Abstract
Introduction:
Chiari II malformation is a complex congenital hindbrain anomaly commonly associated with myelomeningocele and hydrocephalus. Additional cranial and spinal developmental abnormalities may coexist, producing a wide spectrum of neuraxial malformations. We present an unusual case characterized by severe Chiari II malformation associated with type I split cord malformation and diffuse cervicothoracic spinal cord volume loss.
Case Description:
An 11-year-old girl presented with urinary incontinence and inability to walk. Magnetic resonance imaging demonstrated a small posterior fossa, tectal beaking, low-lying torcular herophili, marked cerebellar tonsillar descent to the C4 level, and pronounced medullary kinking. Associated findings included corpus callosal dysplasia, absence of the septum pellucidum, thoracolumbar myelomeningocele, tethered cord, scoliosis, type I split cord malformation with an osseous septum, and a relatively small syringohydromyelic cavity. Diffuse cervicothoracic spinal cord volume loss appeared disproportionate to the size of the syrinx. Right hydronephrosis and nonvisualization of the left kidney were also identified.
Discussion:
This case demonstrates a complex dysraphic phenotype combining severe Chiari II malformation, split cord malformation, tethered cord, and marked cervicothoracic spinal cord volume loss. Although the underlying mechanism cannot be established from a single examination, both congenital developmental abnormalities and longstanding secondary mechanical factors may have contributed to the observed spinal cord changes.

Key words: Chiari II malformation; split cord malformation; spinal cord volume loss; medullary kinking; syringohydromyelia; tethered cord