Hemivertebra is a type of vertebral anomaly that results from a lack of formation of one half of a vertebral body. It is a common cause of congenital scoliosis.
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Epidemiology
The estimated incidence is at ~0.3 per 1000 live births 2.
Associations
Recognized associations are many and include:
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.
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
dorsal hemivertebra: classically results in kyphosis
lateral hemivertebra: classically results in scoliosis
ventral hemivertebra (extremely rare): results in lordosis
Radiographic features
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 5.
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 dependant 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 7.
Differential diagnosis
Consider
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