Retrocerebellar Anachroid Cyst causing/worsening toe walking?

My 13 year old son started toe walking about 15 months ago. We have done 4 months of physical therapy, a neurologist visit, x rays, CT scan of his spine and just a few days ago a MRI of his brain. We discovered a Retrocerebellar arachnoid cyst measuring 3.7 x 1.7 x 1.9 cm associated with minimal surrounding local mass effect. He is scheduled to have tendon lengthening surgery in 16 days. I of course don't want him to undergo surgery if the cause of the toe walking, potentially this cyst, is not treated first. I am waiting for calls from his neurologist and orthopedic surgeon. He recently started having migraines with visual disturbances and tingling/numbness in his hands. He is also always tired and we are waiting for a sleep study. He has terrible balance and falls often. He has no stamina for walking or standing which has gotten worse over time. I'm wondering if these are all connected to the cyst?