Nervous System Pathology Diseases of the CNS Recall CNS includes the brain and spinal cord Examples of diseases that affect the CNS include: (1) Infections (meningitis, encephalitis, polio) (2) Degenerative diseases (Huntington’s, Alzheimer’s, Parkinson’s, ALS, MS) (3) Epilepsy (4) Cerebral palsy (5) Genetic (Spina bifida, Tay Sachs) Meningitis Meningitis is the inflammation of the meninges Recall the meninges consists of three protective layers that surround the brain and spinal cord (dura mater, arachnoid, pia mater) Meningitis can be caused by viral, bacterial, or fungal infections Swelling of the meningeal tissue often causes the typical symptoms: headache, fever, stiff neck, confusion, vomiting Bacterial infections are especially serious and can lead to death in the matter of a few days without treatment Meningitis Encephalitis Encephalitis is inflammation of the brain due most often to viral infections Examples of viruses that can cause encephalitis include: mosquito-borne like West Nile, Powassan virus (tick-borne), Symptoms can include flu-like symptoms, such as a fever or severe headache. It can also cause confused thinking, seizures, or problems with senses or movement Many cases of encephalitis present with mild flu-like to no symptoms Polio Also known as poliomyelitis, an infectious disease caused by the polio virus Highly infectious disease that can damage the brain or spinal cord and paralyze a person within hours Before introduction of the polio vaccine, tens of thousands of children developed paralytic polio 4 part series of shots now to prevent polio virus FDR hid his disease so well many never knew he had polio until after his presidency. Only 3 photos of him in a wheelchair are known to exist. Huntington’s Disease An autosomal dominant disease (inherited) that causes the progressive breakdown of nerve cells in the brain. Huntington's disease has a broad impact on a person's functional abilities and usually results in movement, thinking (cognitive) and psychiatric disorders. Most people with Huntington's disease develop signs and symptoms in their 30s or 40s, but the onset of disease may be earlier or later in life. Eventually, a person with Huntington's disease requires help with all activities of daily living and care. Late in the disease, he or she will likely be confined to a bed and unable to speak. However, he or she is generally able to understand language and has an awareness of family and friends. Huntington’s Disease Alzheimer’s Disease Alzheimer's is the most common form of dementia, a general term for memory loss and other intellectual abilities serious enough to interfere with daily life. Alzheimer's disease accounts for 60 to 80 percent of dementia cases. Alzheimer's is a progressive disease, where dementia symptoms gradually worsen over a number of years. Plaques, abnormal clusters of protein fragments, build up between nerve cells. Dead and dying nerve cells contain tangles, which are made up of twisted strands of another protein. Alzheimer’s Disease Alzheimer's disease disrupts both the way electrical charges travel within cells and the activity of neurotransmitters. Alzheimer's disease leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all its functions. Shrinkage is especially severe in the hippocampus. Parkinson’s Disease Parkinson's disease is caused by the progressive impairment or deterioration of neurons (nerve cells) in an area of the brain known as the substantia nigra. When functioning normally, these neurons produce a vital brain chemical known as dopamine. Dopamine serves as a chemical messenger allowing communication between the substantia nigra and another area of the brain called the corpus striatum. This communication coordinates smooth and balanced muscle movement. A lack of dopamine results in abnormal nerve functioning, causing a loss in the ability to control body movements. ALS (Lou Gehrig's Disease) Amyotrophic lateral sclerosis is the progressive degeneration of motor neurons that eventually leads to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With voluntary muscle action progressively affected, patients in the later stages of the disease may become totally paralyzed. ALS (Lou Gehrig's Disease) As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. When muscles no longer receive the messages from the motor neurons that they require to function, the muscles begin to atrophy (become smaller). Limbs begin to look "thinner" as muscle tissue atrophies. Multiple Sclerosis (MS) MS is an autoimmune disease that destroys the myelin sheaths in the nerves of the spinal cord and brain, as well as the optic nerves. Sclerosis means scarring, and people with MS develop multiple areas of scar tissue in response to the nerve damage. Depending on where the damage occurs, symptoms may include problems with muscle control, balance, vision, or speech. Epilepsy Epilepsy stems from an electrical glitch or malfunction, usually in one region of the brain. During an epileptic seizure, disturbances in the brain's orderly flow of electrical signals are interrupted by abnormal electrical discharges. The type of epileptic seizure depends on the area affected and the pattern in which it spreads. Epilepsy Scientists have identified specific damage to the neuron dendrite areas of the cell. The observed dendrite damage accounts for the occurrence of cognitive impairment seen in those with seizure disorders. Cerebral Palsy Cerebral palsy is a group of problems that affect body movement and posture. It is related to a brain injury or to problems with brain development. It is one of the most common causes of lasting disability in children. It can be caused by: Problems from being born too early (premature birth). Not getting enough blood, oxygen, or other nutrients before or during birth. A serious head injury. A serious infection that can affect the brain, such as meningitis. Some problems passed from parent to child (genetic conditions) that affect brain development. In many cases, the exact cause of cerebral palsy is not known (idiopathic). Cerebral Palsy Spina Bifida Spina bifida is a type of birth defect called a neural tube defect. It occurs when the bones of vertebrae don't form properly around part of the baby's spinal cord. Spina bifida can be mild or severe. The mild form is the most common. It usually doesn't cause problems or need treatment. You can't see the defect, but some people may have a dimple, birthmark, or hairy patch on their back. A rare and more severe form is meningocele. In this form, fluid leaks out of the spine and pushes against the skin. You may see a bulge in the skin. Spina Bifida The most rare and severe form is myelomeningocele. Part of the spinal nerves push out of the spinal canal, and the nerves are often damaged. You may see a bulge in the skin. In some babies, the skin is open and the nerves are exposed. Tay Sachs Disease Children with Tay-Sachs disease lack a vital enzyme, hexosaminidase A (Hex-A). Hex-A is needed for the body to break down a fatty waste substance found in brain cells. Without Hex-A, this substance accumulates abnormally and causes progressive damage until the nervous system can no longer sustain life. Tay Sachs Disease A baby with Tay-Sachs disease appears healthy at birth, and seems to be developing normally for a few months. Symptoms generally appear by six months of age. While symptoms vary from one child to the next, there is always a slowing down of development. Gradually, Tay-Sachs children lose motor skills and mental functions. Over time, the child becomes blind, deaf, mentally retarded, paralyzed and non responsive to the environment. Tay-Sachs children usually die by age five. Diseases of the PNS Recall the PNS includes the nerves that stem from the brain and spinal cord throughout the rest of the body Examples of diseases that affect the PNS include: (1) Carpal Tunnel Syndrome (2) Peripheral Neuropathy Carpal Tunnel Syndrome Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the palm of the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move. Peripheral Neuropathy The term peripheral neuropathy encompasses a wide range of disorders in which the nerves outside of the brain and spinal cord—peripheral nerves—have been damaged. Peripheral neuropathy is a widespread disorder, and there are many underlying causes. Some of these causes are common, such as diabetes, and others are extremely rare, such as leprosy. Peripheral Neuropathy Typical symptoms of neuropathy are related to the type of affected nerve. If a sensory nerve is damaged, common symptoms include numbness, tingling in the area, a prickling sensation, or pain. Pain associated with neuropathy can be quite intense and may be described as cutting, stabbing, crushing, or burning. In some cases, a nonpainful stimulus may be perceived as excruciating or pain may be felt even in the absence of a stimulus. Damage to a motor nerve is usually indicated by weakness in the affected area. Treatment for CNS Disorders Degenerative diseases and disorders of the central nervous system (CNS) afflict tens of millions of people worldwide, and often arise due to the failure of CNS tissue due to the loss of functional cells. For many of these conditions, there are no curative treatment options today and effective long-term therapies remain limited. Stem Cell Research Deep Brain Stimulation (DBS) Stem Cell Research Most of the advances in stem cell research have been directed at treating degenerative diseases. While many treatments aim to limit the damage of these diseases, in some cases scientists believe that damage can be reversed by replacing lost cells with new ones derived from cells that can mature into nerve cells, called neural stem cells. Highly controversial; Embryonic stem cells must be used rather than Adult Stem Cells Using embryonic stem cells kills the developing embryo Stem Cell Research Deep Brain Stimulation (DBS) Procedure whereby electrodes are placed in the brain and deliver weak electronic impulses to stimulate neurons Patients return every 4 years for battery replacement Has shown tremendous promise in Parkinson’s, individuals with major depression, and PTSD Early Diagnosis is Key Early Diagnosis - A new blood test for Alzheimer’s appears to detect the disease as many as 10 years before clinical diagnosis is possible -far sooner than other tests in development. So far diagnosis has been correct in 100% of the cases. A single protein in the brain involved in insulin signaling, called IRS-1, that appears to be defective in Alzheimer’s patients. They found that patients with Alzheimer’s had higher amounts of the inactive form of the protein and lower amounts of the active form than healthy individuals. The diabetics had intermediate levels. These levels were so consistent that the team could predict whether a blood sample came from an Alzheimer’s patient, healthy individual, or a diabetic -- with no errors. This was true even for samples from Alzheimer’s patients taken 10 years before they were diagnosed.