The Mayo Clinic says : Many people with Chiari malformation have no signs or symptoms and don't need treatment. Their condition is detected only when tests are performed for unrelated disorders.

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

My MRI/MRA showed "a slight out-pouching" of an artery in the occipital area. When I looked at the image, slight was an understatement in my observation. I guess the radiologist is more accustomed to seeing this type of out-pouching.

I would consider your report to likely be in the same vein. Unless you have symptoms that fill the spectrum for a Chiari Malformation Type I, I would not be concerned.

Keep in mind that a Chiari Malformation can be exacerbated by the inflammation caused by your auto accident or vice versa. That would only effect those symptoms that pertain to to the Chiari Malformation. The rest of your brain will still exhibit normal PCS symptoms.

I suggest you try to not worry. If there was a concern, you would have been called by the doctor's office for quick follow-up.