The nurse provides care for a patient with an 8-year history of Parkinson's disease. The patient has difficulty getting out of chairs, makes tremulous movements, and mumbles words. What is the best explanation for these clinical manifestations?

Choice A reason: Ischemia of the motor and sensory neurons in the brain is not the cause of multiple sclerosis, but a possible consequence of it. Ischemia is a lack of blood supply to the tissues, which may result from inflammation, thrombosis, or embolism. It may cause neuronal death, stroke, or dementia.

Choice B reason: Damage and scarring of the white matter in the brain is the best description of the cause of multiple sclerosis. Multiple sclerosis is an autoimmune disorder that causes the immune system to attack the myelin sheath, which is a protective layer that covers the nerve fibers. The damage and scarring of the myelin sheath, also called demyelination, disrupts the transmission of nerve impulses and causes various neurological symptoms.

Choice C reason: Infection of the parietal and temporal lobes of the brain is not the cause of multiple sclerosis, but a rare complication of it. Infection of the brain, also called encephalitis, may occur due to viral, bacterial, or fungal agents. It may cause fever, headache, confusion, seizures, or coma.

Choice D reason: Increased amounts of epinephrine and acetylcholine in the brain are not the cause of multiple sclerosis, but a possible effect of it. Epinephrine and acetylcholine are neurotransmitters that regulate the sympathetic and parasympathetic nervous systems, respectively. They may be affected by the demyelination of the nerve fibers, which may alter the autonomic functions such as heart rate, blood pressure, digestion, or bladder control.

Choice A reason: Decrease in sympathetic nervous system outflow is the best explanation because it is a condition that affects the regulation of blood pressure, heart rate, and skin temperature. The sympathetic nervous system is a part of the autonomic nervous system, which is the part of the nervous system that controls the involuntary functions of the body, such as breathing, digestion, and circulation. The sympathetic nervous system is responsible for the fight-or-flight response, which prepares the body for action or danger, by increasing the blood pressure, heart rate, and skin temperature. The sympathetic nervous system is composed of nerve fibers that originate from the thoracic and lumbar regions of the spinal cord, which are the middle and lower parts of the spinal cord. A complete spinal cord injury at the C3 to C4 level is a condition where the spinal cord is severed or damaged at the neck, which interrupts the communication between the brain and the rest of the body. A complete spinal cord injury at the C3 to C4 level can cause the loss of sympathetic nervous system outflow, which means that the nerve impulses that normally stimulate the blood vessels, the heart, and the sweat glands are reduced or absent. This can result in hypotension, which is a low blood pressure, bradycardia, which is a slow heart rate, and warm and dry skin, which are the observations noted in the client.

Choice B reason: Decreased fluid volume in the intravascular space is not the best explanation because it is a condition that affects the amount of fluid in the blood vessels, which can be caused by various factors, such as dehydration, bleeding, or vomiting. Decreased fluid volume in the intravascular space can cause hypotension, which is a low blood pressure, but it can also cause tachycardia, which is a fast heart rate, and cool and clammy skin, which are not the observations noted in the client.

Choice C reason: The effects of opiate medication administration is not the best explanation because it is a condition that affects the pain perception and the central nervous system, which can be caused by various types of medications, such as morphine, codeine, or oxycodone. The effects of opiate medication administration can cause hypotension, which is a low blood pressure, and bradycardia, which is a slow heart rate, but it can also cause respiratory depression, which is a slow and shallow breathing, and miosis, which is a constriction of the pupils, which are not the observations noted in the client.

Choice D reason: Onset of acute systemic bacterial infection is not the best explanation because it is a condition that affects the immune system and the whole body, which can be caused by various types of bacteria, such as staphylococcus, streptococcus, or salmonella. Onset of acute systemic bacterial infection can cause hypotension, which is a low blood pressure, but it can also cause fever, which is a high body temperature, and chills, which are sensations of coldness and shivering, which are not the observations noted in the client.