safe and effective procedure during tympanoplasty if manubrium is severely retracted and it brings good improvement in hearing also.

Consent
Informed consent was obtained from all individual participants included in the study.

Disclosure
Animals were not involved in this study.

Conflict of Interests
The author of this paper declares that he has no conflict of interests.