Occipitocervical Fixation

 Injury to cord, cranial nerve 12, C1 and C2 roots


image Incidence of cord injury in OCF very low


• Vertebral artery (VA) injury primarily from screw placement (4%)
image If intraoperative injury to dominant VA occurs, attempts should be made to control bleeding and repair injury

image Normal immediate VA angiogram does not preclude later pseudoaneurysm formation

image Bilateral VA injury can be fatal, so no screw placed contralateral to VA injury

image Bony and VA variations seen in 18-23%
– ↑ risk of VA injury

– If high-riding VA at C2, C2 pars becomes very narrow and limits safe screw placement



image
(Left) This is a resection of a C2 aneurysmal bone cyst. Lateral CT localizer shows halo instrumentation and occiput-C5 fixation. Three screws fix the occipital plate with bilateral C1 lateral mass screws and C3-C5 lateral mass screws.


image
(Right) Postoperative sagittal NECT in the same patient shows that a rib allograft image was used as a scaffold for bony fusion. Occipital hardware is partially visible image, and gas is present in resection site image.

image
(Left) Axial NECT in the same patient shows that the left pars screw extends ventrally into the vertebral foramen image. The left vertebral artery (VA) was coil embolized after verifying that the right VA was patent.


image
(Right) Sagittal NECT following resection of a giant cell tumor of the C2 shows the occipital part of the hardware construct with 3 screws extending through the inner table image.


TERMINOLOGY


Abbreviations




• Occipitocervical fixation (OCF)


Synonyms




• Occipitoatlantoaxial fixation


PRE-PROCEDURE


Indications




• OC instability, C1-C2 instability where C1-2 arthrodesis not possible or failed
image Trauma: Occipitoatlantal dislocations, atlantoaxial subluxation

image Rheumatoid arthritis: Cranial settling with brainstem or cord compression

image Tumors

image Infection: Instability and destruction of occipitocervical junction

image Congenital (basilar invagination)

• Symptoms
image Cord and brainstem compression with respiratory distress, pain, cranial nerve dysfunction, paresis and paralysis, sudden death

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Oct 5, 2016 | Posted by in NEUROLOGICAL IMAGING | Comments Off on Occipitocervical Fixation

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