Hearing Improvement in Interposition Ossiculoplasty and Myringostapediopexy

Abstract

Chronic otitis media (COM) may lead to partial or complete loss of tympanic membrane and erosion of the ossicles. Ossicular chain reconstruction may be done by interposition ossiculoplasty or myringostapediopexy. The aim of our study was to determine the hearing outcome in interposition ossiculoplasty and myringostapediopexy using autologous incus or cortical bone graft in intact canal wall tympanoplasty. 64 patients with COM, who underwent interposition ossiculoplasty or myringostapediopexy were included in the study. Audiometric evaluation was done after 3 months after surgery and all patients were followed up for a period of 1 year. The hearing results were compared in terms of mean pre-op and post-op Air conduction thresholds, Air-Bone gap (ABG) and hearing gain or ABG closure. In this study the mean ABG closure for interposition ossiculoplasty and myringostapediopexy was 15.4 dB and 21.8 dB, respectively. Hearing gain with cortical bone graft was higher than hearing gains with incus in both the groups, but not statistically significant. Myringostapediopexy provides marginally better hearing gain compared to interposition ossiculoplasty. Aulogous incus, and cortical bone graft are suitable autologous materials for ossicular reconstruction and provide similar hearing outcome.

Introduction

Chronic otitis media (COM) may lead to partial or complete loss of tympanic membrane and erosion of the ossicles resulting in attenuation of sound transmission from tympanic membrane to the oval window. A conductive deficit in excess of 40 dB indicates ossicular discontinuity usually due to erosion of the long process of incus or stapes suprastructure [1].

With the development of newer technology in middle ear surgeries over the years, the aim of otology surgeons at present is eradication of disease and prevention of recurrence along with reconstruction of tympano-ossicular chain for improvement of hearing.

Depending on the type of ossicular defect autologous sculptured incus, or cortical bone may be used to bridge the gap between the malleus and the stapes suprastucture—interposition ossiculoplasty or may be used to establish a link directly between the tympanic membrane and the stapes suprastructure—myringostapediopexy.

Aims and Objectives

To determine the hearing outcome after interposition ossiculoplasty and myringostapediopexy using sculptured autologous incus or cortical bone in intact canal wall tympanoplasty with or without cortical mastoidectomy.

Methodology

This study was carried out at the Department of Otorhinolaryngology and Head and Neck surgery, R.L. Jalappa hospital, Tamaka, Kolar.

Inclusion Criteria

Patients diagnosed with chronic otitis media (COM) with hearing loss and undergoing interposition ossiculoplasty or myringostapediopexy using autologous incus or cortical bone graft with intact canal wall tympanoplasty with or without mastoidectomy.

Exclusion Criteria

1. Patients with sensorineural hearing loss.

2. Patients with otosclerosis.

3. Patients with chronic otitis media undergoing type I tympanoplasty.

64 patients diagnosed with COM and posted for tympanoplasty were included in the study. All patients underwent surgery under general anaesthesia and post-aural approach was used in all our cases. The patients with Austin type A (erosion of incus with intact malleus and stapes) and type C (erosion of incus and malleus with intact stapes) were considered for ossiculoplasty [2].

32 patients underwent interposition ossiculoplasty (Group A) and 32 patients underwent myringostapediopexy (Group B) using sculptured autologous incus or cortical bone graft.

Removal and Sculpturing of Incus

The incus with necrosed lenticular/long process was detached from the incudomaleal joint and taken out. It was then held with Derlacki’s ossicle holding forceps. Drilling of incus was performed using 0.6 mm diamond burr.

For Interposition ossiculoplasty, the short process was drilled to make it flat and a socket was drilled in the remodelled short process area for the head of stapes. A slit was made to accommodate the stapedial tendon. A notch was made towards the long process to fit the handle of malleus.

For myringostapediopexy, the remnant long process of incus was drilled out to make it cylindrical with a flat base. A socket was drilled in under surface of remodelled long process to fit the head of stapes. Part of short process and the articular facet of the body removed to avoid ankylosis with the posterior canal wall. The superior border of the body of incus was then flattened to favour its attachment with TM (Fig. 1).

Fig. 1.

Sculpturing the autologous incus graft

Harvesting and Reshaping of Cortical Bone

A cortical bone graft was harvested from the mastoid region in cases where:

• Necrosed incus was left in place for attic support to prevent postoperative retraction of neo-tympanum

• Incus was eroded up to the bony annulus

• Incus was too fragile for drilling or

• Incus was lost during drilling—three autologous incus were damaged or lost during reshaping in our study (Fig. 2).

Fig. 2.

Harvesting a cortical bone graft from the mastoid region

Bone graft was held with a Derlacki’s ossicle holding forceps and drilled into appropriate size (Fig. 3). A socket was drilled on one surface for the head of stapes and the opposite surface was made flat for myringostapediopexy (Fig. 4) or a notch was drilled to accommodate the handle of malleus for interposition ossiculoplasty.

Fig. 3.

Sculpturing the cortical bone graft

Fig. 4.

Cortical bone graft placed in middle ear for myringostapediopexy

Outcome Measures

Audiometric evaluation was done 3 months after surgery and all patients were followed-up for a minimum period of 1 year. The hearing results were compared in terms of mean pre-op and post-op Air conduction thresholds, Air-Bone gap and hearing gain or ABG closure. Postoperative ABG closure was measured as the difference between the preoperative ABG and postoperative ABG. The audiometric results were reported according to AAO-HNS guidelines and threshold at 4 kHz were used in all cases instead of threshold at 3 kHz as both are equally comparable as suggested by the committee on hearing and equilibrium [3].

Results

64 patients with ossicular chain defect were included in the study. 32 patients underwent interposition ossiculoplasty (Group A) and 32 patients underwent myringostapediopexy (Group B). Table 1 shows the profile of all 64 cases analysed.

Table 1.

Basic profile of the two groups

Parameters	Interposition ossiculiplasty (n = 32)	Myringostapediopexy (n = 32)
Mean age (range 16–67 years)	24.75	27.25
Female:male	21:11	19:13
Right:left side	20:12	18:14
Non-cholesteatoma:choleateatoma	32:00	28:04

Table 2 shows the presenting complains of patients in both groups and the tympanic membrane findings are shown in table 3. Follow-up with postoperative audiological evaluation was done 3 months after surgery. All patients had well healed neo-tympanum with no evidence of retraction.

Table 2.

Distribution according to presenting complaints and comparison between two study groups

	Group
	Interposition (Group A)		Myringostapediopexy (Group B)
	Number (n = 32)	%	Number (n = 32)	%
Presenting complaints
Ear discharge	2	6.2	2	6.2
Loss of Hearing	2	6.2	2	6.2
Ear ache	1	3.1	1	3.1
Tinnitus	0	0.0	1	3.1
Itching	1	3.1	0	0.0
Ear discharge + loss of hearing	17	53.1	11	34.4
Ear discharge + ear ache	3	9.4	6	18.8
Loss of hearing + ear ache	3	9.4	6	18.8
Loss of hearing + tinnitus	3	9.4	3	9.4

Table 3.

Distribution of various pathology of tympanic membrane findings and comparison between two study groups

	Group
	Interposition (Group A)		Myringostapediopexy (Group B)
	Number (n = 32)	%	Number (n = 32)	%
Pathology tympanic membrane
Central perforation	14	43.8	9	28.1
Subtotal perforation	14	43.8	16	50.0
Marginal perforation	0	0.0	1	3.1
Attic retraction with perforation	1	3.1	2	6.2
Posterior-superior retraction	3	9.4	4	12.5
Total perforation	0	0.0	0	0.0

The mean preoperative air-conduction threshold for Group B was higher than Group A, which was statistically significant. The mean preoperative air-conduction thresholds for Group A and Group B were 47.9 dB (SD 5.3) and 55.9 dB (SD 7.7) respectively. Mean postoperative air-conduction thresholds for Group A and Group B were 31.1 dB (SD 6.7) and 34.5 dB (SD 7.7) respectively (Table 4).

Table 4.

Pre Op and Post Op AC distribution and comparison between two study groups

	Group						p value b/w two groups
	Interposition (Group A)			Myringostapediopexy (Group B)
	Mean	SD	p value with in group	Mean	SD	p value with in group
Pre Op AC	47.9	5.3		55.9	7.7		< 0.001
Post Op AC	32.1	6.7	< 0.001	34.5	7.7	< 0.001	0.190

The mean preoperative ABG for Group B was higher than Group A, which was statistically significant. There was improvement in post-op ABG in both groups. In Group A the mean pre op ABG was 31.8 ± 3.8 dB and the mean post op ABG was 16.5 ± 4.8 dB. In Group B, mean pre op ABG was 40.7 ± 6.9 dB and mean post op ABG was 19.2 ± 7.6 dB (Fig. 5).

Fig. 5.

Pre Op and Post Op ABG distribution and comparison between two study groups

There was a statistically significant difference between ABG closure of the two groups. Group B had higher ABG closure of 21.8 dB compared to ABG closure of Group A i.e. 15.4 dB. This may be due to higher pre-op ABG in Group B as reported in other studies [5, 8] (Figure 6).

Fig. 6.

Distribution according to ABG closure and comparison between two study groups

In Interposition group, 28 patients underwent ossiculoplasty using autologous incus and in 4 patients cortical bone graft was used. The mean ABG closure was 15.17 dB when autologous incus was used and the mean ABG closure was 16.70 dB when cortical bone was used. There was no significant difference in ABG closure with respect to material used (Fig. 7).

Fig. 7.

ABG closure in interposition group with respect to material used

In Myringostapediopexy group, 24 patients underwent ossiculoplasty using autologous incus and in 8 patients cortical bone graft was used. The mean ABG closure was 22.05 dB when autologous incus was used and with cortical bone ABG closure was 25.02 dB. There was no significant difference in ABG closure with respect to material used (Fig. 8).

Fig. 8.

ABG closure in myringostapediopexy group with respect to material used

Discussion

Chronic otitis media may lead to partial or complete loss of tympanic membrane and erosion of the ossicular chain. The goal of ossiculoplasty is to restore the hearing to normal or near normal levels.

In a study done in Kolkatta, 20 patients underwent interposition ossiculoplasty using autologous incus. Their mean pre-op and post-op AC thresholds were 47.7 dB and 38.05 dB respectively. An average of gain of 9.65 dB was seen in the post-op AC thresholds [4]. In an Italian study, patients with mean pre-op AC thresholds of 49.9 dB underwent myringostapediopexy using autologous incus or cartilage. On follow-up the mean post-op AC threshold was 36.6 dB and an average gain of 13.3 dB was seen after surgery [5].

In the present study, the mean pre-op AC thresholds for Group A and Group B were 47.9 dB and 55.9 dB respectively which was statistically significant and higher in Group B. These results were similar to the above mentioned studies. At 3 months follow-up post-op AC threshold showed improvement in both groups which was statistically significant and higher than the above mentioned studies. Mean post-op AC threshold in Group A (32.1 dB) showed a gain of 15.8 dB and the mean post-op AC threshold in Group B (34.5 dB) showed a gain of 21.4 dB.

The mean pre-op BC threshold for Group A and Group B was 16.1 dB and 15.8 dB respectively. Post-operatively it was 15.3 dB for both Group A and Group B.

In our study, the average pre-op Air-Bone gap (ABG) in Group B was higher than Group A and was statistically significant (31.8 dB in Group A and 40.7 dB in Group B). At the end of 3 months after surgery, 100% patients in both groups showed an improvement in ABG which was statistically significant. The mean improvement in post-op ABG for Group A and Group B was 15.4 dB and 21.8 dB respectively.

A study conducted at the university of Pittsburgh medical centre showed that Interposition ossiculoplasty using autologous graft achieved a post-op ABG of 18.6 dB [6]. In a retrospective study by Iurato et al., it was concluded that post-op ABG was 12 dB at 12 months follow-up for patients undergoing Interposition ossiculoplasty for Austin-Kartush class A defects with the use of autologous incus [7]. Our study achieved a mean post-op ABG of 16.5 dB in Group A which was similar to the above mentioned studies. Various studies in literature show, post-op ABG ranging from 15.8 to 22.5 dB for patients who underwent myringostapediopexy using autologous grafts with better results shown by Quaranta et al. from their series of staged tympanoplasty and ossiculoplasty [8–10]. Our study shows similar results with a mean post-op ABG of 19.2 dB for Group B. The average post-op ABG for Group B was higher than Group A but was not statistically significant.

A study conducted at Belgaum, Karnataka shows an ABG closure of 18.8 dB in patients who underwent interposition ossiculoplasty by using autologous incus [1]. A retrospective study conducted in Italy revealed an ABG closure of 14.89 dB in patients who underwent myringostapediopexy using autologous incus or cartilage [5]. Another study comparing myrigostapediopexy and interposition ossiculoplasty conducted in Uttrakhand inferred that ABG closure for myrigostapediopexy and interposition ossiculoplasty was 10.7 dB and 18.0 dB respectively [11].

In our present study, it was concluded that mean ABG closure for Group A and Group B was 15.4 dB and 21.8 dB respectively. This was comparable to the study conducted at Belgaum when interposition ossiculoplasty was taken into consideration [1].

The mean ABG closure for Group B was higher than Group A and was statistically significant. This may be due to higher pre-op ABG in Group B as reported in other studies [7, 10]. When patients with similar preoperative hearing loss in either groups of our study were compared hearing gain was marginally better with myringostapediopexy than interposition ossiculoplasty.

A review article from Belgaum, Karnataka on ossiculoplasty documented incus as the most common autologous material used for ossiculoplasty [12] which was similar to our study where 87.5% (28) patients in Group A and 75% (24) patients in Group B underwent ossiculoplasty using sculptured autologous incus.

A study done in Finland reported higher improvement in post-op ABG with cortical bone (13.9 dB) when compared to incus (7.2 dB) [13]. Other studies reported no significant difference in hearing results when incus or cortical bone grafts was used for ossiculoplasty [14, 15].

In our study, the mean ABG closure for the patients who underwent interposition ossiculoplasty using autologous incus was 15.17 dB and the ABG closure with cortical bone graft was 16.70 dB. In myringostapediopexy Group the mean ABG closure was 22.05 dB when autologous incus was used and 25.02 dB with cortical bone graft. Improvement in post-op ABG was better with cortical bone graft in both the groups but was not statistically significant.

Conclusion

This study reveals that Ossicular reconstruction by interposition ossiculoplasty and myringostapediopexy using autologous grafts provide significant hearing improvement in patients with COM. Improvement in hearing is better in patients with higher preoperative hearing loss when compared to patients with lesser preoperative hearing loss. Myringostapediopexy provides marginally better hearing gain compared to interposition ossiculoplasty. However the marginal gain was not statistically significant in this study.

Both incus and cortical bone grafts are suitable autologous materials for ossiculoplasty and hearing improvement is similar when either of them is used for interposition ossiculoplasty and myringostapediopexy. However in practice incus is more frequently used as it is readily available in the surgical field and does not involve harvesting an additional graft.