Question

Imagine that you are working as a neuropsychologist at a clinic. You are involved in the diagnosis of the cases described below. You are asked to identify the probable cause(s) of the disorders in terms of nervous system malfunctions. Based on the information in this chapter, indicate the probable location of any brain damage or the probable disturbance of neurotransmitter activity. The answers can be found in the back of the book in Appendix A. Ricardo, a 28 -year-old computer executive, has gradually seen his strength and motor coordination deteriorate badly. He is diagnosed as having multiple sclerosis.

Short answer

Answer: Probable causes of strength and motor coordination deterioration in individuals with multiple sclerosis include damage to the myelin sheath in the central nervous system due to the immune system attacking and destroying the myelin, and inflammation in the brain or spinal cord, which can lead to the formation of scar tissue (sclerosis) that further impairs the conduction of electrical signals in the central nervous system.

Step-by-step solution

Understanding multiple sclerosis (MS)

MS is a chronic disease of the central nervous system (CNS) – it means that it affects the brain and the spinal cord. In MS, the immune system mistakenly attacks the protective covering of nerve fibers (myelin) causing inflammation and leading to myelin damage. This damage disrupts the normal flow of electrical signals, which causes a range of symptoms, including muscle weakness, coordination and balance difficulties.

Location of brain damage and neurotransmitter disturbance

The location of brain damage in multiple sclerosis varies from person to person, as it can affect any part of the brain or spinal cord. However, the most commonly affected areas are: 1. Optic nerves (optic neuritis) - may cause visual problems 2. Brainstem (where the major motor and sensory nerves connect) - may lead to balance and coordination issues 3. Cerebellum (responsible for muscle coordination) - may cause ataxia or tremors 4. Spinal cord (transmits signals between the brain and the body) - may cause muscle weakness, spasticity, or numbness In addition to these areas, demyelination or nerve damage in other areas of the CNS may also cause a variety of other symptoms. The probable disturbance of neurotransmitter activity in MS involves the disruption of electrical signals due to myelin damage, which affects the conduction of impulse between neurons.

Identifying the probable cause(s) of the disorder

In the case of Ricardo, who has been diagnosed with multiple sclerosis, the probable causes of his strength and motor coordination deterioration include: 1. Damage to the myelin sheath in the CNS - due to the immune system attacking and destroying the myelin. 2. Inflammation in the brain or spinal cord - this can lead to the formation of scar tissue (sclerosis) which further impairs the conduction of electrical signals in the CNS. Although the exact cause of multiple sclerosis is still unknown, it is believed to involve an interplay of genetic and environmental factors. The disorder is more common in individuals with a family history of the disease, and certain genetic mutations have been associated with an increased risk of developing MS. Environmental factors such as low sun exposure, low vitamin D levels, and exposure to certain infections, especially during childhood, have also been implicated in the development of the disease.

Key concepts

Central Nervous System

The central nervous system (CNS) is the primary command center of our bodies, consisting of the brain and the spinal cord. Its responsibility is to process all of the information received from our senses and to coordinate action and reaction. Understanding the CNS is vital in diseases like multiple sclerosis (MS), where the system's normal functioning is impaired.

In MS, the CNS's ability to send and receive signals is disrupted, leading to a variety of symptoms. When discussing Ricardo's condition, it's the CNS's components, specifically the brain and spinal cord, that are under siege by the body's own immune system, causing the symptoms described.

Myelin Damage

Myelin is the protective covering that insulates nerve fibers and facilitates the rapid transmission of electrical signals in the CNS. When this covering is damaged, signals slow down or stop. In MS, the immune system mistakenly attacks myelin, thinking it's a foreign body.

This attack leads to the myelin damage observed in patients like Ricardo. Symptoms such as muscle weakness and poor motor coordination are a direct result of such damage since the nerves can no longer conduct signals effectively. Myelin damage represents a critical point in understanding MS, as restoring or managing this damage is an important focus of treatment.

Neurotransmitter Disruption

Neurotransmitters are the body's chemical messengers; they facilitate communication between neurons. When myelin is damaged, this communication is hampered, which can result in neurotransmitter disruption.

Ricardo's muscle weakness and coordination issues can be partially explained by this disruption. His nerve cells struggle to efficiently transmit messages, which directly influences his control over muscle movements. Even though MS isn't primarily a disease of neurotransmitters, their role in disease manifestation cannot be overlooked.

Immune System Dysfunction

Our immune system is designed to protect us from outside invaders like viruses and bacteria. However, in autoimmune diseases like MS, the system mistakenly identifies healthy tissue as a threat and attacks it. In the context of MS, this 'friendly fire' targets myelin.

The immune system dysfunction represents a core problem in MS and links directly to the disease's unpredictability. Since the immune response varies from person to person, the extent, timing, and specific symptoms like those Ricardo experiences, can differ substantially between patients.

Brain Damage Localization

In MS, the specific locations of brain damage often correlate with the symptoms a patient experiences. For instance, damage to the optic nerves may lead to vision problems, while harm to the cerebellum can affect coordination.

Identifying where Ricardo's brain damage has occurred helps us understand why his motor skills are suffering. Detailed scans and tests are used to pinpoint these regions, which is essential for diagnosis and formulating an effective management plan. Addressing the individualized pattern of brain damage is crucial in treating and managing MS to improve patient outcomes.