Case of simultaneous Chiari 1.5 malformation and syringobulbia.

Chiari 1.5 malformation (C1.5) is a rare condition characterized by caudal descent of the brain stem, together with descent of the cerebellar tonsils characteristic of Chiari I malformation (CIM). Syringobulbia (SB) is rarely associated with CIM and to date has not been reported in a patient with C1.5. An adolescent female presented with Valsalva-induced headaches and a left abducens nerve palsy. Imaging revealed C1.5 and a huge syringomyelia extending cranially into the herniated medulla oblongata as syringobulbia. Simultaneous cases of C1.5 and syringomyelia (SM) have been described, but, to our knowledge, this is the first reported case of simultaneous C1.5 and SB. As SB can have life altering consequences, the clinician should keep this possibility in their differential diagnosis.