Thèse d'exercice : Médecine. Cardiologie et pathologies vasculaires : Nantes : 2007. / Bibliogr.

The well-known neurological disturbances associated with caudal displacement of the cerebellar tonsils through the fora men magnum (Chiari malformation) have lead to many radiological studies of the region. With MRI, routine sagittal and parasagittal views of the craniovertebral junction have shown that the position of the cerebellar tonsils is variable, and in many otherwise healthy individuals, the inferior tonsillar margins lie within the fora men magnum itself. In some cases, this topography is associated with little signal from the surrounding cerebra-spinal fluid (CSF), indicating reduction of the cerebellomedullary cistern and, therefore, crowding of neural structures within the confines of the fora men. The objective of this study has been to examine the spatial relationship between the contents of the foramen magnum ie. the medulla and cerebellar tonsils, using a normal sample comprising 120 volunteers. Instead of the conventional measurements of distance, a ratio, the Foramen Magnum Index (FMI), has been determined, derived from the relative surface areas (pixels) of neural parenchyma and CSF, over axially and sagittaly-defined boundaries of the fora men. The FMI, with a 95th centile of 0.77, exhibits appropriate statistical correlation with tonsillar position below the level of the foramen, and is therefore considered specific. As a quantitative means of assessing the cerebellomedullary cistern, the FMI also identifies certain subjects whose tonsils are at the foramen, in whom the cistern is small with resultant neural crowding.

The existence of a patent foramen ovale (PFO) has been known about for nearly 2,000 years. The prevalence of a PFO has been shown to be 25-40% in the general population. Despite the fact that blood flowing through a PFO acts as a shunt, there has been little research looking at the effect a PFO has on physiology in otherwise healthy humans. In Chapter IV, the effect of a PFO on core temperature (Tcore) prior to, and during exercise, was investigated. The design of this experiment included appropriate controls for a thermoregulatory study (i.e. measuring at same time of day, appropriate hydration and food intake, etc.). Results from this study indicate that subjects with a PFO (PFO+) have a Tcore that is ~0.4°C higher at rest and during exercise than subjects without a PFO (PFO–). Additionally, this study showed that PFO– subjects do not increase Tcore to the same extent breathing cold air as they do breathing ambient air during a 10-minute exercise bout, whereas there was no difference in Tcore increase between these two conditions for PFO+ subjects. These findings suggest that the difference in Tcore between PFO+ and PFO– subjects is potentially due to differences in respiratory heat loss. The studies for Chapter V examined differences in thermoregulatory and ventilatory responses during hot water (40°C) and cold water (20°C) immersion. This study found that compared to PFO– subjects, PFO+ subjects 1) increase Tcore at the same rate during hot water immersion and 2) do not cool off as quickly during cold water immersion. Additionally, in subjects who reached a ventilatory threshold, PFO+ subjects had blunted ventilatory responses to increased Tcore compared to PFO– subjects. Finally, in Chapter VI it was shown that PFO+ subjects have blunted ventilatory responses during acute exposure to hyperoxic and normoxic hypercapnia. However, there were no differences in ventilatory responses between PFO+ and PFO– subjects during exposure to either isocapnic or poikilocapnic hypoxia. These findings suggest that PFO+ subjects have a blunted central chemoreflex. This dissertation contains previously, unpublished co-authored material.

Objectives: As cone beam computerized tomography is used more widely for initial data collection and treatment planning, more valuable anatomic information is at the disposal of clinicians. The scans provide a very accurate display of the patient’s anatomy and these beneficial findings can be used to prevent surgical complications as well as advancing anatomical knowledge. This study aims to expand the current knowledge on the location of the infraorbital nerve in relation to the maxillary sinus in a group of patients who had CBCT scans taken for diagnosis and treatment planning. The study also aims to determine if age, gender or ethnicity have a relationship with the location of the nerve in relation to the sinus. Materials and Methods: 821 CBCT scans were take at Temple University Kornberg School of Dentistry Department of Oral and Maxillofacial Radiology from January 1, 2009 to July 31, 2013. These scans were evaluated using i-CAT computer imaging software. Patients under 18, patients without posterior or maxillary dentitions and patients who’s scans did not include the infraorbital nerve were excluded from the study. A total of four hundred three (403) CBCT scans were included in the study. Patients with visible infraorbital nerves were selected and location, age, gender and ethnicity were recorded. Individual scans had infraorbital nerves identified and examined for relationship superior to a specific tooth, and distance above the floor of the sinus. Results: After reviewing 680 scans, only 403 were included in the study due to exclusions. Scans were subdivided into age, gender, ethnicity and location of the nerve in relation to tooth position. The total average distance from the infraorbital foramen to the floor of the maxillary sinus was 23.94 mm on the right side and 22.84 mm on the left side. The average distance of males was 25.3 mm on the right and 24.27 mm on the left. The females’ average distance was 22.77 mm on the right and 21.62 mm on the left. The distance increased as the patients aged. The most common maxillary tooth inferior to the foramen was second premolar 46.65% of time, followed by the first molar 41.69% of the time. The difference between genders, right and left sides, and age groups all showed statistical significance. The differences between the ethnicities were not statistically significant. Conclusion: Based on the data collected and analyzed in the present study, the infraorbital foramen appeared to be located above the second premolar or first molar 88% of the time. The distance of the foramen from the floor of the sinus was larger in men than women. The right and left side can be different, and the distance tends to increase with the age of the patient. This information can be applied to better achieve local anesthetic delivery success, and avoid complications and nerve damage when performing procedures. / Oral Biology

Patent foramen ovale (PFO) has been associated with an increased risk of decompression sickness (DCS) in divers. Pathophysiologicaly this has been ascribed to paradoxical embolization of nitrogen bubbles from venous blood to systemic circulation, resulting in obstruction of peripheral capillaries and ischemic injury. However, the role of PFO has been largely debated and experimental and prospective clinical data has been missing. It is of note, that this hypothesis is not only of theoretical importance. The proof of PFO as a causative factor of DCS and, importantly, of unpredictable events (unprovoked DCS) could affect millions of divers worldwide through improved therapy and prevention. In our research we aimed to describe the pathophysiological role of PFO in decompression sickness and to determine whether the prevention of arterialization of post-dive venous gas emboli (VGE) would decrease the incidence of unprovoked DCS in divers. We have screened 489 scuba divers for the presence of PFO by means of transcranial color-coded Doppler ultrasonography. In a retrospective analysis we found that the incidence of unprovoked decompression sickness was 7% among these divers and that PFO was the only risk factor. Subsequently, we have studied the occurrence of VGE and arterial gas emboli (AGE) in divers with...

The location of mental nerve has been extensively studied anatomically and radiographically. This systematic review aims to summarize the common location of mental foramen (MF) as well as its anatomical variation, the accessory mental foramen (AMF). The PubMed and Google Scholar databases were both searched for the available study until Jan 2020. The database search yield 2766 study of which 47 were included in this study according to the inclusion criteria. The study concludes that in general the position of the mental foramen is between area distal to the first premolar root apex and the long axis of the apex of second premolar in 82% to 90% according to panoramic and CBCT studies reported until 2020 respectively. Importantly, AMF incident has been found in 8.3% of the population, according the all of the CBCT studies included in this systematic review.

Introduction Achondroplasia is associated with foramen magnum stenosis (FMS) which can lead to sudden unexpected death in infants. There is no wide consensus regarding the best management of FMS. Aim The study aimed to describe the prevalence of FMS in a population of children with achondroplasia and to evaluate screening and neurosurgical interventions of FMS in regard to its effects and complications. Material and Methods This is a retrospective cohort study including all children with achondroplasia assessed or treated at Karolinska University Hospital between September 2005 to June 2020. Severity of FMS was graded using MRI Achondroplasia Foramen Magnum Score (AFMS). AFMS was correlated to neurological exams and polysomnography results. Results 51 children were included and severe FMS (AFMS3-4) was present in 35%. Sixty-five percent of the children underwent foramen magnum decompression (FMD). Neurological examination had a high specificity (94%), but a low sensitivity (28%) for severe FMS. Signs of central apnea on polysomnography did not correlate to severity of FMS (p=0.735). Surgery improved FMS (p<0.001) and decreased central apnea (p=0.070), but carried a risk of 9% for severe complications. Conclusions This study suggests that severe FMS is common in children with achondroplasia, that neurological symptoms may be absent even in severe FMS, and that FMD improves both FMS and central apnea. In order to limit morbidity and mortality by identifying children with severe FMS in need of FMD, we recommend routine MRI on all children with achondroplasia.

BACKGROUND:There is an association between cryptogenic stroke and patent foramen ovale (PFO). The optimal treatment strategy for secondary prevention remains unclear. The purpose of this study was to analyze aggregate data examining the safety and efficacy of transcatheter device closure versus standard medical therapy in patients with PFO and cryptogenic stroke.METHODS:A search of published data identified 3 randomized clinical trials for inclusion. The primary outcome was a composite end-point of death, stroke and transient-ischemic attack (TIA). Pre-defined subgroup analysis was performed with respect to baseline characteristics including age, sex, atrial septal aneurysm and shunt size. Data was synthesized using a random effects model and results presented as hazard ratios (HRs) with 95% confidence intervals (CIs).RESULTS:A cohort of 2,303 patients with a history of cryptogenic stroke and PFO were randomized to device closure (n=1150) and medical therapy (n=1153). Mean follow-up was 2.5years. Transcatheter closure was not superior to medical therapy in the secondary prevention of stroke or TIA in intention-to-treat analysis (HR: 0.66, 95% CI: 0.43 to 1.01 / p=0.056). However, the results were statistically significant using per-protocol analysis (HR: 0.64, 95% CI: 0.41 to 0.98 / p=0.043). Males had significant benefit with device closure (HR: 0.48, 95% CI: 0.24 to 0.96 / p=0.038).CONCLUSIONS:In this meta-analysis, using intention-to-treat analysis, transcatheter device closure of PFO was not superior to standard medical therapy in the secondary prevention of cryptogenic stroke. Transcatheter closure was superior using per-protocol analysis.

Basioccipital foramen (bof) is found in four acropomatid species, including Apogonops anomalus, Doederleinia berycoides, Neoscombrops annectens, and Synagrops japonicus belonging to four genera. This structure is just near the fish¡¦s inner ear and to which the anterior diverticulae of the swim bladder in the species protrudes. This configuration is though to be closely related to enhance hearing capabilities and an important synapomorphic system to the phylogeny of acropomatids. The structural parameters of the sagittae (i.e., otolith area, otolith sulcus area, ratio of sulcus to area, otolith weight, hair cell density in otolithic macula, and the stereocilia number per hair cell bundle) were estimated, measured, and analyzed. The data of the parameters from the ¡¥bof-possessing¡¦ acropomatids are lower than that of the ¡¥non-bof¡¦ acropomatids. These values infer a probable poorer auditory capability of the ¡¥bof-possessing¡¦ acropomatids. COI, cytochrome b, and rhodopsin sequences of 12 species in five acropomatid genera (i.e., Acropoma, Doederleinia, Malakichthys, Neoscombrops, Synagrops) were analyzed to resolve the issue whether the configuration between ¡¥bof¡¦ and anterior diverticulae of swim bladder representing synapomorphic characters. The constructed Bayesian and maximum parsimony trees indicate that the ¡¥bof-possessing¡¦ acrpomatids do not form a clade. These results suggest that thses specialized structures (¡¥bof¡¦ and anterior swim bladder diverticulae) have developed more than once in Acropomatidae (i.e., a case of convergence).

A biomechanical study of intervertebral foraminal narrowing during simulated automotive head-forward and head-turned rear impacts. The objective of this study was to quantify foraminal width, height and area narrowing during head-forward and head-turned rear impacts, and evaluate the potential for nerve root and ganglion impingement. Muscle weakness and paresthesias, documented in whiplash patients, have been associated with neural compression within the cervical intervertebral foramen. Rotated head posture at the time of rear impact has been correlated with increased frequency and severity of chronic radicular symptoms, as compared to facing forward. No studies have quantified dynamic changes in foramen dimensions during head-forward or head-turned rear impacts. Six whole cervical spine specimens with muscle force replication and surrogate head underwent simulated whiplash at 3.5, 5, 6.5 and 8 g, following non-injurious baseline 2 g acceleration. Continuous dynamic foraminal width, height and area narrowing were recorded, and the peaks were determined during each impact and statistically compared to baseline narrowing. During head-forward rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline were observed at C5-C6 beginning with 3.5 g impact. No significant increases in average peak foraminal height narrowing were observed, while average peak foraminal areas were significantly narrower than baseline at C4-C5 at 3.5, 5 and 6.5 g. During head-turned rear impacts, significant increases (P<0.05) in average peak foraminal width narrowing above baseline of up to 1.8 mm in the left C5-C6 foramen at 8 g were observed. Average peak dynamic foraminal height was significantly narrower than baseline at right C2-C3 foramen at 5 g and 6.5 g, while no significant increases in foraminal area were observed. Extrapolation of the present head-forward rear impact results indicated that the greatest potential for ganglia compression injury was at the lower cervical spine, C5-C6 and C6-C7. The present head-turned rear impact results indicated that the greatest potential ganglia compression injury exists at C5-C6 and C6-C7. Greater potential for ganglia compression injury exists at C3-C4 and C4-C5 due to head-turned rear impact, as compared to head-forward rear impact. Acute ganglia compression may produce a sensitized neural response to repeat compression leading to chronic radiculopathy following head-forward and head-turned rear impacts. Dynamic ganglion or nerve root compression may also lead to chronic radiculopathy.