The pathophysiology of syrinx development is controversial. The authors rep
ort on a patient with progressive cervical myelopathy and a Chiari I malfor
mation in whom spinal cord swelling preceded, by a few months, the developm
ent of a syrinx in the same location. The patient underwent a craniocervica
l decompressive procedure and duraplasty, and complete resolution of cord s
welling and syringomyelia was achieved. This report is consistent with the
theory that patients with Chiari I malformation have increased transmural f
low of cerebrospinal fluid, which causes spinal cord swelling that later co
alesces into a syrinx. The pathophysiology of syrinx development from spina
l cord edema and the success of surgical decompressive treatments that do n
ot invade the central nervous system support the prompt treatment of patien
ts with spinal cord edema who are at risk, for the development of a syrinx.