Check out the YouTube below. 

Treating Alar Ligaments Without Surgery by Chris Centeno, M.D.
This is a power point talk from the Academy of Orthopedic Medicine  conference titled TREATING CRANIO-CERVICAL JOINT INSTABILITY: INJECTION OF THE ALAR/TRANSVERSE LIGAMENTS THROUGH POSTERIOR OROPHARYNX.

Note from the talk:

• The embryology shows that the head and upper neck evolve from the same segment. (Childs Nerv. Sys. 2011 Apr; 27 (4): 523-564)

• Hence upper cervical problems can lead to headaches

•  The upper c-spine is also rich in proprioceptors that coordinate head, eye, and inner-ear data, hence upper cervical spine disturbances can cause dizziness (Curr Opin Neurol. 2015 Feb;28 (1): 69-73)

·        The original name for this syndrome is: Barre-Lieou, named for the European physicians who described a Posterior Cervical Sympathetic Syndrome in the 1930s that included headaches, dizziness, disorientation, & cognitive symptoms (J Med Bord. 1945 Nov;121 122:527) 

This doc goes on to state that actual transverse ligamentous tears increasing the Atlanto-Dental Interspace (ADI space) are not common, but ligament laxity will be seen much more frequently. He noted that when he injected the C-2,3 joint, that was the most common location for headaches and dizziness.