Occasionally, a posterior fossa arachnoid
cyst can induce compression of the spinal cord and cause
syringomyelia. Here, we report the case of a 29-year-old man with both progressive
shoulder pain and gait disturbance, who was found to have a huge retrocerebellar arachnoid
cyst associated with
syringomyelia. Accordingly, posterior fossa
decompression and arachnoid
cyst excision were performed. Post-operative MRI showed a marked reduction in the size of the arachnoid
cyst and
syringomyelia. The patient's symptoms were clearly improved compared to before surgery. In our view, treatment in such patients should focus on decompressing the foramen magnum and include the removal of the coexistent arachnoid
cyst walls, which appear to be the crucial factor in development of
syringomyelia. In this report, we discuss the pathogenic mechanisms underlying
syringomyelia-associated retrocerebellar arachnoid
cyst and review the current literature on this topic.