Changes in the Neurovascular Unit in Meniere's Disease.

HYPOTHESIS: Degenerative changes in the neurovascular unit (NVU) in the human spiral ganglia (SG) in patients with Meniere's disease (MD) compared with normal patients underlie the clinical manifestations of MD. BACKGROUND: Endolymphatic hydrops (EH) is the pathologic correlate of MD, yet the etiology of MD is poorly understood. EH alone does not adequately explain the changes in permeability of the cochlear blood-labyrinthine barrier seen with delayed contrast MRI or fluctuations in symptoms. METHODS: Hematoxylin and eosin sections of the cochlea were obtained from temporal bones of normal patients (n=5, age: 47 to 63 y, 1 male/4 female) and patients diagnosed with MD (n=8, age 51 to 88, 4 male/4 female). The number of spiral ganglia neurons (SGNs) in each cochlea was estimated. SGNs and blood vessels in the cochlea from normal and MD patients (archival celloidin sections from the same patients) were reliably identified with antibodies against acetylated-3-tubulin and glucose transporter-1, respectively, and visualized by immunofluorescence and laser confocal microscopy. RESULTS: There was a significant decrease (50% loss) of SGNs among patients diagnosed with MD compared with age-matched controls ( P <0.05) and contralateral unaffected cochlea (35% decrease). Immunofluorescence-stained sections showed a marked decrease of blood vessels and a corresponding loss of SGNs in MD cochlea compared with controls. CONCLUSIONS: The decrease of spiral ganglia neurons and associated blood vessels showed regional damage of the cochlea. These results suggest that the NVU interaction may be critical to preserve the SGNs in MD and establish a framework for understanding the etiology and treatment of MD beyond EH. LEVEL OF EVIDENCE: Not applicable.