An acceleration / deceleration neck injury, aka whiplash, is not only painful, but can also result in weakness in the neck, loss of normal cervical curvature, hypertonic muscles, and impingement of nerves that exit the spine in the cervical region.
This nerve impingement may manifest as Thoracic Outlet Syndrome (TOS), with symptoms including pain traveling down the arm, alteration of sensation in the arm and / or hand such as numbness, tingling, and lack of normal perception of touch---hypoesthesia (diminished sensation) or hyperesthesia (accentuated sensation) in the upper extremity.
Symptoms may not be immediately noticeable, but may appear slowly following the injury, and often take a while to resolve.
Proper treatment, including precise, gentle adjustments with the Activator instrument as soon as possible after the injury; rest; a neck brace if needed; ergonomic counseling; anti-inflammatory soft tissue therapy, including ice & topical arnica; and appropriate introduction of gentle stretches + exercises will assist healing and recovery.