We all know chemotherapy can
be administered via an intravenous route. However, chemotherapy can also be administered directly
into the brain, in what is known as intrathecal administration.
For some patients whose
cancer has spread to the central nervous system (CNS), intrathecal chemotherapy
offers a unique method of chemotherapy administration. This is a cool, direct
application of what we have recently learned in our Anatomy course 631A:
The blood brain barrier is a
highly selective barrier that prevents most compounds from entering our brain
tissues. Therefore, a patient with CNS cancer will not benefit from IV method
of chemotherapy administration. For these patients, chemotherapy has to be
administered directly to the CNS to have an effect. To bypass the natural
protective mechanism of a blood brain barrier, an Ommaya can be placed in the
patient’s head.
An Ommaya is a device that
has 2 components: a plastic, dome shaped region and a catheter that is
attached. To place an Ommaya in a patient, the surgeon creates a small hole
through to the dura. The catheter portion is then inserted and guided to a
lateral ventricle in the brain. The incision is then closed off, and now
providers have direct access to the patient’s CNS to administer chemotherapy
and to extract CSF for cancer cell surveillance during treatment. A small
needle is inserted into the plastic dome just beneath the patient’s scalp to
access the device for these purposes.
An animation describing
Ommaya placement:
http://www.neuronwbs.com/ommaya-reservoir-placement/
The Ommaya device is a very interesting technique and I had not heard of it before. I was curious to see if there were less invasive ways to pass the blood brain barrier because it seems there would be a lot of risk that could be avoided by not having to open up the brain. Although I did not find any other methods that are widely used, I found a new method that could eventually be just as beneficial and less invasive than the Ommaya device. In this article (http://www.scientificamerican.com/article/breaching-the-brain-barrier/), the technique of microbubbles and ultrasound in order to pass the blood brain barrier is discussed. This is done by injecting the microbubbles into the blood stream and then guiding them to the blood brain barrier with ultrasound. These bubbles can target the area they need to pass and open it in order to inject a drug in the exact location it is needed. This technique has not been used on humans because there is still problems with the ultrasound causing tissue damage. However, I would imagine that this technique will eventually be very useful.
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ReplyDeleteAlana, thanks for sharing! It is a very cool concept, indeed. I noticed the link you had was from 2010, so I was curious to see if there had been advancements made to this technology over the past 5 years.
ReplyDeleteI found this link: http://www.cnet.com/news/flying-across-the-blood-brain-barrier-in-microbubbles/
It seems like they are in the beginning stages of testing this technology on human subjects. If it is successful with minimal adverse events, I would imagine this would revolutionize intrathecal drug administration. It will be interesting to see in the future if this technology significantly improves patient outcomes by delivering the much needed drugs to the exact locations where they are needed the most.