Raul Hinojosa

Particulate Matter in the Posterior Semicircular Canal

The pathoetiology of benign paroxysmal positional vertigo (BPPV) is controversial. Particulate matter within the posterior semicircular canal has been identified intraoperatively in patients with BPPV but has also been reported in non‐BPPV patients at the time of translabyrinthine surgery (Parnes LS, McClure JA. Free‐floating endolymphatic particles: a new operative finding during posterior semicircular canal occlusion. Laryngoscope 1992;102:988‐92; Schuknecht HF, Ruby RRF. Cupulolithiasis. Adv Otorhinolaryngol 1973;20:434‐43; Kveton JF, Kashgarian M. Particulate matter within the membranous labyrinth: pathologic or normal? Am J Otol 1994;15:173‐6). The nature of the particulate matter remains unknown.

Presbycusis: a human temporal bone study of individuals with downward sloping audiometric patterns of hearing loss and review of the literature.

Objective: The purpose of this retrospective case review was to identify patterns of cochlear element degeneration in individuals with presbycusis exhibiting downward sloping audiometric patterns of hearing loss and to correlate these findings with those reported in the literature to clarify conflicting concepts regarding the association between hearing loss and morphologic abnormalities.

Labyrinthitis Ossificans: Histopathologic Consideration for Cochlear Implantation

Labyrinthitis ossificans may be a hindrance to cochlear implantation by making electrode insertion difficult. We performed a histopathologic study of 24 temporal bones with labyrinthitis ossificans from multiple causes. The organ of Corti was graphically reconstructed and the degree of obstruction was estimated for each millimeter of the cochlea. Correlations were calculated between the degree of new bone formation and the cause, patients age and sex, and time from the original temporal bone insult. Our results demonstrate that complete cochlear ossification is rare. The scala tympani in the basal turn of the cochlea is the most frequent area of ossification, regardless of the cause of the labyrinthitis ossificans. Meningogenic labyrinthitis, usually a childhood disease, was associated with the greatest amount of ossification. When ossification resulted from tympanogenic labyrinthitis, the scala tympani was completely ossified near the round window niche in all temporal bones. Neo-ossification of the basal turn associated with otosclerosis was limited to the proximal 6 mm of the scala tympani in all cases. Three temporal bones had a patent round window niche and basal turn, but significant apical and middle-turn ossification. Peripheral sensorineural elements were severely degenerated in the region of the ossification in all specimens, and spiral ganglion cell counts were decreased.

Postnatal Development of Endocochlear Potential and Stria Vascularis in the Cat

The postnatal development of the stria vascularis and endocochlear potential was studied in the kitten. Maturation of the stria was completed at about the 25th postnatal day. The development of the basal cells was characterized by its reduction in size and shape and by reduction of content of glycogen particles. The intermediate and marginal cells developed into complex elements with a large number of cytoplasmic compartments containing a striking conglomeration of mitochondria. Postnatal development of EP paralleled that of the stria vascularis. The increase in EPs values from birth (about 8.8 mV) to the 27-29th day (about 75.7 mV) described an S-shaped curve.ZUSAMMENFASSUNGDie Entwicklung der Stria Vascularis und des endokochlearen Potentials nach der Geburt, wurde bei jungen Katzen untersucht. Die Stria war ungefahr am 25. Tag nach der Geburt ausgereift. Die Entwicklung der Grundzellen wurde dadurch ausgezeichnet, dass sich die grossen Zellen mit reichlichem Zellplasma in Grosse und Form zu kleinen, a...

Temporal bone histopathology in connexin 26-related hearing loss

Objective: Mutations in GJB2, a gene that encodes a gap junction protein, Connexin 26 (Cx26), are responsible for approximately one third of sporadic severe‐to‐profound or profound congenital deafness and half of severe‐to‐profound or profound autosomal recessive nonsyndromic hearing loss (ARNSHL). Mouse mutants homozygous for knockouts of this gene are nonviable, precluding histopathologic studies of the associated inner ear pathology in this animal model. Therefore, we studied archival temporal bone sections to identify temporal bone donors with Cx26‐related deafness.

A Note on Development of Corti's Organ

The structure and postnatal transformation of Köllikers organ in the cat were studied by means of both light and electron microscopes. Köllikers organ, which is located in the inner sulcus area of the cochlear duct during embryonic development of the kitten, appeared to undergo a major transformation during the first 30 days after birth. On the level of the organ as a whole the possible nature of this transformation is briefly discussed. On the cellular level, the transformation of this organ was found to involve a process of cellular autophagocytosis. Köllikers organ consists of numerous tightly packed, tall columnar cells filling the inner sulcus. Autophagic vacuoles containing cell organelles were observed in these cells in all stages of transformation of the organ. Cellular autophagocytosis reduced the number of cells present in each section from approximately 50 in the newborn, to approximately 12 in the 30-day-old kitten. The apparent transformation of Köllikers organ was observed as progressing from base to apex and from the limbus to the inner hair cell. The relationship of the tectorial membrane to Köllikers organ and that of the tectorial membrane to the area in and around the inner hair cells are discussed.

Insertional trauma of multichannel cochlear implants

Insertional trauma to the cochlea from three different multichannel cochlear implant electrodes was evaluated in a single‐blind controlled study in fresh human temporal bones. Sixteen fresh human temporal bones were implanted with one of three types of multichannel electrodes (Symbion/InnerAid, Cochlear/Nucleus®, or Storz/UCSF). Seven temporal bones were used as controls where a cochleostomy only was created. The temporal bones were evaluated histologically and cochlear histograms of the trauma were created.

Quantification of the mitochondrial DNA common deletion in presbycusis

This study was conducted to evaluate the association between the mitochondrial DNA (mtDNA) common deletion (CD) level in cochlear tissue and the severity of hearing loss in individuals with presbycusis.

Association of Mitochondrial DNA Deletions and Cochlear Pathology: A Molecular Biologic Tool†‡

The purpose of these experiments was to develop a method of isolation, amplification, and identification of cochlear mitochondrial DNA (mtDNA) from minute quantities of tissue. Additionally, studies were designed to detect mtDNA deletions (mtDNA del) from the cochlea that previously have been amplified from other organ systems and tissues. MtDNA del have been associated with many pathologies, including neurological disorders, sensorineural hearing loss, ischemia, cardiomyopathies, and aging.

Presbycusis: A human temporal bone study of individuals with flat audiometric patterns of hearing loss using a new method to quantify stria vascularis volume

Objective: The purpose of this study was to determine the prevalence of stria vascularis atrophy in individuals with presbycusis and flat audiometric patterns of hearing loss. Individuals with presbycusis have historically been categorized by the shape of their audiograms, and flat audiometric thresholds have been reported to be associated with atrophy of the stria vascularis. Stria vascularis volume was not measured in these studies. Study Design: Retrospective case review. Methods: Archival human temporal bones from individuals with presbycusis were selected on the basis of strict audiometric criteria for flat audiometric thresholds. Six temporal bones that met these criteria were identified and compared with 10 temporal bones in individuals with normal hearing. A unique quantitative method was developed to measure the stria vascularis volume in these temporal bones. The hair cell and spiral ganglion cell populations also were quantitatively evaluated. Results: Only one of the six individuals with presbycusis and flat audiometric thresholds had significant atrophy of the stria vascularis. This individual with stria vascularis atrophy also had reduced inner hair cell, outer hair cell, and ganglion cell populations. Three of the individuals with presbycusis had spiral ganglion cell loss, three individuals had inner hair cell loss, and all six individuals had outer hair cell loss. Conclusions: The results of this investigation suggest that individuals with presbycusis and flat audiometric patterns of hearing loss infrequently have stria vascularis atrophy. Outer hair cell loss alone or in combination with inner hair cell or ganglion cell loss may be the cause of flat audiometric thresholds in individuals with presbycusis.