Pathology
Parkinson’s disease is a medical condition, which can cause extensive brain damage. Patients with this illness often experience difficulties with walking, balance, and coordination. The development of the disease transpires over a prolonged period of time, as it can last for years and sometimes decades. The most alarming aspect of this illness is that it cannot be cured with contemporary medical solutions (Brogley, 2019). Treatment can improve the symptoms, but the ultimate outcome is complete degeneration of neural cells to the point where a patient can no longer mover, write, or speak. In any case, Parkinson’s disease negatively impacts the quality of life.
Human brain has many areas and structures responsible for the execution of vital body functions. One such part is substantia nigra, which is situated in the midbrain. It contains large quantities of dopamine neurons, which project to another area of brain – striatum. The connection between striatum and substantia nigra is called nigrostriatal pathway. Once the majority of dopamine neurons die, a person begins to experience movement problems. When Parkinson’s disease develops, some of the neurons on the nigrostriatal pathway die. Substantia nigra sends signals to the thalamus, which in its turn affects the motor cortex. If the number of dopamine neurons is not sufficient, thalamus cannot properly activate the motor cortex to generate sufficient movement. In the deceased patients, lewy bodies are found in the place of dopamine neurons (Ball et al., 2019). Their function and purpose is still not clear, which constitutes one of the reasons for the lack of cure.
Aside from Alzheimer’s diseases, Parkinson’s disease is the number one cause of movement impairment in patients worldwide. Ball et al. (2019) write that there are at least 10 million patients with this condition around the world, which constitutes “1–3% of the global population aged over 60 years” (p. 1) There is also statistical evidence that men are more prone to contracting Parkinson’s disease, which is explained by men’s overall greater urge to “to engage in sensation-seeking and impulsive behaviours than females” (Riley et al., 2018, p. 4). Also, there is genetic predisposition as the disease can be inherited. Overall, the primary demographic are men over 60 years old with a family history of Parkinson’s disease.
The most common recognizable sign that a person has Parkinson’s disease is the loss of movement. The reason for the mobility impairment lies in the loss of dopamine neurons in the brain. However, brain damage can also lead to psychiatric problems, namely depression, cognitive problems, such as memory loss or trouble with concentration, and other limitations, including the loss of smell and sleep disturbance (Park et al., 2020). The disease progresses gradually starting from slight tremor and ending with severe loss of movement.
Diagnostic Pathway
Patients who are suspected to have Parkinson’s diseases are presented with slight movement difficulties. For instance, it can a tremor in a hand, muscle rigidity, and overall slowness. All of these symptoms can indicate entirely different conditions, yet the older the patient is the more it is likely that these signs of Parkinson’s disease (Verschuur, 2019). The diagnosis begins with inquiring questions, such as family medical history and list of health complaints. Specifically, the patient is asked whether they have experienced difficulties initiating movements and resting tremors. As all of these are also symptoms of other medical conditions, the presence of a combination of them is symptomatic of Parkinson’s disease.
It should be noted that lab tests are not used for diagnosing Parkinson’s diseases. The reason for this is that this condition can not be confirmed via blood tests or brain scans. They can rule other conditions out, but there is no way to use the results of the lab tests to confirm Parkinson’s disease (Brogley, 2019). Instead, after a series of inquiring questions, patients undergo neurological exams. The patient is requested to walk, sit, stand up, while the doctor monitors their balance, posture, and overall body stability. Afterwards, the patient can be asked to lay their hand on the table and not move it. If there is tremor, which stops with initiation of movement, then there is a sign that a patient has Parkinson’s disease.
The next step in diagnosing the condition is giving the patient medicine, which increases levels of dopamine. If the patient gets better, but over time deteriorates, it can be interpreted as a symptom of Parkinson’s disease (Riley, 2018). Finally, the patient can be subjected to a nuclear medicine procedure, which would showcase the amount of brain cells using dopamine, which can be used as an additional reference for diagnosing Parkinson’s disease. The ultimate diagnosis can be made after the passage of time, as Parkinson’s is a progressive disease.
Review of Nuclear Medicine Procedure and Uptake
Nuclear medicine is a branch of molecular imaging, which provides visual representation of the processes inside the brain on the cellular level. In order for this procedure to transpire, an imaging agent should be injected, ingested or inhaled by the patient. The agent is detected by an external camera, which provides input on the structure and function of the area of interest. If the agent encompasses a radioactive atom or isotope, then it is a radiotracer. Radiotracers are essential in conducting nuclear medicine procedures.
There are two types of nuclear medicine procedure, which can be used to help the doctor diagnose Parkinson’s disease – PET and SPECT. PET is positron emission tomography, while SPECT is single photon emission computed tomography. Both encompass the injection of a radiotracer into the patient’s bloodstream. The difference between them is the type of radiotracer used. SPECT is particularly useful because it allows the doctor to evaluate the amount of dopamine-using neurons (Nuclear Medicine, 2016). In any case, a radiopharmaceutical is injected into the bloodstream.
The nuclear medicine procedure itself requires prior preparation, which includes both the radiotracer and the patient. The patient should assume the lying position, after which they are transferred to the camera. The equipment yields X-Ray, PET, and SPECT images, which provide the necessary input data for the diagnosis of Parkinson’s disease (Lu & Yuan, 2015). As radiation is involved in the procedure, there is a certain risk to a patient’s health; however, appropriate timing makes the procedure safe.
Alternate Diagnostic Tool or Therapeutic Agent
So far, Parkinson’s disease can not be cured as there is no definitive cause. The most common way of managing the symptoms is using the medicine, which restores dopamine levels, thus causing the thalamus to activate the motor cortex and generate more movement. However, medication is not always effective, because the disease progresses and the therapeutic agent no longer helps the treatment. The medication used in managing the symptoms is known as L-dopa or Levodopa (Verschuur et al., 2019). Once the agent crosses the blood brain barrier, it is converted into dopamine. However, aside from the medicine no longer functioning, there is also a possibility of levodopa being converted into dopamine before it reaches the brain.
The disadvantages of the medications have caused the researchers to seek alternative ways of managing Parkinson’s disease. One particular option is conducting a surgery known as deep brain stimulation. This method is not in the regular clinical use because there is no distinct explanation why it works (Dong et al., 2016). The procedure itself is executed by inserting an electrode into the brain, which provides information on the damaged dopamine neurons. Once the surgeons understand where they are located, the electrode is replaced with permanent ones, which will remain in the patient’s brain.
Permanently inserted electrodes adjust neuron activity in the brain areas. If the thalamus cannot activate the motor cortex to generate enough movement, the electrodes compensate by increasing the intensity of dopamine neurons. More importantly, there is evidence that deep brain stimulation removes the necessity to consume levodopa, which can lead to negative side effects (Park et al., 2020). Furthermore, this procedure slows the progression of Parkinson’s disease, prolonging patients’ lives. As a result, despite the unclear nature of its beneficial effect, deep brain stimulation is a viable alternative therapeutic tool with stable positive output.
Another way is targeting alpha synuclein, which is a key protein for the development of Parkinson’s disease. While the proteins themselves are not inherently harmful, there is evidence that the spread of aggregated alpha synuclein precipitates this medical condition (Sheng et al., 2019). Yet, even when the treatment is working effectively, the disease will not likely be cured with it. Most likely, targeting alpha synuclein will reduce the severity of the symptoms at its most effective performance.
The actual method of fighting Parkinson’s disease is focused around immunotherapy. Immunotherapy is a medical approach to treating patients via the strengthening of their immune system by enabling them to fight the disease on their own. In the case of Parkinson’s disease, the therapy presupposes generation of monoclonal alpha synuclein antibodies, which will reduce cell toxicity caused by the aggregated proteins (Sheng et al. 2019). Although this approach is not in clinical use, it has the potential to explain the origins of Parkinson’s disease and the means to cure it.
However, there are disadvantages to using this approach, which underscore its absence in the clinical use. First, current technologies do not allow the doctors to measure the amount of alpha synuclein accumulated in the brain. Subsequently, it is challenging to ascertain how many antibodies are needed to generate the healing effect. Second, there is no medical consensus on the long term consequences of targeting alpha synuclein. Finally, as most of the patients have damaged health and limited abilities of their bodies to recuperate, there is a chance that their organism will not produce enough antibodies to fight the disease.
References
Ball, N., Teo, W. P., Chandra, S., & Chapman, J. (2019). Parkinson’s disease and the environment. Frontiers in Neurology, 10 (218), 1-8.
Brogley, J. E. (2019). DaTQUANT: The future of diagnosing Parkinson disease. Journal of Nuclear Medicine Technology, 47(1), 21-26.
Lu, F. M., & Yuan, Z. (2015). PET/SPECT molecular imaging in clinical neuroscience: Recent advances in the investigation of CNS diseases. Quantitative Imaging in Medicine and Surgery, 5(3), 433-447.
Nuclear Medicine. (2016). Web.
Park, H. R., Ha, S., Lee, D. S., Im, H. J., & Paek, S. H. (2020). Determination of Parkinson disease laterality after deep brain stimulation using 123I FP-CIT SPECT. Clinical Nuclear Medicine, 45(4), e178-e184.
Riley, M., Bakeberg, M., Byrnes, M., Jefferson, A., Ghosh, S., Stell, R., Mastaglia, F. L., Hince, D. & Anderton, R. S. (2018). Demographic and clinical predictors of trait impulsivity in Parkinson’s disease patients. Parkinson’s Disease, 2018(9472120), 1-7.
Shen, N., Song, G., Yang, H., Lin, X., Brown, B., Hong, Y., & Cao, C. (2019). Identifying the pathological domain of alpha-synuclein as a therapeutic for parkinson’s disease. International Journal of Molecular Sciences, 20(9), 1-16.
Verschuur, C. V., Suwijn, S. R., Boel, J. A., Post, B., Bloem, B. R., van Hilten, J. J.,… & de Bie, R. M. (2019). Randomized delayed-start trial of levodopa in Parkinson’s disease. New England Journal of Medicine, 380(4), 315-324.