**3. Radiological features**

Spinal integrity may be restored through reduction of misalignments at the cranio-cervical junction. Image Guided Atlas Treatment (IGAT tm) has been shown to be effective at restoring

Image-Guided Atlas Treatment (IGAT) utilizes dynamic upright MRI imaging sequences in

Cerebrospinal fluid (when unencumbered) contains low-molecular weight chelating agents that remove metal atoms from the interstitial spaces of the brain and spinal cord, as well as from neurons and glial cell membranes. Abnormal iron deposition is a consequence of the cascade of malevalence associated with cerebellar ectopia induced CSF stasis [24]. What is equally surprising, if not more so, is the fact that ferromagnetic mineral magnetite (Fe3 O4) crystals are formed biochemically as a manifestation of normal brain tissue metabolism. Parkinson's and Alzheimer's diseases may by induced by toxic build-up of heavy metalswithin the basal ganglia in the case of Parkinson's, and in the cortical and sub-cortical regions

**Figure 11.** Disruption of CSF flow (left) with restoration of normal flow post IGAT (right) on phase contrast cine CSF

With the cascade of CSF pathophysiology induced by cerebellar tonsilar ectopia, there is compromise of the total encephalic venous outflow due to obstruction of the venous system that cannot be adequately shunted from the cranial vault. Portions of the superficial venous system draining the frontal, parietal, temporal, and occipital lobes are also drained by direct connections into the transverse sinuses and the middle cerebral veins. The inability to redistribute or disperse the obstructed superficial venous outflow results in intracerebral venocongestion, leading to loss of intracerebral compliance thereby decreasing intracerebral blood flow.

Review of available data provides a reasonable model of cerebral venous outflow that, when used in conjunction with our understanding of arterial blood supply and CSF dynamics, may

Simultaneous obstruction of both the "principal" and "collateral venous outflow" tracts (as an indirect result of cerebellar tonsillar ectopia) can lead to elevated venous pressure and

of the brain in the case of Alzheimer's disease (**Figure 12**).

flow MR.

34 Hydrocephalus: Water on the Brain

explain much of the pathophysiology of hydrocephalus [25].

CSF flow reducing and reversing the neurodegenerative cascade [23].

order to permit proper visualization of the CCJ misalignments (**Figure 11**).

Imaging studies of the cranio-cervical junction, particularly standard MRI, lacks sensitivity when viewing the CCJ ligaments for signs of sub-failure. X-ray based imaging (conventional radiographs, fluoroscopy and CT), do not show ligament tears, particularly when chronic scarring replaces the "thickness" of the normal cable-like arrangement of collagen in healthy ligaments [33, 34]. Intraligamentous heme is released when ligaments are torn, creating a susceptibility artifact, particularly on T2 weighted images, making the torn ligament appear "normal" (uniform, hypointense, "dark" signal with uniform thickness) [35]. With proper MRI sequences, such as "Proton Density" thin section data sets, the "gray" intermediate signal indicative of ligamentous disruption can be contrasted by a background of adjacent "brighter" CSF (versus intermediate signal with T1 weighting) [36].

**Author details**

\*, John W. Baird2

1 Private Practice, Rock Hill, NY, USA

2 Private Practice, Markham, ON, Canada

3 Private Practice, Little Rock, AR, USA

4 Private Practice, McLean, VA, USA

Spine. 1987;**12**:732-738

1987;**12**:197-205

1990;**19**:521-525

**2**:243-250

\*Address all correspondence to: drscottrosa@hvc.rr.com

Journal of Roentgenology. 1989 Sep;**153**(3):565-569

Biomechanics (Bristol, Avon). 2000;**15**:633-648

injuries: MR findings. Radiology. 1991;**180**:245-251

Spine. 3rd ed. Philadelphia, PA: Lippincott-Raven; 1998. p. 1003

cal stability in the cervical spine. Clinical Orthopaedics. 1975:85-96

, David Harshfield<sup>3</sup>

[1] Cone RO, Flournoy J, MacPherson R. The craniocervical junction. Radiographics. 1981;**1**(2)

[2] Kao SC, Waziri MH, Smith WL, Sato Y, Yuh WT, Franken EA Jr. MR imaging of the Craniovertebral junction, cranium, and brain in children with Achondroplasia. American

[3] Clark CR, Ducker TB. Cervical Spine Research Society Editorial Committee. The Cervical

[4] Penning L, Wilmink JT. Rotation of the cervical spine: A CT study in normal subjects.

[5] White AA III, Johnson RM, Panjabi MM, Southwick WO. Biomechanical analysis of clini-

[6] Bogduk N, Mercer S. Biomechanics of the cervical spine, I: Normal kinematics. Clinical

[7] Dvorak J, Panjabi M, Gerber M, Wichmann W. CT-functional diagnostics of the rotatory instability of upper cervical spine, 1: An experimental study on cadavers. Spine.

[8] Monu J, Bohrer SR, Howard G. Some upper cervical spine norms. Spine. 1987;**12**:515-519

[9] Bohrer SR, Chen YM, Sayers DG. Cervical spine flexion patterns. Skeletal Radiology.

[10] Davis SJ, Teresi LM, Bradley WG, Ziemba MA, Bloze AE. Cervical spine hyperextension

[11] Green JD, Harle TS, Harris JH. Anterior subluxation of the cervical spine. AJNR. 1981;

and Mahan Chehrenama<sup>4</sup>

http://dx.doi.org/10.5772/intechopen.72890

37

Craniocervical Junction Syndrome: Anatomy of the Craniocervical and Atlantoaxial Junctions…

Scott Rosa1

**References**

Standard T1 W and T2 W CCJ MRI protocols with 5- to 7-mm-thick slices are insufficient to demonstrate such membrane/ligament lesions [37]. Sections 2–3 mm thick give adequate spatial resolution with an adequate signal-to-noise ratio. The low membrane/ligament signal afforded by proton density (PD)-weighted images provide better delineation from both CSF and adjacent soft tissues compared to the standard T1- and T2-weighted sequences that typically comprise standard cervical MRI studies [38].

On T1-weighted images, ligaments are not as well defined because a damaged ligament and the surrounding edema/inflammation and adjacent CSF will all be 'gray', or intermediate in T1 signal [15]. However, with the PD sequence (especially with fat suppression) the edema/ inflammation and CSF become hyperintense (increased in PD signal) while depicting intact ligaments as relatively hypointense (lower) signal. The reason PD-weighted images are not routinely used to replace the standard T1-weighted images (on current C-spine protocols) is that PD can "miss" medullary space lesions [39].

In hyperflexion trauma, all posterior cervical ligaments and membranes are subjected to strain forces. When the atlanto-occipital membrane is stretched beyond its elastic limit, these forces are transmitted to the adjacent dura mater. The rupture of the latter indicates a sprained/ injured membrane.
