Figure 6. Parkinson Sketch (Gowers, W.R., 1886)
Figure 7. Medication Bottles (Pixabay,2014)
Figure 8. Deep Brain Stimulation (National Institute of Neurologic Disorders and Stroke, 2010)
Diagnosis of Parkinson’s disease (PD) is made difficult by the fact that many associated symptoms can be attributed to the normal aging process. This includes gradual loss of fine motor skills, digestive complaints, and changes in memory. Diagnosis is typically completed following a physical examination to determine the presence of four cardinal symptoms indicative of PD: resting tremor, rigidity, bradykinesia (progressing to akinesia), and postural instability. Diagnosis of PD also includes a neurological exam, detailed medical history provided by the patient and close family members, blood tests for biochemical markers, and CT or MRI scans. Blood tests, genetic tests, CTs and MRIs are typically completed to rule out differential diagnoses and ensure the proper diagnosis of PD. Often, non-motor symptoms can precede motor manifestations, making identification of PD difficult. An L-Dopa test may be performed in an attempt to ensure a correct diagnosis. This involves the patient trialing the medication Levodopa and observation for symptom reduction. Rapid symptom improvement indicates diagnosis of PD.
The goal of pharmacotherapy is to restore dopamine and counter excess acetylcholine levels. Drug therapy can involve two general approaches: 1) dopaminergic agents (to directly or indirectly activate dopamine receptors and 2) anticholinergic agents (to counter excess acetylcholine). The most commonly used drug in the former category is levodopa, while the latter category may include antihistamines and amantadine (Lehne, 2010). Dopaminergic drugs may act through several mechanisms. These include (direct) promotion of dopamine synthesis (through drugs such as levodopa), dopamine agonists activating dopamine receptors, inhibition of monoamine oxidase (MAO inhibitors) to block dopamine breakdown, promotion of dopamine release (through drugs such as amantadine), and catechol-O-methyltransferase (COMT) inhibitors that enhance the effect of levodopa. All anticholinergic agents act using the same mechanism: blocking muscarinic receptors in the striatum (Lehne, 2010).
During early stages of PD, MAO inhibitors may be used for mild symptomatic benefit. For patients with more severe initial symptoms, the most common oral drug used is levodopa. Levodopa is a dopamine precursor with the ability to cross the blood-brain barrier via active transport. Once inside the brain, it is converted to dopamine. Long-term use of levodopa carries side-effects; the most severe of which are motor fluctuations, including dyskinesias. Other side effects include nausea and vomiting (usually early in drug treatment), cardiovascular effects (postural hypotension), visual hallucinations and nightmares and even paranoid ideation. Levodopa may also darken sweat and urine. At least some of these side-effects can be mitigated through drug combinations. For example, second generation antipsychotics such as clozapine and quetiapine can be used to manage levodopa-induced psychosis, and amantadine can reduce levodopa-induced dyskinesias.
For patients in the later stages of PD whose symptoms cannot be managed through pharmacotherapy alone, surgery can be an option for treatment. Deep brain stimulation is a surgical option in which a neurostimulator is implanted within the patient’s brain to send controlled electrical impulses to specific areas. Deep brain stimulation is currently the surgical gold standard for symptom relief, improved motor function, as well as minimal tissue damage within the brain. Other surgical procedures include a thalamotomy, pallidotomy, and subthalamotomy.
All stages of PD treatment should include an integrated healthcare approach to assist in managing symptoms arising as the disease progresses and in improving functional status. Thus, use of occupational therapy, speech therapy, and physical therapy are key in assisting PD patients. Occupational therapy can assist the patient in completing activities of daily living and remaining safe in his or her living environment. Physical therapy (PT) can assist patients in pain relief, managing range of motion, and with the progression of symptoms. PT can also aid in adjustment to using assistive devices. Speech therapy can assist patients in managing dysphagia and affected speech patterns.