Sagittal cervical MRI imaging are usually four (4) to five (5) millimeter slices which can miss detailed structures of the CCJ like cerebellar tonsils
, which are small peg-like structures at the base of the brain, and CCJ ligaments, which average two (2) mm in diameter.
The obex position is low and the cerebellar tonsils
are also herniated beyond normal range.
There was no herniation of the temporal lobe unci or cerebellar tonsils
. On coronal sections, the left frontal lobe exhibited a 3-cm cavitary lesion filled with necrotic and gelatinous material.
In clinical practice, SIH may manifest itself as a loss of the prepontine cistern due to leak of CSF, with flattening of the brainstem and downward herniation of the cerebellar tonsils
, which may mistakenly lead to a diagnosis of Chiari I malformation (10,11).
In pediatric clients, the Chiari I malformation may spontaneously correct as the cerebellar tonsils
rise normally with growth.
Chiari I malformation consists of herniation of the cerebellar tonsils
into the foramen magnum, thus crowding the craniocervical junction.
(1) cerebellar tonsils
are situated above the foramen magnum, although occasionally it may pass through the foramen magnum.
Computed Tomography Scan of the head showed multiple hypodense areas in the cerebellum, inferior herniation of cerebellar tonsils
with obstructive hydrocephalus.
Subsequent magnetic resonance imaging detected a herniation of the cerebellar tonsils
to the level of C2 and the presence of a cervical syrinx--findings consistent with a Chiari I malformation.
Disturbances to the cerebellum result in decrease muscle tone on the ipsilateral side, poor coordination of fine motor movements and problems with gait. Other problems include ataxia, intention tremor, diadochokinesia, dysmetria, hypotonia and asthenia. Another important problem which may occur, especially in a hemorrhagic stroke or other situations leading to increased intracranial pressure, is the downward movement of the cerebellar tonsils
through the foremen magnum resulting in a tonsillar herniation and compression of the medulla.
Chiari I Malformation: Chiari I malformation is characterized by inferior displacement of cerebellar tonsils
into the rostral cervical spinal canal (Figure 4).
Basal skull and cervical spine CT findings include spinal canal stenosis, mild platybasia with angulation and compression into the cervicomedullary junction, and downward displacement of the cerebellar tonsils