Unbiased Stereological Estimation of the Spiral Ligament and Stria Vascularis Volumes in Aging and Ménière’s Disease Using Archival Human Temporal Bones

Abstract

The present study applies the unbiased stereological technique-Cavalieri principle to measure the volumes of the stria vascularis (SV) and the spiral ligament (SL) using postmortem archival human temporal bones from normal young and older subjects and subjects with Ménière_s disease. Normative data was obtained from subjects without ages ranging from 15 to 84 years old who had no history of audiovestibular disease (N = 25). For comparison purposes, the normative specimens were divided into three groups: group 1 (n = 8) had ages ranging from 15 to 38 years old, average age = 23.9; group 2 (n = 8) had ages ranging from 51 to 59 years old, average age = 55.1; group 3 (n = 9) had ages ranging from 64 to 84 years old, average age = 74.3. The average SV volume of group 3 (0.479 mm 3 ) was significantly lower than that of group 1 (0.705 mm 3 ) (p G 0.0005) and was significantly lower than that of group 2 (0.603 mm 3 ) (p = 0.01). The average SL volume of group 3 (8.42 mm 3 ) was significantly lower than that of group 1 (9.54 mm 3 ) (p G 0.05), but was not significantly lower than that of group 2 (8.58 mm 3 ). Five subjects with Ménière_s disease, confirmed by histopathological examination (ages ranging from 63 to 91 years old, average age = 73.4), were studied. The average SV volume in Ménière_s subjects (0.378 mm 3 ) was significantly lower than age-matched controls (p G 0.05). The average SL volume in Ménière_s subjects (7.01 mm 3 ) was also significantly lower than age-matched controls (p G 0.05). The SV and SL volumes were unaffected by gender. The present study demonstrates for the first time the use of the unbiased stereological technique-Cavalieri principle-as a reliable and efficient method to obtain volumetric estimates of the SV and the SL by using archival human temporal bone specimens.

Head Bobber: An Insertional Mutation Causes Inner Ear Defects, Hyperactive Circling, and Deafness

“…Similar alterations of the scala media that resulted in deafness were reported in mice lacking the Kir4.1 potassium channel subunit of the strial intermediate cells (Rozengurt et al 2003) and the NKCC1 co-transporter of the strial marginal cells (Flagella et al 1999). Thus, deafness in head bobber is likely due to the absence of a functional stria vascularis, which is indispensable for the generation and maintenance of the endocochlear potential, and its dysfunction results in hearing deficiencies in rodent models (Ohlemiller 2009) and in humans (Boulay et al 2009;Ishiyama et al 2007). …”

Divergent Aging Characteristics in CBA/J and CBA/CaJ Mouse Cochleae

“…11F). Strial thinning with age is commonly described in humans and animals (Kusunoki et al 2004;Suzuki et al 2006;Ishiyama et al 2007), and may reflect cell changes that lead to EP decline ). Both CBA/J and CBA/CaJ showed significant strial thinning throughout most of the cochlea (Fig.…”

“…Strial thinning is a commonly reported aspect of cochlear aging (Kusunoki et al 2004;Suzuki et al 2006;Ishiyama et al 2007), although it is often not clear when thinning is functionally meaningful. However, differences in strial thickness in our material (Fig.…”

“…BALB/c mice in particular combine somewhat low marginal cell density and a thin spiral ligament with slightly reduced EP (∼10 mV) from an early age, and these become more pronounced with time. There is disagreement about the existence of any causal linkand direction thereof-between pathology of the stria and spiral ligament (e.g., Hequembourg and Liberman 2001;Spicer and Schulte 2002;Wu and Marcus 2003;Ishiyama et al 2007). Aging appears reliably associated with progressive reduction in ligament volume and loss of fibrocytes in both humans and animals (Wright and Schuknecht 1972;Spicer and Schulte 2002;Kusunoki et al 2004;Ishiyama et al 2007).…”

“…There is disagreement about the existence of any causal linkand direction thereof-between pathology of the stria and spiral ligament (e.g., Hequembourg and Liberman 2001;Spicer and Schulte 2002;Wu and Marcus 2003;Ishiyama et al 2007). Aging appears reliably associated with progressive reduction in ligament volume and loss of fibrocytes in both humans and animals (Wright and Schuknecht 1972;Spicer and Schulte 2002;Kusunoki et al 2004;Ishiyama et al 2007). However, comparison of the extent of ligament degeneration and strial pathology across multiple inbred mouse models suggests that these need not be closely related (Ohlemiller 2009).…”