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Programmable Shunts

 

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Method for Programming Codman, Medtronic, and Miethke Programmable Shunt Valves in Hydrocephalus & NPH

 

By: Stephen Dolle, Scientist, Hydrocephalus Patient, and Inventor of the DiaCeph Test

 

Updated: Jan. 31, 2013

 

Codman, a division of Johnson & Johnson, introduced the “Medos” programmable shunt valve for the treatment of hydrocephalus in 1998. Since that time, programmable shunt valves have become the valve of choice for most neurosurgeons in developed countries. Codman has since introduced an upgrade to the Medos, the Certas valve. Medtronic has similarly introduced the Strata valve. Miethke has introduced the proGAV. And Sophysa has introduced the Polaris. Programmable valves have become particularly popular in the treatment of adult hydrocephalus and NPH (normal pressure hydrocephalus). But, the mystery still remains as to how to program these valves to find the best setting, and in a reasonable amount of time.

 

Stories abound on Internet forums of hydrocephalus patients complaining about experiencing continued complaints, and being told by their neurosurgeon that their programmable valve is set properly. In addition to valves that were never set properly from the start, many valves are loosing their setting through accidental reprogramming by such things as toys and telephone handsets with magnets strong enough to trip the valve's setting. Many of the new programmable shunts now have a more sophisticated mechanism or lock to avoid most accidental reprogramming. I wrote earlier on this problem, and also spoke to some of the shunt manufacturers, and I proposed a simple home screening method of offending magnets through the use of a simple sports compass and tape measure.

 

Some of the popular programmable valves and their settings include:

 

Codman Medos or Hakim Programmable Valve: Opening pressure range from 30mm to 200mm in 10mm increments

 

Codman Certas Programmable Valve: Opening pressure range from Setting 1 - 8; corresponding to 36mm, 71mm, 109mm, 146mm, 178mm, 206mm, 238mm, and 400mm.

 

Medtronic Strata Programmable Valve:  *****

 

Miethke proGAV Programmable Valve: *****

 

Sophysa Polaris Programmable Valve: *****

 

To be completed/updated soon***********************

 

 

Hydrocephalus is complicated by the fact that each person has their own unique degree of shunt dependence, internal ventricular pressures, abdominal cavity pressures, and a specific distance between the position of the shunt on their head, and where it ends in their abdomen (distance from CSF flow inlet to outlet). These variables must be matched with a shunt system that can maintain ICP for them at the varying postures and physical activities that may undertake over the course of a day. This is termed physiologic ICP, or intracranial pressure.

 

Hydrocephalus is characterized by a person having insufficient CSF clearance in the brain from one of many causes, or etiologies, and then having the fluid back up, or swell in the brain, and exert abnormal and often dangerous pressure on the brain’s vital structures. The surgical procedure for placement of a CNS shunt is rather simple. CNS shunts have been used in the U.S. for more than 50 years, with more than 1,000,000 people implanted with CNS shunts today. But there still is no portable test or means to alert the patient when their shunt is not working correctly, albeit a mismatched setting of their programmable shunt, a shunt malfunction, or intermittent dysfunction of their shunt system - from a multitude of causes, and also a very common occurrence.

 

My initial programming method came from my being a Codman programmable shunt user in 2007, and a not so happy one at that. I found the entire process for finding the correct pressure to be too simplistic, and unscientific. I’m not suggesting that neurosurgeons throw out the manufacturer’s labeling instructions for finding the best setting. But I speak from experience in having the Codman Medos, Miethke proGAV, and now the Codman Certas valve, and having the benefit of knowing what I went through to get these valves optimally set. Much of my methods are base upon my DiaCeph Test monitoring system, a method I pioneered in 1997 amid challenges with siphon control devices. The DiaCeph Test could enable shunt users to non-invasively monitor their status and help make their quality of life more manageable. I'm still looking at what it would take to make it available as a mobile phone app.

 

The earlier belief and method had been to get the programmable shunt setting down as low as possible and tolerable a setting, and then gradually raise it upwards in 10 mmH2O or so increments. But, I have revised this in light of the risks posed by overdrainage, that is, a collapsed ventricle with ventricular catheter obstruction, a subdural hematoma, and/or a subdural hygroma. The risks here are not worth the tradeoff in expediency to get to your best setting.

 

 

 

SUGGESTED METHOD & SETTING FOR YOUR PROGRAMMABLE SHUNT:

 

The neurosurgeon should start by selecting a pressure setting near the middle range (or higher if the patient has been shown to require a high pressure valve/setting). Then send the patient home with instructions on how to monitor his/her status for a period of 2-3 weeks. I have forms available on my web site. Or you can hire me as a consultant on your monitoring. I suggest using more than one of the markers below to evaluate your status and physiologic match at each setting. Below are my suggested markers to monitor:

 

1) Bend Over/Head Down:  While sitting or standing after a period of at least 15 minutes, bend over so that your head is lower than your waste line, and hold it there for about 10 seconds. Slowly come back to your sitting or standing position. Note the feeling in your head as to head pressure, any headache, and any uncomfortable feeling and difference between the two postures. If unsure, repeat the maneuver. On a piece or paper, a form, or by entry into your mobile phone or tablet, write down your observation as to how each posture felt. Do this twice a day: once in the morning about an hour after you get up, and later in the afternoon or evening.

 

2) Hold Breath & Strain Assessment:

 

 

3) Supine Headache/Head Pressure upon Awaking in the Morning: Immediately upon awaking in the morning,

 

 

4) Percutaneous Pressure/Patency Assessment:  Another important point I will only touch on here is the percutaneous evaluation (finger pressure) of the shunt (main chamber) to determine whether the valve chamber is open, or closed, and when the patient might be experiencing unexplained complaints. For example, if the patient is experiencing a headache in the daytime while sitting or standing, and the percutaneous finger test indicates the main chamber to be “open,” the finding would suggest a pressure setting that is too low. Conversely, if percutaneous sampling continues to reveal the primary chamber to be closed during periods when headache and other complaints are occurring, this is a pretty clear indication the setting it too high. You should evaluate each setting at least 8 or 10 times over a 7-14 day period.

 

But for these purposes, we’re only interested in knowing whether the valve is open or closed during periods of complaints. Conversely, you might want to check the status of the shunt (open vs. closed) on a few occasions when no complaints are present, just to confirm in what position the patient felt better. This method would apply to makes of other programmable shunts, notwithstanding the consideration that must be paid to the differences in pressure setting values and terminology.

 

 

Korean Study and Programming Methods:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2773397/

 

With the above information in hand from the patient or family member, the neurosurgeon can then adjust the shunt accordingly to find the most optimized setting for each patient. Of course, it would be extraordinarily beneficial if the patient and family had the DiaCeph Test or a PMR (personal medical record) palm device, or alternately, DiaCeph software embedded into their personal cell phone. The DiaCeph Test is notably different from a PMR in that it is a patented disease management program, designed to address the many unique needs of users with CNS shunts.