1 Department of Otolaryngology – Head & Neck Surgery, Hospital for Sick Children, University of Toronto, Canada.
During interlay tympanoplasty (IT) the graft is placed between the fibrous and squamous layers of tympanic membrane (TM) whereas in lateral graft tympanoplasty (LGT), the graft is placed under the TM remnant and malleus handle but lateral to the entire annular groove. This study compares outcomes from IT and LGT using a trans-canal totally endoscopic surgery (TEES) approach.
– Study Design:
Prospective observational comparative study
Tertiary referral center
101 children, mean age 12 years (range 2 – 18), with tympanic membrane (TM) perforation without cholesteatoma
TEES tympanoplasty with porcine-derived collagen graft using either LGT or IT. LGT was generally used for subtotal or anterior perforations and IT for more central perforations. Other techniques were used less commonly and are excluded from this study.
– Main Outcome Measures:
Proportion with perforation closure; change in hearing (pre – post-operative 4-tone average air conduction threshold (AC)); complications.
Perforation closure was achieved in 44/50 IT and 45/51 LGT surgeries (88%, NS, X2-test). AC hearing improved by 8dB to 21dB HL after LGT and by 9dB to 17dB HL after IT (NS, Mann-Whitney). Inclusion cholesteatoma cysts required revision surgery after 3 (6%) IT but no LGT cases.
Perforation closure and hearing outcomes are similar between LGT and IT. Incomplete elevation of the squamous from the fibrous TM layer or malleus handle causes a risk of inclusion cholesteatoma after IT from squamous remnants that become covered by the graft. Although the underlay graft placement of LGT is more technically demanding, avoidance of this complication makes LGT a preferable option.