Mosaic Turner syndrome with improved Chiari type 1 malformation after growth hormone therapy: A case report.

We described a three-year-old girl whose Chiari type 1 malformation associated with mosaic Turner syndrome disappeared after GH therapy. She was diagnosed with mosaic Turner syndrome at the age of 1 yr and 7 mo by a chromosomal analysis (G-band) for short stature and was treated with GH. Sagittal T1-weighted magnetic resonance imaging (MRI) performed before the start of GH demonstrated herniation of the cerebellar tonsils 7 mm below the foramen magnum into the cervical spinal cord. After the initiation of GH therapy, the growth in height was favorable and improved from 70.6 cm (-3.5 SD) to 92 cm (-1.5 SD) in 2 yr. An MRI examination 19 mo later showed the disappearance of Chiari type 1 malformation. GH therapy either exacerbates or ameliorates Chiari type 1 malformations associated with GH deficiency (GHD). Since Turner syndrome uses more GH than GHD, careful follow-up is required if the disease is associated with Chiari type 1 malformation.