Ommaya ventricular access device and VP shunt
The patient has had a previous craniotomy and shunt for cerebral infection with subsequent hydrocephalus. He presents with worsening disturbance of cognition and mobility.
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Lateral skull and upper neck xray was performed as part of a shunt series to determine continuity of the shunt.
There is a frontal reservoir and a parietal VP shunt. There is no fracture or disconnection on this image.
In addition, the xray shows mini-plates and lucency of previous frontal craniotomy.
A shunt series is a collection of xrays along the length of a shunt from head to insertion site (usually peritoneum, but can be pleural or atrial) including skull xray in two planes if not available from CT scanogram, neck, chest and abdomen. If distal migration into the pre-peritoneal space is suspected, a lateral abdominal xray is useful. Most common site of shunt fracture is near the clavicle. Disconnection can occur at the valve.
Although the xray is not of very good quality, the difference between the left parietal VP (ventriculo-peritoneal) shunt with Miethke reservoir and valve and the left frontal Ommaya reservoir aka ventricular access device are seen: the frontal reservoir is a blind-ended catheter just anterior to the coronal suture whereas the shunt is seen to be connected to the metal-rimmed reservoir at the site of the parietal burr hole, a valve and a distal catheter which is tunnelled through the soft tissues of the neck.