What Causes Dizziness Along With Numbness In Lower Legs?

My sister was daignosed with vertigo in 2013 and then Arnold chiari malformation with holocord syrinx. She undergone surgery named-posterior fossa craniectomy with coagulation right tonsil with duraplasty by doctor Mazhar hussain in Lucknow. For last two years she is taking following medicines 1.Vertin 2.Clonafit beta Still she feels weak, heavy diziness during walk or travel and collapses to ground. There is still numbness n loss of sensation along with pain esp in lower part of legs. There is no alternative therapy like acupuncture or physiotherapy just she does minor meditation n yoga. Please just wayout. We have been through deep crisis since last two years.