Neonatal non-ketotic hyperglycinemia: report of five cases

Efficacy and safety of ketamine for neonatal refractory status epilepticus: case report and systematic review

Background

Evidence-based data on treatment of neonatal status epilepticus (SE) are scarce. We aimed to collect data on the efficacy and safety of ketamine for the treatment of neonatal SE and to assess its possible role in the treatment of neonatal SE.

Methods

We described a novel case and conducted a systematic literature review on neonatal SE treated with ketamine. The search was carried out in Pubmed, Cochrane, Clinical Trial Gov, Scopus and Web of Science.

Results

Seven published cases of neonatal SE treated with ketamine were identified and analyzed together with our novel case. Seizures typically presented during the first 24 h of life (6/8). Seizures were resistant to a mean of five antiseizure medications. Ketamine, a NMDA receptor antagonist, appeared to be safe and effective in all neonates treated. Neurologic sequelae including hypotonia and spasticity were reported for 4/5 of the surviving children (5/8). 3/5 of them were seizure free at 1-17 months of life.

Discussion

Neonatal brain is more susceptible to seizures due to a shift towards increased excitation because of a paradoxical excitatory effect of GABA, a greater density of NMDA receptors and higher extracellular concentrations of glutamate. Status epilepticus and neonatal encephalopathy could further enhance these mechanisms, providing a rationale for the use of ketamine in this setting.

Conclusions

Ketamine in the treatment of neonatal SE showed a promising efficacy and safety profile. However, further in-depth studies and clinical trials on larger populations are needed.

Glycine Administration Alters MAPK Signaling Pathways and Causes Neuronal Damage in Rat Brain: Putative Mechanisms Involved in the Neurological Dysfunction in Nonketotic Hyperglycinemia

High glycine (GLY) levels have been suggested to induce neurotoxic effects in the central nervous system of patients with nonketotic hyperglycinemia (NKH). Since the mechanisms involved in the neuropathophysiology of NKH are not totally established, we evaluated the effect of a single intracerebroventricular administration of GLY on the content of proteins involved in neuronal damage and inflammatory response, as well as on the phosphorylation of the MAPK p38, ERK1/2, and JNK in rat striatum and cerebral cortex. We also examined glial fibrillary acidic protein (GFAP) staining, a marker of glial reactivity. The parameters were analyzed 30 min or 24 h after GLY administration. GLY decreased Tau phosphorylation in striatum and cerebral cortex 30 min and 24 h after its administration. On the other hand, synaptophysin levels were decreased in striatum at 30 min and in cerebral cortex at 24 h after GLY injection. GLY also decreased the phosphorylation of p38, ERK1/2, and JNK 30 min after its administration in both brain structures. Moreover, GLY-induced decrease of p38 phosphorylation in striatum was attenuated by N-methyl-D-aspartate receptor antagonist MK-801. In contrast, synuclein, NF-κB, iκB, inducible nitric oxide synthase and nitrotyrosine content, and GFAP immunostaining were not altered by GLY infusion. It may be presumed that the decreased phosphorylation of MAPK associated with alterations of markers of neuronal injury induced by GLY may contribute to the neurological dysfunction observed in NKH.

Diagnostic tools of metabolic and structural brain disturbances in neonatal non-ketotic hyperglycinemia

Non-ketotic hyperglycinemia (NKH) is a rare autosomal recessive disorder of glycine metabolism. We report a newborn case of NKH and discuss the effects of this rare disease on brain metabolism and structure together with amplitude-integrated electroencephalography, cranial magnetic resonance and magnetic resonance spectroscopy findings which are very rarely reported together so far.

MR imaging workup of inborn errors of metabolism of early postnatal onset

Immediate or early postnatal onset forms of neurometabolic disorders represent a clinically important subgroup because these often present as a life-threatening episode of metabolic decompensation shortly after birth. This article focuses on this group of diseases, often referred to as "devastating neurometabolic diseases" of the newborn. Awareness of the most common entities and their clinical, biochemical, and diagnostic imaging manifestations is important because if undiagnosed and untreated, the diseases may have catastrophic consequences. Although formal diagnosis relies on laboratory tests, diagnostic imaging is often pivotal in both reaching the correct diagnosis and/or orienting further targeted investigative efforts.

Valproate-induced worsening of seizures: clue to underlying diagnosis

The use of valproate sodium as an antiepileptic is not advised in children with an undiagnosed metabolic condition because of the increased risk of hepatotoxicity and encephalopathy. Here the authors describe a 2.5-year-old girl with a history of developmental delay, failure to thrive, and a seizure disorder whose seizures worsened after the introduction of valproate sodium. This led to a search for an underlying metabolic disorder, and after extensive investigations, a diagnosis of nonketotic hyperglycinemia was made. In this report, the authors discuss the metabolic conditions that can be worsened by valproate sodium. Valproate sodium interferes with the glycine cleavage enzyme synthesis in the mitochondria, hence increasing glycine levels. The increased glycine levels are responsible for worsening of the underlying metabolic condition and increased seizure frequency.