**2. CSF flow**

stroke, transient or permanent motor deficits, central sleep apnea, trigeminal neuralgia, as

FONAR upright weight bearing MRI has been shown to be most sensitive in detecting cerebellar tonsillar ectopia since weight- bearing posture presents the cerebellar tonsils further distended into the foramen magnum [18]. Visualization of misalignment of the craniocervical junction and its effects on the nervous system is also demonstrated when images are acquired under the effects of gravity. Imaging of the sagittal, coronal and axial planes ensure a fulsome evaluation of the adequacy of the foramen magnum and provides good sensitivity in the

well as brain stem compression syndrome [19–21].

32 Hydrocephalus: Water on the Brain

evaluation of the cerebellar tonsils (**Figures 7**–**10**).

**Figure 7.** Normal position of cerebellar tonsils.

**Figure 8.** Cerebellar tonsillar ectopia.

In 1891, Chiari discovered anomalies involving the cerebellar tonsils while performing postmortem examinations on children and adolescents with cerebral hydrocephalus. He recognized that the size of these structural defects in the brain was not related to the severity of the hydrocephalus [18].

The classic definition of Chiari malformation is herniation of the cerebellar tonsils 3 to 5 mm below the foramen magnum. This excess tissue in the upper cervical spinal canal creates pressure and disrupts the flow of cerebrospinal fluid (CSF). Blocked spinal fluid can cause hydrocephalus or, as is more common in Chiari malformation, a fluid-filled cyst known as a syrinx [22].

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

Image-Guided Atlas Treatment (IGAT) utilizes dynamic upright MRI imaging sequences in order to permit proper visualization of the CCJ misalignments (**Figure 11**).

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

eventually to insufficiency of cerebral blood flow (CBF). With increased intracranial pressure (and decreasing intracranial compliance), ventricular enlargement may occur due to atrophy

**Figure 12.** Obstructed effusion of CSF from the cranium may result in pooling and stasis (left). Correction of spinal

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

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

35

Cerebrospinal fluid shunting (surgically) results in an initial increase in CBF as the essential therapeutic effect in treating patients with hydrocephalus, but ultimately CSF shunting precipitates venocongestive brain edema, which helps explain the reduced ventricular size along

Upright Ciné MRI of the cranio-cervical junction demonstrates CSF flow dynamics. MRI examination of the brain reveals subtle structural defects in addition to any obvious tonsillar ectopia. Subtle deformities within the posterior fossa, with or without frank herniation, can be more problematic in their effect on brain function than a large but simple ectopia that leaves room for normal fluid flow. This explains why short, thick cerebellar tonsils that barely plug the foramen magnum can cause a serious impediment, while a longer herniation that is thin or peg-shaped sometimes may cause few problems [27]. The encroachment of the cerebellar vermis and tonsils on the foramen magnum disturbs the CSF flow patterns, thereby precipitating

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

of the periventricular white matter.

misalignment results in improved CFS flow (right).

**3. Radiological features**

with the known side effects of shunting [26].

headaches and other neurological symptoms [25–32].

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

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 explain much of the pathophysiology of hydrocephalus [25].

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 Craniocervical Junction Syndrome: Anatomy of the Craniocervical and Atlantoaxial Junctions… http://dx.doi.org/10.5772/intechopen.72890 35

**Figure 12.** Obstructed effusion of CSF from the cranium may result in pooling and stasis (left). Correction of spinal misalignment results in improved CFS flow (right).

eventually to insufficiency of cerebral blood flow (CBF). With increased intracranial pressure (and decreasing intracranial compliance), ventricular enlargement may occur due to atrophy of the periventricular white matter.

Cerebrospinal fluid shunting (surgically) results in an initial increase in CBF as the essential therapeutic effect in treating patients with hydrocephalus, but ultimately CSF shunting precipitates venocongestive brain edema, which helps explain the reduced ventricular size along with the known side effects of shunting [26].

Upright Ciné MRI of the cranio-cervical junction demonstrates CSF flow dynamics. MRI examination of the brain reveals subtle structural defects in addition to any obvious tonsillar ectopia.

Subtle deformities within the posterior fossa, with or without frank herniation, can be more problematic in their effect on brain function than a large but simple ectopia that leaves room for normal fluid flow. This explains why short, thick cerebellar tonsils that barely plug the foramen magnum can cause a serious impediment, while a longer herniation that is thin or peg-shaped sometimes may cause few problems [27]. The encroachment of the cerebellar vermis and tonsils on the foramen magnum disturbs the CSF flow patterns, thereby precipitating headaches and other neurological symptoms [25–32].
