Chiari malformation associated with vitamin D-resistant rickets: Case report

INTRODUCTION: Craniocervical junction abnormalities have a wide range of origins, from rare congenital conditions to common arthritic processes. We present a rare case of foramen magnum stenosis with Chiari I malformation and associated syringomyelia, which resulted from vitamin D-resistant hypophosphatemic rickets. METHODS: This 12-year-old male patient had a history of vitamin D-resistant rickets, and he presented with a 1-year history of increasing upper extremity weakness and sharp pain in the left shoulder and arm. Magnetic resonance imaging of his spine showed a large syrinx from C2 to T7, with significant foramen magnum stenosis and a Chiari Type I malformation. RESULTS: The patient underwent craniocervical decompression, consisting of a suboccipital craniectomy and C1 laminectomy with duraplasty. A pathological evaluation of bone yielded no diagnostic abnormality. Postoperative magnetic resonance imaging showed significant reduction in the diameter of the cervical thoracic spinal cord syrinx 3 months after surgery. The patient's pain and sensation in his left arm had not improved by that time, and he still had some diffuse weakness in his arms. Two years later, he had persistent left shoulder girdle pain and his syrinx had collapsed, except for a small residual from T2 to T6. DISCUSSION AND CONCLUSION: The bone disease of vitamin D-resistant rickets can involve the base of the cranium, precipitating the development of the Chiari malformation and associated syringomyelia. We review the association between rickets and Chiari malformation and discuss the management of these patients.