Hemimetameric shift in spina bifida: three case reports.

PURPOSE: Hemivertebrae is the most frequent reason of congenital scoliosis, and hemimetameric shift is a finding, which is characterized by two hemivertebraes located contralateral, with at least one normal vertebra between them. Embryologically, hemivertebrae is caused by delay in somite movements and as a result, a total vertebral shift occurs because of mismatches in the following segments. Hemimetameric shift accompanying spina bifida is described as extremely rare. There are only two case series of hemimetameric shift in literature but no spina bifida patient was reported in these series.

METHODS: We report three cases of hemimetameric shift with spina bifida with their detailed clinical and radiological evaluations.

RESULTS: Case 1 is a 3-year-old congenital scoliosis patient with tethered cord. She has mild scoliosis with a very demonstrative hemimetameric shift. Case 3 is an infant with multiple-level hemivertebrae anomalies and hemimetameric shift who had myelomeningocele closure and ventriculoperitoneal shunt installation neonatally. Case 3 is a 9-year-old male who had operated for myelomeningocele in the neonatal period. He had evident scoliosis with cervicothoracic hemimetameric shift and he is the only patient we operated for prominent scoliosis.

CONCLUSIONS: The present classification of hemimetameric shift was described by Kawakami et al. in 2009. It is based on development of anterior and posterior hemivertebrae segments but we think it is not suitable for patients with posterior fusion defects such as spina bifida patients. Spina bifida patients with scoliosis and hemimetameric shift are a rare but important patient group to evaluate in terms of understanding scoliosis patients with neural tube defects.