Evaluation Purpose and Procedures
Families that come to San Antonio will go through a series of clinical evaluations. Even if the study participant has already had these evaluations in his or her hometown, we repeat the evaluations in San Antonio. This enables the same team of health care providers to perform the same sets of evaluations using the same protocols and procedures. This is important in ensuring that the data collected is reliable and meaningful. This page describes the various procedures that may occur during this visit as well as the purpose of these various procedures.
MRI
Purpose: To learn more about how a chromosome 18 change affects the structure of the brain. The MRI uses magnetic fields to produce detailed computer generated images of the brain.
Procedure: The MRI is performed at the Research Imaging Institute at UT Health San Antonio. This MRI is very similar to an MRI that might be ordered by a physician in a hospital. The main difference between a standard MRI scan and the MRI performed at the Research Imaging Institute is the data analysis that follows the MRI.
The MRI takes about 2 hours. It requires that the research participant lies on a table that is moved into the center of the imager. The imager makes a series of very loud clicks as well as a loud humming noise while it is working. There is a television screen inside of the imager, and videos can be played during the scan. Special earplugs or headphones and padding will be provided to reduce the noise and to help the research participant stay motionless and comfortable. If being inside the imager is difficult, the MRI scan can be stopped.
In some cases, the research participant is not able to lie still for the entire test. In this situation, we typically provide a medicine to help them relax and sleep. This medicine is called chloral hydrate and has minimal side effects. In a very small number of patients, chloral hydrate has been associated with skin rashes (2 cases in 196,134 patients) and breathing problems (1 case in 196,134 patients). If chloral hydrate is used to help the research participant relax, there will be a nurse present to monitor the participant.
Endocrinology
Purpose: To examine how the pituitary gland (a part of the brain) and other glands, such as the thyroid, function in individuals with a chromosome 18 change. These glands produce hormones which are important in growth and muscle strength. These hormones also play a role in immune system function; bowel and bladder function; and sleep patterns.
Procedure: The procedure for testing pituitary function is called a provocative test. It is called a “provocative” test because certain medications must be used to “provoke”, or force, the pituitary gland to release various hormones into the blood stream. These tests require the placement of a needle within a vein to allow multiple blood samples to be drawn over the course of several hours. An anesthetic cream can be used to reduce the pain associated with insertion of the needle, if requested. The needle has a tiny piece of tubing attached to it. This device (the needle and the tubing) is called a “heparin lock”. In most cases, the heparin lock can be used throughout the testing process. However, if the heparin lock stops functioning at some point during the testing, it may need to be replaced. Placement of the herparin lock may cause bruising or tenderness at the site after it is removed.
As mentioned above, testing growth hormone function requires administration of medicine to stimulate pituitary function. There is no single medication that can cause all the pituitary hormones to be produced at once. Therefore, different medications must be used. These medicines are either administered orally or through the heparin lock.
Please note that, if the study participant is pregnant, she can not take part in some of these tests. We will perform a pregnancy test before the other tests are performed. We do not know the effects the various testing drugs (TRH, CRF) may have on an unborn child.
In addition to the blood tests discussed above, x-rays will also be taken of the study participant’s hands. This x-ray is completed in order to determine bone age. Bone age is a measure of the maturity of the bones of a person. This information gives researchers information about growth in people with chromosome 18 changes.
Lastly, it is important to note that not every test is appropriate for every individual. Decisions about which tests will be offered to the study participant will be based on the study participant’s age, condition, and medical history. The reasons for doing or not doing each test will be explained.
Orthopedics
Purpose: To learn more about how a chromosome 18 change affects bone development.
Procedure: The orthopedic evaluation involves a physical examination by an orthopedic surgeon as well as a series of x-rays. X-rays will be taken of the feet, knees, pelvis, the spine, the skull, the forearm, and the chest.
X-rays expose the body to small amounts of radiation. However, the amount of radiation that the participant is exposed to is very small. It is about the same as a person would ordinarily be exposed to naturally in our environment. Also, it is important to realize that the x-rays performed at the Chromosome 18 Clinical Research Center do not use any more radiation than those that are performed in routine clinical practice. Nevertheless, if there has been other x-rays or radiation exposure within the last year, this part of the evaluation may not be completed to ensure that the patient is not exposed to too much radiation in a short time frame.
Ophthalmology
Purpose:To learn more about how a chromosome 18 change affects the eyes and vision.
Procedure: The ophthalmology examination completed at the Chromosome 18 Clinical Research Center is similar to those examinations that might be completed in the participant’s hometown. First, their visual acuity will be evaluated. This means that they will be evaluated for near-sightedness and far-sightedness. A slit lamp will be used to examine the health of the anterior (front) part of the eye.
In addition, participants will have their eyes dilated. This allows the physician to examine the health of other parts of the eye, including the cornea, iris, and retina. Dilation of the eye requires the use of 2 or 3 eyedrops per eye.
If the study participant is an adult or a cooperative teen, a glaucoma test will be completed. A topical anesthetic is used to numb the eye for this test.
Genetics
Purpose: The purpose of the genetics evaluation is to determine whether people with chromosome 18 changes have different physical characteristics from people who do not have chromosome 18 changes.
Procedure: The genetics evaluation involves a physical examination. The physician will take a series of measurements as well as photographs. If your child’s pictures are used in a publication, you and your child will not be identified in any way. The evaluation takes between 30 minutes to an hour.
Neuropsychology
Purpose: The goal of neurocognitive and behavioral evaluation is to learn more about the cognitive, memory, attentional, behavior and social emotional development of persons with chromosome 18 changes.
Procedure: The four- to six-hour one-on-one evaluation involves the administration of a series of standardized tests. These tests are tailored to the participant’s age and ability level. The relevant domains always assessed include intellectual and executive functioning, memory development, attention capacity, language and motor skill development and social/personality development. We also assess for the presence or absence of autistic spectrum disorders. Parents/guardians, and study participants if they are able, are asked to provide information regarding participant’s past and current development. The overall aim is to provide a comprehensive evaluation using multiple instruments from multiple informants.
Hearing
Purpose: The purpose of the hearing evaluation is to determine whether there is any hearing loss present in the study participant. If there is hearing loss, these evaluations will tell us more about the type and degree of hearing loss.
Procedure: The hearing evaluation is comprised of several different tests and procedures. These are outlined below.
Behavioral Audiometry. This test determines the softest tones and the quietest speech that the participant can hear when listening in a quiet room. This test also determines whether the participant can repeat words at a level that is easy to hear. This test takes about 30 minutes.
Intermittence Audiometry. This test involves the placement of an eartip in the ear canal. A sound is transmitted through this tip. The tester will measure how much sound is conducted through the ear by measuring the movement of the eardrum. As a part of this test, the air pressure in your child’s ear will be changed in order to measure how this affects the sound that is conducted. This test is used to determine the volume of your child’s ear canal and whether your child’s eardrum and middle ear bones function normally. It will also give us information about whether your child has fluid in the middle ears. This test will take about 5 minutes.
Otoacoustic Emissions. A healthy inner ear not only can “hear” a sound, but will also make an “echo” of that exact sound, which can be recorded in the ear canal with a microphone. This test is done in two ways. The first involves stimulating the ear with a click presented many times per second while the response is recorded. The second involves stimulating with two tones of differing frequencies and recording the response. Both tests can be done in under 5 minutes and involve the placement of a soft probe tip in the ear canal that both stimulates and records responses.
Auditory Brainstem Response (ABR). This test measures the brainstem’s response to sound. The ABR measures electrical activity of the hearing nerve in response to sound. This test provides information about the health of the nerve pathways that carry sound information to your child’s brain. Your child will need to lie still for approximately 45 minutes while responses to clicks are measured. Your child will hear some of the sounds through earphones and some of the sounds through a vibrator. The responses are measured through small metal disks that are attached to the scalp and connected to the measuring instrument by wires. This test does not cause pain or discomfort. However, sometimes, the participant is unable to lie still and relaxed for 45 minutes. In this situation, we typically give the child a medicine to help them relax and sleep. This medicine is called chloral hydrate and has minimal side effects. In a very small number of patients, chloral hydrate has been associated with skin rashes (2 cases in 196134 patients) and breathing problems (1 case in 196134 patients). If chloral hydrate is used to help the research participant relax, there will be a nurse present to monitor the participant. The complete ABR test including set-up takes about 60 minutes.
Gastroenterology
Purpose: The purpose of the gastroenterology evaluation is to learn about problems with the digestive tract in people with chromosome 18 changes.
Procedure: The gastroenterology evaluation involves a detailed medical history and a physical examination by a board-certified pediatric gastroenterologist.
Neurology
Purpose: The goal of the neurology evaluation is to determine whether people with chromosome 18 changes have any neurological problems. It will evaluate the study participant’s balance and coordination.
Procedures: The neurology evaluation involves a detailed medical history and a physical examination by a board-certified neurologist.
Dental
Purpose: The goal of the dental examination is to learn more about tooth development in people with chromosome 18 changes.
Procedure: As a part of the dental evaluation, the study participant will undergo a visual examination of the teeth. X-rays will also be taken of the teeth. This evaluation will be completed by a dentist and will take about 30 minutes.
Speech and language
Purpose: The purpose of the speech and language evaluation is to study how chromosome 18 changes impact the way in which people form speech sounds and express themselves through language. Our goal is to learn more about the nature and cause of speech delays in people with chromosome 18 changes.
Procedure: The study participant will be evaluated by a series of standardized speech and language tests. The evaluator will also pay attention to the way that the participant talks to learn about how they form speech sounds. The results of this evaluation will be compared to results from people without a chromosome 18 change to better understand the precise impact of the change on speech and language development.
GAIT Lab
Purpose: The purpose of the GAIT lab evaluation is to create a detailed description of the gait patterns of people with chromosome 18 changes. Basically, we want to learn more about how people with chromosome 18 changes walk. This will inform decisions about orthopedic interventions, physical therapy, and other treatment options.
Procedure: This study will be performed in the GAIT lab. The GAIT Lab is located in the Audie Murphy Memorial Veterans Hospital. The purpose of the lab is to bridge the gap between the biomechanical engineer (who studies movements) and the clinician. The GAIT Lab is a 1200 square foot space. It is equipped with specialized instrumentation to capture the mechanics of human movement. The Vicon MX Motion Analysis system® incorporates ten high-speed digital video cameras to capture three dimensional body movement. There are five force plates that measure the amount and direction of force that is required for the person to move. There is an EMG Analyzer that measures muscle activity. Lastly, we have a sophisticated, networked computer hardware and software system that combines all of these measurements to create a computer image of the individual moving. From this image, we can learn many different things. For example, we can determine how much the individual’s knees bent or rotate as they swing their leg forward; how symmetrically they move their limbs as they walk; their walking speed and degree of balance; what muscles are most active; and what magnitudes of torque/force are exerted on their joints as they walk.
During the evaluation, the study participant will be outfitted with recording electrodes that are placed on the skin’s surface over the participant’s leg muscles. These electrodes are held in place by Co-Band (a sort of elastic Velcro). They indicate and record when a muscle is contracting or relaxing. Additionally, small, 14 mm Styrofoam reflective markers are taped to the arm and leg joints, torso, and head. These markers are used by the camera and computer system to track the participant’s body movements.
The study participant will be asked to walk across the laboratory space at their normal speed and then again at a faster walking speed. Finally, the participant is directed to walk along a designated path. As the participant walks and strikes the force plates, the amount of force generated as they move forward is captured and combined with the information from the marker tracking. Together, this provides us with measures of the forces that act on their joints.
All this information is collected simultaneously as the participant walks across the laboratory space. Once enough data is collected, all the recording instruments are removed and we begin to process the data. Data processing typically takes 2 to 3 hours. The data is then interpreted by an expert in computerized gait analysis. This expert will consider the information gained from the evaluations as well as the information obtained from a physical exam. Taken together, these data will provide researchers with information about how people with chromosome 18 changes walk.
Psychiatry
Purpose: The goal of the psychiatric evaluation is to learn if individuals with chromosome 18 changes are at risk for different psychiatric conditions, such as depression or ADD.
Procedure: The evaluation involves an interview with a psychiatrist. This interview will involve questions about your family history, as well as the study participant’s medical and developmental history. The interview will take between 30 minutes and three hours to complete.