Assessment of Maturational Changes in White Matter Anisotropy and Volume in Children: A DTI Study.

BACKGROUND AND PURPOSE: Anisotropy is a good indicator of white matter fascicle macrostructure and organization but the interpretation of its changes with age remains difficult. The increase of WM fascicle fractional anisotropy with time and its relationship with WM fascicle volume have never been examined during childhood. We studied the maturation of associative WM fascicles during childhood using MR imaging-based DTI. We explored whether the fractional anisotropy increase of the main WM fascicles persists beyond the period of brain growth and is related to WM fascicle volume increase. MATERIALS AND METHODS: In a series of 25 healthy children, the fractional anisotropy and volume of 15 associative WM fascicles were calculated. Several regression linear mixed models were used to study maturation parameters (fractional anisotropy, volume, and total telencephalon volume) considered as dependent variables, while age and sex were independent variables (the variable identifying the different WM fascicles was considered as a repeated measure). RESULTS: In children older than 8 years of age, WM fascicle fractional anisotropy increased with age (P value = .045) but not its volume (P value = .7) or the telencephalon volume (P value = .16). The time course of WM fascicle fractional anisotropy and volume suggested that each WM fascicle might follow a specific pattern of maturation. CONCLUSIONS: The fractional anisotropy increase of several WM fascicles after 8 years of age may not result from an increase in WM fascicle volume. It might be the consequence of other developmental processes such as myelination.

Hydrocephalus and Chiari malformation pathophysiology in FGFR2-related faciocraniosynostosis: A review.

BACKGROUND: Patients with syndromic faciocraniosynostosis due to the mutation of the fibroblast growth factor receptor (FGFR) 2 gene present premature fusion of the coronal sutures and of the cranial base synchondrosis. Cerebrospinal fluid (CSF) circulation disorders and cerebellar tonsil prolapse are frequent findings in faciocraniosynostosis. OBJECTIVE: We reviewed the medical literature on the pathophysiological mechanisms of CSF disorders such as hydrocephalus and of cerebellar tonsil prolapse in FGFR2-related faciocraniosynostosis. DISCUSSION: Different pathophysiological theories have been proposed, but none elucidated all the symptoms present in Apert, Crouzon and Pfeiffer syndromes. The first theory that addressed CSF circulation disruption was the constrictive theory (cephalocranial disproportion): cerebellum and brain stem are constricted by the small volume of the posterior fossa. The second theory proposed venous hyperpressure due to jugular foramens stenosis. The most recent theory proposed a pressure differential between CSF in the posterior fossa and in the vertebral canal, due to foramen magnum stenosis.

The growth of the posterior cranial fossa in FGFR2-induced faciocraniosynostosis: A review.

BACKGROUND: The growth of the posterior fossa in syndromic craniostenosis was studied in many papers. However, few studies described the pathophysiological growth mechanisms in non-operated infants with fibroblast growth factor receptor (FGFR) type 2 mutation (Crouzon, Apert or Pfeiffer syndrome), although these are essential to understanding cranial vault expansion and hydrocephalus treatment in these syndromes. OBJECTIVE: A review of the medical literature was performed, to understand the physiological and pathological growth mechanisms of the posterior fossa in normal infants and infants with craniostenosis related to FGFR2 mutation. DISCUSSION: Of the various techniques for measuring posterior fossa volume, direct slice-by-slice contouring is the most precise and sensitive. Posterior fossa growth follows a bi-phasic pattern due to opening of the petro-occipital, occipitomastoidal and spheno-occipital sutures. Some studies reported smaller posterior fossae in syndromic craniostenosis, whereas direct contouring studies reported no difference between normal and craniostenotic patients. In Crouzon syndrome, synchondrosis fusion occurs earlier than in normal subjects, and follows a precise pattern. This premature fusion in Crouzon syndrome leads to a stenotic foramen magnum and facial retrusion.

The apex of the aortic arch backshifts with aging.

BACKGROUND: Only a few studies, involving small numbers of patients, have globally assessed the curvature of the thoracic aorta but without any details concerning the location of the supra-aortic trunks. OBJECTIVES: Using CT to describe normal aortic-arch morphology and its changes with age and sex. METHODS: 344 CT scans were studied. We measured the distances from the apex to the ascending and descending aorta, the curvilinear length of the entire arch, that of the segment, including bifurcations of supra-aortic vessels, and the angle, height, and shift of the arch. RESULTS: In men, the arch was significantly longer (146.2 vs 122.8 mm; p < 0.001), higher (49.3 vs 40.1 mm, p < 0.001), and wider transversely (83.6 vs 73.3 mm; p < 0.001) than in women. The average men's arch also had a more acute angle at the apex (79.7° vs 83.7° p < 0.001). Neither morphology nor age influenced the winding angle around the mediastinum. Aging was accompanied by deflection and extension of the aortic arch, which grew more anteroposteriorly (6.1 mm/10 years in men) than vertically (2.5 mm/10 years in men), while the apex moved towards the rear of the arch. The ascending aorta was the only curvilinear length unaffected by age, whereas the supra-aortic trunks parted from each other. CONCLUSION: We believe that all these original observations could lead to a better assessment of normal aging of the aorta and guide technical choices during surgical or hybrid procedures.

Personalized mapping of the deep brain with a white matter attenuated inversion recovery (WAIR) sequence at 1.5-tesla: Experience based on a series of 156 patients.

OBJECTIVE: Deep brain mapping has been proposed for direct targeting in stereotactic functional surgery, aiming to personalize electrode implantation according to individual MRI anatomy without atlas or statistical template. We report our clinical experience of direct targeting in a series of 156 patients operated on using a dedicated Inversion Recovery Turbo Spin Echo sequence at 1.5-tesla, called White Matter Attenuated Inversion Recovery (WAIR). METHODS: After manual contouring of all pertinent structures and 3D planning of trajectories, 312 DBS electrodes were implanted. Detailed anatomy of close neighbouring structures, whether gray nuclei or white matter regions, was identified during each planning procedure. We gathered the experience of these 312 deep brain mappings and elaborated consistent procedures of anatomical MRI mapping for pallidal, subthalamic and ventral thalamic regions. We studied the number of times the central track anatomically optimized was selected for implantation of definitive electrodes. RESULTS: WAIR sequence provided high-quality images of most common functional targets, successfully used for pure direct stereotactic targeting: the central track corresponding to the optimized primary anatomical trajectory was chosen for implantation of definitive electrodes in 90.38%. CONCLUSION: WAIR sequence is anatomically reliable, enabling precise deep brain mapping and direct stereotactic targeting under routine clinical conditions.

[Medico-economic analysis of a neurosurgery department at a university hospital]. / Analyse médico-économique d'un service de neurochirurgie en centre hospitalier et universitaire.

OBJECTIVE: Economic and societal constraints require to take into account the economic dimension and medical performance of hospital departments. We carried out a self-assessment study, which we thought could be useful to share with the neurosurgical community. MATERIAL AND METHODS: Care and research activities were assessed from 2009 to 2013. We used institutional and assessment-body parameters in order to describe activities and perform a financial evaluation. It was a retrospective descriptive study based on the guidelines of the DHOS/O4 circular No. 2007/390 of October 29, 2007. RESULTS: The average annual, analytic income statement was +1.39 millions euros, for 63 beds with a 92% occupancy rate, including 6.7 full-time equivalent neurosurgeons (and assistants), for 2553 patients and 1975 surgeries. The average mortality rate was 2.74%. The annual mean length of stay was 6.82 days. Per year, on average 15.6% of patients were admitted in emergency and 76.9% returned home. The annual, act-related-pricing and publication-related incomes represented 77% and 0.6%, respectively of the total funding. Difficulties to find downstream beds for the most severe patients induced 1401 "waiting days" in 2012. CONCLUSION: Medico-economic analysis of a neurosurgery department at a university hospital was useful in order to take into account the care, teaching and research activities, as well as its related financial value.

[Embryology of the heart walls]. / Embryologie des cloisons du cœur.

Although anatomically simple structures, the atrial septum and the ventricular septum have complex embryological origins. Recent findings in molecular biology allowed better comprehension of their formation. As soon as the heart tube is formed, cells migrate from several cardiogenic fields to take part in the septation. Elongation, ballooning, and later inflexion of the heart tube create chamber separating grooves, facing the future septa. The systemic venous tributaries conflate at the venous pole of the heart; it will partially involute while contributing to the atrial septum. The primary atrial septum grows from the atrial roof towards the atrioventricular canal. It fuses there with the atrioventricular cushions, while its upper margin breaks down to form the ostium secundum. Then a deep fold develops from the atrial roof and partly covers the ostium secundum, leaving a flap-like interatrial communication through the oval foramen. It will close at birth. The interventricular septum has three embryological origins. The ventricular septum primum, created during the ballooning process, origins from the primary heart tube. It will form the trabecular septum and the inlet septum. The interventricular ring, surrounding the interventricular foramen, will participate in the inlet septum and also form the atrioventricular conduction axis. The outflow cushions will separate the outflow tract in the aorta and pulmonary artery, and grow to create the outlet septum. After merging with the atrioventricular cushions, they will also be part of the membranous septum.

Anatomy and physiology of cerebrospinal fluid.

The cerebrospinal fluid (CSF) is contained in the brain ventricles and the cranial and spinal subarachnoid spaces. The mean CSF volume is 150 ml, with 25 ml in the ventricles and 125 ml in subarachnoid spaces. CSF is predominantly, but not exclusively, secreted by the choroid plexuses. Brain interstitial fluid, ependyma and capillaries may also play a poorly defined role in CSF secretion. CSF circulation from sites of secretion to sites of absorption largely depends on the arterial pulse wave. Additional factors such as respiratory waves, the subject's posture, jugular venous pressure and physical effort also modulate CSF flow dynamics and pressure. Cranial and spinal arachnoid villi have been considered for a long time to be the predominant sites of CSF absorption into the venous outflow system. Experimental data suggest that cranial and spinal nerve sheaths, the cribriform plate and the adventitia of cerebral arteries constitute substantial pathways of CSF drainage into the lymphatic outflow system. CSF is renewed about four times every 24 hours. Reduction of the CSF turnover rate during ageing leads to accumulation of catabolites in the brain and CSF that are also observed in certain neurodegenerative diseases. The CSF space is a dynamic pressure system. CSF pressure determines intracranial pressure with physiological values ranging between 3 and 4 mmHg before the age of one year, and between 10 and 15 mmHg in adults. Apart from its function of hydromechanical protection of the central nervous system, CSF also plays a prominent role in brain development and regulation of brain interstitial fluid homeostasis, which influences neuronal functioning.

White matter anatomy of the human deep brain revisited with high resolution DTI fibre tracking.

BACKGROUND AND PURPOSE: Deep white matter (WM) fascicles play a major, yet poorly understood, role in the overall connectivity of human brain. Better knowledge of their anatomy is requisite to understand the clinical correlates of their lesions and develop targeted treatments. We investigated whether MR-based diffusion tensor imaging (DTI) and fibre tracking could reveal in vivo, in explicit details, the 3D WM architecture within the subthalamic region and the internal capsule. METHODS: High-resolution DTI images were acquired on six healthy volunteers on a three Tesla MR scanner. We studied using single-subject analysis WM fascicles within the subthalamic region and the internal capsule, as follows: DTI deterministic fibre tracking (FT) of fascicles; embedding fascicles in the volume-rendered brain coupled with a triplanar view; rigorous anatomic labelling of each fascicle according to classical knowledge as described by pioneer neuroanatomists. Deterministic FT effects were taken into account. RESULTS: We charted most of WM fascicles of the deep brain, in particular large and complex fascicles such as the basal forebrain bundle and the ansa lenticularis. A topographic classification of subthalamic fascicles was proposed into three groups: the cerebellorubral, the reticulo-dorsal and the tegmento-peripheral one. CONCLUSIONS: Beyond to demonstrate the feasibility of imaging the deepest WM fascicles in vivo, our results pave the way for a better understanding of the brain connectivity and for developing targeted neuromodulation.

[Derivation of cerebrospinal fluid: consequences on inner ear biomechanics in adult patients with chronic hydrocephalus]. / Dérivation du liquide cérébrospinal avec valve: ses conséquences sur la biomécanique de l'oreille interne chez les patients atteints d'hydrocéphalie chronique de l'adulte.

BACKGROUND AND PURPOSE: Patients suffering from hydrocephalus are often treated by the surgical placement of a shunt, directing the excess of cerebrospinal fluid towards another body compartment. However, the degree of clinical improvement is variable and the dynamics of cerebrospinal fluid pressure in shunted hydrocephalus is poorly understood. A recently developed noninvasive technique makes it possible to follow pressure variations: it is based on otoacoustic emissions, sounds naturally emitted by the cochlea and routinely detected in audiology. When cerebrospinal fluid pressure changes, emissions undergo a phase shift while crossing the oval window. The goal of this work is to study how this shift is affected by shunt placement. METHOD: Otoacoustic emissions were recorded repeatedly in 22 adult patients who suffered from chronic hydrocephalus. Their phase shifts were measured, in sitting and recumbent positions, before and after surgical placement of a ventriculo-peritoneal shunt (Sophysa SM8). RESULTS: Postural shift in normal subjects is a phase lead, and this outcome was found in 17 of 22 patients preoperatively. After shunt placement, the postural effect became a phase lag in 18 patients of 20. In a given posture, sitting or recumbent, phase shifts changed from pre to postoperative measurements in a systematic manner. CONCLUSION: Otoacoustic emissions respond in a characteristic way to posture changes in normal adults, and having received a shunt for chronic hydrocephalus reverses the effect, presumably in relation to the existence of a "vacuum" in the inner ear.

[Surgical anatomy of the brain stem]. / Anatomie chirurgicale du tronc cérébral.

We reviewed the literature on brain stem anatomy, to identify possible and non-hazardous entry zones with a minimum of functional risks. Using the reticular formation defined as a median structure in a coronal plane, we determined six anatomic zones, 3 ventral, 3 dorsal (mesencephalic, pontic, medulla-oblongata). Considering the functional structures surrounding each zone, the possible penetration points are described. There are ventral, one for the mesencephale, one for the pons, one for the medulla oblongata; and dorsal, one for the mesencephale, two for the floor of the 4th ventricle, one for the medulla oblongata.

[Therapeutic indications for central nervous system cavernomas]. / Indications thérapeutiques des cavernomes du système nerveux central.

We describe the therapeutic indications for central nervous system cavernomas based on three criteria: 1) Single and multiple lesions: indications are the same, considering that in multiple lesions, one location can be symptomatic; 2) locations: indications are easy to define for exophytic cavernomas close to the hemisphere, brain stem or cerebellum pial surface, or to the ventricular ependyma; 3) symptomatic and non symptomatic presentations: usually, symptomatic forms require surgery except deep lesions located in functional zones distant from the ependyma or the pia matter, unless life prognosis is compromised. Treatment of a symptomatic forms remains debatable, opinion being divided between therapeutic abstention and surgery (in case of cavernomas close to the pia matter or the ependyma). Scientific data strongly support surgical indication for lesions presenting with epilepsy specially when drug-resistant; 4) natural history: prevention against hemorrhage is an argument in favor of surgery for the lesions located in non functional zones or where the risk of bleeding is higher, especially in the brain stem. Discrepancy in the risk of bleeding reported in the literature tends to temper this attitude. Radiosurgery is exceptionally reserved for technically inoperable cavernomas. Partial protection for two years can be expected. Epileptic seizures decrease but few prospective randomised studies are available. The rate of complication appears to be higher than in other affections.

[Analysis of a series of cavernomas of the central nervous system: 39 non operated cases, 39 operated cases, 1 dead]. / Analyse d'une série de cavernomes du système nerveux central: 39 cas non opérés, 39 cas opérés et un cas décédé

Cavernomas are vascular malformations frequently localized in the central nervous system. Debate remains open concerning proper treatment. We reviewed a series of cavernomas in order to collect information concerning the natural history. This retrospective study concerned 79 patients seen over a 15-year period. The epidemiologic, clinical, radiological, therapeutic and follow-up data were analyzed. The cavernomas were encephalic (including brain stem and cerebellum) in 74 patients, and in the spinal cord in 5 patients. Average age was 40.08 years, without sex predominance. The most frequent clinical sign was a focal neurological deficit. The cavernoma was solitary in 71 patients. The subtentorial localization was most frequent (44 cases). Bleeding was observed in 31 patients giving a hemorrhagic risk of 0.013%/patient/year. One patient died at admission, 39 were operated and surgical abstention with clinical and radiological follow up was decided for 39 patients (no bleeding in 64.2%). The course in these patients was marked by bleeding in six during 29.5 months follow-up of (rate of hemorrhagic risk 6.27%/patient/year). These results are not in total agreement with the literature. They demonstrate the difficulties for an exact evaluation of the hemorrhagic risk in cavernomas of the central nervous system. So, it is very important to meticulously discuss surgical indications.

[The meninges, an anatomical point of view]. / Les méninges vues par l'anatomiste.

The meninges correspond to an anatomical concept. For the morphologist, the microscopic organization, the hypothetical presence of a subdural space, the nature of the interface between the deep meningeal layer and the nervous parenchyma in the perivascular spaces are the central issues. For the clinician, dynamic aspects of cerebrospinal fluid flow, secretion, and resorption are essential factors with practical consequences in terms of disease and patient management. Comparative anatomy, embryology, and organogenesis provide an interesting perspective for the descriptive and functional anatomy of the meninges. Usually considered as protective membranes, the meninges play a prominent role in the development and maintenance of the central nervous system. The meninges are in constant evolution, from their formation to senescence. The meninges present three layers in children and adults: the dura mater, the arachnoid and the pia mater. The cerebrospinal fluid is secreted by the choroid plexuses, flows through the ventricles and the subarachnoid space, and is absorbed by arachnoid granulations. Other sites of secretion and resorption are suggested by comparative anatomy and human embryology and organogenesis.

Problematic differential diagnosis between cerebellar liponeurocytoma and anaplastic oligodendroglioma.

A cerebellar tumour, first diagnosed as an anaplastic oligodendroglioma, received radiation therapy (45 Gy) following gross total resection. The second histological study revealed a liponeurocytoma, a benign tumour not requiring adjuvant therapy. This case emphasizes the importance of considering this diagnosis to prevent unnecessary irradiation of such rumours.

[Anatomy and physiology of the vestibular system: review of the literature]. / Anatomie et physiologie du système vestibulaire. Revue de la littérature.

The vestibular system is a complex system involving not only posterior labyrinth but also central structures such as cerebellum, striatum, thalamus, frontal and prefrontal cortex to assure balance, movements and walking. Information reaching the vestibular complex are not purely vestibular but also from visual, somatosensory and cerebellar origins. The equilibrium is also a complex physiological function needing concordance of vestibular, visual and somatosensory information or either central compensation after an injury but also an integrity of the central nervous system.

[Treatment of central and neuropathic facial pain by chronic stimulation of the motor cortex: value of neuronavigation guidance systems for the localization of the motor cortex]. / Traitement des douleurs centrales et neuropathiques faciales par stimulation chronique du cortex moteur. Intêret des systèmes de neuronavigation pour le repérage du cortex moteur]

Thirty two patients with refractory central and neuropathic pain of peripheral origin were treated by chronic stimulation of the motor cortex between May 1993 and January 1997. The mean follow-up was 27. 3 months. The first 24 patients were operated according to the technique described by Tsubokawa. The last 13 cases (8 new patients and 5 reinterventions) were operated by a technique including localization by superficial CT reconstruction of the central region and neuronavigator guidance. The position of the central sulcus was confirmed by the use of intraoperative somatosensory evoked potentials. The somatotopic organisation of the motor cortex was established peroperatively by studying the motor responses at stimulation of the motor cortex through the dura. Ten of the 13 patients with central pain (77%) and nine of the 12 patients with neuropathic facial pain had experienced substantial pain relief (75%). One of the 3 patients with post-paraplegia pain was clearly improved. A satisfactory result was obtained in one patient with pain related to plexus avulsion and in one patient with pain related to intercostal herpes zoster. None of the patients developed epileptic seizures. The position of the stimulating poles effective on pain corresponded to the somatotopic representation of the motor cortex. The neuronavigator localization and guidance technique proved to be most useful identifying the appropriate portion of the motor gyrus. It also allowed the establishment of reliable correlations between electrophysiological-clinical and anatomical data which may be used to improve the clinical results and possibly to extend the indications of this technique.

[Endoscopic surgery of third ventricle lesions]. / Approche endoscopique des lésions du troisième ventricule.

The endoscopic approach of the tumors of the third ventricle interests mainly the colloid cysts but also offers the possibilities of biopsies. Twenty two patients (16 men and 6 women, average age 41 years) presenting with hydrocephalus related to a tumor of the pineal area were treated by a ventriculostomy with attempt at biopsy : they are outside of the limits of this report. Twenty two other patients (15 men, 7 women, average age 39 years) were operated on from 1994 to 1999 for a colloid cyst, and 2 of them were admitted in emergency in sudden coma. The CT scan showed a colloid cyst (hyperdense in 16 patients) associated with an hydrocephalus, except for a patient previously shunted. The diameter of the cyst varied from 4 to 50 mm (average of 20 mm). All the patients were operated on using a rigid endoscope. Among the 20 patients presenting a tumor of the pineal area, a biopsy was possible only in 4 cases (20%). There were no hemorrhage nor neurological disorders. In all the cases, the size and the number of the specimens were sufficient to allow the histological diagnosis. For the patients presenting with colloid cyst, the average follow-up is 2 years. All the preoperative symptoms disappeared except for the memory disorders which were improved. The post-operative Evans index decreased significantly. No residual cyst was observed on the post-operative MRI in 14 patients (63%). Among these patients, an asymptomatic recurrence was observed and remained stable after 44 months of follow-up. A residual cyst was observed in 8 patients (36%), with a diameter from 5 to 25 mm (average 9 mm). No patient required a shunt procedure, and no patient presented hemorrhagic complication. Endoscopy is especially useful in the first line treatment of the colloid cysts of the third ventricle.

The murid filaria Monanema martini: a model for onchocerciasis. Part I. Description of lesions.

A study of the anatomo-pathological lesions induced by Monanema martini, a filaria with skin-dwelling microfilariae, was performed using 65 Lemniscomys striatus fixed from 30 minutes to 36 months after inoculation of the infective larvae, 5 Arvicanthis niloticus and 3 Meriones unguiculatus fixed during the patent phase, and controls. Attempts at quantification of lesions in L. striatus was made. Approximately 20% of L. striatus had microfilariae in the eyeballs, and many more presented ocular lesions. The delay of the patent period seems to have more effects on the gravity of lesions than repeated inoculations. The location of the lesions and parasites presuppose that microfilariae enter the eyeball through the lymphatic capillaries of the irido-corneal angles. Cutaneous lesions were often severe: there is a parallel between the importance of lesions and the abundance of microfilariae. Larvae are responsible for damage to various structures of the lymphatic system (thrombo-lymphangitis, acute or granulomatous lymphadenitis...) into which they migrate, explaining the mechanism of elephantiasis. These rodent lesions appear similar to those observed in human onchocerciasis and lymphatic filariasis. Whatever the M. martini stage and the organ examined, major lesions belonged to the inflammatory process. Various types of inflammatory reaction (acute, subacute, or chronic inflammation, scarring sclerosis etc.) can co-exist within a single tissue area. The accidental escape of a microfilaria from a lymphatic capillary into the connective tissue (including the corneal stroma) induces an inflammatory reaction. Thus M. martini, as human Onchocerca species, causes a chronic disease, associating recent lesions to old ones.