[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.

[Pituitary metastasis presenting as diabetes insipidus: a report of four cases and literature review]. / Diabète insipide révélateur de métastases hypophysaires : quatre observations et revue de la littérature.

INTRODUCTION: Pituitary metastases are a rare cause of central diabetes insipidus and usually complicate advanced cancers. CASE REPORTS: We report four cases in which diabetes insipidus revealed a metastatic stage of a lung (two cases) or a breast (two cases) cancer. One patient presented with a panhypopituitarism, three had diabetes insipidus including one with corticotroph insufficiency. In one case, the cerebrospinal fluid analysis showed a lymphocytic meningitis. On brain magnetic resonance imaging there was an absence of high intensity signal in the posterior pituitary lobe (one case) or an infiltration of the posterior lobe (three cases). CONCLUSION: Breast and lung malignancies are the most frequent causes of metastasis of the pituitary gland. In most cases there are often other metastatic locations; however insipidus diabetes can reveal the metastatic stage of the cancer. A pituitary biopsy may be necessary to obtain the diagnosis.

[Cranial nerve functional neurosurgery: evaluation of surgical practice]. / La neurochirurgie fonctionnelle des nerfs crâniens Evaluation de l'activité

We report the results of an investigation carried out on the activity of functional neurosurgery of the cranial nerves in the French-speaking countries, based on the analysis of a questionnaire addressed to all the members of the SNCLF. Eighteen centers responded to this questionnaire, which showed that activities and indications varied greatly from one unit to another. The results appear homogeneous and comparable with those reported in the literature. The questionnaire sought to provide a global perspective, open to the comments and questions of all responders on the various techniques raised, with the objective of establishing a common decisional tree for these pathologies and providing if possible to a consensus for better dissemination of these therapies.

[Unruptured intracranial aneurysm and microsurgical exclusion: the need of a randomized study of surgery versus natural history]. / Anévrisme intracrânien non rompu et exclusion microchirurgicale: justification d'une étude randomisée chirurgie versus histoire naturelle.

Although unruptured intracranial aneurysm (UIA) is becoming a more common finding nowadays, determining the optimal treatment strategy is difficult because the risk of rupture is poorly understood and surgery is not without its own hazards. As the mortality rate after rupture is estimated to range from 56 to 83%, the final therapeutic decision is the result of an analysis of rupture risk and the risks related to surgical exclusion, which may be determined by consideration of the risk factors. We considered the UIA to have a high risk of rupture if it was located on the vertebrobasilar arterial system (RR: 4.4; CI 95%, 2.7-6.8), between 7 and 12 mm in size (RR: 3.3; CI 95%, 1.3-8.2) or larger (RR: 17; CI 95%, 8-36.1), multilobular and had a ratio of depth to width greater than 3.4 (risk x 20). A family history of UIA would constitute a major rupture risk (two to seven times that of spontaneous UIA). Other factors related to UIA rupture include arterial hypertension (RR: 1.46; CI 95%, 1.01-2.11) and smoking (RR: 3.04; CI 95%, 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were calculated as 9 and 1.5%, respectively. Microsurgical risk factors were age (32% > 65 years), and factors related to the UIA itself and surgery, such as size (14% > 15 mm), location, presence of atherosclerosis and difficulty of surgical clip application. The incidence of rupture after microsurgical exclusion was estimated to be 0.2% per year, and complete microsurgical exclusion was achieved in 90% of patients. A randomised study of microsurgical exclusion of UIA would offer further proof of our therapeutic hypotheses.

[Benign intracranial hypertension: history, definition, and physiopathology]. / Hypertension intracrânienne bénigne: historique, définition et physiopathologie.

Benign intracranial hypertension (BIH) is a rare condition in which the pathophysiology remains unclear. Multiple theories have been proposed in the past to explain BIH. Today it is widely accepted that the condition occurs in situations where alteration of cerebrospinal fluid (CSF) reabsorption is encountered. The venous system is therefore involved and may be the common denominator of the pathophysiological theories. A distinction must be made between idiopathic benign intracranial hypertension and BIH resulting from drugs, other pathological conditions, or toxics (secondary BIH), which are reported in this paper. We emphasize the crucial role of exhaustive clinical, biological, and neuroradiological investigations aiming to establish the diagnosis of BIH.

[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.

[Role of radiosurgery in the management of intracranial cavernomas. Review of the literature]. / Place de la radiochirurgie dans la prise en charge des cavernomes intracrâniens. Revue de la littérature.

From a review of the literature dealing with radiosurgery of cavernous malformations, we have analyzed its impact on hemorrhagic risk, epilepsy, histological modifications, morbidity and potential indications of treatment. Radiosurgery could significantly reduce the hemorrhagic risk, in a selected population with a high risk of hemorrhage, after an interval of about 2 years, but cannot provide protection against rebleeding. As for epilepsy related to the lesion, a significant reduction of seizures has been observed in certain cases, with better control in case of recent evolution and simple seizures linked to the site of the vascular malformation. Histologic lesions are vascular fibrosis, fibrinoid necrosis and ferrugination, without good correlation with results of CT scan or MRI. Morbidity of radiosurgery seems higher compared to other diseases with similar doses and target volumes. The rate of transient complications was about 25%, with permanent sequelae in 5 to 10% of patients. This would be due to a radiosensitizing effect of the hemosiderin halo around the lesion. Radiosurgery can be proposed for non-surgical lesions with a high risk of hemorrhage, nevertheless the superiority of the technique over conservative treatment has to be proven. Without long-term prospective studies, the efficiency of RS for cavernomas remains questionable and subject to debate. New imaging methods proving the obstruction of the cavernous malformation are needed.

[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.

An evidence-based information booklet helps reduce fear-avoidance beliefs after first-time discectomy for disc prolapse.

OBJECTIVE: We aimed to assess the impact of a booklet integrating the biopsychosocial model of chronic pain management on reducing disability among patients undergoing lumbar discetomy. METHODS: In a prospective, controlled, time-series study with an alternate-month design, we enrolled 129 patients from a tertiary care university hospital after they underwent uncomplicated lumbar discectomy for the first time. The intervention group received the biopsychosocial evidence-based booklet and the control group a biomedical-based booklet; the booklets differed only in information content. Patients were blinded to treatment group. The main outcome was disability at 2 months (measured by the Quebec back-pain disability scale [QBPDS]). Secondary outcomes were fear and avoidance beliefs measured by the Fear-Avoidance Beliefs Questionnaire (FABQ). All data were collected by self-reporting questionnaires. RESULTS: At 2 months, disability did not differ between the 2 groups (QBPDS score 32.4±22.8 vs 36.1±18.7, P=0.36). FABQ physical activity score was lower with the evidenced-based booklet as compared with controls (8.0±7.14 vs 11.2±6.3, P=0.008). CONCLUSIONS: Providing an evidence-based booklet had no effect at 2 months after surgery on disability but reduced fear-avoidance beliefs about physical activity. This booklet could be an effective tool for health care professionals in helping with patient education. CLINICALTRIALS. GOV IDENTIFIER: NCT00761111.

[Adenocarcinomas of the ethmoid sinus: retrospective analysis of prognostic factors]. / Adénocarcinomes de l'ethmoïde: analyse rétrospective des facteurs pronostics.

OBJECTIVES: Determinate the different prognostic factors of survival in ethmoidal sinus adenocarcinomas (ADK). MATERIAL AND METHODS: 60 patients with ethmoidal sinus ADK. 59 men and one woman. Average of 62.2 years (41-82). Retrospective study between 1985 and 2005. The following data were analyzed: exposure time to wood dust, disease incidence, primary clinical symptoms and ASA score. Radiological data were recovered by tomodensitometry and magnetic resonance imaging. Histological groups were described. TNM classification according to UICC 2002 and Roux/Brasnu was established on clinical and radiological constatations. Different treatments used were analyzed. Estimate of survival rate and impact of different prognostic factors were based on Kaplan-Meier actuarial method and multivariate analysis. RESULTS: Incidence rate was 2.86 patients a year. Exposure average time to wood dust was 25.6 years (2-44). T3/T4 stages were predominant (66.7%). the survival rate was 46.5% at 5 years. The survival rate was significantly superior respectively in T1 and T2 stages than in T3 and T4 stages, and in T4a than in T4b stages. Extension of the lesion to the sphenoid sinus was revealed as a significant bad prognostic factor. The ASA score and the exposure time to wood dust were not identified as statistically significant prognosis factors. CONCLUSION: Survival factors of ethmoïd sinus ADK were T stage and the extension of the tumor to the sphenoid sinus. On the results of this study, we consider that extension in sphenoïd sinus could be include in TNM classification of ethmoïd sinus adenocarcinomas.

[Hemorrhagic lumbar juxta facet cyst. A case report]. / Kyste lombaire hémorragique juxta-articulaire. A propos d'un cas.

We report the case of a hemorrhagic lumbar juxta facet cyst (L2-L3), revealed by a chronic right lumbocruralgia, in a 77-year-old woman treated by anticoagulants for cardiac arrhythmia. Computerized tomography and magnetic resonance imaging suggested the diagnosis of benign tumor. During surgical removal of the whole lesion, a hemorrhagic synovial cyst was evoked. The operation dramatically relieved the symptoms. The diagnosis was confirmed by the histopathological analysis confronted with the clinical and the radiological findings. This uncommon observation allows the discussion of the pathogenic mechanism and of the differential diagnosis.

[Pedagogic focus-group in pediatrics]. / Initiation à la pédagogie narrative en pédiatrie : le focus-groupe pédagogique.

AIM: To assess a new behavioral teaching technique called "focus group pedagogy" (FGP), which consists in a three-step meeting between sick children's parents and medical students (first with students alone, then with parents and students together, then with students alone). METHODS: This qualitative research ran two sessions (each totaling four to six parents and six students) in which parents were questioned on four main themes: their knowledge of the medical hierarchy, their ability to identify the people in the hospital, their communication with medical staff, and the overall care delivered to their children. A thematic analysis of the verbatim transcript was performed. RESULTS: In the FGP sessions, medical students voiced opinions on their degree of insertion in the medical and paramedical staff, and reported their presence as ambiguous, between care and learning. Parents voiced their experience of their child's hospital stay but also their wider conception of the parent/patient-physician relationship based on their parent-of-patient/parent-as-patient experiences. The meeting of parents and students highlighted divergent narratives on relationships with caregivers, communication, attitudes, knowledge, and competencies. This approach made it possible to hear and learn the point of view "from the other side," which proved beneficial for students, session leaders, and the care unit organization alike. CONCLUSION: FGP is a novel and easy way to discover diverse narratives and the technique is feasible and beneficial in pediatric settings.

[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.

Incidence and survival of childhood central nervous system tumors: A report of the regional registry of childhood cancers in Auvergne-Limousin.

INTRODUCTION: Central nervous system tumors (CNST) are the most lethal of solid tumors in childhood cancer. PATIENTS AND METHODS: We report incidence and survival data for all CNST (International Classification of Diseases for Oncology third edition, category III or Xa) recorded in children under 15 years of age by the Auvergne-Limousin cancer registry for the period 1986-2009. RESULTS: Annual incidence of all CNST was 3.27 per 100,000 and the male to female ratio was 0.95. Over 45.0% of CNST were glial. Astrocytomas (36.2%) showed the highest incidence for each age group except between 1 and 4 years where embryonal tumors were more common. For all CNST, no significant variation in incidence over time was observed for the evaluated period of 23 years (annual percent change: -0.4%, 95% CI, [-2.8-2.1]). Globally, 5 years overall survival was 67% [59-73] and had increased by more than 16% between 1986-1999 and 2000-2009, mainly due to better survival for astrocytomas, other gliomas, ependymomas and choroid plexus tumors (P=0.01). CONCLUSION: We report that the incidence of CNST in Auvergne-Limousin is similar to that in the literature and did not increase between 1986 and 2009. In addition, 5 years overall survival increased after 1999, especially for surgically treatable tumors.

[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.

High-dose BCNU followed by autologous hematopoietic stem cell transplantation in supratentorial high-grade malignant gliomas: a retrospective analysis of 114 patients.

Conventional treatment of high-grade glioma includes maximal surgical resection followed by external radiation therapy. Despite this treatment, the prognosis for patients is poor. High doses of chemotherapy might be another way to increase the response rate and median survival. Increasing doses of BCNU might be more effective, but also provokes unacceptable myelotoxicity. This dose-limiting toxicity can be circumvented by using autologous blood stem cell rescue. We report our experience of high-dose BCNU followed by transplantation of autologous hematopoietic stem cells in 114 patients with high-grade gliomas. Of the 114 gliomas, 78 were glioblastoma multiforme (GM) (68%), 24 anaplastic astrocytomas (AA) (21%), and 12 anaplastic oligodendrogliomas (OD) (11%). Complete surgical resection was performed for 22 patients (18 GM and 4 AA). The median age was 44 years (range 17-65). A total of 84 patients received autologous hematopoietic stem cells from bone marrow harvest, while 30 patients received granulocyte colony-stimulating factor followed by apheresis and received peripheral blood progenitor cells (PBPC). High dose of BCNU (800 mg/m(2)) was given at least 1 month after neurosurgery. Bone marrow or PBPC was transplanted 48-72 h after chemotherapy. Radiotherapy was started approximately 40 days after transplantation to a total of 60 Gy. Median follow-up was 89 months (19-163). The overall survival (OS) was, respectively, 12 months for GM, 37 months for OD and 81 months for AA. Histological type appeared to be the main discriminating factor, with a worse prognosis for GM. Within the GM population, age, completeness of surgery, and response appeared to be one important prognostic factors. The AA and OD populations were small to reliably assess prognostic factors. On multivariate analysis, the main prognostic factors were histologic type, quality of surgery, and age (P<0.005). Five of 114 patients had lethal complications from the procedure. Four of these patients had a Karnovsky performance score (KPS) of 60%. The protocol thus appears to be feasible but patients should be selected for KPS more than 70%. We observed long-term survivors, although the OS and the time to treatment failure seem to be comparable to that described for other treatment. Additional pilot studies are unlikely to reveal more than a modest benefit from this procedure and therefore a randomized study should be performed.

Otoacoustic emissions: a new tool for monitoring intracranial pressure changes through stapes displacements.

Changes in hydrostatic intracranial pressure (ICP) are thought to be transmitted to cochlear liquids, thereby altering the mechanical load on the stapes footplate. Hence the stiffness of stapes' annular ligament is expected to reflect ICP changes. Corresponding middle-ear transmission changes have been assessed using click-evoked otoacoustic emissions (EOAE) in two experiments. The first one was performed in 22 normal human subjects submitted to posture changes. In the second one, controlled ICP increases were applied to 18 patients in neurosurgery operating theater. EOAEs were monitored in these subjects throughout the experiments and their phases and amplitudes were analyzed as a function of frequency. ICP affected EOAEs in a systematic manner in both experiments, i.e., the main effect of ICP increase was phase lead of EOAE components below 2 kHz without any significant amplitude or frequency shift. Their variations were much more evident than the modifications in middle-ear impedance assessed by standard impedance or admittance measurements. The second experiment led to a quantitative linear relationship between ICP and EOAE phases. It demonstrated that the sensitivity of EOAE phase monitoring technique proves to be quite high, i.e., 55 daPa increases in ICP are readily detected in all subjects. The results are consistent with the predictions of classical middle-ear models as to the transmission alterations induced by ICP-related changes in the stiffness of the annular ligament of the stapes. Non-invasive monitoring of ICP in patients with hydrocephalus treated with ventriculo-peritoneal shunts might be attempted with this technique, although it is restricted to patients with detectable EOAEs (i.e., about 50% in this series).

Middle-ear influence on otoacoustic emissions. II: contributions of posture and intracranial pressure.

Although it seems likely that body tilt or surgically provoked variations in intracranial pressure (ICP) can result in variations of intralabyrinthine pressure, the channels for pressure transmission remain controversial and the reasons why evoked otoacoustic emissions (EOAEs) exhibit attendant modifications are unclear. The theoretical framework implemented in the companion paper [Avan et al. part I, 2000] provides sensitive and non-invasive means to identify the middle-ear mechanism(s) entailed in EOAE changes. It was thus applied to analyze the influence of posture on EOAE phases and magnitudes as a function of frequency, in a series of experiments involving body tilt from sitting to supine (0 degrees or -30 degrees ). Controlled ICP variations were surgically carried out in a series of hydrocephalic patients and the resulting EOAE changes were compared to posture data and model predictions. In all cases, the EOAE changes closely resembled those due to an increase in the stiffness of the stapes' annular ligament, in keeping with the assumption that ICP gets transmitted to intralabyrinthine spaces and modifies the hydrostatic load on the stapes, thereby influencing EOAE features. A small additional contribution of middle-ear pressure to EOAE changes was identified in addition to the main stapes component. Dynamical EOAE measurements showed that sudden ICP changes were transmitted to the inner ear within 8-30 s. The high sensitivity of EOAE phases below 2 kHz to ICP changes, together with the absence of any significant confounding middle-ear effect, favors EOAEs for a reliable non-invasive monitoring of ICP and intralabyrinthine pressures.