by Holly Paauwe
Hello. My name is Avery. I am almost 3 years old now. I have undergone 3 brain surgeries in my short life to remove the left cerebral cortex of my brain. The procedure is called a hemispherectomy. Why did I undergo such a drastic surgery?
You’ll have to read on to find out!
I entered the world on July 17, 2005. Within hours of my birth, my Mommy and Daddy knew something was not quite right with me. I was sent to the nursery that first night for observation by the nurses. By the next morning, they came to tell Mommy and Daddy that I had what they suspected were seizures during the night. After reviewing my CT scan, the pediatrician stopped in to talk to us. She said that it looked as if I had a condition known as hemimegalencephaly (I can't pronounce it either!), commonly referred to as HME for short. She couldn't offer us a whole lot more information, but she was very kind to us all. Since the hospital was not equipped to deal with such a potential diagnosis, they sent me to the neonatal intensive care unit at the James Whitcomb Riley Children's Hospital in Indianapolis, Indiana. It was there that I spent the next 3 weeks of my life and where my diagnosis was confirmed.
Specifically, I have left-HME. Hemimegalencephaly translates to "half big brain" in medical terms. My "big" half is the left half of my cerebral cortex. It is a problem of cortical brain development. For whatever reason (some people at Walsh Labs are investigating this "reason" now), the left side of my cortex did not form properly. This is why I was having all those seizures. The epilepsy that results from HME is intractable in almost all cases. Sometimes it is intractable early on (like in my case); in fewer instances it may be controlled with medications for a few months or even a few years. When I came home from Riley, I was having 100 clinical seizures per day! On my best days before surgery, I was having 7-15 per day…and that doesn’t count any subclinical seizure activity that can only be seen on EEG.
Because I was born with this malformation, I had and still have a lot of developmental delays and a hemiparesis of my right-side. I do move my right leg pretty well, but I struggle a bit more with moving my right arm, and especially my right hand and its fingers. This is typical of HME kiddos. I also have some tone abnormalities; some doctors call that cerebral palsy (secondary to HME). With all the seizure activity that was going on in my brain, my brain activity had a hard time really reaching a normal baseline. Also, because I was on so many medications for the seizures, I and my brain in general were often pretty sedated. Both of these things made it very hard for the "good" parts of my cortex (i.e my right cortex) to function normally. That's where the hemispherectomy came in.
A hemispherectomy is the removal of one-half of the cerebral cortex. A hemispherectomy can be anatomical or functional or some combination of both. In the anatomical version, the surgeon actually removes that brain tissue of the affected side. In the functional type, the surgeon removes only the temporal lobe and then simply neurologically disconnects the bad side of the cortex from the good side so that it, hopefully, can no longer affect the good side or send signals to the rest of the body. The combinations of the two are variable and ever changing. Some children, like me, have to undergo several surgical internevtions to fully complete the hemispherectomy. Sometimes, neurosurgeons start with a functional type because of the reduced risks of that particular surgical procedure. For some kids, that alone is successful…at least for a time. In my case, the functional was not enough and I had to go back in to the OR only 2 ½ weeks later for a 2nd surgery to begin the anatomical hemispherectomy. That surgery allowed me to be seizure free for almost 8 months. Then, last summer (2007), I had a return of seizure activity and it slowly ramped up to be a concern. In February 2008, I went back for the 3rd surgical intervention. During this surgery, the surgeon worked to remove the occipital lobe that remained on my left side (which was the origin of all the seizures I was having at that time).
The main purpose of the hemispherectomy, from a surgical standpoint, is seizure cessation. Seizures cessation is not always achieved for various reasons, but significant reductions in seizures and severity are nearly always achieved. The improvements that are often seen in development (motor, speech, cognitive) post-surgery are mostly a side-effect of seizure cessation or reduction. While developmental prognosis is not the driver for such a radical surgery, it can't be ignored. The theory is that, because the infant and young child's brain is very “plastic”, a lot of what is lost with removal (or often simply never present to begin with due to the malformation of the HME side itself) can be picked up by the normal side (hopefully composed of normal functioning neurons and helper cells). Pretty COOL huh? Everything I am doing today is coming from my good side and my last EEG showed normal brain activity for my age on that side. That is great! Not everything can transfer over though.
Vision does not transfer. For that reason, children like me have what is called a visual field cut (loss). For me, it is a right field cut. You see, each eye has a right and left field of vision, each of which are controlled by the contralateral (opposite) side of the cerebral cortex. So, after surgery, I don’'t have vision in the right field of each eye (version 4 or 5 on the diagram).
Sounds scary, huh? Well, luckily, children learn to compensate well. Essentially, the only perceived loss should be in my right peripheral vision. That would mean that I will have to turn my head to my right to see anything on that side; it will be my blind side. Funny enough, my vision is likely improved overall from what it was prior to these surgeries. Because of the seizures and my malformed cortex, and even though we know that some visual signals are being received by the brain, I was also diagnosed with what eye doctors call cortical vision impairment. This means that, even though my brain may be receiving visual signals, it may not be properly interpreting what it "sees" or do so consistently and accurately...though this is changing with time and therapy. Most everyone feels confident that I do "see" things, they just aren't sure that I "know" what I see because I am not able to tell them. I am starting to show them clues that indicate that I do know now, suggesting that the CVI is improving. To top it all off, there is also a concern about the potential for functional vision in my left eye as a whole because an ophthalmology exam revealed some physical abnormalities in that eye. The doc had said that I may have little no functional vision in the left eye. This may mean that I only have functional vision in the left field of my right eye. Time will tell us all more about that. I think I might surprise them all. Kids have been known to have more functional vision that anyone would expect given the extent of their brain injury, malformation, or resection.
The other things that are physically apparent after a hemispherectomy are due to the resulting hemiparesis of the contralateral side. One is a "limp" caused by a gait problem with the opposite leg (that would be right leg for me). That's right, hemispherectomy kids can walk with only half-a-brain! Some learn to do it faster than others for various reasons, but it seems all eventually learn to walk. I’m obviously behind schedule, but it is not impossible if I work hard. The other thing that occurs has to do with the opposite hand. While most hemispherectomy kiddos can move the opposite arm at the shoulder and elbow, there is much less gross and fine motor control in the hand of that side. They learn to do things one-handed in a two-handed world. My Mommy got to see demonstrations of this first-hand at the Hemispherectomy Reunion we attended in Baltimore in July of 2006. We met several kids like me (with HME) there, as well as other hemispherectomy children. (You see, hemispherectomies are also performed for other brain problems that result in intractable epilepsy, such as Rasmussen's Encephalitis, cortical dysplasia, Sturge-Weber syndrome and strokes). They were all amazing!!! All the older left-sided HME children we met were walking and TALKING post-surgery. That's pretty amazing since language usually comes from the left side of a person's brain.
Cognitive abilities post-operatively run the full spectrum. For HME, the spectrum is typically a little narrower (and not quite as good) than it is for some of those other conditions. I do still experience seizures at this point in time, but they are less severe, shorter and less frequent than they have ever been at each prior stage on this journey. I am currently weaning from the medication Phenobarbital, which I have continuously taken ever since I was only a few hours old. We are all excited to see what possibilities that will open up for me…not having the good side of my brain so drugged too!
To be sure, the remaining journey before me and my family is going to be long and hard…but, I am going to fight for everything I can and my Mommy and Daddy and other family and friends will challenge me and provide lots and lots of stimulation to help my brain pick up and retain as much as possible. I think I will do better that anyone can anticipate. I certainly will try hard! I'm looking forward to each new day!.
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