Department of Neonatal Services, Royal Women's Hospital, Parkville, Victoria, Australia.
Pediatr Neurol. 2010 Mar;42(3):219-22. doi: 10.1016/j.pediatrneurol.2009.10.013.
Nonketotic hyperglycinemia is an inborn error of glycine metabolism leading to the accumulation of glycine in the brain. The neonatal form presents in the first days after birth with encephalopathy, seizures. and characteristic "hiccups." Rapid progression can lead to intractable seizures, coma, and respiratory failure. The outcome is invariably poor, and many die before age 1 year. The diagnosis of nonketotic hyperglycinemia is traditionally based on the finding of a raised cerebrospinal fluid-to-plasma-glycine ratio. An elevated glycine peak, using long echo time proton magnetic resonance spectroscopy, is also specific to nonketotic hyperglycinemia. The presence of blood in a cerebrospinal fluid sample is known to render the glycine level uninterpretable. However, there have been no reports of intracerebral blood confounding the cerebral glycine detected on long echo time proton magnetic resonance spectroscopy. We report on an infant who presented with neonatal encephalopathy and imaging findings consistent with hypoxic-ischemic encephalopathy, as well as intracerebral hemorrhage and an abnormal glycine peak on spectroscopy. The source of the abnormal glycine on long echo time proton magnetic resonance spectroscopy was intracerebral blood, highlighting an important confounder in the interpretation of long echo time proton magnetic resonance spectroscopy in suspected nonketotic hyperglycinemia.
非酮症高甘氨酸血症是一种甘氨酸代谢的先天性错误，导致甘氨酸在大脑中积累。新生儿型在出生后最初几天出现脑病、癫痫发作和特征性“打嗝”。快速进展可导致难治性癫痫发作、昏迷和呼吸衰竭。结果始终不佳，许多患者在 1 岁前死亡。非酮症高甘氨酸血症的诊断传统上基于脑脊液与血浆甘氨酸比值升高的发现。使用长回波时间质子磁共振波谱也可特异性检测到升高的甘氨酸峰。众所周知，脑脊液中存在血液会使甘氨酸水平无法解释。然而，还没有报道颅内血液会干扰长回波时间质子磁共振波谱检测到的脑内甘氨酸。我们报告了一例婴儿，其表现为新生儿脑病，影像学表现与缺氧缺血性脑病一致，以及颅内出血和光谱上异常的甘氨酸峰。长回波时间质子磁共振波谱上异常甘氨酸的来源是颅内血液，这突出了在疑似非酮症高甘氨酸血症中解释长回波时间质子磁共振波谱时的一个重要混杂因素。
