Friday, July 14, 2006

3rd Week- Dealing with patients

Dealing with patients

I want to share my experiences dealing with the patients in the neuropathology clinic, because this is kind of new for me. All the patients are conscientious while we are doing the tests and as can you imagine, being poked or being electrocuted is not very pleasant.

So at the beginning we introduce ourselves to the patient (me and the person who is going to do the test), if the patient looks “friendly” we stretch hands. It is very important, to explain the whole procedure to the patient at the beginning and then at each step during the test. So this are some of the words of a doctor during a test: “Now you are going to feel a shock: 1,2 ,3… now a little bit stronger: 1 ,2 3… now you are going to feel a needle 1,2 ,3… “ and he keeps counting (this makes me nervous)…

They are all kinds of patient’s responses, some are very nice and we can talk during the test… but some others feel like they were made of porcelain and are very mean. Many of them are just crying babies, I can remember one patient that was volunteering for research and during the shocks she was screaming and even saying bad words, I am not sure if they were really bad because most of them I never had heard . (My vocabulary keeps improving) . My favorite type of patient are the funny ones, because in their resignation they just say something like: “Do you enjoy your work?” or “ Ok Ok, I will confess but stop” or “I am being tortured by 2 women”(if
me and a girl is doing the test)…

But, have you ever have patients that can make you cry? I mean, in my case the patient usually is accompany by someone. Sometimes, we have scenes pretty commoved: when they are couples, mother and son, and they get worried about the other. The one that I have this week was a very old, sick patient and his daughter… She was so worried and protective. Seems that she was also doing the test, she was telling her father “breath” and counting (like when some one is in labor) or holding hir hand if the test allowed it. I was so touched (if is something good about getting old?). Anyway, companions may make the test a bit harder because we have to deal with them as well and explain them every detail.

In conclusion, I think that the most important thing is to treat the patient with respect and the patient has to feel that we are very confident in what we are doing.
Monday July 10 I witnessed a lumbar spinal decompression. We met Dr Maher from Research at 7:30, then navigated the process to get scrubs. It must have been almost 9:30 when we finally went into the OR to watch. The surgeon was phenomenal. He has unbelievable stamina, standing alongside the patient for hours. We tried to stay out of the way, because a mishap during this operation could have such serious consequences. As an engineer, I found the quality control measures to be interesting and reassuring. The doctor x-rayed the patient after the initial incision to verify that he was at the correct site. The nurses and techs counted every piece of gauze one by one before and after to make sure everything was accounted for. Robbie studies spines, so I'm sure his entry has more detail.
On Tuesday, I went to the ambulatory care center to watch arthroscopic knee and shoulder. Here the outpatient surgeries are performed and the operating rooms are much smaller as is the nursing station. The knee proceeded normally. I like watching the doctor's hands more than the television screen. Surgery really is a skill that needs to be learned. The knowledge needed to apply that skill correctly is tremendous, but the skill itself is related to a skilled woodcarver or stonemason. The shoulder was interesting because it required arthroscopic knot tying to stitch the tissues (maybe a subscapularis tendon?) to tighten the shoulder after removing the scar tissue. The camera had a lot of room to maneuver before the procedure, but once it was stitched, it didn't have much of a view.
I saw an evaluation of a child with hemiplegic cerebral palsy on Thursday. One of the doctors at HSS is one of only a few doctors worldwide who treats upper extremities in children with CP. The child amazed everyone by using her affected hand to turn over 5 index cards, one at a time. The doctors will analyze the examination results to determine what surgical procedures will give the child the most activity. Typically this means tendon transfers so that spastic muscles change from flexors to extensors.

Wednesday, July 12, 2006

Spines and Technology

After getting the opportunity to spend a day in the operating room viewing spinal surgeries, I have a new appreciation for the technology of the operating room, the need for new technology, and the need for well trained physicians to make use of the technology.

Current Technology

The first thing I noticed after entering the OR was all the technology that was present. First, there was the anestesia equipment sitting on one end of the operating table that would allow a very complex and dare I say gruesome surgery to be conducted without pain being experienced by the patient. Without this piece of technology such a surgery would simply not be possible. Upon the wall I saw the x-ray, MRI, and CT images all hung up indicating the pathology of the patient. Each of these images represented another technology developed and perfected throughout medical history. Without these images the patients pathology would not be known in such detail if at all before the surgery. This would either extremely limit the surgery or simply make it impossible to perform. Upon a table were numerous metalic tools and screws that would be used to help correct the patients condition. Each of these tools and screws represents some engineers work to develop biocompatiable instruments that would allow the Doctor to effectively maneuver during the procedure. One surgery was also conducted using image guidance to effectively align the screws. This was accomplished through an instrument that used LEDs to track the spine and instruments which were synced with the CT scan data. This allowed the proper placement of the screws during a difficult procedure. This list of instrumentation comes well short of the naming all the technology present in the OR during the spinal operations but gives us an idea of the amount o technology present. Also, I saw how all the technology fed of one another making the other technology more useful. Without the CT scan the image guided surgery was impossible and without the instrumentation the diagnosis of the pathology made by the MRI and CT scan would go untreated. Each new piece of technology not only provides its own advantages but increases the effectiveness of the other technology in the OR.

Future Technology

Despite the all the wonderful technology in the OR. The nurse discussed the need for better treatments for the spine. Simply put, the current technology for treating the spine is "terrible". She said that what is needed is a biological treatment for the degenerated spine. This was extremely exciting to me as my PhD research involves the development of a tissue engineered Intervertebral disc. This really gave me a feeling that I was working on something important and increased my desire to get back into the lab and conduct my research. Hopefully, some day someone will be implanting a IVD implant that will greatly increase the effectiveness of the surgery and the technology that has taken us to this point.

The People

While I have spent the last few paragraphs singing the praises of the technology present in the OR. I must make mention of the incredible people in the OR that are most responsible for the effective use of the technological advances. From the incredibly skilled surgeons to the pleasent knowledgable nurses, they all worked together to make the surgery possible. The anestesiologist effectively put the patient to sleep, the radiologists skillfully read the CT and MRI images, the nurses kept the OR running smoothly, the surgeons expertly cut and drilled to heal the patient, and the technicians kept the technology running smoothly. All of this technology and skill working together was quite impressive and left me feeling quite proud to be involved in such a process.

Monday, July 10, 2006

2nd Week Report- Nerve conduction Studies

2nd Week Report

Nerve Conduction Studies and Needle Electromyography

After 2 weeks of be present in nerve conduction and needle electromyography tests, I have gotten a broad understanding of how these tests work and how the tests help the doctors to diagnostic a patient. So the other day I told my mentor that now I can be in charge of perform the test (at least the nerve conduction test) because the fellow doctor is leaving, but he just laughed. I guess that was a No.
Even though I haven’t perform any test yet, I will explain the principles of electro diagnosis and why this techniques are very useful.

What we want to know?

The patients candidates for electrodiagnosis test (nerve conduction studies and needle electromyography) are those who have neuromuscular disorders. The most common symptoms that the patients complain are pain, weakness or lack of sensation in specific parts of the body.
Using electrodiagnostic the physician is able to respond the following questions:

*localization of the lesion (nerve, neuromuscular junction, muscle)
*fiber type involved (motor or sensory)
*pathology(demyelination or axonal loss)
*level of severity
*temporal course

A little explanation

The nervous system is responsible for sending, receiving, and interpreting information from all parts of the body. Nerves and muscles create electrical signals that deliver messages to and from the brain.

There are two types of cells in the perypherial nervous system, sensory neurons and motoneurons. Thus, there are nerves that the carry the information from the surroundings to the central nervous system (sensory), and other nerves that carry signals from the central nervous system to the muscles. This is important to know because when we perform the nerve conduction test is necessary to know which type of nerve we are looking at.
Injuries or diseases can affect nerves and/or muscles altering the transmission of the information. This is going to be reflected in the bioelectrical signals and measuring the speed and degree of electrical activity in the muscles and nerves can help in make a proper diagnosis.

Nerve Conduction
I will describe in brief this method for a patient in general.
After the patient refer to us, which of his muscles are affected, the doctor associate the nerves that innervate that muscles. Then, we will able to know which nerves we are going to record from. I have to recognize that I don’t know a lot of anatomy and that there are more than 600 muscles which I can not localize them, this become more complicated when I have to learn the nerves that innervate them. But it’s true, that in some nerves we test more frequently than in others. The next picture shows the median and peroneal nerve.
peroneal motor median motor
Then, superficial electrodes are places along the nerve pathway and a electrostimulator. After stimulate a nerve with an electric shock, we capture the signal and time that travel through the nerve. The current applied is not more than 100 mA. But, this is enough to make the patient jump or complain.

The picture shows a patient that has placed electrodes to record from the ulnar sensory nerve while we stimulate the wrist and the elbow.

(images taken from )

Finally the doctor compares the results obtained with those from a healthy subject. The parameters that they look are:

Latency: is the time between the stimulus and the response.

Amplitude: dependent on the number of axons that conduct impulses from the stimulus point to the muscle, the number of functioning motor endplates and the muscle volume. The amplitude is measured from the baseline to the negative peak.

Area: represents a combination of the amplitude and the duration. Reflects the number and synchrony of the muscle fibers activated.

Duration: reflects the synchrony of individual muscle fiber discharges. If there is a significant difference in the conduction velocity among nerve fibers, the duration will be prolonged.

Conduction velocity: is calculated by dividing the length of the nerve segment between the two stimulation points by the difference between the proximal and distal latency. It reflects the fastest motor axons. Rapid propagation results from faster rates of action potential generation, increased current flow along the axons, lower depolarizaion thresholds of the cell membrane and higher temperatures. The Normal velocity is about 40-60 m/s but can increase 2-3 m/sThe conduction velocity is also dependent on the axonal diameter and the properties of the membrane. Conduction velocity increases with myelin thickness.

F-waves: travel from the stimulation point on the nerve to the neurone and back to the muscle. They reflect conduction along the entire nerve. We stimulated 10 times to get the F waves because represent recurrent discharges from different groups of motor neurons with different conduction characteristics

M-wave: when the stimulus reaches the muscle fiber, it elicits a strong muscle contraction(m-wave).

H-reflex: is a monosynaptic reflex that can be elicited by the stimulation of muscle spindle afferents in the limbs.

One quick example

Daily, the patients come to the clinic and we have to discover what is wrong with them. I will mention a random case that we treated during last week.


a 58 women with bilateral thigh weakness, numbness in her feet because she underwent a chemotherapy, She has mild spinal stenosis at L4-L5 and disc bulge at the L5-S1 level. They wanted to assess myopathy and polyneuropathy.

Results from the test:

1)There are left peroneal motor response when recording from the extensor digitorum brevis.
2)A moderately reduced amplitude right peroneal compound muscle action potential. They presented values around 1.2 mV when should be 5+-2 mV. The conduction velocity is slowly as well, it is around 38 m/s when should be around 50 m/s.
3)The tibial CMAPs are moderately reduced. The proximal stimulation elicited tibial CMAP responses are multiphasic suggesting temporal dispersion.
4)The right median and ulnar motor responses are normal
5)The F waves are significant for absent bilateral peroneal F wave responses and mild right tibial F wave minimal latency prolongation, and moderate left tibial F wave minimal latency prolongation. The patient had a minimal latency of tibial Right of 61.3 ms and on tibial Left 68.4 ms when should be around 50 ms.
6)Right median and ulnar F-waves are normal with values of 28 ms and 27.6 ms respectively.
7)Sensory nerve conduction studies are normal in the legs and right arm
8)Bilateral tibial H-reflexes are prolonged.
9)Blink reflex studies are normal

Conclusion from the physician

Slightly asymmetric motor neuropathy process. Left leg is more affected than right. And the right arm is minimally affected. Could be a motor polyneuropathy or a lumbosacral polyradiculopathy. A demyelinating component is suggested by the bilateral tibial temporal dispersion.

Summary of what I did on the week

-See more patients
-Read a lot of physiology and anatomy
-Read about test collisions

Ben Hawkins: Week 2

This week transitioned my experience from the PICU with Dr. Pon, to the NICU, working with Dr. Schulman. Dr. Schulman's rounds included 18 patients in the Neonatal ICU, which seems a little overloaded, as they have expanding into other areas of the hospital. NICU and PICU are both in the Greenburg Pavillion, 6th floor. NICU has expanded also to the 8th floor, where they have annexed another section of the hospital for their overflow. I found a few of their conditions to be interesting, and would like to present a few here.

Patient A
Patient A is a full term child with patent ductus arteriosus(PDA). A PDA creates a left to right shunt, allowing blood flow to bypass pulmonary circulation and pass into the descending aorta.

Complete info on PDA here: Patent Ductus Arteriosus

While the surgery itself is simple and effective as a treatment method. Patient A is not operable due to complications of the condition. He is on an oscillator (high-frequency ventilation), and is having difficulty maintaining oxygenation in his blood (which is a consequence of the PDA, but also means that he would not likely survive the operation).

In order to help him grow and gain strength for surgical repair (ligation), Patient A began receiving steriod treatment. This treatment continued through the week, and his condition improved. His ligation procedure is scheduled for next week.

Patient B
Patient B is another full-term male child. He has a significant respiratory difficulties. While treatment for the symptoms (respiratory problems) is available, the underlying cause is not apparent, and there are other indications that he may have a genetic condition.

I find this case interesting because it involves questions of diagnostic techniques. Initially, the child was treated for his most life threatening symptoms, and he survived due to the doctor's efforts. But to determine the underlying cause, a number of tests must be run. Rather than running tests for every genetic condition that has the subset of symptoms Patient B is exhibiting, there are a few, easier, limiting tests that can point doctors in the right direction. In this case, they wish to test his hair for abnormalities to rule out or limit the scope of genetic tests required.

Friday, I observed an open heart surgery to repair a patient with a Tetralogy of Fallot.

Complete information on Tetralogy of Fallot: Tetralogy of Fallot

Watching this procedure has been one of the most engrossing experiences of the immersion term. In 5 hours, I watched the parents drop off a 13 month old child who was awake and crying, I watched him anesthetized, prepared, opened, repaired, closed, cleaned, and finally returned to the post-op room. The concert of corrdinated movements involved in this procedure is exceedingly complex. From the surgeon's motions, to every doctor responsible for aspects of patient care; I was amazed at the interplay of proceedures at every level.

The surgical procedure begins by anesthetizing the patient, first through an inhalant, then intraveinously as IV's are placed. After the patient is anesthetized and prepared for surgery, the surgeon and his assistant begin opening the chest, cutting through layers of skin, fat, muscle, and bone to reach the heart. In a series of cuts and bypasses, the blood is shunted around the heart through a perfusion machine. After the blood flow has been diverted, the heart is stopped by the application of ice (cryocardioplegia). The heart is then cut into and the repair proceedure is completed. In this case, a Gore-Tex membrane was placed in between the ventricles to repair the VSD (ventricular septal defect). A tissue graft was applied to the experior of the heart to repair the right ventricular hypertrophy (thickened muscle tissue which interferes with blood flow from the ventricle). After the repair is completed the heart is restarted and blood re-introduced to the tissue. Several layers of sutures are applied to close the chest cavity.

NY Times Editorial

Editorial Here

second week

Most of this week has been concerned with trying to get one of two projects done:

The first project has to do with the lens fogging on the da vinci robot. At several times in the course of a surgery the tube ending in camera lenses gets fogged up. The doctors must remove it from the patient, dip it in warm water and return it. It sometimes takes up to fifteen minutes to accomplish probably because if the lens is still too cold when it is put back in the patient it will fog up quickly. The obvious solution is to heat the lens.

The first way Dr Tewari was thinking of solving the problem was heating the top of the stainless steel camera that is inserted into the patient. He hoped that heat would conduct down the tube, and heat the lens. This however ran into a critical problem. It turns out that the heat conductivity of stainless steel is closer to that of glass, than copper. You can actually take a stainless steel rod, hold one end in yaur bare hand, then heat the other end with a blow torch until it is white hot, without burning your hand.

The next idea is to create a sleeve that wraps around the tube, and heats it. I spent a great deal of time looking at commercial heaters and came across a few that seemed promising. First I found band heaters that were intended to be wrapped around a pipe to heat it. For a while I believed that this was the perfect solution to the problem. Then I took a look at the system again. When the tube is inserted into the patient it goes through a port that holds the patient's skin out of the way to simplify the process of getting the lens in and out. That port os only slightly larger than the tube. I have maybe a milimeter clearance at best. So, I must find a heater that is very flat so it only slightly increases the diameter of the tube when wrapped around it. Looking online, and emailing vendors, I found what are refered to as 'flexible heaters.' These heaters come as thin as a thousandth of an inch. From what I can tell there are no physical constraints stopping one of these heaters from being employed. Was it any other application I would buy one, duct tape it to the end, and be done with the project. However talking to vendors I have been unable to locate a flexible heater that is made to be in contact with patients in surgery. This means I may need to buy a heater, then coat it with stainless steel, or some biologically inert material. This scares me a little though so I will probably look a little longer for a commercial product fitting the specifications.

Another easy idea to get around the heating of the lens would be to cool the CO2 that is inflating the patient of the stomach. Condensation will occur when a gas comes in contact with a cooler surface(or the gas is being cooled as in the case of dew). So either the temperature of the surface can be heated, or the gas cooled. While after a bit of presenting my case I was able to convince Dr Tewari that a cooler gas would help the problem he still seemed to prefer heating the lens. My guess is either there is a medical reason for heating the gas, or he has tried it before, although he didn't explicitly say either.

The second project is trying to determine whether the display on the robot is releasing dangerous levels of radiation. I have read a long series of mostly dismissive journal articles, however I have not figured out what machine I would need to use in demonstrating the low levels of radiation explicitly.

Medical Databases, Spreadsheets, and Echocardiograms… Oh My!

So with the 4th of July landing on a Tuesday this year, I was given Monday off by my clinician; resulting in a 4 day weekend! This free time allowed me to head off and explore more parts of the city: window shopping on 5th Ave, meandering about the southern part of Central Park, visiting Rockefeller Center, and of course watching more of the World Cup at the ESPN Zone. A group of us got together to watch the fireworks display on the East River from the roof of Olin Hall, which turned out to be quite amazing. After seeing smiley faces and cubes explode in the night sky, Ben decided that if the whole PhD thing does not work out, he’s going into pyrotechnics.

So after a relaxing weekend, I got up bright and early for rounds again with the cardiology residents and fellows in 4 North. The weekend was quite uneventful for the 4 North staff and there were only a few new patients that had been admitted into the ward, but rounds took three and a half hours to get through (in comparison to last week where they only took about two hours). By the end of the rounds, I was feeling more comfortable in understanding all the acronyms that the doctors were using and was beginning to see the standard methodologies used to diagnose and to treat the conditions that the patients had. After rounds I met up with Dr. Weinsaft and was introduced to the patient medical record database that the hospital uses to store all the medical information on all its patients. The database turned out to be very user friendly and accessing the records was easier than I had imagined it would be ( I guess they want to make it as user friendly to the doctors and nurses which have to deal with it on a daily basis, rather than some convoluted CS major’s personal pet project for a CS database class). Through this database I was able to identify over 350 patients that had obtained a cardiac MRI within the last two years. This I then placed into a spreadsheet and was done about two hours later.

Thursday began again with 8am rounds in 4 North, but this time lasting the normal two hours. After rounds, I met up with Dr. Weinsaft once again and we proceeded to read some cardiac MRI images (diagnosing the condition of the patients, determining where the damage had been done during a myocardial infarction (aka a heart attack), and determining the functionality of the viable tissue.) With a few hours spent in a dark room and looking at a computer screen, I moved to another room with another computer screen and began to do more work on compiling the spreadsheet with the patients that we are going to be using for my project. This time I was cross referencing if the patients also had an echocardiogram done in addition to the cardiac MRI. I’ll describe what an echocardiogram is in the following paragraph. After a few hours spent accessing the database, I finished cross-referencing and cut the list down to about 250 patients. Still a lot of patients, but slowly narrowing down the study group that we are going to work with. Later that evening, I was able to finally obtain internet in my dorm room which made life a lot easier by not having to depend on when the library was open. This no longer gives me the excuse to not get work done since I’m jacked into the whole world 24/7.

Friday morning began as the last few days have begun, with rounds at 8am in 4 North. Following rounds, I was introduced to the echocardiography staff and sat and watched echocardiograms for the majority of the afternoon. An echocardiogram is another non-invasive method to visualize the heart and to obtain important data that can help diagnose what is happening with the patient. An echocardiogram uses an ultrasound machine (exactly the same type as used to visualize fetuses in pregnant women) to take images of the heart in real-time. Unlike SPECT or CT or cardiac MRI, these images are two dimensional and the visual resolution is not as high, but very important data can still be obtained. The patient comes in and lays down on a table and the technician just takes the ultrasound probe, applies a bit of ultrasound jelly to the chest, and begins to image the heart. The advantage over the other three methods of imaging is that the machine is portable (it does not need a whole room specifically devoted to the instrument), its very quick (the whole procedure is done in about 15 minutes), and to capture the image the patient does not need to hold their breath (to capture a clear image with CT/MRI, you need to hold your breath and lay perfectly still, which is a problem for some patients). An example of an echocardiogram image is shown below, and more information can be found here:

After observing eight echocardiograms, I went back to and continued to work on the spreadsheet and continued to narrow down the list of patients that would fit the study. This time I took the 250 patients and read through each medical record to see what type of echocardiogram they had, if the diagnosis had a normal or abnormal heart, and what the EF (ejection fraction: percentage value of blood pumped out from the heart upon systole) value was. From this analysis, I was now able to classify the patients into two groups: those with normal heart and those with abnormal ones. This refined spreadsheet will be analyzed again on Monday and a few more criteria will be added to narrow down the number of patients. From this final spreadsheet, we will choose a number of patients to perform our study on.

This weekend was another adventure in the city with excursions into the central part of Central Park, exploring the West Side of Manhattan, heading to the West side to party at a few clubs, and culminating back at the ESPN Zone in Times Square to watch the Finals of the World Cup. The whole building was packed with French and Italian fans with Italy finally winning with penalty shots. And with that, rounds begin anew tomorrow at 8am.

What is an Arteriovenous Malformation (AVM)?

Once again, here we are. I am over my speechlessness and ready to get everyone up to speed. This week was not as exciting as there were more of the same procedures presented in last week’s blog. Don’t stop reading yet as this was one of the most exciting procedures to date. In the previous blog, I didn’t give much patient information as I have had limited patient interaction. When the patients finally get to the neurosurgical team, their health is fleeting at best.

This patient presented with sharp head pains and loss of consciousness as a result of a seizure. He is a 47 year old Asian-American in relatively good health. After a thorough history, the patient was taken for CT. Upon analysis of the scan, it was found that this patient had “blood one the brain.” After further analysis with MRI, it was determined that the reason for this hemorrhage was AVM. AVM is short for Arteriovenous Malformation and are extremely rare. There are only about 250,000 reported cases. AVMs are abnormal collections of blood vessels in which arteries lead directly into veins, nidus. These blood vessels don’t follow the normal network path using the smaller blood vessels such as arterioles and venuoles. In turn, pressure develops on the arterial end of the vessel causing hemorrhage and swelling. This condition, normally present from birth, presents the most danger from 10-55. If no problems have developed by this time, the chances of problems appearing decrease rapidly. On the other hand, if there has been a hemorrhage during this time, then the chances for more and more intense hemorrhages increases rapidly.

There are at least four different types of treatments for AVMs. Radiation, angiography, surgery and no treatment are all valid choices given the particular circumstances of the AVM. The size, position and complexity of the blood vessel arrangement are all things that must be taken into account.

Now that the requisite background has been given, let’s jump into the amazing case. Based on the factors from the previous paragraph, it was the determined that the best course of action for this particular patient was embolization.

What is Embolization Therapy?

“Embolization is a method of plugging the blood vessels of the AVM. Under X-ray guidance, a small tube, a catheter is guided from the femoral artery in the leg up into the area to be treated.

A neurological exam is performed before and after a small amount of medicine is injected. This can help tell if the vessel that feeds the AVM also feeds normal and important portions of the brain. After this, a permanent agent is injected into the AVM and the catheter removed. This is repeated for each vessel that feed the AVM.”

Excerpt from

So, after getting the patient on the table for the procedure, things went extremely well. The main arteries feeding the AVM were isolated and epoxy or glue was used to close the vessel. This procedure proved be very complex as the angiogram show more vessels than were revealed by MRI. With the information from angiography, a 3D image is generated that obviously gives the physicians a more complete and detailed image. At this point, the game plan changed. Dr. Riina decided to plug as many arteries as possible but the craniotomy would be necessary to give the patient the best chances of a full recovery. Because of the size of the hemorrhage, the patient was scheduled for a craniotomy the next morning.

Briefly, the procedure for attacking an AVM is to clip all the blood vessels that feed the AVM. After clipping, imaging and visual inspection allow the physician to excise the AVM in its entirety. This procedure is much like that of removing a tumor. It is imperative to close off all vessels that feed the abnormal mass or the result can be severe hemorrhaging and ultimately loss of life. Fortunately, Dr. Riina was able to perform the procedure without any complications. The patient is expected to make a full recovery although there will be some discomfort and maybe minimal memory loss.

For your enjoyment, I have enclosed a links to diagrams of an AVM and a movie of an AVM removal via craniotomy, which has two parts.

The image “” cannot be displayed, because it contains errors.

The image “” cannot be displayed, because it contains errors.

Julius N. Korley

Sunday, July 09, 2006

Second Week

This week I have been working with Dr. Winchester in interventional radiology on the 5th floor. Dr. Winchester was incredibly helpful, and introduced me to several other doctors in order to help me find a research project. Dr. Trost (name may be corrected later) mentioned that he was writing a proposal for the study of correlations between stent size and the percentage of patients returning for future operations. This may materialize into a project for me to work on, if he can figure out the logistics.

Meanwhile, I observed Dr. Winchester and other members of the interventional radiology team as they conducted surgeries. On the first day (Wednesday), I watched an ultrasound assisted catheter insertion for a woman admitted with morbid obesity. A stent from a previous operation became infected, and she needed antibiotics delivered to that location. However, due to the large amounts of flesh, traditional methods for catheter insertion proved difficult. Thus, ultrasound was used to guide the insertion of the catheter, and the antibiotics were delivered through it. This led to my having a discussion with one of the senior medical students, who participated in the surgery, about the need for ultraportable inexpensive ultrasound devices. I knew that such research was ongoing, and found a few papers on the subject:

1. IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control. 49 (10), 2002
2. J. Acoust Soc. Am. 114 (3), 2003 - This lists patents for various ultrasound devices

On Thursday, I observed the insertion of a renal stent. This was different from the surgeries I observed with Dr. Wong, since it involved the vasculature on the right side of the patient’s body. Most of the surgeries I observed with Dr. Wong dealt with vessels on the left side of the heart, stemming from the left coronary artery. Some of the equipment malfunctioned during this procedure, and it had to be repaired on the fly.

On Friday I observed Dr. Thomas use ultrasound and angiography for diagnosis. He gave detailed information to the medical students about the art of forming good images. The equipment technician in the room mentioned to me that different people have different techniques, and that the procedure I witnessed was not set in stone. I noted the similarity to Secondary Electron Microscope (SEM) operation, where the skill of the operator greatly affects the quality of the image.

A brief description of stents:

A stent is a wire mesh used to give support to blood vessels after they have been expanded in an operation. There are two types of stents, self expanding and balloon expanding. Both are packaged in a compressed state before use in an operation. The balloon expanding stents are compressed plastically, while the self expanding stents are compressed elastically. The operations I witnessed all used balloon expanding stents. Once a stent is inside of a blood vessel, pressure from a balloon causes the stent expand, until it is deformed plastically. Stresses from blood flow may cause the stent to continue to expand to some extent.