Discussion

This case illustrates the acute intraoperative recognition and management of an unanticipated high-flow CSF leak unmasked by routine myringotomy in a child with a previously undiagnosed congenital inner ear malformation. The precipitation of CSF otorrhea from inner ear malformations by myringotomy or ventilation tube placement is well described [5,7], but most reported cases are identified after one or more episodes of meningitis or in children already known to harbor a labyrinthine anomaly. The present case is distinguished by the absence of any prior meningitis or established diagnosis and by antecedent clear rhinorrhea that had not been recognized as CSF, such that the high-flow otorrhea presented as an abrupt intraoperative event. We therefore focus on the practical decision-making this scenario demands.

When high-flow clear otorrhea appears unexpectedly during myringotomy, the immediate priorities are to halt the procedure, avoid suctioning that may enlarge the fistula, collect fluid for beta-2 transferrin, and to temporize the leak while follow-up care is arranged [8]. In this patient, endoscopic placement of a butterfly biodesign graft followed by sequential fibrin-gelatin-fibrin sealant achieved a temporary seal, after which intracranial pressure was lowered and the child was intubated and transferred to the PICU. This staged strategy, starting with acute temporization, then imaging, and then planned definitive repair ten days later, permitted both anatomic characterization and a controlled reconstruction, rather than emergent exploration of an undiagnosed malformation.

Congenital inner ear malformations, including incomplete partition anomalies and other dysplastic labyrinthine configurations, can result in abnormal communications between the subarachnoid space and the inner ear. In this particular case, the malformation was a common cavity deformity, a severe congenital anomaly in which the cochlea and vestibule fail to differentiate and are represented by a single cystic cavity lacking internal bony architecture, typically associated with profound sensorineural hearing loss [9]. Depending on the malformation, CSF or perilymph may track into the middle ear through several routes, including the oval window, the round window, the internal auditory canal along the facial nerve, the hypotympanum, or preformed fissures such as the Hyrtl fissure [6,7]. Although an intact tympanic membrane can keep such leaks clinically silent, in this patient it instead directed CSF down the Eustachian tube, so that the fistula manifested as chronic rhinorrhea rather than otorrhea until the myringotomy created a direct otologic route. That CSF had been draining chronically by the nasal route indicates the fistula was already active before any otologic intervention; a leak brisk enough to egress by both nasal and, once the tympanic membrane was breached, otologic routes underscores its high-flow nature. This dual egress also compounded the risk of ascending infection, since the child was already exposed through the nasopharynx before the external auditory canal provided a second pathway. A problem like this is associated with significant morbidity and mortality, largely attributable to its elevated risk of meningitis [6,10]. In a cohort with persistent CSF rhinorrhea, Daudia et al. reported a meningitis risk of approximately 19% (0.3 episodes per patient-year) prior to definitive repair; comparable rates of around 20% are described for spontaneous CSF otorrhea [10,11].

Beta-2 transferrin analysis remains the gold standard for biochemical confirmation of CSF leakage due to its high specificity for CSF compared with serum or middle ear effusion. In a study done by Bhat et al., beta-2 transferrin demonstrated a pooled sensitivity of 96% and specificity of 94.6% for detecting CSF leaks [12]. Prompt collection of fluid in this case was appropriate and aligned with established diagnostic algorithms. However, the high-flow nature of the leak and the patient’s congenital anatomy necessitated early surgical intervention rather than conservative management.

Intraoperative exploration demonstrated that the tegmen tympani, the most common site of spontaneous CSF leaks in adults, was intact [4]. Instead, the leak originated from the vestibule through a congenital oval-window/footplate defect, further confirming the diagnosis of a common cavity deformity. This finding is consistent with prior reports describing congenital vestibular fistulas associated with a malformed cochleovestibular structure and profound sensorineural hearing loss [13,14].

The definitive approach must be tailored to leak location, flow rate, and hearing status. Recent literature has emphasized minimally invasive repair of inner ear-derived CSF leaks, including transcanal endoscopic stapedectomy with vestibular packing and transmastoid vestibule obliteration, with good outcomes in appropriately selected patients [5,7]. In the present case, several factors favored a more extensive approach: the leak was high-flow and had already proven refractory to initial endoscopic temporizing measures. The leak originated from the vestibule through a congenital oval-window/footplate defect in a young child with a labyrinthine anomaly, and since hearing was defective bilaterally, a blind-sac canal closure and Eustachian tube obliteration added no further functional compromise while closing residual escape pathways and mitigating the risk of ascending infection. We therefore performed a lateral temporal bone resection with multilayer closure. This included packing the vestibule with temporalis fascia, reinforcing the repair with cartilage, obliterating the Eustachian tube, placing a collagen-matrix dural substitute, covering the area with a pedicled temporalis muscle flap, and closing the external auditory canal as a blind sac. This approach has been previously described for spontaneous otogenic CSF leaks in children [15]. We emphasize that this extensive reconstruction reflects the specific high-flow, non-serviceable-hearing context and should not be regarded as the default, as in many patients a minimally invasive approach is appropriate and preferable.

This case reinforces the need for heightened preoperative suspicion in children with congenital hearing loss undergoing middle ear procedures. Review of imaging, awareness of anatomic risk factors, and preparedness for intraoperative CSF leak management are essential to prevent catastrophic complications. This case supports the consideration of preoperative temporal bone imaging before middle ear procedures in pediatric patients with sensorineural hearing loss, particularly when congenital ear anomalies may be present.