Le magnésium et le calcium réduisent la sévérité des troubles de la mémoire spatiale pour le modèle kaïnique d'épilepsie mésiale temporale chez la souris.

Calcium and magnesium are divalent multipotent ions playing a major role in metabolism, excitability and neuroglial plasticity. Because of these multiple properties, their deficiency induces complex brain processes leading to acute or even lasting disorders in excitability and neural networks. These ions are usually prescribed in clinical contexts of neuronal hyperexcitability such as preeclampsia and chronic stress. Our aim was to evaluate whether magnesium at 20 mg/kg and calcium at 100 mg/kg could improve the memory prognosis in the kainic model of mesial temporal epilepsy in mice. The animals were organized into 6 groups: control group (without kainate), reference group (GR) without administration of ions, groups treated with magnesium or calcium from the third day (respectively G1m, G1c), groups treated with magnesium or calcium from the third week (respectively G2m, G2c). The mice treated by ions performed better than GR mice, but magnesium was more effective. Memory (short term-long term) was differently affected by kainate or improved by magnesium-calcium. In addition, magnesium demonstrated an increasing therapeutic effect over time while calcium had an acute and apparently decreasing action in the G1c group that received calcium early.

Le calcium et le magnésium sont des ions divalents multipotents importants pour le métabolisme, l'excitabilité, et la plasticité de la névroglie. En raison de leurs multiples propriétés, leur carence provoque des processus cérébraux complexes menant à des aberrations aigües voire durables au niveau de l'excitabilité et des réseaux neuronaux. Ces ions sont habituellement prescrits dans des contextes cliniques d'hyperexcitabilité neuronale comme la prééclampsie et le stress chronique. Notre objectif était d'évaluer si le magnésium à 20 mg/kg et le calcium à 100 mg/kg pouvaient améliorer le pronostic mnésique dans le modèle kaïnique d'épilepsie mésiale temporale chez les souris. Les animaux furent organisés en six groupes : groupe témoin (sans kaïnate), groupe de référence sans administration d'ions (GR), groupes traités au magnésium ou au calcium dès le troisième jour (respectivement G1m, G1c), groupes traités au magnésium ou au calcium à partir de la troisième semaine (respectivement G2m, G2c). Les souris traitées ont toutes présenté de meilleures performances que les souris GR, mais le magnésium était plus efficace. La mémoire (court terme­long terme) était touchée différemment par le kaïnate ou améliorée par le magnésium et le calcium. De plus, le magnésium a démontré un effet thérapeutique croissant avec le temps alors que le calcium avait un effet aigu qui semblait se dégrader pour le groupe G1c qui reçut précocement du calcium.

Pre-hospital delay in patients with ischemic stroke in the Fann Teaching Hospital, Dakar, Senegal in 2020.

Introduction: stroke is a cerebrovascular disease. Early reperfusion in neurovascular units can reduce its morbidity and mortality. Even when neurovascular units exist, patients usually arrive late in the emergency department. to the purpose of this study was to determine prehospital delay in patients with acute ischemic stroke and associated factors. Methods: we conducted a retrospective cross-sectional study in the neurology department of the Fann University Hospital in Dakar from January 1s t to June 30th, 2020. We included patients younger than 80 years seen in the emergency unit for ischemic stroke. The median time to presentation was calculated based on the time of stroke onset and that of arrival at the hospital. Multivariate analysis was used to determine factors associated with prehospital delay. Results: a total of 56 patients were enrolled, among whom 58.6% arrived at the hospital in less than 3 hours. Of them, 37.5% presented to a level 3 or 4 hospital first. Less than 34% of our patient presented to a level 2-3 hospital in less than 3 hours. Based on bi- and multivariate analysis, being married (OR = 7.2 [CI à 95%: 1.5 - 35.8]), being a female (OR = 5.5 [CI à 95%: 1.5 - 19.8]) and having stroke during week days (OR = 4.3 [CI à 95%: 1.3-13.9]) were associated with prehospital delay. Conclusion: most of our patients arrived late at a level 2 or 3 hospital. Being a married woman increased the risk of late arrival. This study highlights the importance of improving awareness in order to increase the proportion of patients potentially eligible for revascularization.

Are Sub-Saharan epileptic people less photosensitive? A Senegalese study of photoparoxysmal response in a reference epilepsy centre.

The photoparoxysmal response (PPR) is defined as the occurrence of generalized spike, spike-wave or polyspike-wave discharges consistently elicited by intermittent photic stimulation (IPS). PPR is not well studied in Sub-Saharan African people. We prospectively studied the epidemiological, clinical, and EEG characteristics of PPR among consecutive patients recorded at the clinical neurophysiology unit of Fann University Hospital (Dakar, Senegal). Among 6,808 EEG recordings including 3,065 pathological EEGs, we collected 56 EEGs with PPR (0.8% of all recorded EEGs and 1.8% of anormal EEGs), from 31 women and 25 men (sex ratio: 0.8). The mean age was 13.3 years (range: 8 months to 59 years). The peak of photosensitivity was found in the range of 6 to 10 years. Of the PPR cases, 12 had clinical manifestations during IPS. Generalized epilepsy was diagnosed in 23 (41%) patients and 18 (32%) had focal epilepsies. The most epileptogenic stimulation frequencies were between 12 and 24 Hz (range: 1-28 Hz). PPR were mainly triggered during eye closure (64%), and 41 patients (73% of PPR cases) were classified as Type 4 (Waltz classification). Our results confirm lower rates of photosensitivity in African Sub-Saharan people compared with others. Although the current data do not support a role of short-term ambient light levels, subject to consistent data from larger cohorts, it may be interesting to study the probable epigenetic-mediated protective role of sunshine against photosensitivity.

Can magnesium reduce central neurodegeneration in Alzheimer's disease? Basic evidences and research needs.

Magnesium (Mg) is a crucial divalent cation with more than 300 cellular functions. This ion shows therapeutic properties in several neurological diseases. Although there are numerous basic evidences showing that Mg can inhibit pathological processes involved in neuroglial degeneration, this low-cost option is not well-considered in clinical research and practice for now. Nevertheless, none of the expensive drugs currently recommended by the classic guidelines (in addition to physiological rehabilitation) had shown exceptional effectiveness. Herein, focusing on Alzheimer's disease (AD), we analyze the therapeutic pathways that support the use of Mg for neurogenesis and neuroprotection. According to experimental findings reviewed, Mg shows interesting abilities to facilitate toxin clearance, reduce neuroinflammation, inhibit the pathologic processing of amyloid protein precursor (APP) as well as the abnormal tau protein phosphorylation, and to reverse the deregulation of N-methyl-D-aspartate receptors. Currently, some crucial details of the mechanisms involved in these proved effects remain elusive and clinical background is poor. Therefore, further studies are required to enable a better overview on pharmacodynamic targets of Mg and thus, to find optimal pharmacologic strategies for clinical use of this ion.

Neuromyelitis optica spectrum disorders (NMO-SD) in a Sub-Saharan Africa country: A preliminary study of sixteen Senegalese cases.

BACKGROUND: Neuromyelitis optica (NMO) is an autoimmune disease of the central nervous system. In Sub-Saharan Africa, publications are rare and deal with isolated cases. Our goal was to analyze the characteristics of NMO spectrum disorders in a Senegalese cohort compiled in Dakar. PATIENTS AND METHOD: This was a retrospective descriptive study conducted at the Neurology Department of Fann Teaching Hospital. We included all patients with NMO-SD according to the 2014 diagnostic criteria. RESULTS: Sixteen patients were enrolled, 4 men and 12 women with an average age of 30 years. Ten patients (62.5%) presented an acute myelopathy associated with retrobulbar optic neuritis and 5 (31.25%) had isolated spinal cord injury. Spinal MRI showed abnormal cervical (6 patients), dorsal (4 patients), bulbar-cervical (3 patients) or cervico-dorsal (2 patients) signal extended (≥3 vertebral segments) of the spinal cord. Visual evoked potentials (VEP) showed demyelinating optic nerve involvement in 8 patients. Ten patients were positive to AQP-4 IgG. Systemic corticosteroid therapy was the rule in all patients, associated with azathioprine in 10 of them. The clinical course at 3 months was predominantly favourable (10 patients). CONCLUSION: This cohort is the first one compiled in Dakar. African multicentric epidemiological studies are needed.