Each optic lobe is as the synthesis of a large cavity, both sides are combined into the mesencephalon cavity, the boundary is not obvious, and the cavity is back to the
fourth ventricle.
Unenhanced MRI showed, extraventricular communicating hydrocephalus; hypoplasia of inferior cerebellar vermis, dilatation of
fourth ventricle with enlarged posterior fossa, multiple cysts in the posterior fossa indicating a Dandy-Walker variant.
The severity of hydrocephalus with tumor in the lateral or third ventricle was significantly higher than that with tumors in the
fourth ventricle (severe hydrocephalus: lateral ventricle, 51.7%; third ventricle, 47.0%;
fourth ventricle, 11.1%; ?2 = 26.0, P < 0.001).
Repeat cranial CT showed a progression of the left cerebellar infarct with swelling and acute hydrocephalus (prominently in the temporal horns) due to the
fourth ventricle obstruction (Figure 2B).
Intra-operatively, the electrode is placed into the lateral recess of the
fourth ventricle. The correct position of the electrode is identified by detecting electric stimuli in the auditory pathways instead of adjacent cranial nerve nuclei or sensory/motor tracts (extra-auditory stimulation).
MRI Brain was performed when showed signal drops out on SWI in the
fourth ventricle and bilateral parietal sulci representing haemorrhages.
Ventricular drainage led to improved consciousness, and contrastenhanced head MRI confirmed nodular lesions with contrast effects in the floor of the third ventricle, cerebral aqueduct, and
fourth ventricle (Figure 3).
A moderate contrast-enhancing mass in T1-weighted sequences in the posterior fossa with surrounding brain edema and anatomical contact to the vermis and the
fourth ventricle were typical findings.
Medulloblastoma cases arise frequently in the midline, especially in the posterior vermis, adjacent to the roof of the
fourth ventricle. Interestingly, the majority of adult cases are hemispheric in origin [5].
Dandy-Walker malformation (DWM), a congenital anomaly of the posterior cranial fossa, characterized by the triad of cystic dilatation of the
fourth ventricle, enlarged posterior fossa, and complete or partial agenesis or absence of the cerebellar vermis and hydrocephalus (1,2).
Dandy-Walker malformation is defined by enlarged posterior fossa, cystic dilatation of the
fourth ventricle, and cerebellar hypoplasia.
Bilateral superior cerebellum appears hypoplastic with prominent
fourth ventricle giving "Bat wing appearance" (Figure 5).
fourth ventricle - an irregular ventricle between the third ventricle and the central canal of the spinal cord