Endoscopic Assessment of the Isthmus Tympanicum and Tensor Tympani Fold and their Relationship with Mastoid Pneumatization in Chronic Otitis Media

Abstract

Objectives: To endoscopically evaluate the patency of the isthmus tympanicum and integrity of the tensor tympani fold as routes of ventilation of the attic and mastoid in chronic otitis media (COM) and to assess their effects on mastoid pneumatization.

Materials and methods: Sixty patients with COM were categorized into two groups: (1) Group A: 36 patients with tympanic membrane perforation (2) Group B: 24 patients with limited attic disease of whom 14 patients had attic retraction pockets and 10 with limited attic cholesteatoma. A multislice computed tomography scan of the temporal bone was performed for each patient to assess the degree of mastoid pneumatization. Notably, either myringoplasty or tympanomastoid surgery was performed in all patients. An endoscope was inserted into the middle ear for evaluation of the isthmus tympanicum and tensor fold area.

Results: The isthmus tympanicum was patent in most ears (83.3%) of group A, whereas it was blocked in most ears (83.3%) of group B. The tensor fold was complete in 77.8% of ears in group A and 83.3% of ears in group B. It was observed that 94.1% of ears with patent isthmus in both groups had normal mastoid pneumatization and 5.9% of ears had poorly pneumatized mastoid. By contrast, 7.7% of ears with blocked isthmus tympanicum had normal mastoid pneumatization and 92.3% had poor mastoid pneumatization. Normal mastoid pneumatization was observed in 50% of ears in both groups with complete tensor fold, and 83.3% of ears with an incomplete tensor fold.

Conclusion: A significant correlation was observed between COM with limited attic disease and obstruction of the isthmus tympanicum. Obstruction of isthmus tympanicum was associated with poor mastoid pneumatization. Furthermore, an incomplete tensor fold was associated with well pneumatized mastoid.

Figure 1. a–d

a) Patent isthmus and complete tensor fold in case of left dry perforation. b) patent isthmus in case of left wet perforation. c) and d) blocked isthmus and complete tensor fold in case of left dry perforation. M: malleus, IC: incus, CT: chorda tympani nerve, CP: cochleariform process, IS: isthmus tympanicum, TF: tensor fold area, FN: facial nerve, ISP: blocked posterior isthmus, STR: supratubal recess, ST: stapedial tendon

Figure 2. a–d

a) Blocked isthmus in case of left retraction pocket. b) partially blocked isthmus, retracted malleus, and eroded scutum in case of left non-self cleaning attic retraction pocket. c) patent isthmus, partially eroded lenticular process of incus, high jugular bulb in case of left retraction pocket. d) blocked isthmus because of cholesteatoma sac and medialized retracted malleus, complete erosion of the long process of incus in case of left attic cholesteatoma. M: malleus, IC: incus, IS: isthmus tympanicum, ST: stapedial tendon, RW: round window, JB: jugular bulb, FN: facial nerve, CHO: cholesteatoma sac.