Research

Introduction: Neurological deficits are a known complication of congenital kyphosis. The role of the type of anomaly is documented, but the role of canal diameter is not documented.

Purpose: To investigate the relationship between the anomaly and canal size in congenital kyphosis and the occurrence of neurological deficits.

Methods: A retrospective chart and radiographic review was performed on all cases of congenital kyphosis seen. The canal diameter narrowing was expressed as the percent of the adjacent normal level, where a is the anterior posterior (AP) size of the canal at the level above the apex of the kyphosis and b is the AP size of the canal at the apex of the kyphosis.

Results: Twelve of the 61 cases had neurological loss due to the kyphosis, ranging from reflex changes to paraparesis. The Type 1 kyphosis was divided into three subcategories – complete vertebral agenesis, a rudimentary vertebra (hypogenesis) and a wedged vertebra (hypoplasia).

N Neuro-Loss Kyphosis Stenosis
Type I. Agenesis 6 4 (67%) 59° 53%
Type I. Hypogenesis 7 3 (43%) 47° 37%
Type I. Hypoplasia 13 3 (23%) 41° 13%
Type II 27 0 46° 2%
Type III 8 2 (25%) 58° 20%

The average stenosis increased sharply if the kyphosis was >50°, with kyphosis of 60° being accompanied by canal narrowing of 50%. In addition the number of cases of neurological loss increased if the kyphosis was >60°.

Summary: The occurrence of neurological loss in congenital kyphosis is related to the type of anomaly, the degree of kyphosis and the canal stenosis at the apex of the deformity.