J Neurosurg 77:69-77, 1992 Scoliosis in pediatric Chiari malformations without myelodysplasia MICttAEI. G. MUHONEN, M.D., ARNOLD H. MENEZES, M.D., PAUL D. SAWIN, M.D., AND STUART L. ~/EINS'I'EIN, M.D. Division Of Neurosurgeo, and Department ~f Orthopedic Surgery, The University of lowa College of Medicine, Iowa City. Iowa ~" A prospective study was undertaken in 1985 to better understand how the surgical manipulation of hind- brain herniation affected abnormal spinal curvature. Eleven patients under 16 years of age with Chiari mal- formation (not associated with myelodysplasia) and scoliosis of at least 15 ~were studied. The mean curve an- gle at the time of original treatment was 29~ , with the convexity to the right in seven patients. The curvature was rapidly progressing in four patients. The most common presenting signs were myelopathy and weakness. Investigative procedures included spine radiographs with the patient standing and magnetic resonance (MR) imaging of the brain, spinal cord, and craniovertebral junction. Eight children had associated hydrosyringo- myelia. Surgical intervention consisted of a dorsal posterior fossa decompression in all patients and a transoral ventral decompression of the cervicomedullary junction in five. All patients were followed at 3, 6, and 12 months, and at yearly intervals thereafter with clinical evaluations, spine radiographs in the standing position, and postoperative MR imaging. The mean follow-up period was 35 months. The scoliosis improved in eight patients, stabilized in one, and progressed in two. Only one child required postoperative spinal fusion and instrumentation for progression of scoliosis. Hematomyelia or hematobulbia was associated with persistent scoliosis in two patients. The presence of hydrosyringomyelia and bone erosion did not preclude curve im- provement. All patients under 10 years of age had resolution of their scoliosis, despite preoperative curves of more than 40 ~ . These findings emphasize the importance of early surgical intervention, with the restoration of normal cerebrospinal fluid dynamics at the craniovertebral junction in children with symptomatic Chiari mal- formations. KEy WO~DS 9 Chiari malformation 9 hematomyelia 9 hydrosyringomyelia scoliosis children T HE association between pediatric Chiari malfor- mations and the development of scoliosis has been well documented in the spina bifida pop- ulation) v-~9~3L34'36-38 Scoliosis occurs in 50% to 70% of these patients, and is therefore a common cause of functional decline. 36 The scoliosis is thought to be sec- ondary to a generalized paresis of the trunk muscula- ture, to congenital structural changes in the vertebrae, and to the effects of abnormal intramedullary pressure with interference of the postural tonic reflexes. 34 The association between scoliosis and hindbrain herniation without myelodysplasia has not previously been ana- lyzed and followed after surgical therapy of the Chiari malformation. A prospective study was undertaken in the pediatric population beginning in 1985 in an attempt to better understand the relationship between the development of scoliosis and Chiari malformations not associated with myelodysplasia. Patients with myelomeningocele, tethered spinal cord, lipoma, or diastematomyelia were excluded. Eleven children were assessed; they were all aged 2 to 15 years, had scoliosis of at least 15", and had undergone surgical intervention for symptomatic Chiari malformations without myelodysplasia between the years 1985 and 1989. The purpose of this study was to analyze the progression of the scoliosis before and after surgical manipulation of the craniovertebral junction compression. The patients were grouped to allow com- parison of those who experienced postoperative reso- lution of their scoliosis with those who had scoliosis that worsened or stabilized but did not improve despite surgical intervention. This group analysis allowed us to study the relationship among age, duration of symp- toms, associated signs, and progression of the scoliosis. J. Neurosurg. / Volume 77/Ju(v, 1992 69