Disorders of the Neurological System (RRD#10)

Maintenance of cerebral blood flow is dependent on keeping what two forces in balance?

cerebral perfusion pressure (CPP) and intracranial pressure (ICP)

What is cerebral perfusion pressure (CPP)?

the pressure required to get oxygenated blood into the brain to perfuse the cells of the brain. If it is too low or too high, cerebral edema and increased ICP can result.

What is intracranial pressure (ICP)?

the totality of pressures in the brain: arterial pressures + venous pressures + CSF pressures, etc.

because the cranium is a bony structure, very little increase in pressure in the brain can be tolerated.

What is the main culprit that causes an increase in ICP?

cerebral edema

What can cause cerebral edema?

ischemia from a blockage of an artery in the brain (hypoxia), brain tumors, injuries, irritants (infections, acidosis), hypertension / hypotension, etc.

What is a "brain attack" or a stroke?

the process of any interruption of the normal blood supply to a part of the brain or the entire brain, resulting in damaged brain tissue. AKA: stroke, cerebral vascular accident (CVA)

What are the most common etiologies of a brain attack?

atherosclerosis of the cerebral arteries or of the incoming arteries (vertebrals and carotids), hypertension, heart problems that can lead to not enough cardiac output or blood to the brain, and brain aneurysms.

What are the risk factors for a brain attack?

atherosclerosis in any part of the body, hypertension, older age, family history, diabetes, lifestyle issues (smoking and high fat diets)

What are the two main types of brain attacks?

ischemic brain attacks and hemorrhagic brain attacks

(although...actually the negative effects of a stroke come from cerebral edema and IICP (which are the result of the stroke)...no matter what type of stroke it is.)

How do you know what type of stroke it is or what treatment is best?

You can't tell from the patient's symptoms...you must have a CT scan (or an MRI) to be able to tell if it is a hemorrhagic or ischemic stroke.

Ischemic brain attack is usually caused by a ________ or _______ of the arteries that supply the brain or are in the brain.

narrowing or blockage.

This means that a stroke can be thrombotic or embolic in nature.

What types of events can contribute to a thrombotic or embolic ischemic stroke?

atrial fibrillation, atherosclerosis of the carotids, air emboli, clots around a mitral / aortic valve prosthesis, or the development of intracranial artery plaque.

What is a transient ischemic attack (TIA)?

Happens in a thrombotic or embolic situation and causes the same s/sx as a fully evolved stroke, but symptoms resolve themselves within 24 hours and the event does not damage brain tissue.

TIAs are a warning that a more serious, fully-evolved stroke can occur at a later date.

What is a hemorrhagic brain attack (stroke)?

usually caused by the effects of blood that leaks out directly onto brain tissue. This causes an inflammatory process-> swelling -> and cerebral edema -> increased ICP ->cellular ischemia, injury, and possibly infarction of the surrounding area.

What are some possible causes of a hemorrhagic brain attack?

the pressure from hypertension

weakened arterial walls from atherosclerosis

the presence of aneurysms

congenital vascular malformations

bleeding into a tumor

coagulation disorders

What are the three main assessment points for a stroke patient?

1.) assess autonomic status (includes level of consciousness and vital signs).

2.) assess sensorimotor status above and below the shoulders

3.) assess reflexes

What are typical vital signs to assess and what do they indicate when they are normal?

Blood pressure (BP), heart rate (HR), respiratory rate (RR), temperature. When they are within a normal range, it is an indicator that the brain stem is functioning normally.

What does level of consciousness mean?

It refers to the brain's ability to respond appropriately to the environment. Expected LOC includes:

being alert or easily arousable to alertness if asleep

being oriented x 4 (self, time, place, events)

following commands appropriately

having normal speech

conversing appropriately (cognition, "mental status" ok)

Give some examples of abnormal LOC findings.

lethargy or inability to waken patient at all (coma)

not oriented to some or all of self, time, place, or events

doesn't follow commands

speech might be garbled or no speech at all

verbal responses might show confusion, delirium, dementia, or behavioral changes.

What is delirium?

An acute state of confusion due to problems such as high fever, electrolyte imbalances, etc.

What is dementia?

A chronic dysfunction of memory and / or function that develops over time.

What are normal, expected sensorimotor findings in a neurological assessment?

Normal sensation, muscle tone, and movement that is symmetric bilaterally.

What "rules" sensorimotor status above the shoulders?

The 12 cranial nerves.

If there is a focal lesion related to a cranial nerve, what type of assessment findings would you expect to have?

Asymmetric findings with the defect manifesting itself unilaterally on the opposite side.

Example: if there is focal cerebral edema around the right cranial nerves you would see facial drooping on the left side of the face.

What rules sensorimotor status below the shoulders?

The corticospinal and spinothalamic tracts.

What are the functions of the corticospinal tracts?

They carry impulses that produce voluntary movements of purpose and skill from the brain via the spinal cord to various peripheral spinal nerves to the neuromuscular junctions between the nerves and muscles.

What are the functions of the spinothalamic tracts?

They carry sensations of pain, temperature, and crude and light touch from the body to the brain (thalamus) for processing.

If there is a focal lesion related to the corticospinal or spinothalamic tracts, what types of assessment findings would you expect to have??

The pathological changes will usually be unilateral, on the contralateral (opposite) side of the body because of the decussation of the nerves.

What are normal, expected reflex assessment findings in a neurological assessment?

Normal peripheral reflexes included an expected degree of response, which is equal bilaterally, reflects good connections in the reflex arc of he spine and also normal interpretation in the brain.

Normal central reflexes include a normal cough, gag, and swallow reflex.

With any type of brain lesion, some reflexes might...

diminish or become absent. Examples:

1. deep tendon reflexes may become hypoactive

2. gag, swallow, or cough reflexes may fail to protect adequately.

3. inappropriate reflexes may appear (ie. a Babinski reflex in adults)

What would be the cause of a diffuse brain / brain stem stroke?

An event would have to happen that causes the whole brain to become hypoxic and edematous with increased ICP. For example: the patient's heart stops beating and they stop breathing or there is a complete occlusion of the vertebral - basilar artery.

What would be some typical s/sx of a diffuse injury stroke?

s/sx are seen equally throughout the body (above and below the shoulders)

sensation, muscle tone, movement, strength, and reflexes would be weaker bilaterally and often fairly symmetrically.

you may also observe brain stem abnormalities due to diffuse cerebral edema and IICP which will result in diminished LOC, heart rate, breathing, and/ or blood pressure changes.

What are two bizarrely abnormal motor responses to stimuli that may be present in a patient with brain stem abnormalities?

decorticate and decerebrate posturing

What would be some typical s/sx of a patient with a cerebellar stroke?

There are usually problems with coordination and balance. S/sx may also include vertigo, nystagmus, nausea / vomiting, loss of coordination, and falling down. This can also occur because of a vertebral-basilar artery occlusion / near occlusion.

What would be the location of a cerebral hemispheric stroke?

a lack of blood flow or bleeding in an area of the left or right hemisphere of the cerebrum that results in swelling and edema. This could occur because of a lack of blood flow or bleeding in the left or right middle cerebral artery or one of its many branches.

What would be some typical s/sx of a patient with a cerebral hemispheric stroke?

1. sensorimotor deficits caused by the lesion / pressure on the CNs in / near the affected area in that hemisphere

2. sensorimotor deficits caused by the lesion / pressure on the corticospinal tracts in / near the affected area in that hemisphere

3. deficits based on what special functions are controlled by that hemisphere

In most people, the left hemisphere controls...

many aspects of speech, so the patient may have dysphasia or aphasia

the ability to do math, organize, reason, and analyze

In most people, the right hemisphere controls...

spatiality (where you are in space and where things are around you). These patients have a tendency to develop left-sided neglect.

The right hemisphere is also the seat of insight, creativity, face recognition, musical ability, etc.

What is the "Act FAST..." scale?

A method of assessing for stroke that the public is encouraged to use.

Face = Ask the person to smile. Does one side of the face droop?

Arms = Ask the person to raise both arms. Does one arm drift downward?

Speech = Ask the person to repeat a simple sentence. Are the words slurred? Can s/he correctly repeat the sentence?

Time = If the answer to any of the above three questions is yes, time is important. Immediately call 911 or go to the nearest hospital emergency room. Brain cells are dying.

What are the first interventions in a hospital setting for stroke?

1. Prevention of further increase of ICP: give oxygen, manage BP, keep the head of the bed up at least 30 degrees, administer diuretics, sometimes monitor ICP more directly.

2. Determine the type of stroke (hemorrhagic or ischemic) by using a CT scan.

3. Treatment is based on the type of stroke: ischemic stoke = anticoagulant therapy of some type, hemorrhagic stroke = possibly a surgical intervention.

What are some typical s/sx of alzheimer's disease?

Dementia, behavioral changes, emotional upset, possible posture and motor/gait changes due to neurofibrillary tangles and amyloid plaques present in brain.

What are some typical s/sx of parkinson's disease?

overall muscle rigidity, difficulty forming words / swallowing, tremors, a stooped, shuffling posture due to a dysfunction in the basal ganglion in which there is a depletion of dopamine.

What are some typical s/sx of multiple sclerosis?

S/sx are usually variable, individualistic, and usually asymmetric due to demyelination of the axons in the brain. This auto-immune disease typically has patterns of exacerbation and remission. Symptoms may include, but are not limited to: paresthesias, weakness of certain muscles, vertigo, incoordination, ataxia, dysarthria, double vision, bladder control problems, etc.

What are some typical s/sx of migraines?

a prodrome (s/sx before the headache, which may also include an aura)

the headache itself, which may be unilateral, and accompanied by nausea, vomiting, photophobia, or phonophobia.

a postdrome, where the patient complains of feeling week, tired, or washed out.

What are some potential causes of migraines?

The exact cause is unknown, but it is thought to be a disorder of blood flow to the brain. In addition, some individuals have are thought to have a hyperreactivity to certain stressful events or chemicals.

What are some potential causes of seizures?

It can be a congenital problem (such as epilepsy) or due to an acute problem in the brain (fever, stroke, head injury).

What are the two types of seizures?

General seizures: the patient is always unconscious and the movement is tonic-clonic (alternating ridigity and contraction of muscles of the whole body)

Partial seizures: begin locally and the patient can have varied levels of consciousness.

What are the s/sx of a patient who is post-ictal?

The patient is often dazed, confused, and may be combative. The brain's circuits are still not back to normal.

What is meningitis?

An infection & inflammation of the meninges. There are two types viral (aseptic) and bacterial meningitis.

What are the s/sx of bacterial meningitis?

edema of meninges surrounding the brain, increased ICP, photophobia, headache, irritability, restlessness, decreased LOC, nausea and vomiting, neck stiffness (nuchal rigidity), positive Brudzinski and Kernig's signs,, fever, purpura, petechiae, leukocytosis.

CSF will be positive for high WBC count, higher than normal protein count, lower than normal glucose count, and blood.

What are the s/sx of myasthenia gravis?

this is a chronic auto-immune disease that blocks, alters or destroys the receptors for acetylcholine. This results in progressive muscle weakness with motor activity that improves with rest.

What is mydriasis?

pupillary dilation that usually occurs equally in both pupils upon exposure to less light as a result of the SNS releasing norepinephrine.

What is miosis?

pupillary constriction that usually occurs equally in both pupils upon exposure to more light as a result of the parasympathetic fibers within CN III releasing acetylcholine.

Damage to CN III will cause what to happen?

the loss or diminishing of pupillary constriction abilities, so that the pupil will dilate abnormally and not respond to light (or respond sluggishly).

Why is an unequal pupil size (from one eye to the other) important?

When one eye responds to a stimulus (such as a light) and the other eye does not, it could be a potentially important sign of a neurological disorder or such as increased ICP or intracranial hemorrhage.

What is diplopia?

double vision. It may be caused by a week ocular muscle, neuromuscular disease, cerebral hemispheric diseases, or thyroid disease.

What is nystagmus?

rhythmic, involuntary, unilateral or bilateral movement of the eyes. It can be horizontal or vertical movement. It can be congenital or a sign of cerebellum or inner ear dysfunction and associated with vertigo and balance problems.

What is papilledema?

Edema and inflammation of the optic nerve where it enters the retina. This is caused by the blockage of venous return from the retina mainly because of increased ICP.

What is glaucoma?

An age-related disease process in which there is an elevation of intra-occular pressure that results in a loss of visual fields and can eventually lead to blindness.

What are the symptoms of open angle glaucoma?

In this type of glaucoma, the angle doesn't close completely, but instead slowly diminishes and stays diminished. The patient experiences a painless, slow loss of peripheral vision.

What are the symptoms of closed-angle glaucoma?

In this type of glaucoma, the angle closes suddenly and unexpectedly. The patient experiences acute eye pain, blurred vision, and haloes around objects. This is considered a medical emergency.

What is age-related macular degeneration?

A severe and irreversible loss of central vision due to the destruction of the macula (it's like having a black spot in the center of your vision). There is no effective treatment.