Study design: A case series of patients with hemimetameric shift.
Objectives: To describe the radiographic and physical findings as well as treatment provided to a subset of patients with congenital scoliosis.
Summary of background data: Hemimetameric segmental displacement, or hemimetameric shift, is a clinical entity defined by two contralateral hemivertebrae separated by at least one normal vertebra. Although the entity is briefly described in textbooks, there are no published series to date.
Methods: From 1974 to 2000, 186 cases of congenital scoliosis were identified from two referral centers. Of these, 27 cases (15%) of hemimetameric shift were identified. Medical records and radiographs were reviewed, as well as magnetic resonance imaging when available.
Results: There were an average of 2.9 hemivertebrae per patient (range 2-6) with the following distribution: T1-T6 (29), T7-T11 (28), T12-L1 (10), L2-L4 (11), and L5 (1). The average curve magnitude at presentation was 28 degrees (range 9 degrees -55 degrees). Nine patients required surgery-most commonly with involvement of the thoracolumbar or lumbosacral junction. Eleven patients also had associated anomalies to include Klippel-Feil syndrome (3), Goldenhar syndrome (2), imperforate anus (2), tracheoesophageal fistula (2), and a single kidney (2). There was only one patient who had an abnormal magnetic resonance imaging (1 out of 17; 6%).
Conclusions: Hemimetameric shift is a common finding in congenital scoliosis. Hemivertebrae are most commonly found in the thoracic spine; however, surgical intervention is most commonly observed when the caudal hemivertebrae is located from the thoracolumbar to lumbosacral junction. The incidence of abnormal magnetic resonance imaging findings is low (6%).