6.2.10\ Shunt Catheter Mechanical

Failure

6.2.10.1\ Discussion

Mechanical failure of cerebrospinal fluid shunt catheters can be due to kinking or disconnection or breakage. While kinking is typically an early complication, disconnection and breakage of the tubing tend to be late complications that are usually related to aging/degradation of the catheter material and

less often mechanical trauma. Radiographs as part of shunt series are usually adequate for depicting these complications (Figs. 6.46 and 6.47). Disconnected or fractured shunts have abnormal lucent gaps. Comparison with prior shunt series can be helpful for discerning subtle defects. It should be noted that some VP shunts contain radiolucent components that should not be misinterpreted as discontinuities.

6.2.11\ Intraparenchymal

Pericatheter Cysts

and Interstitial Cerebrospinal

Fluid

6.2.11.1\ Discussion

Intraparenchymal pericatheter cysts are rare complications of shunt surgery. These typically result from increased resistance to outflow or obstruction

a

c

and are often preceded by cerebrospinal fluid edema around the catheter. On imaging, these cysts appear as ovoid collections with characteristics of cerebrospinal fluid around the shunt catheter (Fig. 6.48). Low attenuation on CT and high T2 signal on MRI in the surrounding brain parenchyma can also be present. The pericatheter cysts are reversible with shunt revision or may resolve spontaneously with conservative management.

b

d

Fig. 6.48  Pericatheter cyst and interstitial cerebrospinal fluid. Initial axial CT (a) image shows an unremarkable course of the right transfrontal VP shunt catheter. Axial CT (b) obtained 3 weeks later shows interval development of a low-attenuation collection surrounding the shunt

catheter. The corresponding axial T2 FLAIR (c) and post-­ contrast T1-weighted (d) MR images show that the collection follows cerebrospinal fluid signal. Although there is high T2 signal in the surrounding white matter, there is no associated enhancement to suggest abscess