MS5.pdf

10/24/23, 3:16 PM Realizeit for Student Parkinson's Disease Pathophysiology PD is associated with decreased levels of dopamine resulting from degeneration of dopamine storage cells in the substantia nigra in the basal ganglia region of the brain. Fibers or neuronal pathways project from the substa...

10/24/23, 3:16 PM Realizeit for Student Parkinson's Disease Pathophysiology PD is associated with decreased levels of dopamine resulting from degeneration of dopamine storage cells in the substantia nigra in the basal ganglia region of the brain. Fibers or neuronal pathways project from the substantia nigra to the corpus striatum, where neurotransmitters are vital to the control of complex body movements. Through the neurotransmitters acetylcholine (excitatory) and dopamine (inhibitory), striatal neurons relay messages to the higher motor centers that control and refine motor movements. The loss of dopamine stores in this area of the brain results in more excitatory neurotransmitters than inhibitory neurotransmitters, leading to an imbalance that affects voluntary movement (Hickey & Strayer, 2020). Clinical symptoms do not appear until 60% of the pigmented neurons are lost and the striatal dopamine level is decreased by 80%. Cellular degeneration impairs the extrapyramidal tracts that control semiautomatic functions and coordinated movements; motor cells of the motor cortex and the pyramidal tracts are not affected. Researchers are working on uncovering the exact mechanism of neurodegeneration. Current theories suggest a combined and complicated interweaving of both environmental and genetic factors that affect numerous fundamental cellular processes. Fifteen percent of early PD cases are associated with multiple genetic mutations (Poewe, Seppi, Tanner, et al., 2017). Ongoing research includes recognition of biomarkers and development of individualized treatment options (Poewe et al., 2017). https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IUFUzXhwrkmByRPKGm7XOkO3V8uhfXYXOmPZGy%2b… 1/5 10/24/23, 3:16 PM Realizeit for Student https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IUFUzXhwrkmByRPKGm7XOkO3V8uhfXYXOmPZGy%2b… 2/5 10/24/23, 3:16 PM Realizeit for Student Clinical Manifestations PD has a gradual onset, and symptoms progress slowly over a chronic, prolonged course. The cardinal signs are tremor, rigidity, bradykinesia/akinesia, and postural instability (Hickey & Strayer, 2020). Two major subtypes of PD are tremor dominant (most other symptoms are absent) and nontremor dominant (akinetic-rigid and postural instability). Tremor Although symptoms are variable, a slow, unilateral resting tremor is present in the majority of patients at the time of diagnosis. Resting tremor characteristically disappears with purposeful movement and during https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IUFUzXhwrkmByRPKGm7XOkO3V8uhfXYXOmPZGy%2b… 3/5 10/24/23, 3:16 PM Realizeit for Student sleep but is evident when the extremities are motionless or at rest. The tremor may manifest as a rhythmic, slow turning motion (pronation–supination) of the forearm and the hand and a motion of the thumb against the fingers as if rolling a pill between the fingers. Rigidity Resistance to passive limb movement characterizes muscle rigidity. Passive movement of an extremity may cause the limb to move in jerky increments, referred to as lead-pipe or cogwheel movements. Involuntary stiffness of the passive extremity increases when another extremity is engaged in voluntary active movement. Stiffness of the arms, legs, face, and posture are common. Early in the disease, the patient may complain of shoulder pain due to rigidity (Hickey & Strayer, 2020). Bradykinesia A common feature of PD is bradykinesia, which refers to the overall slowing of active movement (Bronner & Korczyn, 2017). Patients may also take longer to complete activities and have difficulty initiating movement, such as rising from a sitting position or turning in bed. Postural Instability The patient commonly develops postural and gait problems. Due to a loss of postural reflexes, the patient stands with the head bent forward and walks with a propulsive gait. The posture is caused by the forward flexion of the neck, hips, knees, and elbows. The patient may walk faster and faster, trying to move the feet forward under the body’s center of gravity (shuffling gait). Difficulty in pivoting causes loss of balance, either forward (propulsion) or backward (retropulsion). Gait impairment and postural instability place the patient at increased risk for falls (Hickey & Strayer, 2020). Other Manifestations The effect of PD on the basal ganglia often produces autonomic symptoms that include excessive and uncontrolled sweating, drooling, paroxysmal flushing, orthostatic hypotension, gastric and urinary retention, constipation, and sexual dysfunction (Bronner & Korczyn, 2017). Dysphagia is a substantial problem, with more than 50% of patients reporting choking as well as vision and olfactory changes (AANN, 2019). Neurogenic orthostatic hypotension occurs in 30% to 50% of patients with PD (Sin & Khemani, 2020). Psychiatric changes include depression, anxiety, dementia, delirium, hallucinations, and psychosis. Depression and anxiety are common; whether these are reactions to the disorder or related to a biochemical abnormality is uncertain (AANN, 2019). Stress, medications, and depression contribute to the cognitive changes of diminished executive functions, attention difficulties, decreased thinking, and word-finding challenges. More than 80% of patients with a 20-year disease duration of PD experience dementia, a broad term for a syndrome characterized by a general decline in higher brain functioning, such as reasoning, with a pattern of eventual decline in ability to perform even basic ADLs, such as https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IUFUzXhwrkmByRPKGm7XOkO3V8uhfXYXOmPZGy%2b… 4/5 10/24/23, 3:16 PM Realizeit for Student toileting and eating (Gale, Acar, & Daffner, 2018). In addition, auditory and visual hallucinations have been reported in people with PD and may be associated with depression, dementia, lack of sleep, or adverse effects of medications. Hypokinesia (abnormally diminished movement) is also common and may appear after the tremor. The freezing phenomenon refers to a transient inability to perform active movement and is thought to be an extreme form of bradykinesia. The patient tends to shuffle and exhibits a decreased arm swing as well. As dexterity declines, micrographia (small handwriting) develops. The face becomes increasingly masklike and expressionless, and the frequency of blinking decreases. Dysphonia (voice impairment or altered voice production) may occur as a result of weakness and incoordination of the muscles responsible for speech. In many cases, the patient develops dysphagia, begins to drool, and is at risk for choking and aspiration (AANN, 2019). Complications associated with PD are common and are typically related to disorders of movement. As the disease progresses, patients are at risk for respiratory and urinary tract infection, skin breakdown, and injury from falls. The adverse effects of medications used to treat the symptoms are associated with numerous complications such as dyskinesia (impaired ability to execute voluntary movements) or orthostatic hypotension. https://herzing.realizeithome.com/RealizeitApp/Student.aspx?Token=0Dn26kXyU%2f6F5gOCz4%2f2IUFUzXhwrkmByRPKGm7XOkO3V8uhfXYXOmPZGy%2b… 5/5