Cerebrospinal Fluid Otorrhea After a Routine Tympanostomy Tube Placement: A Review of the Literature on Hyrtl Fissure.

Objective: To review the literature on Hyrtl fissure (HF) and contribute our experience with a 2-year old who developed cerebrospinal fluid (CSF) otorrhea during routine tympanostomy tube placement.

Methods: Data Sources: Pubmed and Google Scholar searches were conducted of articles in the English language literature from all time periods using the words Hyrtl, Hyrtl's fissure, HF, and tympanomeningeal fissure. Study Selection: All relevant articles were reviewed to identify cases of HF.

Results: Data Extraction: Nineteen cases, including ours, are described. Patient characteristics, method(s) of diagnosis and repair, and outcomes are reported. Computed tomography and intraoperative endoscopic images from our case are included. Presentation is more common in children (66.7% of cases where age was stated, n = 10) than in adults (33.3%, n = 5), and is most commonly unilateral (89.5%, n = 17). Cerebrospinal fluid otorrhea was the most common presentation. Six were discovered after tympanostomy tube placements while 3 were identified during cochlear implant work-up or after device failure. Surgical approaches described include endaural, transcanal, retrosigmoid, postauricular, and posterior fossa endoscopic. Multiple materials including bone wax, bone pate, fascia, muscle, and tissue sealant have been used. Our case describes an endoscopic repair in a child, which was successful at a 2-year follow-up. Data Synthesis: The small number of cases limits the utility of statistical analysis (n = 19).

Conclusions: Hyrtl fissure is a rare but important entity that may be discovered when routine procedures have unexpected results. Hyrtl fissure should be included in the differential diagnosis when there is persistent clear otorrhea after a tympanostomy tube, cochlear implant misinsertion, meningitis, or unexplained middle ear effusion in an adult.