A standard MRI - sagittal (side) view is used to help identify Chiari Malformation. This will show a herniation of the cerebellar tonsils through the skull into the spinal canal. A cine (stands for cinema) MRI helps to determine the amount of cerebrospinal fluid (CSF) flow. A cine MRI can be useful in cases of borderline/Chiari 0 malformations or if decompression surgery is needed.
By the sounds of your symptoms it sounds like decompression surgery is needed. A head or neck injury can worsen existing Chiari Malformation and in some cases cause it. Two links below from the Chiari Malformation community that are interesting.
http://www.medhelp.org/posts/Chiari-Malformation/Unofficial-Symptoms-List-/show/1192372
http://www.medhelp.org/posts/Chiari-Malformation/4-5mm-symptoms/show/1270893
Excerpt from the Mayo Clinic on some of the many possible symptoms of Chiari Malformation...
"Chiari malformation type I
Headaches, often severe, are the classic symptom of Chiari malformation. They're typically precipitated with sudden coughing, sneezing or straining. People with Chiari malformation type I can also experience:
Neck pain (running down the shoulders at times)
Unsteady gait (problems with balance)
Poor hand coordination (fine motor skills)
Numbness and tingling of the hands and feet
Dizziness
Difficulty swallowing (sometimes accompanied by gagging, choking and vomiting)
Vision problems (blurred or double vision)
Slurred speech
Less often, people with Chiari malformation may experience:
Ringing or buzzing in the ears (tinnitus)
Poor bladder control
Chest pain, in a band-like pattern around the chest
Curvature of the spine (scoliosis) related to spinal cord impairment
Abnormal breathing — specifically, sleep apnea, characterized by periods of breathing cessation during sleep"