LAUSR

Radiol Bras. 2017 Jan/Fev;50(1):62–68 64 http://dx.doi.org/10.1590/0100-3984.2015.0159 The symptoms of SMD vary depending on the age of the patients, the principal symptoms being as follows: limited postnatal growth; rhizomelic shortening of the limbs in early childhood evolving to shortening of the trunk by the age of 10 years; thoracic hypoplasia, which causes respiratory problems in the neonatal period and increases susceptibility to respiratory tract infection; scoliosis with dorsal kyphosis; abnormalities of the metaphyses and pelvis; odontoid hypoplasia; and valgus of the knees and claudication, the latter typically being the first sign of the disease. There might be little or no ossification of the cervical vertebrae, leading to cervical instability and swan neck deformity. A review of the literature revealed that there are currently 10 recognized subtypes of SMD. However, there in no consensus in the medical literature regarding those subtypes, because they are based characteristics that are minimally different. Some subtypes are based on reports of only one case, and others can be diagnosed only after years of follow-up, which is difficult. For example, the longest follow-up period in a report of Sedaghatian-type SMD was 161 days. Therefore, there is no acceptable standard for subclassifying the disease.