6.1.13\ Aqueductoplasty

Fig. 6.25  Endoscopic cyst fenestration into the ventricular system. Preoperative axial T2-weighted MRI (a) shows a large cystic lesion that compresses the left frontal lobe and abuts the left lateral ventricle. Postoperative axial T2-weighted MRI (b) shows interval decrease in size of the cystic lesion, which now communicates with the left lateral ventricle through a surgical defect

Fig. 6.26  Aqueductoplasty and stenting. Axial CT image shows a stent within the aqueduct of Sylvius (arrow)

6.1.14\ Endoscopic Choroid Plexus

Cauterization

6.1.14.1\ Discussion

Choroid plexus surgery is an option for treating hydrocephalus in patients with suspected cerebrospinal fluid overproduction and patients lacking a septum pellucidum. Choroid plexus cauterization can be performed endoscopically and consists of coagulating a portion of the choroid plexus. On imaging, truncation of the treated choroid plexus can be appreciated (Fig. 6.27). Interestingly, following choroid plexus cauterization alone, ventricular size does not necessarily decrease significantly, although sulci become more prominent

a

­indicating decreased cerebrospinal fluid pressure. Nevertheless, choroid plexus cauterization is often performed in conjunction with ventriculocisternostomy.

Choroid plexus papillomas can cause hydrocephalus due to overproduction of cerebrospinal fluid with rates of over 1.0 mL/min as well as subarachnoid obstruction. Total surgical resection of the tumor and vascular pedicle is the treatment of choice. Coagulation of the tumor can facilitate resection. After resection, the hydrocephalus usually resolves (Fig. 6.28). Additional treatment for hydrocephalus after resection may be required due to intraventricular hemorrhage, inflammation from surgery, and mechanical distortion of the ventricular system.

b

Fig. 6.27  Choroid plexus cauterization. Preoperative axial T2-weighted MRI (a) shows dilatation of the lateral ventricles, particularly the atrium of the left lateral ventricle, resulting in cranial vault deformity. Postoperative axial T2-weighted MRI (b) shows interval truncation of

the left lateral ventricle choroid plexus secondary to fulguration (encircled). Sequelae of left ventricular fenestration are also demonstrated, with resultant decompression of the ventricular system and development of extra-axial cerebrospinal fluid

Fig. 6.28  Choroid plexus tumor resection. Preoperative axial post-contrast T1-weighted MRI (a) shows a lobulated mass within the right lateral ventricle and marked

enlargement of the ventricular system. Postoperative post-­ contrast T1-weighted MRI (b) shows interval resection of the tumor and markedly decreased ventricular size

6.2\ Complications Related

to Cerebrospinal Fluid

Diversion Surgeries

6.2.1\ Corpus Callosum Changes

Secondary to Shunt

Catheterization

6.2.1.1\ Discussion

Due to its proximity to lateral ventricle shunt trajectories, the corpus callosum is prone to injury during catheter insertion. This can result in linear areas of high T2 signal in the corpus callosum adjacent to the catheter. Corpus callosal swelling can also occur after ventricular shunting for longstanding obstructive hydrocephalus. This appears

as enlargement and hypoattenuation on CT images corresponding to increased T2 and decreased T1 signal on MRI that are often oriented transversely with a striated pattern, mainly within the body of the corpus callosum (Fig. 6.29). The etiology for the signal changes is likely attributable to compression of the corpus callosum against the rigid falx cerebri from hydrocephalus prior to shunting. These changes are typically not associated with symptoms and should not be misinterpreted as neoplasm, white matter disease, or leukoencephalopathy in particular, the corpus callosum can acquire a scalloping deformity, which is best appreciated on sagittal images. Furthermore, the changes often resolve over time.

Fig. 6.29  Corpus callosal swelling. Axial CT image (a) shows low attenuation and enlargement of the body of the corpus callosum. Axial T2-weighted MRI (b) shows

striated­ high signal in the corpus callosum. Sagittal T1-weighted MRI (c) shows scalloping deformity of the corpus callosum