Hemimetameric segmental shift: a case series and review.

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%).