engleski

Magnetic resonance findings in a neonate with nonketotic hyperglycinemia : case report

This report presents brain imaging and spectroscopy data in a 7‐day‐old neonate with a later confirmed classical neonatal form of nonketotic hyperglycinemia (NKH), an autosomal recessive metabolic disorder characterized by accumulation of glycine in cerebrospinal fluid, plasma and urine. Her CSF glycine was 235 μmol/L, and plasma glycine 875 μmol /L, giving the ratio of 0.27 (normal <0.05). We detailed the changes seen on conventional magnetic resonance imaging (MRI), diffusion weighted imaging (DWI) and magnetic resonance spectroscopy (MRS). At that time‐point her daily protein intake was 1.7 g/kg of b.w. She received no therapy that could influence spectroscopy findings. Changes on MRI, such as increased T2 signal intensity, diffusion parameters showing restricted diffusion and an additional peak on MRS, were previously described in older children. To our knowledge, ours is the only report of such complete analysis of magnetic resonance imaging parameters in a patient with NKH at neonatal age. Conventional T1‐weighted imaging of our patient showed a regular organization of gyri and sulci, with a slightly pronounced diffuse reduction of the telencephalic gray and white matter, with a reduction of the midsagittal area of the corpus callosum. Hypoplasia of the caudal vermis was found, as well. On T2‐weighted images (TR=6000 ; TE=91 ; ETL=17) high‐signal lesions were found in the posterior limbs of internal capsules, tegmentum of the brain stem and in middle and inferior cerebellar peduncles. The same regions had increased signal intensity on diffusion weighted imaging (TR=7600 ; TE=111 ; b=1000 s/mm2) combined with low ADC values, indicating restricted diffusion. However, normal fractional anisotropy was present in these areas, indicating preserved axonal integrity. Single‐voxel proton spectroscopy (TE=2000 ms ; TE=135 ms) showed a clear peak at +3, 6 ppm, corresponding to glycine, in the frontal and parieto‐occipital white matter, the basal ganglia and the cerebellar hemisphere. MR brain imaging shows clear pathological changes in NKH children. The findings of a 7‐day‐old neonate are consistent with the previous reports in older children with NKH, confirming that the pathological changes typical for NKH can be seen in the first postnatal week. The need of a detailed clinical work‐up and an early MRI examination in these children is emphasized by the existence of a classical and transient variant of the disease, with drastically different outcomes, where MR imaging might aid in distinguishing the two forms and in giving the prognosis.

nonketotic hyperglycinemia; magnetic resonance; two forms

nije evidentirano