A Case Series of Positional Variations in the Spine of Henle: A Surgical Conundrum

The temporal bone is a complex anatomical space that houses the middle ear and its ossicles, as well as the inner ear, which includes the vestibule, cochlea, and the semicircular canals. Henle's spine, also known as the suprameatal spine/spina suprameatica/ is found to guide the lateral wall of the mastoid antrum [J Res Med Dent Sci 8(7):420-422, Stat-Pearls Publishing, Treasure Island. Available from: https://www.ncbi.nlm.nih.gov/books/NBK559153/]. It is found that the Henle's spine is present in 85% of the human skulls and when present, it could be used as a reliable anatomical landmark for isolating various foramina during skull base surgeries [J Laryngol Otol 119:856-861], and to assess the location of handle of malleus and subsequently the mastoid antrum, in many cases. We present here 3 cases in which tympanoplasty was planned, and the position of spine of Henle was found to be anterosuperior and so was the handle of malleus. Antrostomy was done by following the spine of Henle in all cases to establish patency and maintain ventilation in the post-operative ear. These 3 cases had a much more anteriorly placed spine. Such cases need to be reported so that it creates a paradigm shift in the way that mastoid surgeries are being done. Any variation in the positioning of the spine of henle points to variability in the position of the mastoid antrum. This is extremely important while drilling the mastoid in the correct position and also to prevent drilling over the sigmoid sinus or the dura. To conclude, an anteriorly placed spine of Henle corresponds to anteriorly placed mastoid antrum.