In vivo endoscopic study of the variations of anatomical structures in the hidden spaces of the middle ear during endoscopic ear surgery

Abstract Objective The middle ear has compartments with the presence of anatomic variations. Transcanal endoscopic middle ear surgery facilitates the exploration of every single compartment with the least possible tissue dissection. Methods This study was conducted on 250 middle ears of patients who had endoscopic ear surgery (tympanoplasty and stapedotomy) at the period of the study with endoscopic recording of the data. Intraoperative examination of the pro, retro, and hypotympanum was performed with 0, 30, and 45° endoscopes and data was collected, processed, and analyzed with Statistical Package for Social Sciences (SPSS). Results Quadrangular conformation (64%), type B (shallow subtensor recess) (64.8%), and type A protinuculum (ridge) were the commonest in the protympanum. Type A jugular bulb which lies below the level of the bony annulus was the commonest finding (75.6%) in the hypotympanum. Type A (ridge) variant was the commonest finding of ponticulus, subiculum, and finiculus 88.4%, 64.8%, and 72.8% respectively in the retrotympanum. Type B (deep) ST 53.6% was the commonest regarding sinus tympani. Type A (present) subcochlear canaliculus, type B (oblique) fustis and type B (absent) RW membrane were the most common regarding the round window region. Conclusion Good knowledge of the anatomical variations of the middle ear has great surgical importance. The study showed variations of the known structures from other studies that can be attributed to being an in vivo study, racial differences, and a larger sample size