Abstract
Objective
A prospective randomized unblinded controlled trial was conducted by comparing acellular dermis with temporalis fascia as graft materials in tympanoplasty (type 1) in terms of operative time, postoperative pain, graft success rate, and audiologic outcome.
Study design
Forty-two patients with (inactive) chronic suppurative otitis media of tubotympanic type were randomized, matched, and divided equally into 2 groups of 21 each. One group underwent tympanoplasty (type 1) via transcanal route using temporalis fascia graft and the other using acellular dermis. Both groups were compared for operative time, postoperative pain, graft success rate, and audiologic improvement in hearing.
Results
There was a statistically significant reduction in operative time ( P < .05) and postoperative pain ( P < .05) in the acellular dermis group. However, there was no statistical difference in graft success rate ( P > .05) and hearing improvement ( P > .05) between both the groups.
Conclusion
Results of tympanoplasty using acellular dermis as graft material are comparable to that using temporalis fascia in terms of graft uptake and hearing improvement. However, tympanoplasty using acellular dermis has the advantage of shorter operative time and lesser postoperative pain.
1
Introduction
Tympanic membrane perforations are commonly seen by the otologist. It not only causes loss of hearing but also the patient has to face the embarrassment of a persistently or recurrent ear discharges. It can be managed by reconstruction of the hearing mechanism by grafting the tympanic membrane perforation. The surgery is called tympanoplasty , which not only gives the patient a dry ear but also improves the hearing. Since first described by Berthold in 1878, a host of materials have been used for tympanic membrane grafting. These include skin, vein, fascia, perichondrium, dura, fat, and so on . All these autologous grafts have excellent success rates of closing the perforation. The most commonly used autologous graft material is temporalis fascia. However, this has its own limitations. To harvest it, an incision has to be made, which often leaves an externally visible scar. Also, it is difficult to harvest this material in revision surgery where the fascia has already been used in the previous operation.
Acellular dermis is an allograft obtained from cadaveric or donor skin banks that has been processed to reduce its immunogenicity by decellularizing it and screening it for HIV, hepatitis B and C, syphilis, human T-lymphotropic virus type 1, and others. The processing leaves the basement membrane and the extracellular matrix intact. Because the tissue is acellular, it does not produce any antigenic inflammatory response after implantation. The implanted dermal matrix provides a template for migration, repopulation, and revascularization of the patient’s own fibroblasts and endothelial cells. It is available in a freeze-dried form and has to be rehydrated before use ( Fig. 1 ). Originally described for wound grafting in patients with burns , acellular dermis is also being used for facial tissue augmentation, intraoral resurfacing, periodontal and maxillofacial surgeries , and repair of nasal septal perforation . Use of acellular dermis in ear surgery as a graft material can reduce donor site morbidity significantly. A review of literature on the use of acellular dermis as the graft material in tympanoplasty was done, and we found that our study was the only prospective study comparing acellular dermis with temporalis fascia as graft material in terms of operative time, postoperative pain, graft success rate, and hearing improvement.
2
Materials and methods
Patients were recruited over 18 months from November 2007 to April 2009 from the otolaryngology clinics. The study protocol and consent forms were approved by the research review committee. The study was unblinded. During the recruitment phase, patients with (inactive) chronic otitis media of tubotympanic type were screened and only those patients in the age group of 18 to 50 years with medium-sized (involving approximately 25%–50% of the tympanic membrane area based on otoscopic examination), central (involving all the quadrants) perforations were included in the study. After application of the exclusion criteria (previously failed tympanoplasty, cholesteatoma, chronic otitis media with complication, tortuous external auditory canal, and those with systemic diseases), the study was discussed with 59 consecutive patients with a purely conductive hearing loss (less than 40 dB). Of these, 42 patients who agreed (fully informed written consents were taken) to be a part of the study were informed about the study design and underwent randomization into 2 groups. The 2 groups were matched for any confounding factors.
2.1
Operative procedure
All patients underwent tympanoplasty (type 1) under local anesthesia via transcanal route and underlay technique. In the first group, temporalis fascia was used. The graft was harvested through a separate incision over the superior attachment of pinna. In the second group, acellular dermis of 0.03 mm thickness was used as a graft material. Acellular dermis was hydrated in 2 saline baths for 5 minutes each before use and tailored according to the size of the perforation. A self-retaining ear speculum was inserted into the external auditory canal. The margins of perforation were visualized under the microscope and freshened, tympanomeatal flap was elevated, canaloplasty was done (so that the entire annulus was visible without changing the position of the microscope or of the patient’s head), and graft placed by underlay technique. Usual canal packing was done using gelfoam and antibiotic-coated merocel ear wick. Patients were prescribed broad-spectrum antibiotics and analgesics orally for 1 week. All patients were discharged on the same day. Patients were advised dry ear precautions and regular follow-up initially after 1 week and then at 3 weeks, 6 weeks, and at the end of 3 months.
2.2
Operative time
Operative time was kept by an independent nurse and included the time at which the incision for harvesting the graft was given till the time of dressing application. This time did not include the time used for infiltration of local anesthesia and preparatory time before the surgery. All the surgeries were done by the same surgeon so that the operative time could be compared between the 2 groups. Mean and standard deviation for each group were calculated and then compared using Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.3
Postoperative pain
Postoperative pain was measured using a visual analog scale, 6 hours after surgery. By this time, the effect of local anesthesia had weaned off. Patients were asked to rate their pain on the visual analog scale from 0 to 10, 0 meaning no pain and 10 as unbearable pain. Mean and standard deviation for each group were calculated and then compared using Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.4
Graft success rate
Graft success rate was measured in terms of closure of perforation at the end of 6 weeks. This was documented using a Hopkins straight 0° tele-otoscope and camera. Graft success rate (percentage) was calculated for each group and then compared using Fisher exact test. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.5
Audiologic assessment
Hearing improvement (gain in air-bone gap) was assessed at the end of 3 months by comparing the average pre- and postoperative air-bone gap at 500, 1000, and 2000 Hz for both the groups. The mean and standard deviation for gain in air-bone gap in each group were calculated and then compared using paired t test and Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2
Materials and methods
Patients were recruited over 18 months from November 2007 to April 2009 from the otolaryngology clinics. The study protocol and consent forms were approved by the research review committee. The study was unblinded. During the recruitment phase, patients with (inactive) chronic otitis media of tubotympanic type were screened and only those patients in the age group of 18 to 50 years with medium-sized (involving approximately 25%–50% of the tympanic membrane area based on otoscopic examination), central (involving all the quadrants) perforations were included in the study. After application of the exclusion criteria (previously failed tympanoplasty, cholesteatoma, chronic otitis media with complication, tortuous external auditory canal, and those with systemic diseases), the study was discussed with 59 consecutive patients with a purely conductive hearing loss (less than 40 dB). Of these, 42 patients who agreed (fully informed written consents were taken) to be a part of the study were informed about the study design and underwent randomization into 2 groups. The 2 groups were matched for any confounding factors.
2.1
Operative procedure
All patients underwent tympanoplasty (type 1) under local anesthesia via transcanal route and underlay technique. In the first group, temporalis fascia was used. The graft was harvested through a separate incision over the superior attachment of pinna. In the second group, acellular dermis of 0.03 mm thickness was used as a graft material. Acellular dermis was hydrated in 2 saline baths for 5 minutes each before use and tailored according to the size of the perforation. A self-retaining ear speculum was inserted into the external auditory canal. The margins of perforation were visualized under the microscope and freshened, tympanomeatal flap was elevated, canaloplasty was done (so that the entire annulus was visible without changing the position of the microscope or of the patient’s head), and graft placed by underlay technique. Usual canal packing was done using gelfoam and antibiotic-coated merocel ear wick. Patients were prescribed broad-spectrum antibiotics and analgesics orally for 1 week. All patients were discharged on the same day. Patients were advised dry ear precautions and regular follow-up initially after 1 week and then at 3 weeks, 6 weeks, and at the end of 3 months.
2.2
Operative time
Operative time was kept by an independent nurse and included the time at which the incision for harvesting the graft was given till the time of dressing application. This time did not include the time used for infiltration of local anesthesia and preparatory time before the surgery. All the surgeries were done by the same surgeon so that the operative time could be compared between the 2 groups. Mean and standard deviation for each group were calculated and then compared using Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.3
Postoperative pain
Postoperative pain was measured using a visual analog scale, 6 hours after surgery. By this time, the effect of local anesthesia had weaned off. Patients were asked to rate their pain on the visual analog scale from 0 to 10, 0 meaning no pain and 10 as unbearable pain. Mean and standard deviation for each group were calculated and then compared using Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.4
Graft success rate
Graft success rate was measured in terms of closure of perforation at the end of 6 weeks. This was documented using a Hopkins straight 0° tele-otoscope and camera. Graft success rate (percentage) was calculated for each group and then compared using Fisher exact test. Result was statistically significant if value of significance ( P ) was found to be less than .05.
2.5
Audiologic assessment
Hearing improvement (gain in air-bone gap) was assessed at the end of 3 months by comparing the average pre- and postoperative air-bone gap at 500, 1000, and 2000 Hz for both the groups. The mean and standard deviation for gain in air-bone gap in each group were calculated and then compared using paired t test and Levene t test for equality of variances. Result was statistically significant if value of significance ( P ) was found to be less than .05.
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