Largest recent impact craters on Mars: Orbital imaging and surface seismic co-investigation.

Two >130-meter-diameter impact craters formed on Mars during the later half of 2021. These are the two largest fresh impact craters discovered by the Mars Reconnaissance Orbiter since operations started 16 years ago. The impacts created two of the largest seismic events (magnitudes greater than 4) recorded by InSight during its 3-year mission. The combination of orbital imagery and seismic ground motion enables the investigation of subsurface and atmospheric energy partitioning of the impact process on a planet with a thin atmosphere and the first direct test of martian deep-interior seismic models with known event distances. The impact at 35°N excavated blocks of water ice, which is the lowest latitude at which ice has been directly observed on Mars.

Autoimmune cerebellar hypermetabolism: Report of three cases and literature overview.

We report three cases of vermian cerebellar hypermetabolism in patients with autoimmune encephalitis. One of our patients was positive for anti-Ma2 antibodies and one for anti-Zic4 antibodies while the remaining patient did not present any known antibodies. The seronegative patient deteriorated after immune checkpoint inhibitor treatment for a pulmonary adenocarcinoma and improved with immunosuppressive drugs, which is in favour of an underlying autoimmune mechanism. They all presented with subacute neurological symptoms. Brain magnetic resonance imaging was normal except in one patient, where hyperintensities were present on FLAIR sequence around the third ventricle and the cerebral aqueduct. 18F-FDG brain positron emission tomography with computed tomography (18F-FDG PET-CT) demonstrated an unusual vermian cerebellar hypermetabolism in the three cases. While cerebellar hypermetabolism on 18F-FDG PET-CT has been described in various neurological diseases, such vermian - and more broadly cerebellar - hypermetabolism was seldom described in previous studies on autoimmune encephalitis. When differential diagnoses have been ruled out, this pattern may be of interest for the positive diagnosis of autoimmune encephalitis in difficult diagnostic cases.

Headache changes prior to aneurysmal rupture: A symptom of unruptured aneurysm?

BACKGROUND AND OBJECTIVES: The symptomatic status of unruptured aneurysms has to be looked for. The objective of this retrospective case-control study was to identify the headache semiologic characteristics of symptomatic aneurysms during the 3 months prior to patient admission. PATIENTS AND METHODS: The case cohort was composed of 40 consecutive patients admitted for the treatment of a ruptured intracranial aneurysm (IA) and able to answer a standardized questionnaire by the same neurologist. This cohort was matched with a control cohort of 40 patients operated on for a degenerative lumbar pathology. This questionnaire, using the criteria for headache characteristics according to the International Headache Society (IHS) enabled us to classify headaches during the previous 3 months prior to the rupture (study period) and during the year prior to the period studied (reference period) in both cohorts. Headache status was considered as unstable if there were modifications of semiologic headache characteristics, thunderclap headaches or de novo headaches, or on the contrary stable. RESULTS: During the status period, chronic headaches were reported by 31 patients (77.5%) in the studied cohort and 35 (87.5%) in the control cohort. During the study period, the cephalagia status was stable in 19 patients (47.5%) versus 35 patients (87.5%) in the control cohort (P<0.001). Modifications of chronic headaches were present in 11 patients (35.5%) in the studied cohort versus 4 patients (11.4%) in the control cohort (P=0.04). Thunderclap headaches were present in 7 patients (17.5%) in the studied cohort but none in the control cohort (P=0.006). DISCUSSION: Modifications of headaches semiologic characteristics during the 3 previous months were significantly more frequent in the studied cohort. This modification could be a sign of IA instability.

Hereditary neuropathy with liability to pressure palsies occurring during military training.

Hereditary neuropathy with liability to pressure palsies (HNPP) is an autosomal-dominant peripheral neuropathy characterized by recurrent isolated nerve palsies, which are precipitated by trivial compression and trauma. Although HNPP has been well-described in literature, it often goes unrecognized. We report a case of HNPP occurring during military training to promote recognition and proper management of this entity.

[Guillain-Barré syndrome and anti-hepatitis A vaccination]. / Syndrome de Guillain-Barré et vaccination contre l'hépatite A.

The Guillain-Barré syndrome (GBS) is an acute inflammatory polyradiculoneuritis. The pathophysiology remains unknown but the existence of triggering factors such as external antigens is regularly suspected. We report the case of a 30-year-old patient with a past medical history of Graves disease, who presented with GBS within the month after receiving an anti-hepatitis A vaccination. GBS rarely happens after a hepatitis A vaccination. However, the responsibility of this vaccine should be considered in the clinical presentation of an acute polyradiculoneuritis.

[Anticonvulsant hypersensitivity syndrome and lamotrigine-associated anticonvulsant hypersensitivity syndrome]. / Syndrome d'hypersensibilité aux antiépileptiques. Cas particulier de la lamotrigine.

Anticonvulsant hypersensitivity syndrome (AHS) is defined by the association of high fever, cutaneous rash and multiorgan-system abnormalities (incidence, one in 1000 to one in 10,000 exposures). Fatal complications are described in 10%. This reaction usually develops 1 to 12 weeks after initiation of an aromatic anticonvulsant. Drug rash with eosinophilia and systemic symptoms (DRESS) can be discussed as differential diagnosis. Several hypotheses have been put forward to explain the pathogenesis of AHS. These include accumulation of toxic metabolites, antibody production and viral infection. The one based on toxic metabolites has found the greatest acceptance due to the fact that it can be proven by an in vitro test, the lymphocyte toxicity assay. In vivo, skin biopsies show characteristic findings of erythema multiform or typical leucocytoclastic angitis. The patch-test is positive in 80% of the cases. Lamotrigine-associated anticonvulsant hypersensitivity syndrome (LASH) is rare and was described in 1998. We report two new cases demonstrating the two particular configurations of apparition of LASH found in the 14 cases from the review of literature (Pubmed: anticonvulsant hypersensitivity syndrome - lamotrigine): high doses of lamotrigine (or lamotrigine in very young or old patients), and lamotrigine associated with another anti-epileptic (phenobarbital or sodium valproate). We discuss the links between DRESS after lamotrigine and LASH as illustrated in a new case.

[Idiopathic intracranial hypertension as a side effect of doxycycline]. / Hypertension intracrânienne bénigne secondaire à la prise de doxycycline.

Idiopathic intracranial hypertension is a rare disorder characterized by elevated intracranial pressure without hydrocephaly or intracranial process. Its mechanism is poorly understood. Most cases of benign intracranial hypertension are presumed to be idiopathic but some of them may be related to some treatment. We report a 26-year-old female with benign intracranial hypertension due to tetracycline, revealed by headaches and gradual visual loss. Standard investigations were unremarkable and favourable outcome after therapeutic lumbar puncture confirmed the diagnosis.

Direct correlation between molecular dynamics and enzymatic stability: a comparative neutron scattering study of native human butyrylcholinesterase and its "aged" soman conjugate.

An incoherent elastic neutron scattering study of the molecular dynamics of native human butyrylcholinesterase and its "aged" soman-inhibited conjugate revealed a significant change in molecular flexibility on an angstrom-nanosecond scale as a function of temperature. The results were related to the stability of each state as established previously by differential scanning calorimetry. A striking relationship was found between the denaturation behavior and the molecular flexibility of the native and inhibited enzymes as a function of temperature. This was reflected in a quantitative correlation between the atomic mean-square displacements on an angstrom-nanosecond scale determined by neutron spectroscopy and the calorimetric specific heat. By the application of a simple two-state model that describes the transition from a folded to a denatured state, the denaturation temperatures of the native and the inhibited enzyme were correctly extracted from the atomic mean-square displacements. Furthermore, the transition entropy and enthalpy extracted from the model fit of the neutron data were, within the experimental accuracy, compatible with the values determined by differential scanning calorimetry.

[Interferon-beta retinopathy]. / Rétinopathie liée à l'interféron-beta 1a sous-cutané

INTRODUCTION: Interferon-alpha associated retinopathy is an ocular complication of hepatitis C treatment well established in the literature. But, there are far fewer reports on multiple sclerosis related interferon-beta retinopathy. CASE REPORT: A 58-year-old male while receiving subcutaneous interferon-beta 1a 44microg thrice a week since 2001 for multiple sclerosis developed blurred vision. Visual acuity remained stable throughout the course of surveillance. Cotton wool spots were found on fundus exam. The retinopathy disappeared without specific therapy 2 months after discontinuing interferon injections. The diagnosis of interferon-beta 1a retinopathy was retained due to the lack of any other etiology. CONCLUSION: An ophthalmological examination including a fundus examination to search for a retinopathy should be undertaken when new ocular symptoms develop in a multiple sclerosis patient receiving interferon. An adverse event linked to interferon can be discussed and favored if the retinopathy resolves after interferon withdrawal.

Hysteresis of insect acetylcholinesterase.

Pre-steady-state catalytic properties of insect acetylcholinesterase (AChE, EC 3.1.1.7) were studied with the neutral substrate N-methylindoxylacetate. Kinetics of soluble Apis mellifera and Drosophila melanogaster AChE forms showed lags (v(i)=0) before reaching the steady-state. Results were interpreted in terms of slow equilibrium between two conformational states E and E' of insect AChE. Hysteresis of insect AChE has been pointed out for the first time. The hysteretic behaviour was found to depend on the NMIA concentration and the nature of the enzyme. The maximum induction times (tau(max)) to reach the steady-state were 800 and 1000s with soluble AChE from A. mellifera and D.melanogaster, respectively. The orders of magnitude of the tau(max) were high and similar to human AChE and BuChE.

[Neurological damage of brain tumor therapy]. / Complications neurologiques des traitements des tumeurs cérébrales.

Damage to the central nervous system induced by treatment of brain tumors is common and impairs the patient quality-of-life. Neurotoxicity is induced by synergistic effects of different cytotoxic treatments such as radiotherapy and chemotherapies administered concurrently or sequentially. Recent progress in the management of brain tumors has led to new neurotoxicities. The growing concern about the neuropsychological performance of patients has disclosed another type of brain damage which has been largely neglected to date. Neurological toxicity can be acute, requiring dose adaptation or a change of drugs. But it also often occurs late and can be irreversible. To date, treatments have been ineffective. The early diagnosis of neurotoxicity is thus a major challenge. Numerous clinical studies suggest an individual sensitivity which is not only related to age or vascular status, but also to genetic predisposition that remains to be detailed. Understanding the mechanisms of personal susceptibilities would be helpful in designing more tailored treatments. In this review we address the question of adverse effects of brain radiation as well as those of chemotherapy protocols which are particularly toxic for the central nervous system that is, methotrexate, platin and aracytin.

An unexpected plasma cholinesterase activity rebound after challenge with a high dose of the nerve agent VX.

Organophosphorus chemical warfare agents (nerve agents) are to be feared in military operations as well as in terrorist attacks. Among them, VX (O-ethyl-S-[2-(diisopropylamino)ethyl] methylphosphonothioate) is a low volatility liquid that represents a percutaneous as well as an inhalation hazard if aerosolized. It is a potent irreversible cholinesterase (ChE) inhibitor that causes severe signs and symptoms, including respiratory dysfunction that stems from different mechanisms. VX-induced pulmonary oedema was previously reported in dogs but mechanisms involved are not well understood, and its clinical significance remains to be assessed. An experimental model was thus developed to study VX-induced cardiovascular changes and pulmonary oedema in isoflurane-anaesthetized swine. In the course of this study, we observed a fast and unexpected rebound of plasma ChE activity following inhibition provoked by the intravenous injection of 6 and 12 microg kg(-1) of VX. In whole blood ChE activity, the rebound could stay unnoticed. Further investigations showed that the rebound of plasma esterase activity was neither related to spontaneous reactivation of ChE nor to VX-induced increase in paraoxonase/carboxylesterase activities. A bias in Ellman assay, haemoconcentration or severe liver cytolysis were also ruled out. All in all, these results suggest that the rebound was likely due to the release of butyrylcholinesterase into the blood stream from ChE producing organs. Nature of the organ(s) and mechanisms involved in enzyme release will need further investigations as it may represent a mechanism of defence, i.e. VX scavenging, that could advantageously be exploited.

[Spontaneous low cerebospinal fluid pressure syndrome. A case report and literature review]. / Syndrome d'hypotension spontanée du liquide cérébrospinal. Revue de la littérature à propos d'un cas.

INTRODUCTION: Spontaneous low cerebrospinal fluid pressure syndrome is a spontaneous intracranial hypotension pressure due to a cerebrospinal fluid leak without any known dural effraction. It is clinically characterised by postural headaches relieved by supine position. We report a 38-year-old patient with this syndrome and review the literature. EXEGESIS: The diagnosis is sometimes difficult in atypical presentation of the syndrome and can lead to incapacitating chronic headache and rarely to complications. Cerebral magnetic resonance imaging has dramatically improved identification, diagnosis and management of this syndrome. Treatment is mainly based on blood patch realisation. Cerebrospinal fluid leak probably due to a spontaneous defect in the dural mater is suspected to be the main mechanism of this syndrome without any history of lumbar puncture or penetrating trauma. CONCLUSION: Early diagnosis, often easy on the basis of clinical characteristics of the headache may avoid complications.

[Listeria monocytogenes abscess of the brain]. / Abcès du tronc cérébral à Listeria monocytogenes.

INTRODUCTION: Listeriosis commonly involves the central nervous system. Meningoencephalitis and rhomboencephalitis are the most frequent manifestations. Brain abscesses are rare. CASE REPORT: We report the case of a 63-year-old man treated with steroids for a long period; he was hospitalized for hemiparesis, confusion and fever. Clinical examination revealed meningeal signs, right hemiparesis and Parinaud syndrome. Initial CT scan was normal. The CSF contained 520 white cells/mm3 with predominance of polymorphonuclear neutrophils. An acute meningo- rhombencephalitis in an immunodepressed patient was suggested. The diagnosis of listeriosis was confirmed by blood cultures. Amoxicillin and gentamycin were started. The outcome on day 4 was severe with coma and tetraparesis. Brain MRI revealed a left peduncle abscess which descended deep into the brain reaching the internal capsule. The final clinical outcome involved residual right hemiparesis and left oculomotor nerve (III) palsy. CONCLUSION: Brain stem abscess is an uncommon form of listerial central nervous system infection. Listeria monocytogenes infection should be considered in patients with altered cell-mediated immunity that develop local neurologic deficits, a diagnosis which pursued rapidly with repeated blood cultures. Successful treatment requires early antibiotic therapy with ampicillin and gentamycin.

[Eulenburg's paramyotonia congenita]. / Paramyotonie congénitale d'Eulenburg.

INTRODUCTION: Paramyotonia congenita is an autosomal dominant sodium channelopathy, caused by mutations in gene coding for muscle voltage-gated sodium channel alpha subunit. CASE REPORT: We report the case of a 38-year-old man who described since childhood muscle stiffness with attacks ok weakness induced by two provocative stimuli: cold exposure and exercise. It primarily concerned eyelids and hands, occasionally limbs. Family history suggested an autosomal dominant mode of transmission. Clinical examination revealed myotonia at the thenar eminence percussion. Generalized myotonic discharges were observed on electromyography. Molecular diagnosis reported an Arg1448Cys mutation in exon 24 in gene coding for muscle voltage-gated sodium channel alpha subunit (SCN4A) in chromosome 17. CONCLUSION: Paramyotonia congenita is not evolutive. Treatment is essentially preventive. Some medications could be proposed: membrane stabilizing agents like antiarrhythmic drugs (mexiletine, tocainide), or the carbonic anhydrase inhibitor (acetazolamide). Precautions may be taken during general anaesthesia because of diaphragm myotonia risk.