Fetal facial nerve course in the ear region revisited.

PURPOSE: The aim of this study was to re-examine the structures that determine course of the facial nerve (FN) in the fetal ear region. MATERIALS AND METHODS: We used sagittal or horizontal sections of 28 human fetuses at 7-8, 12-16, and 25-37 weeks. RESULTS: The FN and the chorda tympani nerve ran almost parallel until 7 weeks. The greater petrosal nerve (GPN) ran vertical to the distal FN course due to the trigeminal nerve ganglion being medial to the geniculate ganglion at 7 weeks. Afterwards, due to the radical growth of the former ganglion, the GPN became an anterior continuation of the FN. The lesser petrosal nerve ran straight, parallel to the FN at 7 weeks, but later, it started to wind along the otic capsule, possibly due to the upward invasion of the tympanic cavity epithelium. Notably, the chorda tympanic nerve origin from the FN, and the crossing between the vagus nerve branch and the FN, was located outside of the temporal bone even at 37 weeks. The second knee of the FN was not evident, in contrast to the acute anterior turn below the chorda tympanic nerve origin. In all examined fetuses, the apex of the cochlea did not face the middle cranial fossa, but the tympanic cavity. CONCLUSION: Topographical relation among the FN and related nerves in the ear region seemed not to be established in the fetal age but after birth depending on growth of the cranial fossa.

Assessment of growth dynamics of human cranium middle fossa in foetal period.

BACKGROUND: Available literature analysis demonstrated smallness of studies of cranial base. OBJECTIVES: The goal of the study was to analyse the medial fossa of the human cranium in the foetal period against other fossae. MATERIAL AND METHODS: Survey material consisted of 110 human foetuses at a morphological age of 16-28 weeks of foetal life, CRL 98-220 mm. Anthropological, preparation method, reverse method and statistical analysis were utilized. The survey incorporated the following computer programmes: Renishaw, TraceSurf, AutoCAD, CATIA. The reverse method seems especially interesting (impression with polysiloxane (silicone elastomer of high adhesive power used in dentistry) with 18 D 4823 activator. Elicited impression accurately reflected complex shape of cranium base. RESULTS: On assessing the relative rate of cranium medial fossa, the rate was found to be stable (linear model) for the whole of the analysed period and is 0.19%/week, which stands for the gradual and steady growth of the middle fossa in relation to the whole of the cranium base. At the same time, from the 16th till 28th week of foetal life, relative volume of the cranium middle fossa increases more intensively than cranium anterior fossa, whereas the cranium middle fossa volume as compared with the cranium posterior fossa is definitely slower. In the analysed period, the growth rate of the cranium base middle fossa was bigger in the 4th and 5th weeks than in the 6th and 7th weeks of foetal life. The investigations revealed cranium base asymmetry of the left side. Furthermore, the anterior fossae volume on the left side is significantly bigger than the one of the fossae on the right side. CONCLUSIONS: Volume growth rate is more intensive in the 4th and 5th than in the 6th and 7th weeks of foetal life. In the examined period, the relative growth rate of cranium base middle fossa is 0.19%/week and it is stable - linear model. The study revealed correlations in the form of mathematical models, which enabled foetuses age assessment.

Anatomical feature of the middle cranial fossa in fetal periods: possible etiology of superior canal dehiscence syndrome.

CONCLUSION: Different from adults, the superior semicircular canal (SSC) protrudes into the cranium during the fetal period. This might cause adhesion of the membranous labyrinth to dura as the bony labyrinth develops much later than the membranous labyrinth. This adhesion interferes with ossification and leads to a bony defect in the SSC. OBJECTIVES: The purpose of this study was to investigate a possible etiology of superior canal dehiscence syndrome (SCDS) from a view point of ontogeny. METHODS: Forty-two adult cadavers and 4 fetal cadavers were used for macroscopic observation of the middle cranial fossa (MCF). In addition, six fetuses underwent computed tomography (CT) examinations. The volume data of the CT obtained from four adults were also used for comparison. Using these CT data, we investigated the anatomic relationship between the MCF and SSC. RESULTS: The SSC and the cochlea in fetuses protruded into the cranium in macroscopic anatomy and CT examination. On the other hand, the SSC of all adults was completely or mostly buried in the temporal bone.

Lateral posterior fossa encephalocele with associated migrational disorder of the cerebellum in an infant.

Encephaloceles are acquired or congenital defects in which intracranial contents protrude through a defect in the calvaria. The embryogenesis of these lesions is incompletely understood. The vast majority of lesions occur at or near the anatomical midline. The authors present an extremely rare case of a laterally oriented, pathologically proven encephalocele associated with a posterior fossa cyst and cerebellar migrational defect in an infant. The authors review past and current theories of encephalocele formation as it relates to this case.

Landmark-based analysis of the morphological relationship between endocranial shape and traces of the middle meningeal vessels.

The morphogenesis and evolution of the cranium are the result of structural interactions among its components, leading to covariance between traits. Soft and hard tissues exert a reciprocal physical and physiological influence, leading to the final phenotype in terms of both ontogeny and evolution. The middle meningeal vessels, interfacing the brain and the braincase, provide an opportunity to study this network, even in extinct human species. Between and within-species variations of the vascular patterns may be mechanically influenced by the cranial morphology (structural hypothesis) or else by actual physiological responses and adaptations, mostly related to oxygen supply and/or thermoregulation (functional hypothesis). In this analysis, we tested the relationship between neurocranial shape and the general morphology of the traces of the middle meningeal vessels in a modern human population, by using landmark-based geometrical models. Although there are some neurocranial differences between groups with different vascular patterns, they are very small or not statistically significant. Only the depth of the imprints may be more influenced by the endocranial morphology. Even if the neurocranial differences among extinct hominids are definitely larger than those within the modern species, the present analysis suggests that it is unlikely that the differences in vascular patterns among the human species are related only to the effects of different neurocranial geometry. This is rather relevant when the marked development of the meningeal network in Homo sapiens is taken into account, compared with the patterns described for nonmodern human species.

[Superior semicircular canal dehiscence syndrome. Embryological and surgical consideration]. / Síndrome de dehiscencia del canal semicircular superior. Aspectos embriológicos y quirúrgicos.

OBJECTIVE: Presenting the first case of superior semicircular canal dehiscence syndrome in the Spanish literature and to establish, using embryological studies, the period in wich superior semicircular canal dehiscence originates. MATERIAL AND METHODS: 52 embryos and foetuses, from 6 mm to foetal maturity, were studied. The case of a patient suffering from superior semicircular canal dehiscence syndrome is presented. RESULTS: The superior semicircular canal and the intracranial space are communicated through bony lacunae, in the period between the 24th and 28th week of foetal development, but this communication is discontinued in the 30th week. Permeability of these lacunae, later in life, could result in the development of superior semicircular canal dehiscence syndrome. The clinical results of the surgical repair of this abnormal communication, in this particular case, using a middle fossa approach and a transmastoid approach is presented. CONCLUSIONS: Superior Semicircular Canal Dehiscence Syndrome could be due to an abnormality in foetal development and its genesis, therefore, could be prenatal. Surgical repair via transmastoid approach is a reasonable alternative treatment to the middle fossa approach.

Síndrome de dehiscencia del canal semicircular superior. Aspectos embriológicos y quirúrgicos / Superior semicircular canal dehiscence syndrome. Embryological and surgical considerations

Presentar el primer caso de síndrome de dehiscencia del canal semicular superior publicado en lengua española y establecer, con estudios embriológicos, el período embriológico implicado en la génesis del síndrome. Material y métodos: Se estudian 52 series embriológicas fetales, desde 6 mm hasta recién nacidos. Se presenta el caso de un paciente que presentaba un síndrome de dehiscencia de canal semicurcular superior. Resultados: Existe una relación de continuidad, a través de lagunas óseas, entre el canal semicircular superior y el espacio intracraneal en el feto de 24 a 28 semanas pero esta relación se pierde en la semana 30. Se exponen los resultados del cierre quirúrgico de la fístula, en el paciente estudiado, con un abordaje por la fosa media y con abordaje transmastoideo. Conclusiones: El síndrome podría ser secundario a una alteración del desarrollo embriológico y, por tanto, su génesis sería prenatal. La reparación quirúrgica por vía transmastoidea es una alternativa razonable a la vía de la fosa media

Objetive: Presenting the first case of superior semicircular canal dehiscence syndrome in the Spanish literature and to establish, using embryological studies, the period in wich superior semicircular canal dehiscence originates. Material and methods: 52 embryos and foetuses, from 6 mm to foetal maturity, were studied. The case of a patient suffering from superior semicircular canal dehiscence syndrome is presented. Results: The superior semicircular canal and the intracranial space are communicated through bony lacunae, in the period between the 24th and 28th week of foetal development, but this communication is discontinued in the 30th week. Permeability of these lacunae, later in life, could result in the development of superior semicircular canal dehiscence syndrome. The clinical results of the surgical repair of this abnormal communication, in this particular case, using amiddle fossa approach and a transmastoid approach is presented. Conclusions: Superior Semicircular Canal Dehiscence Syndrome could be due to an abnormality in foetal development and its genesis, therefore, could be prenatal. Surgical repair via transmastoid approach is a reasonable alternative treatment to the middle fossa approach

Clinical anatomy of the human anterior cranial fossa during the prenatal period.

We examined the prenatal development of the human anterior cranial fossa and considered its clinical aspects. Our purpose was an evaluation of anterior cranial fossa geometry, its measurements and connections with the nasal cavity and middle cranial fossa. The study was performed on 29 foetuses from the first and second trimester of pregnancy. New methods of computer image analysis, Scion for Windows 98 and ELFv 4.2, were applied to examine this anatomical region. Different options used were binarisation, equalisation, filters, linear and non-linear transformations and mathematical operations of images. This enabled the dynamics of prenatal development to be accurately evaluated for parts of the base of the human skull. Measurements were taken of angles of the cranial base. The anterior cranial base angle (the apex in the middle of the sella turcica and the arms running through the zygomatic ossification points) decreased gradually between C-R 6 to 23.5 cm from 170 to 120 degrees and afterwards became constant. The contrary-medial cranial base angle (adjacent to the anterior cranial base angle and with a second arm running through the auricular cartilage) increased from 50 to 70 degrees. The anterior cranial fossa was first located on the same level as the middle and posterior fossae. The process of descent of the middle and posterior cranial fossa begins in the 4th gestational month. The geometry of the anterior cranial fossa changes rapidly, especially in the first trimester of pregnancy. The first trimester of pregnancy is crucial for the development of its defects. Preconception prophylaxis of inborn defects of the anterior cranial fossa is therefore extremely important.