Scoliosis can be broadly broken down into one of 4 types:
Idiopathic: meaning there
is no known etiology
tissue disorders (Marfan’s, Ehlers-Danlos), trisomy 21, Prader-Willi, Retts
syndrome, Beale’s syndrome, muscular dystrophies (e.g. Duchenne’s),
osteochondrodystrophy (dwarfism), neurofibromatosis, Noonan syndrome,
VATER/VACTERL, Angelman, Osteogenesis Imperfecta,
Neuromuscular: such as
cerebral palsy, spina bifida, muscular dystrophies (e.g. Duchenne’s), paralytic
conditions (e.g. polio, spinal cord injury), spinal muscle atrophy,
Of these, the idiopathic category is the diagnosis of
exclusion, meaning patients can be given this diagnosis if there is no known
cause of the scoliosis, there are no known significant medical comorbidities (see
syndromic and neuromuscular categories, above) or atypical bony maldevelopment
of the vertebra (congenital).
The categories of syndromic and neuromuscular (#2 and #3,
above) are rather nebulous and there is some disagreement where to place
certain diagnoses, such as muscular dystrophies.
The last category, congenital, is the one which is solely
based on abnormal vertebral development.
So it is possible to have a patients which has congenital scoliosis, but
also has a syndromic (e.g. VATER/VACTERL) or a neuromuscular diagnosis (e.g.
spina bifida or myelomeningocoele) at the same time.
Within the diagnostic category of congenital scoliosis there
are three main sub-categories:
Failure of formation
(meaning there are parts of the vertebra which never formed)
Failure of segmentation
(meaning the parts of the vertebra did not separate as they were
Mixed type, which is a
combination of the two above categories (failure of formation and failure of segmentation).
This is a classic figure from the work of Dr. McMaster which
nicely demonstrates Defects of Segmentation and Defects of Formation.
More about congenital scoliosis next week……