Central nervous system disease

# Overview
A central nervous system (CNS) disease can affect either the spinal cord (myelopathy) or brain (encephalopathy), both of which are part of the central nervous system.

# CNS Composition and Functions

## Spinal Cord
- The spinal cord transmits sensory information from the peripheral nervous system.
- It also conducts motor information to the body's skeletal, cardiac, and smooth muscles, and glands.
- There are 31 pairs of spinal nerves along the spinal cord. These nerves each contain both sensory and motor axons.
- The spinal cord is protected by vertebrae and connects the peripheral nervous system to the brain, and it acts as a "minor" coordinating center.

## Brain
- It allows the body to function.
- The brain is protected by the skull; however, if the brain is damaged, the results to the human body can be very consequential.
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# Types of Disease

## Bipolar Disorder
- Bipolar disorder is a serious illness of the nervous system.
- Symptoms can include both signs of major depression and mania.
- Mood swings from the highs of mania to the lows of deep depression usually occur over several weeks to months.
- New research suggests that bipolar disorder is actually a neurological disease genetically related to Parkinson's disease.
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## Catalepsy
- Catalepsy is a nervous disorder characterized by immobility and muscle rigidity, along with decreased sensitivity to pain.
- It is considered a symptom of serious diseases of the nervous system (e.g., Parkinson's disease, epilepsy, etc.) rather than a disease by itself.
- Cataleptic fits can range in duration from several minutes to weeks.
- The condition often responds to benzodiazepines (e.g., lorazepam) in pill and I.V. form.
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## Epilepsy/Seizures
- Epilepsy is an unpredictable, serious, and potentially fatal disorder of the nervous system, thought to be the result of faulty electrical activity in the brain.
- Epileptic seizures result from abnormal, excessive, or hypersynchronous neuronal activity in the brain.
- Approximately 50 million people worldwide have epilepsy, and nearly 80% of epilepsy occurs in developing countries.
- Epilepsy becomes more common as people age.
- Onset of new cases occurs more frequently in infants and the elderly.
- Epileptic seizures may occur in recovering patients as a consequence of brain surgery.
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## Encephalitis
- Encephalitis is an inflammation of the brain.
- It is usually caused by a foreign substance or a viral infection.
- Symptoms of this disease include headache, neck pain, drowsiness, nausea, and fever.
- If caused by the West Nile virus, it may be lethal to humans, as well as birds and horses.
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## Meningitis
- Meningitis is an inflammation of the meninges (membranes) of the brain and spinal cord.
- It is most often caused by a bacterial or viral infection.
- Fever, vomiting, and a stiff neck are all symptoms of meningitis.
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## Migraine
- Migraine is a chronic, often debilitating neurological disorder characterized by recurrent moderate to severe headaches.
- It is often associated with a number of autonomic nervous system symptoms.
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## Tropical Spastic Paraparesis
- Tropical spastic paraparesis is caused by human T-lymphotropic virus.
- Patients present with weakness, muscle spasms, and sensory disturbance.
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## Arachnoid Cysts
- Arachnoid cysts are filled with cerebrospinal fluid and covered by arachnoidal cells that may develop in the brain or spinal cord.
- They are a congenital disorder, and can be asymptomatic.
- However, if there is a large cyst, symptoms may include headache, seizures, ataxia (lack of muscle control), andhemiparesis.
- Macrocephaly and ADHD are common presentations among children, while presenile dementia, hydrocephalus (an abnormality of the dynamics of the cerebrospinal fluid), and urinary incontinence are symptoms for the elderly patients (65 and older).
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## Huntington's Disease
- Huntington's disease is a degenerative neurological disorder that is inherited.
- Degeneration of neuronal cells occurs throughout the brain, especially in the striatum.
- There is a progressive decline that results in abnormal movements.
- Statistics show that Huntingtons disease may affect 10 per 100,000 people of Western European descent.
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## Alzheimers Disease
- Alzheimers disease is a neurodegenerative disorder typically found in people over the age of 65 years.
- Worldwide, approximately 24 million people have dementia; 60% of these cases are due to Alzheimers disease.
- Clinical sign of Alzheimers disease is progressive cognition deterioration.
- The ultimate cause is unknown.
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## Attention Deficit/Hyperactivity Disorder (ADHD)
- ADHD (often highly debated and controversial) is now largely considered to be a genuine organic disorder of the nervous system, according to the United States government.
- It can be seriously debilitating in the severe forms.
- The symptoms are thought to be caused by structural as well as biochemical imbalances in the brain; in particular, low levels of the neurotransmitters dopamine and norepinephrine, which are responsible for controlling and maintaining attention and movement.
- Many people with ADHD continue to have symptoms well into adulthood.
- Also of note is an increased risk of the development of Dementia with Lewy bodies (DLB), and a direct genetic association of attention deficit disorder to Parkinson's disease.
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## Locked-in Syndrome
- Locked-in syndrome usually results from a stroke that damages part of the brainstem.
- In this condition, the body and most of the facial muscles are paralysed but consciousness remains intact along with the ability to perform certain eye movements.
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## Parkinson's Disease
- Parkinsons disease (PD) is a progressive illness of the nervous system.
- It is caused by the death of dopamine-producing brain cells that affect motor skills and speech.
- Symptoms may include bradykinesia (slow physical movement), muscle rigidity, and tremors.
- Behavioral changes, thinking disturbance, sensation disorders, and seborrheic dermatitis are some of PD's numerous non-motor symptoms.
- Interestingly, Parkinson's disease, attention deficit/hyperactivity disorder (ADHD), and bipolar disorder appear to have some connection to one another, as all three nervous system disorders involve lower than normal levels of the dopamine (In ADHD, PD, and the depressive phase of bipolar disorder) or too much dopamine (In mania or manic states of bipolar disorder) in different areas of the brain.
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## Tourette's Syndrome
- Tourette's syndrome is an inherited neurological disorder.
- Early onset may be during childhood, and it is characterized by physical and verbal tics.
- The exact cause of Tourette's syndrome, other than genetic factors, is unknown.
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## Multiple sclerosis
- Multiple sclerosis (MS) is a chronic, inflammatory demyelinating disease, meaning that the myelin sheath of neurons is damaged.
- Symptoms of MS include visual and sensation problems, muscle weakness, and depression.
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# Causes

## Trauma
- Any type of traumatic brain injury (TBI) or injury to the spinal cord can result in a wide spectrum of disabilities in a person.
- Depending on the section of the brain or spinal cord that suffers the trauma, the outcome may be anticipated.

## Infections
- An infection is a condition that results from the invasion by microorganisms.
- Infectious diseases are transmitted in several ways.
- Some of these infections may affect the brain or spinal cord directly.

## Degeneration
- Degenerative spinal disorders involve a loss of function in the spine.
- Pressure on the spinal cord and nerves may be associated with vertebral disc herniation or displacement.
- Brain degeneration also causes central nervous system diseases.
- Studies have shown that obese people may have severe degeneration in the brain due to the loss of tissue affecting cognition.

## Structural Defects
- Common structural defects include birth defects, anencephaly, hypospadias, and spina bifida.
- Children born with structural defects may have malformed limbs, heart problems, and facial abnormalities.

## Tumors
- A tumor is an abnormal growth of body tissue.
- In the beginning, tumors can be non-cancerous, but if they become malignant, they are cancerous.
- In general, they appear when there is a problem with cellular division.
- Problems with the bodys immune system can also lead to tumor development.

## Autoimmune Disorders
- An autoimmune disorder is a condition where the immune system attacks healthy body tissue.
- This is caused by a loss of tolerance to proteins in the body, resulting in immune cells recognizing these as 'foreign' and directing an immune response against them.
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## Stroke
- A stroke is an interruption of the blood supply to the brain.
- Approximately every 40 seconds, someone in the US has a stroke.
- This can happen when a blood vessel is blocked by a blood clot or when a blood vessel ruptures, causing blood to leak to the brain.
- If the brain can not get enough oxygen and blood, brain cells can die, leading to permanent damage.
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# Signs and Symptoms
- Every disease has different signs and symptoms.
- Some of the signs and symptoms are listed below:
Headache
Pain in the face, back, arms, or legs
An inability to concentrate
Loss of feeling
Memory loss
Loss of muscle strength
Tremors
Seizures
Increased reflexes
Spasticity
Tics
Paralysis
Slurred speech
- Headache
- Pain in the face, back, arms, or legs
- An inability to concentrate
- Loss of feeling
- Memory loss
- Loss of muscle strength
- Tremors
- Seizures
- Increased reflexes
- Spasticity
- Tics
- Paralysis
- Slurred speech

# Treatment
- There is a wide range of treatment modalities available for central nervous system diseases.
- These can range from medical therapy or rehabilitation to surgery.