Introduction:
Spinal manipulation entails a range of manual maneuvers that stretch,
mobilize, or manipulate the spine, paravertebral tissues, and other
joints to relieve spinal pain (1). Manipulation of the spine differs
from mobilization, as it involves a sudden applied thrust that the
patient generally cannot resist. In contrast, mobilization involves a
low-velocity, passive movement that can be limited or even halted by the
patient (2). Numerous absolute and relative contraindications of spinal
manipulative therapy (SMT) have been proposed (3–5). The safety of SMT
requires rigorous control. In particular, manipulation of the upper
spine has been associated with serious adverse events such as
cerebrovascular accidents, paraplegia, rib fractures, and death (6–9).
The reported cerebrovascular insults were primarily due to vertebral
artery dissection (8). The cervical internal carotid artery (ICA) is
less frequently injured during chiropractic maneuvers, probably because
it lies in the soft tissue of the neck and is thus more mobile. The ICA
has seven segments: cervical, petrous, lacerum, cavernous, clinoid,
ophthalmic, and communication (10). The cervical segment begins at the
carotid bifurcation) usually at the level of C3(and ends at the skull
base and usually has no branches (11). It is assumed that ICA dissection
during chiropractic manipulation results from artery compression against
either the transverse processes or the bony mass of the upper cervical
vertebrae (12). Flexion-extension trauma is more likely to injure the
carotid arteries, whereas rotational trauma more often damages the
vertebral arteries (13,14). Eagle syndrome was first described in 1937
by the German otorhinolaryngologist Watt Eagle, whose clinical and
radiological definition of the condition is still in use. Eagle’s
syndrome is a complex symptom assortment produced by provocation of the
carotid space structures by anomalies of the styloid process (15),
including an elongated styloid of 30 mm or larger (16), insulting
angulation, calcification of the stylohyoid or stylomandibular
ligaments, and/or approximation of the styloid to C1 transverse process,
commonly seen with a styloid of normal length (17). Institutional Review
Board approval was waived, and informed consent was obtained from the
patient to publish the case details and images.