Chiari surgery, just like any other type of surgery, entails some level of risk.  In procedures which include a duraplasty (inserting a patch into the dura, the covering of the brain), cerebrospinal fluid (CSF) leak is one such risk.  Last month, this newsletter reported that the FDA had approved a new product, DuraSeal (the sponsor of this issue), to help prevent CSF leaks.

This month, we spoke with DuraSeal's manufacturer, Confluent Surgical, to learn more about this exciting new product, which should greatly benefit Chiari patients.

Who is Confluent Surgical?
Founded in 1998, Confluent Surgical is the leader in the development of absorbable surgical sealants and adhesion barriers. Confluent’s mission is to contribute to the practice of surgery through the development of surgical sealants and adhesion barriers. Confluent constantly strives to understand, meet, and exceed customer requirements and to maximize shareholder value through ethical business practices.

You recently gained FDA approval for DuraSeal. What is DuraSeal?
DuraSeal Dural Sealant is the only product FDA approved for cranial sealing to prevent cerebral spinal fluid (CSF) leaks. DuraSeal Sealant is a 100% synthetic, cranial dural sealant used to create an immediate, TRUE watertight closure of the dura. When DuraSeal Sealant is sprayed onto the dura, a strong, adherent hydrogel effectively seals the suture line within seconds. A feature unique to the DuraSeal Sealant is the blue colorant that lets the surgeon easily see sealant coverage and thickness.

How does DuraSeal work?
DuraSeal Sealant is a hydrogel that is delivered to the application site by a dual syringe applicator. When the amino acid solution combines with a solution of a modified polyethylene glycol solution, the two liquids crosslink (solidify) to form a strong, adherent hydrogel.

After surgery, the DuraSeal Sealant continues to seal the suture line as healing progresses under the hydrogel. After 4 - 8 weeks, the hydrogel breaks down into water soluble molecules that are absorbed and harmlessly cleared through the kidneys.

Currently, what is the usual method used to seal the dura after surgery?
Although sutures are the current standard for dural closure, sutures alone, do not create a true watertight seal. Surgeons often attempt to obtain a “watertight” closure when suturing the dura, but the dura may dry out during surgery and shrink, so that small gaps remain when it is sutured closed. Additionally, needle holes produced during suturing can leave small holes that may also leak. The DuraSeal Sealant can be applied over suture lines for a TRUE, watertight dural closure.

Fibrin sealants are often used in conjunction with sutures when surgeons deem the patient to be at high risk for a cerebral spinal fluid leak. Fibrin sealants are usually oozed over the suture line for additional sealing. Although many physicians use fibrin sealants, these products are not FDA approved for this indication and the resulting seal is weak. Some fibrin sealants are based on human and/or animal blood. Theoretically, a risk of allergic reaction and disease transmission exists when fibrin sealants are used.

What types of clinical trials were required for FDA approval?
DuraSeal Sealant successfully sealed the dura in two clinical trials: a single center European pilot study, and a multi-center US pivotal study. Both studies showed that DuraSeal is safe and is an effective dural sealant. Clinical results presented to the FDA demonstrated that DuraSeal Sealant was able to achieve intraoperative watertight closure in 98% of cases.

Was DuraSeal used in any Chiari patients?
DuraSeal Sealant was tested on 7 Chiari patients in the two clinical studies. In all 7 patients, DuraSeal Sealant performed well and no CSF leaks were present intraoperatively or post-operatively.

What is the general rate of CSF leak when the dura is opened?
In elective craniotomies, there is a 10% chance of a CSF leak (Retrospective review of University Medical Center St. Raboud, Netherlands). The rate of a CSF leak for extensive skull base procedures has been reported to be 34.6% (Retrospective review of University Medical Center St. Raboud, Netherlands).

What happens to patients who have a CSF leak?
The leakage of CSF can create a potential pathway for infection to get inside the brain and spinal cord. Despite meticulous attempts to close the dura, many patients experience symptoms resulting from CSF leakage after the surgery. These symptoms can include the following:
- Delayed healing of surrounding tissues since CSF is caustic to bone, muscle and skin.
- Collections of CSF under the skin can cause compression of nerves and breakdown of the wound closure.
- Low CSF levels can lead to severe headaches, which are aggravated by sitting or standing up.
- CSF leaks can create a pathway to track bacteria and create life-threatening complications, such as meningitis.

Treatment for CSF leaks includes aspiration and compression, lumbar drains, and re-operations if problems persist.

Does DuraSeal work with any type of graft material?
In the United States, DuraSeal Sealant is approved for use with autologous duraplasty materials, such as fascia, muscle, or fat. DuraSeal has also been successfully used in conjunction with synthetic and bovine dural substitutes to create a TRUE watertight closure.

Is DuraSeal available outside the US? For example in the UK, Canada, and Australia?
DuraSeal Sealant is currently CE Marked and is sold in select European countries. The product is also approved for sale and is available in Australia. Confluent Surgical has submitted a request for approval to Canadian regulatory authorities and approval is expected in 2005.

What do you want patients to know about DuraSeal?
DuraSeal Sealant is the only FDA approved cranial sealant to be used as an adjunct to sutured dural closures. Using DuraSeal, a watertight closure of the sutured dura can be established. Preventing CSF leaks can reduce the risk of infections and other complications that can arise when the dura is not properly sealed.

DuraSeal Sealant is safe, 100% synthetic, and absorbs naturally in the body in 4 – 8 weeks while natural healing occurs.

What do you want medical professionals to know about DuraSeal?
DuraSeal Sealant is the only FDA approved cranial sealant to be used as an adjunct to sutured dural closures to provide TRUE watertight closure. DuraSeal Sealant is much stronger than current fibrin sealants and has 80% higher burst pressure (Results from a bench top testing on file at Confluent Surgical). The device can also be prepared and applied in just 2 minutes, 10 times faster than fibrin sealants. Additionally, DuraSeal Sealant is synthetic, and therefore the risk of allergic reaction or viral transmission associated with fibrin sealants is eliminated.

A feature unique to the DuraSeal Sealant is the blue colorant that provides the surgeon excellent visualization of coverage and thickness of the material upon application to the dura. Postoperatively, the DuraSeal Sealant continues to seal the suture line as healing progresses under the hydrogel. After several weeks, the hydrogel breaks down into water-soluble molecules that are absorbed and cleared through the kidneys. Clinical results presented to the FDA demonstrated the DuraSeal Sealant was able to achieve intraoperative watertight closure in 98% of cases. In the US pivotal study, immediate sealing was obtained on the first application in 95% of cases, and 95% of applications were rated as “easy” to “very easy” by neurosurgeons using the product.

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For more information, visit:  www.duralsealant.com

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