Otopathologic Analysis of Patterns of Postmeningitis Labyrinthitis Ossificans

Abstract

Objective Labyrinthitis ossificans (LO) may occur following meningitis and, in cases where cochlear implantation is indicated, complicate electrode insertion. LO is critical to identify for successful cochlear implantation, and histopathology is more sensitive than imaging for identification of LO. Herein we utilize otopathologic techniques to study the timing and location of intracochlear tissue formation following meningitic labyrinthitis (ML). Study Design Retrospective review. Setting Academic institution. Methods Temporal bone specimens with a history of bacterial ML were histologically evaluated. The location and extent of intracochlear tissue formation within the scala tympani (ST) and scala vestibuli (SV) were graded, and spiral ganglion neurons were counted. Results Fifty-one temporal bones were identified: 32 with no intracochlear tissue formation, 9 with fibrosis alone, and 10 with LO. Fibrosis was identified as early as 1.5 weeks after ML, while ossification was found only in specimens that survived multiple years after ML. All LO cases showed ossification of the ST at the round window membrane (RWM) with continuous extension throughout the basal turn. Extent of SV ossification correlated with that in the ST but showed frequent isolated distal involvement of the cochlea. Spiral ganglion neuron counts were lower than those in age-matched controls. Conclusion In this human temporal bone study, we found that postmeningitic LO results in ossification at the RWM with continuous extension into the ST of the basal turn and variable involvement of the SV. Identification of a patent basal turn beyond RWM ossification of the ST should permit full electrode insertion. Level of Evidence Retrospective review.

Cochlear Ossification After Vestibular Schwannoma Surgery: A Temporal Bone Study

“…All TL samples exhibited varying degrees of CO at various locations within the cochlea, most commonly at the basal turn, without a particular predilection for endolymph versus perilymph. Animal and human models have shown that fibrosis and ossification after bacterial meningitis tend to start most at the area of the round window in the scala tympani via infiltration of proinflammatory cytokines through the cochlear aqueduct and progress from the basal turn 12 The pattern of ossification seen after TL surgery may reflect this pattern as the basal turn was involved in all ossified samples. Only one case from the RS or MF samples showed ossification.…”

Labyrinthitis Ossificans in a Post-Splenectomy Patient With Meningitis: A Case Report and Review of Literature

“…Animal studies indicate that the sequence of events in labyrinthitis ossificans begins with inflammation that progresses to fibrosis and ossification, and further that ossification of the cochlear can continue over the years [12,13]. Histopathological analysis of temporal bone specimens has demonstrated that fibrosis can be identified as early as 1.5 weeks after meningitic labyrinthitis [14]. Labyrinthitis ossificans presents several intraoperative challenges for the CI surgeon, precluding electrode insertion via a round window or cochleostomy approach and requiring drilling of the cochlear basal turn or the use of a split electrode array [15][16][17].…”

“…Post-operative outcomes in CI recipients are more variable in patients with labyrinthitis ossificans. While audiologic outcomes can be adequate in the setting of cochlear fibrosis and ossification, the timing of implantation may influence postoperative outcomes [ 14 , 18 , 19 ].…”

An optically-guided cochlear implant sheath for real-time monitoring of electrode insertion into the human cochlea

“…Aside from visualizing normal cochlear walls, OCT imaging has the potential to detect other obstacles on the insertion path, such as pathological fibrosis and ossification of the ST. This is particularly important in patients who have previously undergone CI surgery 44 , 45 , in patients with cochlear otosclerosis 46 and when cochlear hearing loss is related to a meningitis infection 47 . In patients with these pathologies, the outcome can often be complicated by incomplete electrode insertions, electrode translocations and device failures 46 .…”

“…In patients with these pathologies, the outcome can often be complicated by incomplete electrode insertions, electrode translocations and device failures 46 . Furthermore, the cochlear obstruction is often not clearly visible on preoperative imaging, increasing the risk of complications 47 . OCT-guided insertion could help the surgeon estimate the risk of obstruction intraoperatively and decide whether the obstacle can be bypassed by adjusting the insertion trajectory or if an alternative insertion route is necessary (e.g.…”