Development of the Geniculate Ganglion in Human Fetuses.

AIM: To present the quantitative development of the geniculate ganglion (GG) in foetal cadavers. MATERIAL AND METHODS: This study focused on 60 temporal bones of 30 (15 female and 15 male) foetuses aged 18?30 weeks of gestation (mean age, 22.83 ± 3.49 weeks) to measure the length, width and area of the GG. RESULTS: According to gestational weeks and months, the ganglion length (1.21 ± 0.41 mm), width (1.03 ± 0.28 mm) and area (1.24 ± 0.61 mm < sup > 2 < /sup > ) did not change. In terms of sexes or sides, ganglion dimensions were not significantly different. Positive correlation was found between the length and width (p=0.033, r=0.276), between the length and area (p < 0.001, r=0.762) and between the width and area (p < 0.001, r=0.622). Linear functions were calculated for the ganglion area (y=0.355 + 0.039 × weeks), length (y=0.636 + 0.025 × weeks) and width (y=0.634 + 0.017 × weeks). CONCLUSION: The ganglion size did not change in foetal cadavers aged 18?30 weeks of gestation. This finding may be important for anatomists and embryologists in performing morphometric studies and understanding the development of the GG and for neurootologists and neurosurgeons in achieving greater success in skull base surgeries.

Growth Pattern of the Tympanic Ring in Human Fetuses.

OBJECTIVES: The study aimed to display the growth pattern of the tympanic ring in fetal cadavers of 20-30 weeks of gestation. METHODS: In the study, 32 temporal bones of 16 fetuses (8 males, 8 females) of 24.62 ± 3.44 weeks of gestation were dissected to measure the height (TRH), width (TRW), and perimeter (TRP) of the annulus, and the width (TNW) of the opening part of the annulus at the level of the tympanic notch. RESULTS: The TRH, TRW, TRP, and TNW were measured as 8.25 ± 1.04 mm, 7.64 ± 1.08 mm, 24.93 ± 3.40 mm, and 4.01 ± 0.91 mm, respectively. The parameters were similar at the seventh and eighth months of gestation; therefore, there was no variation from the seventh month. Linear function was calculated as y = 1.328 + 0.281 x weeks (P < .001) for the TRH, y = 1.284 + 0.258 x weeks (P < .001) for the TRW, y = 3.367 + 0.876 x weeks (P < .001) for the TRP, and y = -0.603 + 0.188 x weeks (P < .001) for the TNW. CONCLUSION: The parameters (TRH, TRW, TRP, and TNW) did not alter from the seventh month in utero. The linear functions (which represent the growth pattern of the parameters) of the tympanic ring may be useful for ear professionals to guess the annulus diameters, and to diagnose growth retardation and probable congenital anomalies in utero during sonographic imaging.

Anatomic features of the fetal round and oval windows, and their relations with the tympanic nerve.

OBJECTIVE: The study aimed to examine morphometric properties of the round window (RW) and oval window (OW) and to show their relation with the tympanic nerve (the Jacobson's nerve, JN) in human fetuses from the otologic surgeon's perspective. METHODS: Thirty temporal bones of 15 fetal cadavers (8 males, 7 females) aged with 24.40 ± 3.71 weeks were included in the study. The height, width and surface area of the RW and OW and also distance from the JN to the OW and RW were measured. RESULTS: The height, width and surface area of the RW in this work were measured as 1.48 ± 0.25 mm, 1.57 ± 0.37 mm, and 2.05 ± 0.69 mm2, respectively. The RW was detected as round-shaped (8 cases, 26.7%), oval-shaped (15 cases, 50%), and dome-shaped (7 cases, 23.3%). The height, width and surface area of the OW were measured as 1.42 ± 0.26 mm, 2.90 ± 0.44 mm, and 3.63 ± 0.74 mm2, respectively. The OW was observed as oval-shaped (15 cases, 50%), kidney-shaped (10 cases, 33.3%), D-shaped (4 cases, 13.3%), and trapezoid-shaped (1 case, 3.3%). The JN was found 1.21 ± 0.60 and 1.18 ± 0.54 mm away from the RW and OW, respectively. CONCLUSION: This study containing morphological data about the shapes, diameters and area of the RW and OW may be useful to predict surgical difficulty, and to select implants of suitable size preoperatively for the windows. Knowing the relationship between the JN and the windows can be helpful to avoid iatrogenic injuries of the nerve.

Comparison of fetal and adult tympanic membrane sizes: a cadaveric study.

OBJECTIVE: The work aimed to compare fetal and adult tympanic membrane (TM) sizes for understanding dimensional development from intrauterine life to adulthood. METHODS: Fifty-six temporal bones (18 fetuses, 10 elderly adults, half male and half female in each group) were included in this study. Using a digital image software, the TM height, width and area were measured. RESULTS: The mean area, height and width of the TM in adults were found as 58.84 ± 22.01 mm2, 9.06 ± 1.33 mm, and 8.10 ± 1.43 mm, respectively. Moreover, the mean area, height and width of the TM in fetuses were measured as 47.62 ± 12.57 mm2, 8.22 ± 1.12 mm, and 7.25 ± 1.15 mm, respectively. The TM dimensions were increasing in fetuses between 20-32 weeks of gestation. However, the TM dimension was statistically similar at the 7th month, the 8th month and adult periods. The TM height was greater than its width in fetuses and adults. CONCLUSION: The calculated regression equations of the TM parameters in fetuses may be used to estimate its size. The TM size did not change from the 7th gestational month, and thus the membrane reached adult diameter in fetal life. The TM height and width showed a very wide range; therefore, we thought that the 12 mm (the height) × 10 mm (the width) graft might be ideal dimension during the repair of the TM perforations.

Fetal Anatomy of the Optic Strut and Prechiasmatic Sulcus with a Clinical Perspective.

OBJECTIVE: The main objective of the study was to show the morphologic features of optic strut (OS) and prechiasmatic sulcus (PS) in the fetal skull base with a surgical anatomical perspective. METHODS: Twenty-three fetal cadavers (9 female, 14 male) with an average age of 21.70 ± 3.12 (range: 16-28) weeks of gestation in the inventory of the Anatomy Department were included in the study. Measurements were made with a digital image analysis software and goniometer. RESULTS: The sulcal length, interoptic distance, planum length, and sulcal angle were detected as follows: 3.91 ± 0.74 mm, 6.88 ± 1.04 mm, 6.55 ± 1.51 mm, and 24.52 ± 9.51°, respectively. Considering the location of the posteromedial margin of OS according to PS, OS was identified as the sulcal in 56.5% (13 cases), postsulcal in 30.4% (7 cases), and asymmetric in 13% (3 cases). According to the sulcal length and angle, PS was identified as type 1 in 26.1% (6 cases), type 2 in 21.7% (5 cases), type 3 in 30.4% (7 cases), and type 4 in 21.7% (5 cases). CONCLUSIONS: Our findings suggest that the sulcal length and angle reach adult size in utero. Taking into account the fetal and the gathered adult measurements, the high percentage of steep angle compared to flat angle show that after birth, PS become more flat, probably depending on the variations of the sphenoid sinus pneumatization. Thus, more studies conducted on the alterations in PS and OS types relative to the pneumatization are needed in terms of patient positioning, selection of appropriate surgical approach, and intraoperative decision-making.

Effects of a tumor necrosis factor-alpha inhibitor (etanercept) on the sciatic nerve in a hypoxic ischemia-induced neonatal rat model.

BACKGROUND: Neonatal hypoxic-ischemic (HI) injury has been considered to have acute and long term deleterious effects on many tissues, including the peripheral nerve. OBJECTIVES: In this study, the effects of a tumor necrosis factor-alpha (TNF-a) inhibitor (etanercept) on peripheral nerve damage and the ultrastructure of the sciatic nerve and gastrocnemius muscle in rats exposed to HI during the neonatal period were examined. MATERIAL AND METHODS: In this study, 45 seven-day-old rats were used and they were divided into three groups. The right carotid arteries of the rats in the saline and etanercept groups were ligated and put in a hypoxia chamber containing 8% oxygen for two hours. Just after hypoxia, the etanercept group was given 10 mg/kg etanercept, but the saline group had only saline intraperitoneally. The sham group rats' carotid arteries were not ligated or put in hypoxia. The amplitude, area and latency of sciatic nerve compound motor action potential (CMAP), which mainly reflects axonopathy and myelinopathy, were measured using standard techniques in the seventeenth week following the HI. Sciatic nerve and gastrocnemius muscle were evaluated with a transmission electron microscope, and grading for myelin sheath damage was done to all groups. RESULTS: Neuropathy was seen in rats after HI. While treatment with etanercept showed a protective effect for the axons of sciatic nerve, demyelination could not be recovered with etanercept. CONCLUSIONS: This study is the first in literature to show a partial interruption of the signal through the peripheral nerve fibers caused by axonal and myelin dysfunction continuation in rats exposed to HI after birth, in the 17th week.

Comparison of the effects of different electrocautery applications to peripheral nerves: an experimental study.

BACKGROUND: This study was designed to investigate the effects of bipolar and mononopolar electrocauterization on peripheral nerve tissue. The comparison on the deleterious effects of the different cautery modalities and the importance of probe tip placement are evaluated using electrophysiological, electron microscopic and biochemical assessment parameters. METHODS: Ninety-eight male Wistar albino rats, each weighing 250-275 g, were randomly divided into 14 groups. Each group consisted of seven animals. Monopolar and bipolar electrocautery were performed at 15 watts. The application was performed either directly on the nerve or 1 mm lateral to the longitudinal axis of the nerve for 'near the nerve groups', respectively. RESULTS: The electrophysiological findings showed that the mean amplitudes were at the lowest value in the first day for all the groups. At the end of the 3rd week, we recognised that the electrophysiological recovery continued. Electron microscopic evaluation showed myelin disruption in all groups. Myelin disruption of healthy neurons was at the highest level in the 1st day of application in accordance with the electrophysiological findings. Biochemical evaluation revealed statistical significance between the control and the two of the 'near the nerve groups' (GIII and GV) for NO (nitrite and nitrate) serum level. CONCLUSION: The data of the present study might suggest that electrocautery, independent of the type and form of application, may result in significant damage in histological and electrophysological basis. Although the relative proportions cannot be ascertained, the time course of recovery suggests that both axon and myelin damage have occurred. The probable electrocautery damage may be of substantial importance for the situation that the nerves are displaced by tumor masses or atypical neural traces.

Posterior cranial fossa morphometry in symptomatic adult Chiari I malformation patients: comparative clinical and anatomical study.

BACKGROUND AND OBJECTIVES: The cerebellar tonsillar herniation occurring in Chiari malformation Type I (CMI) mainly results from overcrowding of a normally developing hindbrain within a primary small posterior cranial fossa (PCF) due to an anomaly in the embryological development of the occipital bone. In the present study, the lengths of PCF parameters were studied in adult CMI patients. PATIENTS AND METHODS: The authors retrospectively examined 15 adult patients with CMI. Multiple measurements were made on magnetic resonance images (MRIs). The results were compared with the findings in 25 controls and 30 dry skulls. RESULTS: Length of the neural structures did not significantly differ between the CMI and the control groups. The average length of the basiocciput was significantly shorter in the CMI group as compared with the control group. The mean length of the supraocciput was significantly shorter and the average diameter of the foramen magnum was significantly longer in the CMI group when compared to the control group and dry skulls. CONCLUSIONS: The morphometric data suggest that, in CMI, a hypoplastic occipital bone, possibly due to the paraxial mesodermal defect of the parachordal plate, causes overcrowding in PCF, which contains the normally developed neural structures.