Spinal Deformity Following Haemopoietic Stem Cell Transplant in Mucopolysaccharidosis Type 1(Huler Syndrome): Early Results

Summary: The thoracolumbar gibbus in 19 patients with Hurler's syndrome, mean age 10 years, and at least two years post-stem cell transplant at mean age 0.9 years, progressed by more than 20 degrees in 4. 3 underwent surgery with disappointing results in 2. Scoliosis has occurred in 2, one of infantile onset and one juvenile. The usual rule of paediatric spinal deformity may not apply to this group.

Background: A thoracolumbar gibbus is pathognomonic of the mucopolysaccharidoses, the most common of which is Hurlers syndrome (MPS I). Untreated patients suffer neurological and physical degeneration until death within the first decade. Haemopoietic stem cell transplantation has improved the prognosis, although skeletal dysplasia remains a problem. This study reviews the progress of spinal deformity in Hurler's syndrome after HSCT.

Patients & Methods: Nineteen patients (11 male and 8 female, age 9.4±4.6 years, range 2.5 - 18.4), >2 years post-transplant, (at age 0.9 years ± 0.47, (range 0.27 - 1.8yrs) were investigated. HLA identical donor sources included family members, unrelated adults or cord blood.

Outcome Measures: Serial measurements of the thoracolumbar spines on radiograph using the standard adaptation of the Cobb method. The gibbus itself and the thoracic segment above it were documented.

Results: All showed the characteristic thoracolumbar gibbus. Three patients underwent surgery to correct or maintain this, which was unsuccessful in two; the third is stable, but still young. Two patients have developed scoliosis: one in the juvenile period and one in infancy. Four unoperated patients are postpubertal: three girls have passed menarche without progression of the gibbus; one male, aged 18.4 years, had significant progression of his gibbus at puberty, is now stable, untreated and cosmetically acceptable. The remainder are still pre-pubertal but their deformities are not currently progressive.

Discussion: These interim results suggest that deformity persists, may increase during growth but does not always cause problems. The considerations which govern other spinal deformities of childhood may not apply. The more recent availability of recombinant human _-L- iduronidase adds further interest to the management of these patients and warrants cautious expectation.

Conclusions: Patients with MPS I have complex multisystem disorders, independent of their orthopaedic status and more data on natural history and outcome is needed.