Mucopolysaccharidosis type II (MPS II - Hunter syndrome) is an X-linked lysosomal storage disorder caused by a deficiency in the enzyme iduronate-2 sulfatase (I2S), leading to the accumulation of the glycosaminoglycans, affecting multiple organs and systems. Enzyme replacement therapy does not cross the blood brain barrier, limiting results in neurological forms of the disease. Another option of treatment for severe MPS, hematopoietic stem cell transplantation (HSCT) has become the treatment of choice for the severe form of MPS type I, since it can preserve neurocognition when performed early in the course of the disease. To date, only few studies have examined the long-term outcomes of HSCT in patients with MPS II. We describe the seven-year follow-up of a prenatally diagnosed MPS II boy with positive family history of severe MPS form, submitted to HSCT with umbilical cord blood cells at 70 days of age. Engraftment after 30 days revealed mixed chimerism with 79% donor cells; after 7 years engraftment remains at 80%. I2S activity 30 days post-transplant was low in plasma and normal in leukocytes and the same pattern is observed to date. At age 7 years growth charts are normal and he is very healthy, although mild signs of dysostosis multiplex are present, as well as hearing loss. The neuropsychological evaluation (Wechsler Intelligence Scale for Children - Fourth Edition - WISC-IV), disclosed an IQ of 47. Despite this low measured IQ, the patient continues to show improvements in cognitive, language and motor skills, being quite functional. We believe that HSCT is a therapeutic option for MPS II patients with the severe phenotype, as it could preserve neurocognition or even halt neurodegeneration, provided strict selection criteria are followed.
Introduction: Mucopolysaccharidoses (MPS) can lead to cervical spinal cord compression (SCC). Diagnostic scores for SCC in MPS use the obliteration of the passage of cerebrospinal fluid in the anterior and posterior spinal cord in the sagittal section of magnetic resonance imaging (MRI). The spinal cord occupation ratio (SCOR) published, by Nouri et al (2018), establishes the spinal cord filling index for the spinal cord, identifying disproportionate spinal cord occupation in the canal. When evaluating congenital canal stenosis, the risk of spinal cord injury has been considered increased when the SCOR is ≥70% in the median sagittal plane or ≥ 80% in the axial plane. Although these values have not been validated for MPS populations, they could be useful. Objective: To verify the SCOR in MPS patients with diagnosis of cervical SCC comparing the SCOR with other markers proposed in the existing MPS SCC scores, such as the extent of gliosis, clinical impact and the SCC assessment as represented by the obliteration of CSF flow. Methods: We reviewed imaging tests of the cervical spine from MPS patients with previously confirmed SCC, using the SCOR measure in the median sagittal plane, evaluation of the presence and extent of spinal gliosis on MRI, evaluation of the clinical impact using a clinical score and evaluation of the images for the obliteration of cerebral spinal fluid (CSF) flow. Results: Thirty-one MRI of 24 different patients were included. The average SCOR was 87.1%. This was lower (81.6%) in patients without gliosis, when compared to those with focal (90.5%) and extensive (97%) gliosis. The only patient with gliosis associated with a lacunar lesion, resulting from an acute compressive injury, had a 68% SCOR, due to the atrophic spinal cord injury. As expected, SCOR was higher in patients with total or partial CSF obliteration, but one among the 3 patients without CSF flow obliteration, with a 76% SCOR, had already developed focal gliosis and mild clinical abnormalities. Patients with more extensive gliosis had higher clinical scores. Four patients had more than one imaging scan evaluated. SCOR upward trend showed an annual average increase of 3.8%. Discussion & Conclusions: The use of SCOR allows the diagnosis of cervical spinal canal stenosis in an objective way. It is possible that the cut-off values used by Nouri et al in patients with congenital stenosis could be useful to diagnose cervical stenosis in MPS patients, preceding the finding of CSF flow obstruction, presence of gliosis or clinical abnormalities. Furthermore, the use of SCOR may assist in the longitudinal evaluation of disease progression. Better follow-up and timely diagnosis allows for scheduling of surgery at the best clinical moment, minimizing complications.
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