The leptomeningeal dissemination of metastatic tumors, also known as leptomeningeal carcinomatosis (LMC) is a devastating complication of both solid and hematological tumors. LMC is clinically detected in 4–7% of all cancer patients and in 5–15% of patients with leukemia and lymphoma [6]. It is becoming increasingly common in cancer patients due to enhanced detection through routine use of magnetic resonance imaging and to longer survival of these patients with better systemic control [3]. LMC can cause cranial nerve dysfunction, meningeal irritation, and increased intracranial pressure (ICP) [5], and it is associated with poor prognosis, with average survival of 2 to 4 months despite treatment [7]. The mainstay treatment for patients with LMC is intrathecal (IT) chemotherapy; the IT injection of cytotoxic drugs circumvents the blood brain barrier and blood- cerebrospinal fluid (CSF) barriers [4].

The Ommaya reservoir is a frequently used implantable CSF reservoir that helps to facilitate regular IT drug administration. It can also be used for diagnostic CSF aspiration or therapeutic CSF drainage to control increased ICP. However, there are occasional problems with the Ommaya reservoir. It may not be easily palpated in some patients due to the relatively low height of the collapsible chamber, and this is especially challenging in patients with thick scalp or those with subcutaneous hematoma formation around the reservoir. This may lead to inaccurate administration of cytotoxic drugs, which can cause complications such as skin necrosis. Furthermore, multiple compression of the collapsible chamber to determine and ensure its location may cause traction on the choroid plexus. The dome-shaped silicone port of the Ommaya reservoir is relatively fragile, and therefore, only finegauged straight needles can be used to puncture the port; larger-bored needles or multiple punctures can damage the port, ultimately leading to CSF or drug leakage. In addition, continuous CSF drainage for controlling increased ICP is difficult in patients with Ommaya reservoir because the punctured needle cannot be fixed tightly in the port.

Despite these problems with the Ommaya reservoir, there have been no notable modifications of the IT chemotherapy system to date. In this technical note, we describe a newly developed implantable CSF reservoir that addresses the problems seen with other CSF reservoirs.

In a previously reported study from our institution, the Korean National Cancer Center [2], we introduced the novel surgical technique of installing a Chemoport as a replacement for the Ommaya reservoir in patients diagnosed with LMC. The hard outline of the port’s titanium cage made it easier to palpate than the Ommaya reservoir; in addition, the Chemoport was more durable against multiple punctures and larger-bored needles. We were also able to drain the CSF continuously in patients with increased ICP using a hooked Huber needle that was secured in the Chemoport using only closed dressings. However, the height of a Chemoport (small Celcite^®; B. Braun, Boulogne Cedex, France) is nearly twice of that of a flat-bottomed Ommaya reservoir (Baxter, Heyer-Schulte, Deerfield, IL, USA). Therefore, the additional procedure of skull engraving was necessary when we installed the Chemoport. This extra step involved engraving a station approximately 4–5 mm in depth in the shape of a Chemoport using a high-speed drill; this was to secure the Chemoport on the skull and reduce the elevation of the Chemoport above the skull to prevent postoperative skin problems. Although the average operation time for Chemoport installation (54 minutes) was within an hour, it was longer by an average of 16 minutes than Ommaya reservoir insertion (38 minutes) largely due to this extra step; moreover, in order to acquire the extra space for skull engraving, we had to make larger skin incisions. In order to avoid the additional bone work and shorten the operation time, we developed a new implantable reservoir called the V-Port.

The total operation time, incision size, and estimated blood loss were recorded during each operation. Each neurosurgeon provided feedback about his experiences and impressions of the V-Port. Immediate postoperative CT scans were taken to check for intracerebral hemorrhage (ICH) and malposition of the catheter; the patients were then transferred to their respective oncologists for IT chemotherapy. Each patient was followed up for four weeks after the operation and evaluated for signs of postoperative infection and skin problems. The function and palpability of the V-Port were evaluated during IT chemotherapy and/or CSF drainage.

The average operation time for V-Port insertion was 42 minutes, with an average incision size of 6.6 cm and an estimated blood loss of 16.6 mL. All four neurosurgeons who performed the operation found the surgical technique of V-Port insertion to be intuitive because it was similar to inserting a burr-hole-type Ommaya reservoir. The surgeons also subjectively found V-Port insertion to be much easier than Chemoport installation because it required smaller skin incisions and less bone work.

The average follow-up duration was 26 days because two patients died before the 4-week mark. Ultimately only four patients underwent IT chemotherapy; the oncologists decided on chemotherapy based on the patient’s functional status, the rate of disease progression, and the patient’s and/or guardian’s preference. Seven patients underwent CSF drainage at least once for ICP control, and of those seven, two underwent continuous CSF drainage because the ICP was not effectively controlled by intermittent drainage. A hooked Huber needle was secured in the V-Port and connected to an extra-ventricular drainage bag for continuous drainage of the CSF (Fig. 3). The large-bored Huber needle was well tolerated by the V-Port and was secured well in the V-Port using only closed dressings. The V-Port was easily palpated in all cases, even in patients with relatively thick scalp. There was no obstruction or leakage of the V-Port during IT chemotherapy or CSF drainage. Furthermore, there were no complications including postoperative ICH, infection, and skin problems related to the V-Port.

In this pilot study, we describe a newly developed implantable CSF reservoir called the V-Port and the surgical technique for its insertion. Until now, our institution has actively adopted the use of Chemoports rather than Ommaya reservoirs in LMC patients because they are easier to palpate and more durable against larger-bored needles than the Ommaya reservoir; in addition, we were able to continuously drain the CSF in patients with uncontrolled increased ICP using the Chemoport. However, due to the height of the Chemoport, we had to engrave a station for it on the skull, which led to longer operation times and larger incisions.

We addressed these problems by making the port of the V-Port much shorter than the Chemoport’s while maintaining the titanium cage around the port. The average operation time was shorter than that for Chemoport insertion, and the surgical technique for its insertion was easy and intuitive for the neurosurgeons. Furthermore, there were no malfunctions or complications related to the V-Port during our pilot study.

We believe that the V-Port is a safe and an easy-to-use device that could substitute for previous implantable CSF reservoirs. We acknowledge that a larger clinical trial is necessary before the V-Port can be widely accepted. Therefore, we are currently conducting a nationwide multicenter clinical trial based on this pilot study to further test the V-Port’s safety and function.

V-Port is a safe and an easy to use implantable CSF reservoir that addresses problems of other implantable CSF reservoirs. Further multicenter clinical trial is needed to prove the safety and the function of the V-Port.