Occipitocervical Fixation

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

Incidence of cord injury in OCF very low

• Vertebral artery (VA) injury primarily from screw placement (4%)

If intraoperative injury to dominant VA occurs, attempts should be made to control bleeding and repair injury

Normal immediate VA angiogram does not preclude later pseudoaneurysm formation

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

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

(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.

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

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

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

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

(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 .

(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 .

TERMINOLOGY

Abbreviations

• Occipitocervical fixation (OCF)

Synonyms

• Occipitoatlantoaxial fixation

PRE-PROCEDURE

Indications

• OC instability, C1-C2 instability where C1-2 arthrodesis not possible or failed

Trauma: Occipitoatlantal dislocations, atlantoaxial subluxation

Rheumatoid arthritis: Cranial settling with brainstem or cord compression

Tumors

Infection: Instability and destruction of occipitocervical junction

Congenital (basilar invagination)

• Symptoms

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

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Tags: Diagnostic Imaging Spine

Oct 5, 2016 | Posted by admin in NEUROLOGICAL IMAGING | Comments Off

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