PMC4900199_01
20-year-old male with cerebral parenchymal cyst. Select images from initial noncontrast CT at the level of the centrum semiovale (A) and thalami (B) demonstrated homogeneous low attenuation surrounding a right frontal approach ventriculoperitoneal shunt catheter. Mass effect effaced the right lateral ventricle and resulted in 8 mm of subfalcine herniation with enlargement of the left lateral ventricle, suggestive of entrapment or shunt failure.
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Initial noncontrast enhanced CT of the head (Fig. 1) demonstrated homogeneous low density conforming to the right frontal white matter centered about the right frontal VP shunt.
20-year-old male with cerebral parenchymal cyst. Select images from preoperative MRI performed 24 hours after initial CT demonstrated CSF intensity structure abutting and partly encompassing the VP shunt that was isointense to CSF on T1WI post contrast (A) and on T2 (B) with full suppression centrally on T2 FLAIR (C), and facilitated diffusion on DWI/T2 weighted trace (E) and corresponding ADC map (F). Note the presence of operative fiducial markers on T1 and T2 sequences (A, B, G). There was a faint thin rim of enhancement on the T1 post contrast sequence also visible on the T2 and T2 FLAIR with extensive vasogenic edema in the centrum semiovale (B) and corona radiate (G). Mass effect resulted in effacement of the right lateral ventricle (D) and asymmetric enlargement of the left lateral ventricle, particularly the temporal horn (D). Mass effect is exerted on the brainstem (D). Since imaging characteristics of the collection matched CSF, and not an abscess, and it was located adjacent to the shunt, the patient's surgical exploration was cancelled.
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20-year-old male with cerebral parenchymal cyst. Select coronal (A) and axial (B) T2 FLAIR images 4 days after shunt removal and contralateral EVD placement demonstrated partial crenation of the cyst, decrease in vasogenic edema, and marked improvement in mass effect. Select axial T2 FLAIR images 2 months after initial EVD placement (C and D), with interval transition from EVD to VP shunt, demonstrated normal size and symmetry of lateral ventricles (C) and complete resolution of the cyst and vasogenic edema with residual tract from initial VP shunt (D).
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MRI 4 days after catheter removal and contralateral extraventricular drain placement (Figs. 3A, B) demonstrated decreased size of the fluid collection (7 mm), decreased vasogenic edema, and decompression of the left lateral ventricle. MRI followup 2 months later, and after new VP shunt placemen, (Figs. 3C, D) demonstrated complete resolution of the cyst, surrounding vasogenic edema, and regional mass effect.