ND Lesson 2.5 Jigsaw Case Study #1 Gabby Gabby is 5 years old. Her parents have consulted with many specialists throughout their daughter s life in hopes of finding an explanation for why their daughter behaves so strangely. Gabby s parents first knew that something was wrong when Gabby was only a few months old. Like other babies her age, she was teething. But unlike other babies, who would cry in pain, Gabby never cried. One morning, her father noticed that she had been chewing on her fingers so much that they were bleeding, but again, she never cried. Her mother described Gabby s hand as mangled and nasty, like raw hamburger on her hand. After consulting with several doctors, Gabby s parents had all of her baby teeth removed so that she could not further harm herself. When Gabby was a year old, her mother noticed a white spot on her left eye. She thought it was just something floating in Gabby s eye, but in fact Gabby had somehow scratched her eye. The doctor who treated Gabby told her mother that In most patients, this type of wound would be so painful; they would not be able to open their eye. To prevent Gabby from further scratching her eye, the doctor stitched that eye closed. But, unable to feel pain, Gabby ripped out the stitches. These are just two of the incidents that brought Gabby s parents into see a neurologist for further examination. The doctor diagnosed Gabby with congenital analgesia. Congenital analgesia is a very rare inherited disease in which children, usually from birth, cannot sense pain but maintain their other senses. Like Gabby, children with this disease often suffer from oral damages, like biting off the tip of their tongue, and scratches to the cornea. Researchers have learned that the disease can be caused by a mutation in the SCN9A gene which codes for a voltagegated sodium channel. This voltage-gated sodium channel is found in nociceptors, the specialized receptors that detect pain. In a normal patient, when the nociceptors dendrites detect a pain sensation, the voltage-gated sodium channel amplifies the signal to reach threshold so an action potential will fire. However, for patients with congenital analgesia this voltage-gated sodium channel is unable to function and thus the input from the dendrites never signals an action potential. Patients with congenital analgesia will never lead a normal life. Because patients do not detect pain, they need to closely monitor their bodies for injuries and infections. Congenital analgesia is not fatal, although complications that arise because of inability to feel pain mean that very few patients with this disease live a normal life expectancy.
ND Lesson 2.5 Jigsaw Case Study #2 Mitchell Mitchell is 17 years old and recently noticed that he has been constantly tripping. As he paid more attention, he noticed that he was having difficulty raising his legs to walk. Since he thought this was odd, he mentioned his observation to his doctor at his yearly physical. His doctor asked him to stand up, and then lift just his toes. Mitchell had a really difficult time doing that. The doctor prescribed physical therapy and asked Mitchell to make another appointment if his symptoms got worse. A year later, Mitchell s problem continued. He felt the muscles in his legs were often weak and quite stiff. He also noticed that his sense of balance was not what it once was. Sometimes his legs even felt numb. He called the doctor and returned for another appointment. After many tests, including an MRI to rule out other neurological conditions, Mitchell s doctor diagnosed him with hereditary spastic paraplegia (HSP). HSP is characterized by progressive spasticity, defined as stiff or rigid muscles, in the lower limbs. Patients can also experience bladder disturbances, and impaired sensations in the feet. HSP can develop at any age. Those patients who develop symptoms before the age of 35 have Type 1, and those patients that develop symptoms after 35 have Type 2. For type 1 cases, delayed walking is infrequent and spasticity of the lower limbs is greater than weakness of lower limbs. However, in type 2 cases muscle weakness, urinary symptoms and sensory loss are more pronounced. Mitchell s doctor referred him to a specialist who was studying the genetic causes of HSP. The specialist completed a genetic screen on Mitchell to determine if he was a carrier of the mutation his lab studied. As it turned out, Mitchell did carry a mutation within the specialist s gene of interest, KIF5A. KIF5A is a member of the KIF5 family of kinesins. Kinesins are motor proteins that carry cargo to the axon terminal. Research has demonstrated that mutations within the motor domain of KIF5A can cause HSP because axonal transport is disrupted, which causes disruption to axonal function. There are currently no treatments to slow or reverse HSP. However, regular physical therapy is important for muscle strength and to preserve range of motion.
ND Lesson 2.5 Jigsaw Case Study #3 Albert Albert is 67 years old. He was diagnosed with type II diabetes almost 17 years ago. Despite going on a diet and exercising, Albert is still hyperglycemic, with high levels of glucose in his blood. While he has tried to manage his blood glucose levels, Albert has never successfully gotten them under control. During the last year, Albert noticed a tingling sensation in his feet. Since he is getting older, he did not think much of it. However, when the tingling sensation developed into a deeper pain, he called his doctor. The doctor did a complete examination including testing Albert s ability to detect sensations in his feet using a monofilament. When Albert did not perform well on this test, the doctor told him he has likely developed diabetic neuropathy, a condition that commonly occurs in patients with diabetes 10 to 20 years after their initial diagnosis. A common complication of diabetes, diabetic neuropathy is a condition in which nerves are damaged as a result of hyperglycemia. Diabetic neuropathy can present with any number of symptoms, including tingling or burning sensations in the feet, a deep pain in the arms or legs, muscle cramps, loss of sensitivity to warm or cold, loss of bladder control, and vision changes. The symptoms vary depending on which nerves are affected. Usually feet and legs are affected first, followed by hands and arms. While it is possible to slow diabetic neuropathy, the disease is incurable and prognosis usually depends on how well blood glucose levels are maintained. Researchers have learned that diabetic neuropathy occurs when the blood supply to nerves is reduced. Over an extended period of time, high blood glucose levels damage blood vessels. Damaged blood vessels are less able to deliver oxygen to peripheral neurons. Lack of oxygen to nerves is highly stressfully and reduces their ability to generate ATP. Since fast axonal transport is dependent on ATP, it is specifically vulnerable in diabetic neuropathy. When axonal transport is compromised, the terminal degenerates, resulting in decreased sensitivity and motor control. While there is no cure for diabetic neuropathy, the goal of treatment is to minimize the symptoms and prevent the disease from getting any worse. Control of blood glucose levels is of prime importance, and some medications can be used to help reduce the symptoms in the arms and legs.
ND Lesson 2.5 Jigsaw Case Study #4 Allison Allison is sixteen years old. Recently she noticed that she is having a difficult time walking. Her feet and legs do not seem to be as strong as they were even just a year ago. Allison considers herself to be in good shape, but lately on her daily walks, she has been having a hard time breathing and is frequently tripping. During her yearly physical she mentioned these difficulties to her doctor. Allison s doctor asked questions about her family history. Allison s knew that her uncle has a disease called Charcot-Marie Tooth Disease (CMTD). Her uncle s disease was diagnosed when he was in his early 20s and has made it difficult for him to walk and perform fine motor tasks with his hands. Concerned that Allison might be developing CMTD, her doctor examined Allison s lower legs. Allison s doctor noticed that Allison s lower legs have taken on an inverted champagne bottle appearance due to loss of muscle bulk. Allison s doctor also tested her tendon reflexes and sensory perception. Given Allison s family history and performance on these tests, the doctor ordered electrodiagnostic tests. The electrodiagnostic tests examined the ability of Allison s peripheral nerves to conduct an action potential. The tests are completed by placing electrodes on the skin. These electrodes produce a small electric shock which stimulates sensory and motor nerves. A needle, inserted into the skin, measures the ability of Allison s nerves to conduct an action potential in response to the small electric shock. Unfortunately, Allison s readings on this test indicate that her axons are not conducting action potentials as quickly as normal patients. Given her family history, and her results on the electrodiagnostic test, Allison s doctor diagnosed her with Charcot-Marie Tooth Disease (CMTD). CMTD is the one of the most common inherited neurological disorders. CMTD is commonly diagnosed when patients are in their teens or early twenties. CMTD is caused by damage to the myelin sheath around peripheral nerves. Usually, the motor nerves in the legs are affected first, causing lower leg weakness and muscle atrophy. The degeneration of sensory nerves results in a reduced ability to sense heat, cold, and feel pain. In later stages of the disease similar symptoms may appear in the arms and hands. The severity of the symptoms is variable between patients. CMTD is not fatal and patients with most forms of the disease have normal life expectancy. While there currently is no treatment, orthopedic shoes and braces may help patients to walk. Physical and occupational therapy are also helpful for many patients because therapy helps to maintain muscle strength and independent functioning.
ND Lesson 2.5 Jigsaw Case Study #5 Maria Maria is 37 years old. She has been having reoccurring episodes of muscle weakness in her arms and legs. The weakness lasts for a week or two and then subsides. At other times she noticed numbness in different parts of her body. Since the episodes came and went, she did not think much of it until she started having visual changes. First, she noticed that she was experiencing double vision, and then she noticed that she was having problems seeing out of her left eye. It was at this point that Maria called her doctor. Maria s doctor started the appointment by reviewing Maria s family history, in which there are no cases of neurological disease. The doctor then gave Maria a thorough examination. First, the doctor checked her eye reflexes and noted that her left eye had a decreased pupillary reflex. Next, the doctor checked Maria s sensation which was also decreased in different parts of her body. The doctor ordered both an MRI to see if there were any abnormalities in Maria s brain, and a spinal tap to see if there were any abnormal proteins in Maria s cerebrospinal fluid. The MRI showed a couple of small plaques in Maria s brain, and the spinal tap detected a high level of antibodies. The doctor gave Maria a preliminary diagnosis of multiple sclerosis, but told her that to confirm the diagnosis; he would need to follow her condition and rule out any other neurological abnormality. Multiple sclerosis (MS) can be seen at any age, but is most commonly diagnosed between the ages of 20 and 40. The disease affects more women than it does men. Multiple sclerosis is caused by damage to myelin within the central nervous system. The CNS myelin is damaged because the immune system attacks it. Repeat episodes of inflammation can occur anywhere in the brain, optic nerve and spinal cord. The symptoms of MS vary based on the location of inflammation. Additionally, the duration and intensity of any episode is dependent on the length and severity of inflammation. The most common symptoms of MS include visual disturbances, weakness in the arms or legs, loss of balance, muscle spasms, and numbness or abnormal sensations in arms and legs. Many patients experience periods without any symptoms, and during those stages they are said to be in remission. The life expectancy of patients with MS can be normal or almost normal even though the disease is chronic and incurable. Most patients with MS continue to walk and function normally with minor disability for 20 or more years. Most patients return to normal or near normal function between attacks. But overtime, there is a greater loss of function with less improvement between attacks. Patients at later stages of disease may require a wheelchair to get around. While there is currently no cure for MS, treatment aims to slow the disease progression and lessen symptoms.
ND Lesson 2.5 Jigsaw Case Study #6 Yumiko Yumiko is 66 years old and is feeling incredibly forgetful. She thought her forgetfulness was just part of normal aging but lately her family has expressed concern. At a recent family dinner, Yumiko could not remember the name of her favorite dessert chocolate mousse pie. She also had difficulty remembering how to get home from her son s house. Then, later that week she had to ask for help to balance her checkbook, something she used to do all the time, often without a calculator. When Yumiko saw her doctor, she described her symptoms and asked if her family s worries were reasonable - that her forgetfulness was not normal, but instead something to be concerned about. The doctor asked her a series of questions about her memory, including whether or not she was having difficulty with language, abstract thinking, and misplacing things. He also asked whether or not she had noticed any changes in her mood or behavior. Yumiko reluctantly answered that yes in fact she had been experiencing all of those things to some degree. The doctor told Yumiko that yes, in fact these symptoms, together with her age were cause for further testing. He did a complete physical exam and ordered a thorough neurological exam. The test results ruled out a brain tumor, stroke, and thyroid disease, which all could also cause the symptoms Yumiko was experiencing, so the doctor gave the diagnosis of Alzheimer s disease (AD). Alzheimer s disease is the leading cause of dementia in the elderly. It is estimated that ten percent of people over 65 have AD, and that fifty percent of those over 85 have the disease. AD affects memory, thinking and behavior. Problems with memory, as well as impairments with language, decision-making ability, judgment and personality are necessary features for the diagnosis. AD is caused by an increase buildup of neurofibrillary tangles within the cell bodies of neurons as well as amyloid plagues within the synapse. Researchers have discovered that when plagues develop within the synapse, neurons are not able to communicate with each other. Perhaps due to this lack of neuronal signaling, or perhaps due to the accumulation of tangles within the neural cell body, neurons start to die. Patients with AD often die earlier than normal, although a patient may live anywhere from 3 to 20 years after the diagnosis. The final phase of the disease, in which patients no longer understand language, recognize family members, and are unable to perform basic activities of daily living, may last from a few months to several years. Death usually occurs from an infection or failure of other body systems. While there is no cure for AD, treatment focuses on slowing the progression of the disease.