PMC2876252_01
(a) CT head without contrast, (b) MRI T1 with contrast showing the cyst in the posterior third ventricle (arrow), and (c) MRI T2 showing altered flow through the Sylvian aqueduct (arrow).
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fig1
Initial head CT obtained in the ER to evaluate for headache showed ventriculomegaly suggestive of obstructive hydrocephalus with obstruction in the posterior third ventricle and an atypical appearance in the third ventricle region (Figure 1).
(a) MRI T2 showing migration of the cyst to the anterior third ventricle (arrow) and (b) MRI T2 demonstrating a flow void in the Sylvian aqueduct consistent with restoration of CSF flow (arrow). Of note, reduction in the size of the temporal horns is also appreciated.
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fig2
MRI (Figure 2). Migration of the cyst resulted in restoration of CSF flow and complete resolution of the patient's symptoms. 
Head CT without contrast demonstrating complete removal of cyst.
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fig3
Postoperative brain MR revealed an absence of the cyst (Figure 3).