Neural correlates of consciousness and related disorders: From phenotypic descriptors of behavioral and relative consciousness to cortico-subcortical circuitry.

We report a review of medical aspects of the consciousness. The behavioral dimension, phenotypic descriptors, relative consciousness and neural correlates of consciousness and related disorders were addressed successively in a holistic and chronological approach. Consciousness is relative, specific to each individual across time and space. Historically defined as the perception of the self and the environment, it cannot be separated from behaviors, entailing an idea of conscious behavior with metapractic and metagnostic aspects. Observation of spontaneous and evoked overt behavior distinguishes three main types of disorder of consciousness (DoC): coma, vegetative state or unresponsive wakefulness, and minimally conscious or relationally impoverished state. Modern functional exploration techniques, such as imaging, increase the understanding of DoCs and consciousness. Whether consciousness is a superior function and/or an instrumental function is discussed. Neural correlates can be subdivided into two wakefulness pathways (superior thalamic cholinergic and inferior extra-thalamic), and cortico-subcortical circuitry. The deep brain structures are those described in the well-known sensorimotor, associative and limbic loops, as illustrated in the mesolimbic model of DoC. The cortices can be segregated into several overlapping networks: (1) a global workspace including thalamo-cortical loops; (2) the default mode network (DMN) and related intrinsic connectivity networks (i.e., central executive, medial DMN and salience networks); (3) a 3-fold network comprising the fronto-parietal control system and its dorsal and ventral attentional sub-networks, the fronto-parietal executive control network, and the cingulo-opercular salience network; (4) the internal and external cortices, respectively medial, turned toward the self, and lateral, turned toward the environment. The network dynamics is the reflection of consciousness, notably anticorrelations such as the decrease in activity of the posterior cingulate-precuneus regions during attentional tasks. Thanks to recent advances in DoC pathophysiology, further significative therapeutic progress is expected, taking into account the societal context. This depends notably on the dissemination of medical knowledge and its transfer to a wider public.

Postoperative empyema following chronic subdural hematoma surgery: Clinically based medicine.

INTRODUCTION: Subdural empyema (SDE) is a rare complication of chronic subdural hematoma (CSDH) surgery. We introduced antibiotic prophylaxis (AP) for this procedure in 2014 following a morbidity-mortality conference (MMC) in our department. We report the results of retrospective data analysis to assess the effect of systematic AP and to identify risk factors for SDE. MATERIAL AND METHODS: Two hundred eight patients were recruited between January 2013 and December 2015; 5 were excluded for incomplete data: 107 without and 96 with AP (n=203). SDE was confirmed by clinical examination, imaging and bacteriological analysis. Comparisons between AP-(no cefuroxime) and AP+ (cefuroxime) groups were made with Chi2 test and Student's t-test. RESULTS: One empyema was found in each group, indicating that AP had no effect (P=1). The only criterion associated with SDE for these two patients was a greater number of reoperations for CSDH recurrence (P=0.013). DISCUSSION: The incidence of postoperative empyema was 1%, similar to the range of 0.2%-2.1% reported in the literature. This rare incidence explains why we found no significant effect of AP. The medical decision taken at the MMC did not help to reduce the rate of postoperative SDE. MMCs can help to define factors associated with adverse surgical events and identify opportunities for improvement. CONCLUSION: AP, introduced after an MMC, did not impact SDE rates. In practice, AP should be required only in case of reoperation for CSDH recurrence. However, we still continue to use AP following the MMC considering different parameters discussed in the manuscript.

Long-Term Outcomes After Linac Radiosurgery for Benign Meningiomas.

AIMS: Although several studies on outcomes following stereotactic radiosurgery (SRS) for benign meningiomas have been reported, Linac-based SRS outcomes have not been as widely evaluated. The aim of this retrospective institutional single-centre study was to determine long-term outcomes of Linac-based SRS for benign intracranial meningiomas. MATERIALS AND METHODS: From July 1996 to May 2011, 60 patients with 69 benign meningiomas were included. All patients were treated with single-fraction Linac-based SRS with four to five non-coplanar arcs, dynamic or not. The marginal dose prescribed for the periphery was 16 Gy. Prognostic factors associated with local control, progression-free survival (PFS) and overall survival were tested. RESULTS: The median follow-up was 128 months. No patient was lost to follow-up. The values observed at 1, 5 and 10 years were, respectively, 100%, 98.4% and 92.6% for local control, 94.9%, 93.2% and 78% for PFS and 100%, 94.7% and 92.7% for overall survival. In univariate analysis, local control after SRS was significantly higher for skull base and parasagittal meningiomas compared with convexity meningiomas (P = 0.031). Multivariate analyses showed significantly longer PFS when the minimum dose delivered to the tumour was greater than 10 Gy (P = 0.0082). No grade 5 toxicity was reported. CONCLUSION: Our long-term results from a large sample size of benign meningiomas treated with Linac-based SRS confirmed excellent local control (>90%) and good safety, which is in line with published studies on Gamma Knife surgery. Above all, we showed significantly poorer PFS if the minimum dose to the tumour was under 10 Gy.

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.