hemivertebra

Hemivertebra is a type of vertebral anomaly and results from a lack of formation of one half of a vertebral body. It is a common cause of congenital scoliosis.

Epidemiology

The estimated incidence is at ~0.3 per 1000 live births .

Pathology

It falls under the spectrum of segmentation anomalies and can involve one or multiple levels.

A hemivertebra acts as a wedge within the vertebral column, resulting in curvature away from the side on which it is present.

Associations

Recognized associations are many and include:

Classification

A hemivertebra can be classified according to many types which include:

Attachment
  • fully segmental (free)
    • not attached to either vertebra above or below
    • most concerning
  • semi segmental: half segment is fused with vertebra above or below with no intervening intervertebral disc
  • non-segmental
    • not separated from (i.e. connected to) either level above or below
    • causes less of a concern
  • incarcerated
    • joined by pedicles to levels above and below
    • causes less of a concern
Orientation 

Radiographic features

Antenatal ultrasound

A hemivertebra may be seen as an asymmetrical vertebral body on sagittal or coronal scanning, while on axial scanning, a focal defect may be seen on either side of the vertebral column .

Plain radiograph / CT

Usually directly outlines the bony anomaly and is often seen as a wedge-shaped vertebral body.

Treatment and prognosis

The prognosis can be variable dependent on the type of segmentation anomaly, from being progressive to a non-progressive deformity. The strongest negative impact is when a hemivertebra occurs at the lumbosacral level .

Differential diagnosis

Consider