6.1.7\ Subdural-Peritoneal Shunts

6.1.7.1\ Discussion

Subdural-peritoneal shunting devices can be used to treat chronic subdural hematomas that are sufficiently degraded to a fluid state, such that the

collection can flow into the peritoneal space (Fig. 6.15). Compared with burr hole decompression and drainage alone, subdural-peritoneal shunts result in a lower recurrence rate. Complications include acute subdural hematoma, subdural empyema, and cerebral edema.

Fig. 6.15  Subdural-peritoneal shunt for chronic hematoma. Lateral radiograph (a) shows that the catheter tip lies just beneath the calvarium, in the subdural space (arrow). The rest of the catheter is tunneled in the subcu-

taneous tissues and runs toward the abdomen. The corresponding coronal CT image (b) shows the catheter tip (arrow) located within the right frontal convexity fluid collection

6.1.8\ Cystoperitoneal

and Cystoventriculostomy

Shunts

6.1.8.1\ Discussion

In rare instances, arachnoid cysts can cause symptoms and require surgical intervention. In some reports, cystoperitoneal (subarachnoid-­ peritoneal) shunting has proven effective for

decompression of arachnoid cysts into the peritoneal cavity (Fig. 6.16). Meningoceles and cystic schwannomas are also sometimes amenable to cystoperitoneal shunting. Internal drainage of arachnoid cysts into regional ventricles or cisterns via stereotactic cystoventriculostomy is another feasible treatment approach, in which a drain is inserted in the cyst lumen and directed into an adjacent ventricle or cistern (Fig. 6.17).

Fig. 6.16  Cystoperitoneal shunting. The patient has a history of ventriculoperitoneal shunt placement for arachnoid cyst and presents with headache. Frontal radiograph (a) shows that the tip of the shunt catheter (arrow) projects

over the left hemisphere, not in the expected location of the ventricular system. Axial CT image (b) shows a cystoperitoneal shunt catheter (arrow) within a large left frontotemporal convexity arachnoid cyst

Fig. 6.17  Cystocisternal shunt. The patient has a history of arachnoid cyst secondary to Candida meningitis with obstruction of cerebrospinal fluid at the level of craniocervical junction, resulting in cord compression. Preoperative sagittal T2-weighted image (a) shows a cerebrospinal fluid intensity collection at the craniocervical junction,

which exerts mass effect upon the spinal cord and medulla

(*). Postoperative axial (b) T2-weighted MRI demonstrates a drainage catheter (arrow) within the subarachnoid space anterior to the cervicomedullary junction

6.1.9\ Syringosubarachnoid

and Syringopleural Shunts

6.1.9.1\ Discussion

Direct intervention for syringohydromyelia is generally considered a rescue procedure and can be accomplished via syringosubarachnoid or syringopleural shunting. Syringosubarachnoid shunting can be used to treat syringohydromyelia related to a variety of causes, such as tumor, trauma, and Chiari malformations. This procedure serves to free the obstructed cerebrospinal

a

fluid pathways via myelotomy and insertion of a Silastic T-shaped tube. The tube extends from the syringohydromyelia cavity to the subarachnoid space, into which the excess cerebrospinal fluid drains (Fig. 6.18). The T-shaped configuration of the tube allows cerebrospinal fluid to drain from both superior and inferior directions in the syrinx.

Syringopleural shunts can also be used to treat syringomyelia by extending a catheter from the syrinx to the pleural cavity as a negative pressure terminus (Fig. 6.19).

b

Fig. 6.18  Syringosubarachnoid shunt. Two patients’ status post T-tube insertion for cervical spine syringomyelia decompression. Sagittal (a) CT image in one patient shows the hyperattenuating portions of the T-tube. Sagittal preoperative T2-weighted MRI (b) in another patient

shows a large syrinx (*) in the cervical spinal cord, which was successfully decompressed following T-tube insertion (arrow), as shown on the postoperative T2-weighted MRI (c). There is also new kyphotic deformity after multilevel laminectomy