Sagittal profiles of the spine in scoliosis associated with an Arnold-Chiari malformation with or without syringomyelia.

The sagittal spine of children with Arnold-Chiari I malformation with or without syringomyelia and associated scoliosis (ACS) has been poorly studied. A retrospective review of scoliosis secondary to ACS from three centers was undertaken. Sagittal and coronal plane variables were measured from standing radiographs. There were 30 ACS children (19 girls, 11 boys) with an average curve of 50 +/- 20 degrees and age of 11.2 +/- 3.2 years. Syringomyelia was present in 26 (87%). The scoliosis was thoracic in 25, thoracolumbar in 3 and lumbar in 2; 18 curves were right and 12 were left. A positive correlation was noted between cervical lordosis (CL) and thoracic kyphosis (TK). The 30 children with ACS scoliosis were compared with 26 children with adolescent idiopathic scoliosis (AID). The ACS group had more left curves (40% vs. 0%, P = 0.0002), more boys (37% vs. 8%, P = 0.01), and was younger (11.3 +/- 3.7 years vs. 14.2 +/- 1.8 years, P = 0.004). TK and CL were increased in ACS (TK: 40 +/- 13 degrees vs. 30 +/- 13 degrees, P = 0.005; CL: 16 +/- 21 degrees vs. -5 +/- 12 degrees, P < 0.0001). The ACS and AID groups were subdivided by CL >0 degrees and <0 degrees. In the ACS group, 19% (5 of 21) had CL <0 degrees, in the AID group 77% (20 of 26) had CL <0 degrees (P = 0.0001). When cervical lordosis is >0 degrees or thoracic kyphosis is >40 degrees (Cobb method), the clinician should strongly suspect the presence of an Arnold-Chiari I malformation with or without syringomyelia.