Temporal Bone

Shi SR, Cote C, Kalra KL, et al. A technique for retrieving antigens in formalin-fixed, routinely acid-decalcified, celloidin-embedded human temporal bone sections for immunohistochemistry./. Histochem. Cytochem. 1992 40 787-792. 

Shi S-R, Cote RJ, Taylor CR. Antigen retrieval immunohistochemistry used for routinely processed celloidin-embedded human temporal bone sections standardization and development. Auris Nasus Larynx 1998 25 425-443. 

A second nonheating epitope retrieval method involves the use of sodium hydroxide-methanol solution. This solution was used successfully for epitope retrieval in sections of formalin-fixed, acid-decalcified human temporal bone embedded in celloidin (Shi et al 1991). This solution is prepared by adding 50-100 g of NaOH to 500 ml of methanol in a brown bottle and mixing vigorously. The solution can be stored for 1-2 weeks at room temperature it is also available commercially (BioGenex, San Ramon, CA). The clear, saturated solution is diluted 1 3 with methanol before use. A wider application of this solution is awaited. 

There are three widely accepted routes by which bone-conducted sound stimulates the cochlea. These are the compres-sional, inertial and osseotympanic theories of bone conduction (12). Compressional bone conduction implies that the cochlear shell is compressed slightly in response of the pressure variation caused by a sound. Inertial bone conduction alludes to a relative motion between the ossicular chain and the temporal bone for low frequency vibrations. The osseotympanic theory denotes a mechanism by which relative movement of the skull, with respect to the mandible, sets up pressure variation in the air present in the auditory meatus. Since perception of microwave pulses are correlated with the capacity to hear high-frequency sound, it rules out inertial or osseotympanic bone conduction as potential mechanisms for microwave acoustic effect. 

In a quantitative assessment of vestibular hair cells and Scarpa s ganglion cells in 17 temporal bones from 10 individuals with aminoglycoside ototoxicity, streptomycin caused a significant loss of both type I and type II hair cells in all five vestibular sense organs (19). The vestibular ototoxic effects of kanamycin appeared to be similar to those of streptomycin, whereas neomycin did not cause loss of vestibular hair cells. There was no significant loss of Scarpa s ganglion cells. 

Tsuji K, Velazquez-Villasenor L, Rauch SD, Glynn RJ, Wall C 3rd, Merchant SN. Temporal bone studies of the human peripheral vestibular system. Aminoglycoside ototoxicity. Ann Otol Rhinol Laryngol Snppl 2000 181 20-5. 

Hinojosa R, Nelson EG, Lerner SA, Redleaf MI, Schramm DR. Aminoglycoside ototoxicity a human temporal bone study. Laryngoscope 2001 lll(10) 1797-805. 

Histological examination of the temporal bones from two individuals with ototoxicity due to tobramycin showed reductions in the numbers of both ganglion cells and hair cells (21). Spiral ganglion cell loss was not necessarily subadjacent to areas of hair cell loss in cases of aminoglycoside ototoxicity. Instead, there may be a reduction in the number of ganglion cells in segments of the cochlea with normal-appearing hair cells. 

The human inner ear is embedded in the temporal bone and houses the sensory epithelia of the cochlea and vestibular apparatus (Fig. 1). The sensory epithelia contain hair cells which transduce the stimulus of sound or motion into nerve impulses. Hair cells are equipped with an apical mechano-sensitive apparatus made up by three rows of actin-containing stereocilia of increasing length. Displacement of the stereocilia towards the longest row opens (gates) mechano-electrical transduction channels, whereas deflection into the opposing direction closes the channels [12],... 

Fig. 1 The organization of the human inner ear. The human inner ear is embedded into the temporal bone and contains the sensory epithelia of the cochlea and the vestibular system. In the organ of Corti, IHCs are responsible for afferent signal propagation and OHCs actively amplify sound-induced basilar membrane motion. Hair cells in the otolith organs (utricle and saccule) and the ampullae of the semicircular canals detect linear and rotational movement of the head, respectively, and the overall position of the head. Tags colored in red denote the position of the sensory epithelia red line, organ of Corti open circles, otolith organs closed circles, ampullae. Red arrows illustrate the direction of mechanical movement...

Locate the cochlea and the semicircular canals, detach inner ear from the temporal bone, and remove bulla if necessary. 

Hinojosa R, Riggs LC, Strauss M, Matz GJ (1995) Temporal bone histopathology of cisplatin ototoxicity. Am J Otol 16(6) 731-740... 

The snail-shaped cochlea, located in the temporal bone of the skull, contains a bony labyrinth and a membranous labyrinth. The bony labyrinth consists of the otic capsule (the external shell) and the modiolus (the internal axis). The membranous labyrinth, coiled inside the bony labyrinth, consists of three adjacent tubes the scala vestibuli, the scala media, and the scala tympani (O Figure 4-1). The scala vestibuli and the scala media are separated by Reissner s membrane the scala media and the scala tympani are separated by the basilar membrane and part of the osseous spiral lamina. The scala vestibuli and the scala tympani are filled with perilymph, a fluid whose ionic composition is similar to that of cerebrospinal fluid. The fluid sealed inside the scala media, the endolymph, contains a high concentration of potassium. 

Shi S-R, Tandon AK, Cote C, et al. S-IOO protein in human inner ear Use of a novel immunohistochemical technique on routinely processed, celloidin-embedded human temporal bone sections. Laryngoscope. I992 I02 734. 

Islands of neuroglial tissue occurring outside the central nervous system (CNS) are uncommon but have been described in a variety of sites in the head and neck. Two of the most common sites are the nose ( nasal glioma ) and middle ear-temporal bone. " Ectopic neuroglial tissue (ENGT) should not be confused with an encepha-locele. An encephalocele retains a connection to the CNS, whereas ENGT does not. 

In a review of 36 cases, Thompson and colleagues observed that 25 were found in the middle ear, 4 in the external auditory canal, and 2 in the temporal bone (intraosseous). Five involved multiple sites. 

Gaffey MJ, Mills SE, Boyd JG Aggressive papillary tumor of middle ear/temporal bone and adnexal papillary cystadenoma. Manifestations of von Hippel-Lindau disease. Am J Surg Pathol. 1254 18(12) 1254-1260. 

Thompson LD, Bouffard JP, Sandberg GD, et al. Primary ear and temporal bone meningiomas a clinicopathologic study of 36 cases with a review of the literature. Mod Pathol. 2003 16(3) 236-245. 

Lead is another element of interest in a number of applications. Most of the ingested lead is stored in bone, and is difficult to remove once it is incorporated into the mineral phase. The half-life of lead in bone can be up to 20 years (Anderson and Danylchuck 1977, Drasch 1982). Lead is not distributed equally among the bones of the skeleton, although there seems to be a relationship among anatomical units within one skeleton that would allow an estimation of total skeletal lead burden (Wittmers et al. 1988). In a modern population of humans (n = 240) that had not been exposed to lead occupationally, the mean lead content in the femur was 3.86 mg/kg bone wet weight as compared to the temporal bone (5.59 mg/kg) and the pelvic bone (1.65 mg/kg) (Drasch et al. 1987). An occupationally exposed population had approximately ten to twenty times the amount of lead in bone compared to the unexposed population (Brito et al. 2000). 

Ivfeitz GJ, Beal DD, Krames L. Ototoxicity of ethacrynic acid. Demonstrated in a human temporal bone. Arch Otolaryngol (1969) 90, 152-5. 

The auditory nerve of the human contains about 30,000 afferent fibers. Most (93%) are heavily myelinated and arise from Type I SGCs whose distal processes synapse on IHCs. The rest are from smaller, more lightly myehnated Type II SGCs. Each IHC has, on average, a number of Type I SCCs that synapse with it, 8 in the human and 18 in the cat. In contrast, each Type II SGC contacts OHCs at a rate of about 10 to 60 cells per fiber. The tonotopicaUy organized nerve (low-frequency fibers in the center and high-frequency fibers in the outer layers) exits the modiolus and enters the internal auditory meatus of the temporal bone on its path to the cochlear nuclei. 

The vestibular system is named for its position within the vestibule of the temporal bone of the skuU. It is located in the inner ear along with the auditory sense. The vestibular system has both central and peripheral components. This chapter deals with the mechanical sensory function of the peripheral end organ and its abdity to measure Hnear and angular inertial motion of the skuU over the frequency ranges encountered in normal activities. The transduction process used to convert the mechanical signals into neural ones is also described. 

The vestibular system in each ear consists of the otolith and saccule (coUectively by caUed the otolithic organs), which are the Hnear motion sensors, and the three semicircular canals (SCCs), which sense rotational motion. The SCCs are oriented in three nearly mutually perpendicular planes so that angular motion about any axis may be sensed. The otoliths and SCCs consist of membranous structures that are situated in hollowed-out sections and passageways in the vestibule of the temporal bone. This hollowed-out... 

The utricular otolith sits in the utricle and the saccular otolith is located within membranous saccule. Each of these organs is rigidly attached to the temporal bone of the skuU with connective tissue. The three semicircular canals terminate on the utricle forming a complete circular fluid path and the membranous canals are also rigidly attached to the bony skuU. This rigid attachment is vital to the roll of measuring inertial motion of the skull. 

---