Reaching the Hidden Compartment: Video-Otoscope–Guided Bulla Fenestration for Feline Otitis Media

Efficacy of video-otoscope-guided septum bulla fenestration and middle ear lavage for treating otitis media in cats

Takafumi Osumi; Ikki Onishi; Yuta Baba

Background

Feline otitis media (FOM) is commonly associated with Eustachian tube dysfunction and may cause chronic otorrhoea, vestibular signs, and cranial nerve deficits. In cats, the tympanic bulla is divided by a bony septum into lateral and medial compartments, potentially limiting the effectiveness of standard middle ear lavage. Although video-otoscope (VO)-guided myringotomy and lavage can improve outcomes, recurrence has been reported. This study evaluated whether VO-guided septum bulla fenestration (SBF) enables access to the medial compartment and improves clinical outcomes in cats with FOM.

Methods

This retrospective case series reviewed 31 cats (44 ears) diagnosed with FOM and treated with VO-guided myringotomy, middle ear lavage, and SBF between August 2021 and November 2023. Diagnosis was based on clinical signs, imaging (CT, MRI, or radiography), and myringotomy findings. All procedures were performed by a single operator. Effusion from lateral and medial compartments was assessed cytologically. Cats were followed for a minimum of 6 months (median 18 months) to evaluate clinical remission, recurrence, tympanic membrane regeneration, and complications.

Results

Following SBF, substantial effusion from the medial compartment was drained in 38/44 (86.4%) ears, indicating that conventional lavage alone was often insufficient. Cytology detected bacteria in 13.6% of lateral compartment samples and 5.3% of medial compartment samples, with bacterial presence associated with pre-existing tympanic membrane disruption or prior myringotomy. Initial clinical response occurred in 39/44 (88.6%) ears. However, 16 ears showed failure to resolve or recurrence, typically after tapering adjunct medical therapy. Most of these cases responded to additional medical management or repeat VO-guided lavage. Overall, stable clinical remission without surgical intervention was achieved in 39/44 (88.6%) ears. Tympanic membrane regeneration was confirmed in 61.5% of evaluable ears. Reported complications were mild and transient, consisting of one case each of facial nerve paralysis and Horner’s syndrome.

Limitations

The study’s retrospective design, lack of a control group, and absence of bacterial culture and sensitivity testing limit causal inference and antimicrobial interpretation. Medical management protocols varied among cases, and follow-up examinations were not standardized across all patients. Cytology alone may have underestimated bacterial involvement. Operator experience and anatomical variation may affect reproducibility.

Conclusions

VO-guided SBF enabled access to and lavage of effusion in the medial compartment of the feline tympanic bulla, which is not reliably addressed by conventional lavage. Most cats achieved stable remission with this minimally invasive approach combined with medical therapy, although recurrence was not uncommon. SBF should be considered an adjunct rather than definitive treatment for FOM. Prospective, controlled studies are needed to determine its long-term prognostic value and comparative efficacy.

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