Tympanic Bone: Small Neglected Bone with Extreme Anatomic Importance in Lateral Skull-Base Surgery

Area of Science:

• Otolaryngology
• Neurosurgery
• Anatomy

Background:

• The tympanic bone (TB) is a vital component of the temporal bone, forming the external auditory canal and aiding sound transmission.
• Its surgical significance in lateral skull-base procedures, especially for tympanojugular paraganglioma (TJP), warrants detailed investigation.

Purpose of the Study:

• To highlight the surgical importance of the tympanic bone (TB).
• To elucidate the TB's role in lateral skull-base surgery, specifically the infratemporal fossa approach type A and TJP management.
• To analyze TB infiltration patterns in TJP cases.

Main Methods:

• Examination of 20 formalin-prepared temporal bones to assess TB anatomy and its relation to the styloid process.
• Comprehensive MEDLINE (PubMed) search using the MeSH term 'tympanic bone'.
• Analysis of 272 TJP cases, classifying them by the modified Fisch classification and evaluating TB infiltration.

Main Results:

• TB thickness averaged 10.6 mm, with styloid process length averaging 43 mm.
• TB infiltration was observed in approximately 40% of C1, 70% of C2, and virtually all C3/C4 TJP cases.
• The study quantified TB thickness and styloid process length, correlating them with TJP tumor extent.

Conclusions:

• The tympanic bone (TB), though often overlooked, is critical in otologic and lateral skull-base surgeries.
• Partial or complete TB removal is frequently necessary for accessing deeper structures like the hypotympanum and internal carotid artery.
• High-resolution computed tomography, particularly coronal views, is essential for detailed TB anatomical understanding prior to surgery.