533 Module 5: Neuro

Although AVMs (arteriovenous formations) are usually present at birth, when do they typically become symptomatic?

2nd to 3rd decade of life

What is the color, weight, and consistency of the human brain?

3 pounds, gel like (tofu), grey

At what temperature may febrile seizures occur in children who are prone to them (especially boys) under the age of 5?

38* C or 100.4*F

At what temperature might nerve damage and convulsions occur?

41° C (105.8° F)Death? 43° C (109.4° F)

Acute subdural hematomas develop within

48 hours of a head injury.

What is the difference between acute pain and chronic pain?

Acute pain is sudden onset pain that resolves after the painful stimulus is removed and the tissues have healed. Chronic pain lasts for more than three months.

What three portions of the nervous system are responsible for perception of pain?

Afferent pathways Interpretive centers Efferent pathways

Name and describe two symptoms that could signal an impending seizure.

Anxiety, depression, inability to think clearly, aura (focal seizure)

Bleeding from which type of vessel typically occurs in extradural hematomas?

Artery

Decerebrate posturing (extension and over pronation) is indicative of injury to which parts of the brain?

Associated with severe damage involving midbrain or upper pons. Acute brain injury may cause limb extension regardless of location.

Neuroglia are "nerve glue" that make up one half of the brain and spinal cord and provide support for the neurons. What does each one do?

Astrocytes - nourish and protect neurons Oligodendroglia - form myelin in the CNS Ependymal cells - line the ventricles and the spinal cord Microglia - clean up by using phagocytic activity

Bacterial meningitis is often caused by bacteria that are common in the nasopharnyx. What has to occur before the bacteria can enter the bloodstream and cause meningitis?

Bacteria must be inhaled and cross the BBB

Name the three main spinal nerve plexuses and briefly describes what each one innervates.

Brachial - arm, wrist, and hand Lumbar - anterior portion of lower body Sacral - posterior portion of lower body

Name the two main components of the CNS (central nervous system).

Brain and Spinal Cord

When the actual spinal cord ends, a bundle of nerves extend outward and downward. Name this structure. (For a visual of what this looks like, this is Latin for "horse's tail)

Cauda Equina

There are 31 pairs of spinal nerves that exit the spinal cord what 4 variations are there based on anatomical position?

Cervical, thoracic, lumbar, sacral, coccygeal

85-95% percent of intracranial aneurysms are located in the anterior portion of the

Circle of Willis.

Functioning of the reticular activating system (RAS) is necessary for

Cognition.

Which type of hearing loss can often be corrected, conductive or sensorineural?

Conductive

Which type of nerve injury would stand the best chance of recovery? Crush or cut?

Crush

Briefly define ALS.

Degenerative disorder with loss of lower and upper motor neurons resulting in progressive muscle weakness.

Innervation to the skin is divided into very specific spinal cord segments. What are these areas called? (Note, you do not have to memorize these, but having a diagram as a reference is very helpful).

Dermatomes

Autonomic dysreflexia can occur after a spinal cord injury causing severe paroxysmal hypertension, pounding headache, blurred vision, and diaphoresis and flushing of the skin above the lesion. What is a common cause of this life-threatening condition?

Distended bladder

Name the three protective membranes (meninges) that surround the spinal cord.

Dura mater, Arachnoid mater, Pia mater

In a patient with a subarachnoid hemorrhage, how do early symptoms differ from those of a ruptured vessel?

Early - H/A, mental status change, LOC change, N/V, and focal neurologic defects Ruptured - sudden throbbing, explosive H/A, N/V, visual disturbances, motor deficits, and loss of consciousness related to a dramatic rise in ICP.

Name some mechanisms leading to the development of dementia.

Encephalitis, meningitis, neurosyphilis, anticholinergics, antihypertensives, antihistamines, Alzheimer disease, dementia with lewy bodies,pick disease, Parkinson disease, alcohol, sedatives, page 521.

At what vertebral level does the spinal cord end?

First or second lumbar vertebra in adults

A patient who develops dementia prior to the age of 60 may have what type of dementia?

Frontotemporal

What is the primary fuel source for neurons?

Glucose

Name two ways in which skeletal muscle responds to loss of body heat.

Gradual increase in muscle tone Production of rapid muscle oscillations (shivering - which does not occur in neonates)

What bodily functions does the medulla oblongata control?

HR, respirations, BP, coughing, sneezing, swallowing, and vomiting.

Heat exhaustion

Heat exhaustion is the next most severe and can progress to heat stroke. These people need to immediately stop what they are doing. Rest in a cool place, preferably on their back with their legs elevated above their heart. Drink cool fluids. Stick to water or sports drinks. No caffeine or alcohol. Apply cool water to your skin. If possible, take a cool shower or soak in a cool bath. Don't use alcohol on your skin, but one thing that you can do is mist the person's body with water and use a fan on them if one is available - this would be heat reduction by convection like we discussed earlier.Loosen clothing. Just basically focus on cooling and rehydrating. Collapse due to prolonged high core or environmental temperatures. Prolonged vasodilation, profuse sweating. Dehydration, depressed plasma volumes, hypotension, decreased cardiac output, tachycardia. Manifestations: Dizziness, weakness, nausea, and syncope

Decorticate posturing (flexing of the extremities) is indicative of injury to which parts of the brain?

Hemispheric damage above midbrain releasing medullary and pontine reticulospinal systems

What two areas of the brain are involved in producing fever?

Hypothalmus and brainstem

Briefly discuss the differences in ischemic verses hemorrhagic strokes.

Ischemic - obstruction to arterial blood flow to the brain from thrombus formation, an embolus associated with atherosclerosis, or hypoperfusion related to decreased blood volume or heart failure. Hemorrhagic - primary cause is hypertension. A mass of blood is formed as bleeding occurs into the brain tissue.

Although patients with fever are often uncomfortable and seek ways of reducing the fever, what are some benefits of fever?

Kills many organisms. Decreases serum levels of iron, zinc, and copper. Deprives bacteria of food. Promotes lysosomal breakdown and autodestruction of cells. Increases lymphocytic transformation and phagocyte motility.

What clinical manifestations might occur if the cerebellum becomes damaged?

Loss of balance and posture and fine motor skills

What structures make up the brainstem?

Metencephalon (Cerebellum and Pons) Myelencephalon (Medulla Oblongata)

Where is dopamine synthesized?

Midbrain (mesencephalon) > substantia nigra

What is the difference in myopia and hyperopia?

Myopia is nearsightedness and hyperopia is farsightedness.

How are neurons classified according to their structure? Their function?

Neurons can be structurally classified as unipolar, bipolar, or multipolar depending on the number of projections that protrude from the cell body. There are three functional classifications of neurons. Sensory neurons transmit impulses from sensory receptors to the CNS. Associational neurons transmit impulses from one neuron to the other. And motor neurons transmit impulses from the CNS to the effector organs.

What are some causes of peripheral neuropathic pain?

Neuropathic pain can result from trauma or some type of condition of the nerves and it can be very painful.

What is needed to transport a nerve impulse across the synapse?

Neurotransmitters

Differentiate between non- communicating and communicating hydrocephalus.

Noncommunicating hydrocephalus is caused by an obstruction within the ventricles and can result from congenital abnormalities or tumors. Communicating hydrocephalus occurs when full communication occurs between the ventricles and the subarachnoid space. It can be caused by subarachnoid hemorrhage, tumors can cause compression in the subarachnoid space.

Why is pain important?

Pain provides protection by signaling the presence of disease or injury.

Name two diseases that can be associated with defects of the basal ganglia.

Parkinson's, Schizophrenia

Effects of a concussion that may last for weeks or month after the injury is called

Post concussive syndrome.

Name the period of time after a seizure where the patient appears sleepy and disoriented.

Postictal

Heat stroke

Potentially lethal result of a breakdown in an overstressed thermoregulatory center. Brain cannot tolerate temperatures greater than 40.5° C (104.9° F) Temperature maintained by blood flow through the veins in the head and face. Cardiovascular and thermoregulatory centers may cease functioning in high temperatures. At this point, sweating ceases and the skin becomes flushed and dry. The person must be immediately removed from the heat and cooled off. You will need to get them to a shady area, remove clothing, apply cool to the skin, fan them to promote sweating and evaporation, and place ice packs under armpits and groin.If the person is able to drink liquids, have them drink cool water or other cool beverages that do not contain alcohol or caffeine. Monitor body temperature with a thermometer if one is available and continue cooling efforts until the body temperature drops to 101 to 102 F. Always notify emergency services (911) immediately. If their arrival is delayed, they can give you further instructions for treatment of the victim. Manifestations - Cerebral edema, degeneration of the CNS, swollen dendrites, and renal tubular necrosis Children are more susceptible: Produce more metabolic heat when exercising, Greater surface area-to-mass ratio, Sweating capacity is less than adults

What is the difference in radiation, conduction, and convection?

Radiation - when the temperature of the skin is higher than that of the environment heat radiates from the skin and an example would be how heat radiates from the sun. Conduction is heat loss by direct contact. Convection is the transfer of heat through gasses or liquids and by the way the wind-chill factor is a combination of conduction and convection.

Would a patient with persistent chronic pain typically have an elevated heart rate and BP due to pain?

Response patterns vary, fewer overt signs (adaptation)

What role do Schwann cells play in a neuron become myelinated?

Schwann cells form the myelin sheath, Nodes of Ranvier are spaces in between each Schwann cell caused by the myelin layer being tightly wound around the axon which increases conduction velocity and causes the axon to be considered myelinated. If the Schwann cells are loosely wrapped, the axon is considered to be demyelinated and the conduction velocity is slow. So what happens in unmyelinated axons is that the action potential has to travel the entire length of the neuron but in myelinated axons the action potential quickly jumps from one node to the other making conduction speeds faster and this is called saltatory conduction.

Heat cramps - Severe spasmodic cramps in the abdomen and extremities. Follow prolonged sweating and associated sodium loss. Common in people not accustomed to heat or performing strenuous work in warm climates. Fever, rapid pulse, and increased blood pressure often accompany the cramps. These people need to be given fluids with electrolytes fairly quickly. Heat exhaustion - Heat exhaustion is the next most severe and can progress to heat stroke. These people need to immediately stop what they are doing. Rest in a cool place, preferably on their back with their legs elevated above their heart. Drink cool fluids. Stick to water or sports drinks. No caffeine or alcohol. Apply cool water to your skin. If possible, take a cool shower or soak in a cool bath. Don't use alcohol on your skin, but one thing that you can do is mist the person's body with water and use a fan on them if one is available - this would be heat reduction by convection like we discussed earlier.Loosen clothing. Just basically focus on cooling and rehydrating. Collapse due to prolonged high core or environmental temperatures. Prolonged vasodilation, profuse sweating. Dehydration, depressed plasma volumes, hypotension, decreased cardiac output, tachycardia. Manifestations: Dizziness, weakness, nausea, and syncope

Severe spasmodic cramps in the abdomen and extremities. Follow prolonged sweating and associated sodium loss. Common in people not accustomed to heat or performing strenuous work in warm climates. Fever, rapid pulse, and increased blood pressure often accompany the cramps. These people need to be given fluids with electrolytes fairly quickly.

Name an example of when you might order each of the following tests:

Skull X-ray - to localize bone defects (fractures) X-ray of the cervical, thoracic, or lumbar spine - to localize bone defects (fractures) Head CT - Suspected hemorrhage or tumor Brain MRI - To view the changes that occur during the mental process Brain MRA - to visualize blood vessels PET scan - to visualize the specific brain sites that are involved in the processing of information Brain scan - to identify strokes, tumors, or other problems Angiography - demonstrates cerebrovascular blood flow Myelogram - uses a contrast dye and X-rays or computed tomography (CT) to look for problems in the spinal canal. EEG - localizes foci that initiate seizure activity Lumbar puncture - To analyze CSF for characteristics such as color, blood cells, electrolytes, and proteins.)

Name some major changes in the brain that occur with aging.

Some structural changes that we see in the brain as we age. We see basically atrophy. We see a decrease in the number of neurons, decrease in the size and weight of the brain, increased adherence of the dura mater to the skull, we see fibrosis and thickening of the meninges, the gyri narrow and sulci widen and this corresponds with an increase in the subarachnoid space. And also we see cellular changed such as the presence of plaque and tangles, which as most of you know are associated with Alzheimer's and can only be diagnosed on autopsy. And the lewy bodies can form and these are associated with dementia also and particularly Parkinson's. Also we see functional changes such as slowed response to neural stimulus.

What findings on an ophthalmic exam would indicate papilledema and what are some causes?

Swelling of the optic disc, obliteration of physiologic cup

Describe what is meant by the term blood-brain barrier.

The blood brain barrier protects the neurons and the glial cells from harmful substances and is composed of endothelial cells that form impermeable type junctions. Unlike blood vessels in other parts of the body that are relatively permeable to a variety of molecules, the blood brain barrier keeps many substances, including drugs and toxins, from getting to the cells in the brain. So as far as drugs go, only fat soluble drugs can penetrate the blood brain barrier. So when pharmaceutical companies are looking for medications that act on conditions of the brain they have to make sure that the medications are fat soluble otherwise they will not work. So while it is protective- the blood brain barrier is a protective mechanism- it can also prevent medications used to treat disorders of the brain from actually getting there. So it can cause problems there.

Name the basic functions of the four lobes of the brain and know the location of each.

The frontal lobe is associated with reasoning, planning, parts of speech, movement, emotions, and problem solving. The parietal lobe is associated with movement, orientation, recognition, and perception of stimuli. The occipital lobe is associated with visual processing. The temporal lobe is associated with perception and recognition of auditory stimuli, memory, and speech.

Review the diagram of the vertebrae in your textbook. Injury and degeneration to intervertebral disks are common. When someone has a herniated disk (hint: HNP), what part of the disk actually herniates?

The nucleus pulposus is a gelatinous consistency and this is what protrudes from the disk when the disk herniates. So I tell my patients to imagine a jelly sandwich and you mash down on one side of the sandwich and the jelly kind of squirts out. This is what happens with the nucleus pulposus- when the disk is herniated inward, that can press on the spinal cord and put pressure there or it can encroach on a nerve root and cause pain down in extremity or along the path of that nerve root from irritation.

The Peripheral Nervous System can divided into what two systems?

The somatic nervous system and the autonomic nervous system.

Name and briefly define the two functional components of the PNS.

The somatic nervous system and the autonomic nervous system. Both consist of sensory and motor neurons. The somatic nervous system regulates voluntary muscle movements. The autonomic nervous system regulates the internal environment through involuntary control of organ systems.

Name and briefly define the two peripheral nerve pathways.

There are two peripheral nerve pathways the afferent path, which are composed of sensory neurons that carry impulses from sensory receptors located all over of the body to the CNS, and the efferent which are mainly motor neurons that carry impulses away from the CNS to effector organs such as skeletal, smooth, and cardiac muscles and also glands. An example here would be touching a hot stove. The afferent pathway would send the signal to your brain that pain has occurred and the efferent pathway would cause you to involuntary jerk your hand away from the stimulus before you even realized what has occurred.

Nociception involves four phases during pain modulation. What are the phases and action?

Transduction (stimulation of nociceptors in the periphery) Transmission(Axonal conduction) Perception(cortical processing of stimuli) Modulation (Descending pathways and neurotransmitters that inhibit or amplify pain)

Name some common causes of increased ICP.

Tumor growth, edema, excess CSF, hemorrhage

1. What mechanism of injury can cause a coup and contrecoup brain injury?

a coup injury where the head strikes a hard object and the brain collides with the skull. Keep in mind that the brain is the consistency of custard, so when the brain moves forward it's going to bounce back. When it rebounds off the object that it struck initially, a contrecoup injury occurs. This is just basically the brain striking the opposite side of the skull and it can actually shake back and forth. Depending on how hard the impact was, it can really bruise both sides of the brain.

Agnosia

a defect of pattern recognition - a failure to recognize the form and nature of objects

Epilepsy

a disease of the brain with at least two unprovoked (or reflex) seizures, occurring more than 24 hours apart or one unprovoked (or reflex0 seizure and a probability of further seizures similar to the general reocurence risk (at least 60% after two unprovoked seizures, occurring over the next 10 years or diagnosis of an epilepsy syndrome.

What material acts as insulation for neurons?

a layer of lipid material called a myelin sheath

Seizure

a sudden transient disruption in brain electrical function caused by abnormal excessive discharges of cortical neurons.

Differentiate between persistent vegetative state and locked-in syndrome.

a vegetative state which is a wakeful unconscious state with periods of eye opening, response to painful stimuli, they may exhibit rubbing of the eyes where the eyes just basically go back and forth (one side to the other) and sometimes you will see random movements with no awareness of self or of environment. locked in syndrome which is where the patient is fully conscious but cannot move or speak. the only way that these patients can communicate is through vertical eye movements or blinking.

What important function does the Circle of Willis have?

an arterial structure that is able to compensate for reduced cerebral blood flow by creating a network of collateral circulation which is necessary if an artery becomes occluded.

What are the components of a neuron?

cell body, dendrites, and axons.

Name the number of:

cervical vertebrae - 8 cervical segments - 8 thoracic - 12 lumbar - 5 sacral - 5 coccygeal - 1

The key feature of Huntington's chorea is severe degeneration of the basal ganglia causing classic symptoms such as

chorea.

What is seen clinically when a fever "breaks"?

decreased muscle tone, peripheral vasodilation, and sweating

In Status epilepticus seizures last more than

five minutes and is considered a medical emergency.

What is the "all or none rule"?

if a neuron responds at all, it must respond completely. If the stimulation is too weak, there will be no response. Greater intensity of the stimulation does not produce a stronger signal and this applies to both muscle and nerve cells.

Aphasia

impairment of comprehension or production of language with impaired written or verbal communication.

Dysphasia

language disorder marked by deficiency in the generation of speech, and sometimes also in its comprehension, due to brain disease or damage.

What part of the brain controls respirations?

medulla oblongata

Vasogenic cerebral edema

most common, caused by the increased permeability of the capillaries that form the blood brain barrier. Plasma proteins leak into the extracellular spaces, drawing water to them, and increasing the water content of brain parenchyma, particularly the white matter.

Visceral pain

pain arising from the internal organs such as appendicitis, cholecystitis, constipation, or cystitis.

Somatic pain

pain from a part of the body such as muscle, bone, skin, or connective tissue.

Referred Pain

pain perceived at a location other than the site of the painful stimulus/ origin. It is the result of a network of interconnecting sensory nerves, that supplies many different tissues.

Due to a decrease in dopamine, resting tremors, cogwheel rigidity, and bradykinesia are common features of

parkinson's.

What is a typical cause of tardive dyskinesia?

side effects of anti-psychotic drugs

Differentiate between spondylolysis, spondylithesis, and spinal stenosis.

spondylolysis which is a structural defect of the spine, spondylolisthesis which is one vertebrae slides forward and this is also known in lay terms as a slipped disk, and spinal stenosis which is where the canal that the spinal cord runs through actually becomes stenosed or narrowed.

Name two pathologic changes in the brain that is found in patients with Alzheimer's during postmortem exam.

tangles and plaques

Convulsions

term sometimes applied to seizures and refers to the tonic clonic movement associated with some seizures

How much CSF does our body produce daily?

the body produces approximately 600 CCs per day.

What two arterial systems supply blood to the brain?

the internal carotid artery and the vertebral arteries.

Pain tolerance

the maximum level of pain that a person is able to tolerate.

Pain threshold

the point beyond which a stimulus causes pain.

Nystagmus

the rhythmic movement of one of both eyes. It can be congenital or acquired and there are many causes.

What two systems make up the autonomic nervous system?

the sympathetic and parasympathetic nervous systems that we know as fight or flight which describes the sympathetic nervous system's response to a frightening situation- or new one that I have not heard before which is rest and digest. Which describes the parasympathetic nervous system's response to a nonthreatening situation.

Cytotoxic (metabolic) cerebral edema

toxic factors directly affect the cellular elements of the brain parenchyma (neuronal, glial, and endothelial cells), causing failure of the active transport systems.

Interstitial cerebral edema

transependymal movement of CSF from the ventricles into the extracellular spaces of the brain tissue. The brain fluid volume thus is increased predominately around the ventricles.

Strabismus

usually caused by weak muscles in one or both eyes and is the inability of both eyes to focus on one object - common presenting sx is diplopia or double vision.