Two differential cavities in syringomyelia of pediatric Chiari I malformation presenting with unilateral foot drop.

In contrast to a centrally enlarged syrinx that is often asymptomatic, a paracentrally extended syrinx usually produces segmental signs related to its levels. Thus, the left foot drop in this case would have been due to the ipsilaterally deviated lower cavity that was distinguished from the central upper cavity by 3D-CISS imaging. Further reports using this imaging technique are needed to verify the hypothetic pathology.