Extrapontine myelinolysis in a 4 year old with diabetic ketoacidosis

Extrapontine and central pontine myelinolysis (EPM/CPM) are rare events in pediatric neurology but can have devastating consequences. They are most commonly associated with rapid correction of hyponatremia but have been reported in other situations as well. This condition is relatively more common in adult neurology, not surprisingly, as alcoholism and associated malnutrition are often predisposing conditions. There have been few case reports in children with regards to this. We describe a 4-year old who presented with focal neurological deficits in the setting of diabetic ketoacidosis and the ensuing underlying osmotic imbalances. The patient made a remarkable recovery with no deficits of note-cognitive or motor. To our knowledge this is the youngest case reported so far of EPM in a child with diabetic ketoacidosis. The history of the condition, early animal experiments, clinicopathologic correlates, previous case reports and other scenarios in which this unusual event can occur are discussed--though the exact pathogenesis of this condition still remains unclear. We hope to bring to the attention of clinicians caring for children in the acute care setting, the importance of gradual correction of serum osmolality to reduce morbidity and mortality.     

急性颈脊髓损伤后低钠血症的临床特点及治疗

目的：总结急性颈脊髓损伤后低钠血症的临床特点及治疗体会。方法：将289例急性颈脊髓损伤患者按是否并发低钠血症，分为发病组和未发病组，并对两组的临床资料进行比较，其中包括：性别、年龄、损伤平面、损伤程度、合并颅脑损伤、合并肺内和泌尿系感染及使刚呼吸机。同时回顾性分析低钠血症的治疗方法。结果：在损伤平面颈4以上、完全性脊髓损伤、合并颅脑损伤、合并肺内和泌尿系感染及使用呼吸机方面。发病组与未发病组之间的差异具有显著性意义。本组126例患者经限制水摄入量和适量的补钠治疗。低钠症状3周内改善。24例因感染发热，水摄入量限制不严格，恢复缓慢。结论：急性颈髓损伤后低钠血症的发生与颈髓损伤的平面、损伤程度、合并颅脑损伤、合并肺内和泌尿系感染及使用呼吸机有关。限制水摄入量和适当补钠是安全有效的治疗方法。     

Cell volume regulation: a review of cerebral adaptive mechanisms and implications for clinical treatment of osmolal disturbances: II

Cerebral cell volume regulatory mechanisms are activated by sustained disturbances in plasma osmolality. Acute hypernatremia causes a predictable shrinkage of brain cells due to the sudden imposition of a plasma-to-cell osmolal gradient. However, during chronic hypernatremia cerebral cell volume is maintained close to the normal range as a result of the accumulation of electrolytes and organic osmolytes including myo-inositol, taurine, glutamine, glycerophosphorylcholine, and betaine. The increased cytosolic level of these molecules is generally accomplished via increased activity of sodium (Na⁺)-dependent cotransport systems. The slow dissipation of these additional osmotically active solutes from the cell during treatment of hypernatremia necessitates gradual correction of this electrolyte abnormality. Acute hyponatremia leads to cerebral cell swelling and severe neurological dysfunction. However, prolonged hyponatremia is associated with significant reductions in brain cell electrolyte and organic osmolyte content so that cerebral cell volume is restored to normal. While acute hyponatremia can be treated with the administration of moderate doses of hypertonic saline in order to control seizure activity, chronic hyponatremia should be corrected slowly in order to prevent subsequent neurological deterioration. If the rate of correction exceeds 0.5 mmol/l per hour, or if the total increment in serum [Na⁺] exceeds 25 mmol/l in the first 48 h of therapy, then there is an increased risk of the development of cerebral demyelinating lesions. Chronic hyperglycemia activates the brain cell volume regulatory adaptations in the same manner as hypernatremia. Therefore, during the treatment of diabetic ketoacidosis, it is imperative to restore normoglycemia gradually in order to prevent the occurrence of cerebral edema. It is possible that excessive administration of electrolyte-free solutions and high doses of insulin may increase the risk of this complication. While there are some data to suggest that brain cell size is disturbed during acute uremia, additional work is necessary to clarify the role of cerebral cell volume regulation during acute and chronic uremia.     

迟发性维生素K缺乏性颅内出血患儿血浆心钠素与低钠血症的关系

目的探讨迟发性维生素K缺乏性颅内出血患儿心钠素(ANP)水平变化与低钠血症的关系及其临床意义。方法应用放射免疫分析技术检测108例颅内出血患儿不同病程的血浆ANP水平,同时检测血清钠的含量,选取25例健康同龄儿作为对照。结果(1)颅内出血急性期血浆ANP水平均高于对照组(P<0·05);昏迷组患儿ANP升高更明显(P<0·01);(2)颅内出血患儿血浆ANP与血清钠水平呈负相关(γ=-0·748,P<0·05)。结论(1)迟发性维生素K缺乏性颅内出血患儿血浆ANP水平反映脑损伤严重程度;(2)ANP参与迟发性维生素K缺乏性颅内出血患儿低钠血症的形成过程。     

Decreased serum sodium levels predict symptomatic vasospasm in patients with subarachnoid hemorrhage

Background: Symptomatic vasospasm is a major cause of morbidity and mortality in subarachnoid hemorrhage patients. Hyponatremia and dehydration due to natriuresis after subarachnoid hemorrhage are related to symptomatic vasospasm. Therefore, most institutions are currently targeting euvolemia and eunatremia in subarachnoid hemorrhage patients to avoid complications. We retrospectively investigated the predictors of symptomatic vasospasm with respect to water and sodium homeostasis, while maintaining euvolemia and eunatremia after subarachnoid hemorrhage. Methods: We monitored changes in serum sodium levels, serum osmolarity, daily sodium intake, daily urine volume, and daily water balance for 14 days after subarachnoid hemorrhage. Outcomes were assessed using the modified Rankin scale at 1 month after subarachnoid hemorrhage. Results: Among 97 patients, 27 (27.8%) had symptomatic vasospasm. Patients with symptomatic vasospasm were older than those without symptomatic vasospasm; the occurrence of symptomatic vasospasm affected outcomes. Serum sodium levels were sequentially significantly decreased, but within the normal range from 1 day before the occurrence of symptomatic vasospasm. Serum osmolarity of the spasm group was lower than that of the non-spasm group. Conclusions: Symptomatic vasospasm occurs more often in older patients and affects outcomes. A decrease in serum sodium levels occurs a day before symptomatic vasospasm. This observation may help predict symptomatic vasospasm.     

Neurochemistry of hyponatremic encephalopathy evaluated by MR spectroscopy

MR spectroscopy in a patient with hyponatremic encephalopathy due to the syndrome of inappropriate secretion of antidiuretic hormone revealed decreased N-acetyl-aspartate, creatine plus phosphocreatine, choline-containing compounds, and myo-inositol, with normal glutamate and increased glutamine, which normalized after Na normalization. The decreased concentrations of creatine plus phosphocreatine, choline-containing compounds and myo-inositol are explained by their release as osmolytes from brain cells to adapt to hypo-osmolality induced cerebral edema. Increased glutamine, which not only acts as an osmolyte but also protects neurons under excitotoxic conditions, may suggest that a disrupted glutamate-glutamine cycle may play an important role in the pathogenesis of hyponatremic encephalopathy.