Does body mass index increase risk of hemorrhagic stroke?

✍ Scribed by Ivy Shiue

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 57 KB
• Volume: 68
• Category: Article
• ISSN: 0364-5134
• DOI: 10.1002/ana.22042

✦ Synopsis

We read the article of Vaurs-Barrie `re et al, 1 reporting on a Pelizaeus-Merzbacher-like phenotype in male MCT8 mutated patients, with interest. We share the experience that in infancy, magnetic resonance imaging (MRI) shows a severe lack of myelin in these patients and that the MRI improves over time. This has also been confirmed by other groups. 2 We would, however, like to object to the word "hypomyelination" in this context, because it causes confusion.

MRI is an excellent tool to document myelination of the brain at a certain moment and to follow its progress over time in infants and children. If MRI shows less myelin than normal, the first question should always be whether myelination is delayed or whether the deficit is permanent. Hypomyelination and delayed myelination have a similar appearance on a single MRI, especially if done at an early age, but sequential studies can distinguish between them, showing increasing myelin content in delayed myelination, but an unchanged lack of myelin in hypomyelination. Normal myelination occurs mainly in the first 2 years of life. Within the first year of life, there is so little myelin in normal infants that it is not possible to diagnose permanent hypomyelination. The MRI definition for permanent hypomyelination is an unchanged pattern of deficient myelination on 2 MRIs at least 6 months apart in a child older than 1 year. 3 The differentiation between delayed myelination and permanent hypomyelination is important. Delayed myelination is a rather nonspecific feature observed in most children with a delayed development of any cause. Permanent hypomyelination comes with a specific differential diagnosis. 3 MCT8 mutations are not on the list. A correct MRI diagnosis prevents the confusion.