Ommaya Reservoir Insertion: A Technical Note

Abstract

Ommaya reservoir insertion is an elective neurosurgical procedure to deliver repeated intraventricular therapy, but placement can be complicated by malposition of the catheter, clogging, infection or poor postoperative cosmesis. Here, we describe the technique used by the senior author for accurate placement including preassembly of the reservoir and catheter, and recessing of the reservoir so that others may consider the technique for their practice. Results in a consecutive series of 27 Ommaya placements were reviewed. Catheter tip placement accuracy, complications and surgical times were reported. Indications were leptomeningeal cancer or infection. Postoperative imaging showed the catheter tip was located in the frontal horn (96%) or body (4%) of the ipsilateral lateral ventricle. The median surgical time was 36 minutes (range 17-63 minutes). There were no parenchymal or subarachnoid hemorrhages. Infections occurred in 7% (n=2) of cases, and both infections presented greater than 60 days postoperative. In conclusion, we have found that image guidance can optimize accuracy in placement, that preassembly of the reservoir and catheter may be used with a 25-gauge spinal needle stylet to minimize risk of clogging during placement, and that recessing of the reservoir produces the best aesthetic result.

Keywords: chemotherapy; image guidance; intrathecal; intraventricular; ommaya; reservoir.

Figure 1. Positioning.

(A) The patient is positioned supine in a Mayfield head holder. The incision is based posteriorly, which cuts the cutaneous scalp sensory nerves to the skin over the reservoir, which numbs the area needed for accessing the reservoir, minimizing pain for the patient when it is accessed during the first couple months after placement. (B) A trajectory is planned from the middle of the diploic space to just dorsal to the foramen of Monro.

Figure 2. Equipment setup.

(A) The Ommaya reservoir has 7 mm between the flange, which is placed in the diploic space, and the proximal connection point for the catheter. (B) Given that the planned length (Figure 1B) was 61 mm, the catheter is cut to 54 mm, which achieves the desired distance from the Ommaya flange to the catheter tip. (C) The Ommaya reservoir is preassembled with the catheter and secured with a silk suture. (D) A 25-gauge spinal needle is placed into the reservoir to the tip of the catheter and used as a stylet for placement. (E) A #9 French red rubber catheter is placed over an image-guided stylet, which will be used to create the transcortical path for reservoir placement.

Figure 3. Intraoperative procedure.

After raising the scalp and periosteal flap, (A) the template is used to make out the size of the burr hole. (B) Planned burr hole. (C) The outer rim of the burr hole is drilled partial thickness into the diploic bone, while the center of the burr hole is taken to dura and 3-4 mm of dura is exposed. (D) Once the dura and pia are coagulated and opened, the red rubber catheter is used to create a transcortical path with image guidance into the frontal horn of the lateral ventricle to achieve accurate placement. Cerebrospinal fluid flow after removal of the stylet confirms the correct position. (E) The preassembled Ommaya with the spinal needle acting as a stylet can be gently passed down the cortical trajectory created by the red rubber catheter. (F) The reservoir is secured in place with 5 mm screws angled into the adjacent skull.

Figure 4. Neuronavigation trajectory.

Neuronavigation screenshot showing axial (top left), coronal (top right), and inline/trajectory views (bottom row) of the image-guided stylet at the ideal position slightly dorsal to the Foramen of Monro.

Figure 5. Postoperative imaging.

Postoperative noncontrast CT scan showing ideal catheter placement in (A) axial, (B) coronal and (C) sagittal planes. (D) Bone window coronal CT scan showing the recessed Ommaya reservoir and smooth surface of the skin over the reservoir.