review of nervous system, unconsciousness, and cva. the nursing core functions
TRANSCRIPT
B Y AYINLA K.A
R.N. , R .P .H .N . , B .N .S C . , H O N S . U I .
THE NERVOUS SYSTEM AND SOME
RELATED HEALTH CONDITIONS
OUTLINE
INTRODUCTION
OBJECTIVES
NERVOUS SYSTEM ANATOMIC AND PHYSIOLOGIC REVIEW
UNCONSCIOUSNESS AND CEREBROVASCULAR ACCIDENT
CLINICAL MANIFESTATIONS
DIAGNOSTIC PROCEDURES
MANAGEMENT- Medical and Nursing
CONCLUSION
INTRODUCTION
Disorders of the nervous system can occur at any time
during the life span and can vary from mild, self-limiting
symptoms to devastating, life threatening disorders.
Assessment requires knowledge of the anatomy and
physiology of the system and an understanding of the tests
and procedures used to diagnose neurologic disorders.
Also important is the knowledge about the nursing
implications and interventions for dealing with such
problems.
INTRODUCTION CONTS.
Unconsciousness - is when a person is unable to respond to people and
activities. It is often called a coma or being in a comatose state.
CVA – simply connotes a dysfunction of the nervous and circulatory
system. It is one of the major killer disorders that complicates a host of
other ill-health conditions.
Cerebrovascular accident is the sudden death of some brain cells due
to lack of oxygen when the blood flow to the brain is impaired by
blockage or rupture of an artery to the brain. It is also known as stroke.
Both disorders mentioned above obviously involves the nervous system.
OBJECTIVES
Ability to:
Describe the structures and function of the CNS & PNS
Explain physical assessment for the diagnoses of some
neurological disorders
Explain the pathophysiology of altered level of consciousness
and CVA
Describe the general management of CVA and
unconsciousness
Manage CVA and unconscious patient with NP framework
ANATOMIC AND PHYSIOLOGIC REVIEW OF THE NERVOUS SYSTEM
THE NEURON - the functional unit of
the NS, is about 100 billion in human’s
brain alone!
While variable in size and shape, all
neurons have three parts: Dendrites -
receive information from another cell and
transmit the message to the cell body; Cell
Body - contains the nucleus, mitochondria
and other organelles typical of eukaryotic
cells; Axon conducts messages away from
the cell body.
Neurons could be Sensory – for detection or sensitization,
typically have a long dendrite and short axon, and carry
messages from sensory receptors to the CNS, or
Motor Neurons - for Locomotion, have a long axon and short
dendrites and transmit messages from the central nervous
system to the muscles (or to glands),
The third subclass Interneurons are found only in the CNS
connecting other neurons.
Neurons are also Myelinated or Non- Myelinated (presence
or absence of myelin sheaths)
The junction between a nerve cell and
another cell is called a synapse. Messages
travel within the neuron as an electrical
action potential. The space between two cells
is known as the synaptic cleft. To cross the
synaptic cleft requires the actions of
neurotransmitters.
Neurotransmitters are stored in small
synaptic vesicles clustered at the tip of the
axon. They are either destroyed by specific
enzymes in the synaptic cleft, diffuse out of
the cleft, or are reabsorbed by the cell.
NEUROTRANSMITTERS (NTs)
NTs are small molecules, some are even
hormones. The NTs cross the cleft, binding to
receptor molecules on the next cell, prompting
transmission of the message along that cell's
membrane.
The time for NTs’ action is between 0,5 and 1
millisecond. More than 30 organic molecules
are thought to act as NTs.
Acetylcholine is an example of a NT, as
is norepinephrine, although each acts in
different responses. Once in the cleft, NTs are
active for only a short time. Enzymes in the
cleft inactivate the NTs. Inactivated NTs are
taken back into the axon and recycled.
THE BRAIN – CEREBRUM, BRAINSTEM, AND CEREBELLUM
The human brain is the core of the
human NS and is a highly complex organ.
Enclosed in the cranium, with the same general
structure as the brains of other mammals, it is over
three times as large as the brain of a typical
mammal with an equivalent body size.
Most of the expansion comes from the cerebral
cortex, a convoluted layer of neural tissue that
covers the surface of the forebrain. Especially
expanded are the frontal lobes, which are involved
in executive functions such as self-control,
planning, reasoning, and abstract thought. The
portion of the brain devoted to vision is also
greatly enlarged in human beings.
THE BRAIN – CEREBRUM, BRAINSTEM, AND CEREBELLUM
The brain monitors and regulates the body's actions and reactions. It continuously receives
sensory information, and rapidly analyzes this data and then responds, controlling bodily
actions and functions. The brainstem controls breathing, heart rate, and other autonomic
processes. The neo - cortex is the center of higher-order thinking, learning, and memory.
The cerebellum is responsible for the body's balance, posture, and the coordination of
movement.
MOTOR & SENSORY CONTROL AREAS OF THE BRAIN
In spite of the fact that it is protected by the thick bones of the skull, suspended in
cerebrospinal fluid, and isolated from the bloodstream by the blood-brain
barrier, the delicate nature of the human brain makes it susceptible to many types
of damage and disease. The most common forms of physical damage are closed
head injuries such as a blow to the head, a stroke, or poisoning by a wide variety
of chemicals that can act as neurotoxins.
Infection of the brain is rare because of the BBB that protects it, but is very
serious when it occurs.
More common are genetically based diseases, such as Parkinson's disease,
multiple sclerosis, and many others. A number of psychiatric conditions, such as
schizophrenia and depression, are widely thought to be caused at least partially by
brain dysfunctions, although the nature of such brain anomalies is not well
understood.
THE MENINGES
The meninges is one of the CNS protective structures, that consists of 3
connective tissue membranes external to the central nervous system, just within
(beneath) the Skull and vertebral bone.
Layers of the Meninges
a) Dura Mater
Tough meninx (meninges layer)
2 layered fibrous connective tissue.
b) Arachnoid Mater
Forms the subdural space under the dura mater.
c) Pia Mater
Delicate connective tissue that clings to the brain.
Also forms the subarachnoid space under the arachnoid mater.
MENINGES CONTS.
CEREBROSPINAL FLUID (CSF)
Cerebrospinal fluid (CSF) is a clear, saline bodily fluid that occupies the
subarachnoid space and the ventricular system around and inside the brain. It is
produced continuously at a steady rate and is essential for the normal functioning
of the CNS. Very little protein and virtually no cells are present in normal CSF,
only around 35mg per 100ml compared to 7,000mg per 100ml in typical serum. It
is therefore a greater proportion of water (99%) compared to 93% in serum.
Production - CSF is produced in the brain by modified ependymal cells in the
vascular choroid plexus (approx. 50-70%), and the remainder is formed around
blood vessels and along ventricular walls. The CSF is continually produced,
and all of it is replaced every 6 to 8 hours. Both filtration and secretion occurs
by epithelial cells.
Flow of CSF
Generally CSF flows from the lateral ventricles, through the foramina of Monroe to the 3rd
ventricle, then through the cerebral aqueduct (of Sylvius) to the 4th ventricle. It then mostly
flows out of the lateral foramen of Luschka and into the cisterna magna (a dilation of the
subarachnoid space), or caudally into the central canal of the spinal cord.
Exit/Drainage – Normally, CSF will exit via the arachnoid villi. There are other possible
routes of drainage however; such as absorption by venules in the pia mater, through spinal
veins and lymphatics (around the roots of the spinal nerves) and by direct venous drainage
from the subarachnoid space into the venous sinuses.
Functions of the CSF
Protection: the CSF protects the brain from damage by "buffering" the brain. In
other words, the CSF acts to cushion a blow to the head and lessen the impact.
Buoyancy: because the brain is immersed in fluid, the net weight of the brain is
reduced from about 1,400 gm to about 50 gm. Therefore, pressure at the base of
the brain is reduced.
Excretion of waste products: the one-way flow from the CSF to the blood
takes potentially harmful metabolites, drugs and other substances away from the
brain.
Endocrine medium for the brain: the CSF serves to transport hormones to
other areas of the brain. Hormones released into the CSF can be carried to
remote sites of the brain where they may act.
CEREBRAL CIRCULATION
Four major arteries and their branches supply the brain with blood including
- 2 Internal Carotid Arteries (LT & RT) and 2 Vertebral Arteries that
ultimately join at the inferior surface (base) of the brain to form the arterial
Circle of Willis, or the Circulus Arteriosus.
Circle of Willis is composed of the right and left internal carotid arteries
joined by the anterior communicating artery. The basilar artery (formed by
the fusion of the vertebral arteries) divides into LT & RT posterior cerebral
arteries that are connected (anastomosed) to the corresponding left or right
internal carotid artery via the respective left or right posterior
communicating artery. A number of arteries that supply the brain originates
at the circle of Willis, including the anterior cerebral arteries that originate
from the anterior communicating artery.
CEREBRAL CIRCULATION CONTS.
THE CIRCLE OF WILLIS IN
ACTION
CEREBRAL CIRCULATION CONTS.
Venous Drainage
Cranial Venous Drainage - The brain and spinal cord use a series of
dural sinuses, in addition to veins to remove CSF and venous blood.
Dural sinuses have no valves, (the venous system of the cranium
generally has few valves).
Spinal Venous drainage - A similar system exists to drain venous
blood from the spinal cord. There is a direct continuity with the
cranial sinuses. CSF and venous blood drain via intervertebral veins
into either the vertebral, azygos veins or the vena cava.
Blood-Brain Barrier (BBB)
This simply refers to the greatly reduced permeability of brain capillaries, That 1,200
– 1,400 grams inside our skull is fed by some 650 km of blood vessels. These blood
vessels twist and loop around to make intimate contact with every single one of our
100 billion-or-so nerve cells. They are lined by a strange structure called the BBB. It
closely controls what is, and is not, allowed to leave the blood supply and enter the
brain. It's your own personal customs and border security. In fact they are the least
permeable capillaries in the entire body (However in some areas it is very porous i.e.
hypothalamus)
Glucose, amino, acids, and electrolytes move freely, however toxins, metabolic
wastes etc. do not.
Fats and fat-soluble molecules also move freely. This includes various drugs & alcohol
THE SPINAL CORD
It continues with the brain stem, the main pathway for information
connecting the CNS and PNS.
It protected by the bony spinal column, which is made up of bones
called vertebrae, hence it’s sometimes called the vertebral column, (made up
of 33 bones: 7 vertebrae in the cervical region, 12 in the thoracic region, 5 in
the lumbar region, 5 in the sacral region and 4 in the coccygeal region.
However, in adults the bones in the sacral region join to form one bone called
the sacrum; the bones in the coccygeal region join to form one bone called
the coccyx.).
The spinal cord is located in the vertebral foramen and is made up of 31
segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal. A pair
of spinal nerves leaves each segment of the spinal cord.
SPINAL CORD CONTS.
The spinal cord length is about 45 cm in men and 43 cm in
women; it is shorter than the length of the bony spinal column;
it extends down only to the last of the thoracic vertebrae.
Nerves that extend from the spinal cord from the lumbar and
sacral levels must run in the vertebral canal for a distance before
they leave the vertebral column. This collection of nerves in the
vertebral canal is called the cauda equina (i.e. "horse tail").
AUTONOMIC NERVOUS SYSTEM
There are three divisions of the autonomic nervous system: enteric, sympathetic, and
parasympathetic.
The enteric nervous system is contained wholly within the organs of the digestive system and
is composed of 100s of millions of neurons found in the walls of the digestive tract. It
regulates the motility of viscera and the secretion of digestive enzymes and acid in concert
with the ANS. Thus, the brain can impact the enteric nervous system, but it is capable of
regulating itself without input.
The other two divisions of the ANS are the sympathetic and parasympathetic nervous
systems. These systems innervate the same target organs and may have cooperative or
contrasting effects (as seen below)
The sympathetic division prepares the body for physical activity while
the parasympathetic division has a calming effect on many body functions and assists
in bodily maintenance.
STRUCTURESYMPATHETIC
STIMULATION
PARASYMPATHETIC
STIMULATION
Iris (eye muscle) Pupil dilation Pupil constriction
Salivary Glands Saliva production reduced Saliva production increased
Oral/Nasal Mucosa Mucus production reduced Mucus production increased
Heart Heart rate and force increased Heart rate and force decreased
Lung Bronchial muscle relaxed Bronchial muscle contracted
Stomach Peristalsis reducedGastric juice secreted; motility
increased
Small Intestine Motility reduced Digestion increased
Large Intestine Motility reducedSecretions and motility
increased
LiverIncreased conversion of
glycogen to glucose
Kidney Decreased urine secretion Increased urine secretion
Adrenal medullaNorepinephrine and
epinephrine secreted
BladderWall relaxed
Sphincter closed
Wall contracted
Sphincter relaxed
SYMPATHETIC
STIMULATION
PARASYMPATHETIC
STIMULATION
Pupil dilation
Saliva production reduced
Mucus production reduced
Heart rate and force
increased
Bronchial muscle relaxed
Peristalsis reduced
Motility reduced
Motility reduced
Increased conversion of
glycogen to glucose
Decreased urine secretion
Norepinephrine and
epinephrine secreted
Wall relaxed
Sphincter closed
Pupil constriction
Saliva production increased
Mucus production increased
Heart rate and force decreased
Bronchial muscle contracted
Gastric juice secreted; motility increased
Digestion increased
Secretions and motility increased
Increased urine secretion
Wall contractedSphincter relaxed
• Iris (eye muscle)
• Salivary Glands
• Oral/Nasal
Mucosa
• Heart
• Lung
• Stomach
• Small Intestine
• Large Intestine
• Liver
• Kidney
• Adrenal medulla
• Bladder
STRUCTURE
FUNCTIONS OF THE NERVOUS SYSTEM
The functions have been highlighted in the respective
descriptions above.
Notably however is to state that the NS does both –
cognitive, locomotive and sensory perceptual functions
throughout our entire lives.
DIAGNOSTIC ASSESSMENT Health history
Clinical manifestation e.g. pain, seizures
Physical examination e.g. brain function, cranial nerves, motor functions, reflexes etc.
Specialized Diagnostic Tests e.g.
Computerized Tomographic Scanning (CT- Scan)
Positron Emission Tomography (PET)
Magnetic Resonance Imaging (MRI)
Cerebral Angiography
Myelography
Electroencephalography
Lumbar puncture and examination of cerebrospinal fluid.
GLASGOW COMA SCALE (GCS)
Diagnosis of NS conditions remains incomplete
without a mention of GCS. This assessment tool is
graded and used as follows;
Eye Opening Response
Spontaneous--open with blinking at baseline 4
points
To verbal stimuli, command, speech 3 points
To pain only (not applied to face) 2 points
No response 1 point
Verbal Response
Oriented 5 points
Confused conversation, but able to answer
questions 4 points
Inappropriate words 3 points
Incomprehensible speech 2 points
No response 1 point
Motor Response
Obeys commands for movement 6 points
Purposeful movement to painful stimulus 5
points
Withdraws in response to pain 4 points
Flexion in response to pain (decorticate
posturing) 3 points
Extension response in response to pain
(decerebrate posturing) 2 points
No response 1 point
Categorization:
Coma: No eye opening, no ability to follow commands, no word verbalizations (3-8)
Head Injury Classification:
Severe Head Injury----GCS score of 8 or less
Moderate Head Injury----GCS score of 9 to 12
Mild Head Injury----GCS score of 13 to 15
(Adapted from: Advanced Trauma Life Support: Course for Physicians, American College of
Surgeons, 1993).
Based on motor responsiveness, verbal performance, and eye opening to appropriate stimuli,
the GCS was designed and should be used to assess the depth and duration coma and
impaired consciousness. This scale helps to gauge the impact of a wide variety of conditions
such as acute brain damage due to traumatic and/or vascular injuries or infections, metabolic
disorders (e.g., hepatic or renal failure, hypoglycemia, diabetic ketosis), etc.
UNCONSCIOUSNESS
Coma ( or unconsciousness ) is a state in which a patient is
totally unaware of both self and external surroundings, and
unable to respond meaningfully to external stimuli.
It results from gross impairment of both cerebral hemispheres,
and/or the ascending reticular activating system.
Pathophysiology of Altered Level of consciousness
Altered level of consciousness is not a disorder in itself rather it is a
function and symptom of multiple pathophysiologic phenomena.
The causes may include neurologic (head injury or CVA), toxic (e.g. drug
overdose or poisoning), metabolic (e.g. diabetic keto-acidosis), etc.
There occurs a destruction in the basic functional units of the nervous
system, resulting in faulty impulse transmission and impeded
communication within the brain; and from the brain to other part of the
body.
This leads to the unique presenting clinical manifestations.
MANAGEMENT OF UNCONSCIOUSNESS
Medical
Maintain patent airway
Commence IV fluid therapy
Determine underlying causes
Specific treatment of underlying causes e.g. pharmacology and
Strategies to prevent complications.
Nursing Management of Unconsciousness - Assessment
Assess patient for;
Verbal responses
Level of consciousness using relevant scale, e.g. Glasgow’s neurologic coma scale
Monitor sensory and motor functions
Monitor clinical manifestations, and body functioning such as circulation etc.
SPECIFIC NURSING DIAGNOSESThese may include;
Ineffective airway clearance
Risk of injury
Fluid volume deficit
Disturbed sensory perception
Impaired mobility
Disturbed thought processes
Self-care deficit syndrome (bathing/hygiene, dressing/grooming, feeding and toileting).
Nursing Care Outcomes
These should be properly thought out to resolve the actual & potential problems
(diagnoses) identified above. A proper Nursing care plan must be drawn to implement
the following actions. THIS IS USUALLY BASED ON PRACTICE AREA TOOLS &
POLICIES.
NURSING INTERVENTIONImplement care based on problems identified e.g.
Maintaining airway – positioning with proper head turning, suctioning,
administration of O2
Protecting patient from injury – remove patient from danger/danger from patient
and/or admit patient in danger free zones
Providing and maintain self-care – help patient maintain optimum level of personal
hygiene and overall level of wellness.
Providing sensory stimulation – referral to the physiotherapists is often inevitable.
The nurse therefore require a great deal of knowledge in NS stimulation, example
use of sand bags, some simple massage techniques and range of motion & other
forms of exercise.
Close observation - Monitoring and managing potential complications, etc.
NURSING INTERVENTION CONTS.
Other specific forms of care may include;
pressure area care
care of the mouth, eyes and skin
physiotherapy to protect muscles and joints
risks of deep vein thrombosis
risks of stress ulceration of the stomach
nutrition and fluid balance
urinary catheterization
monitoring of the CVS
infection control
maintenance of adequate oxygenation, with the assistance of artificial ventilation.
EVALUATION
Expected patient outcome may include
Evidence of clear airway
Experience of no injury
Maintenance of adequate fluid status
Attainment and maintenance of healthy
oral mucosa
Maintenance of normal skin integrity, etc.
CEREBROVASCULAR ACCIDENT
(CVA/STROKE)
THE UNTOLD
STORY OF
AN ICE BERG!
PATHOPHYSIOLOGY OF CVA Stroke is a primary cerebrovascular disorder which occurs when there is functional disability
of the CNS as a result of disruption of the normal blood supply to the brain. It is mainly
categorized as ischemic (ICVA) and hemorrhagic (HCVA) types.
The former implies disruption of blood flow due to obstruction of a blood vessel, while the
later primarily involves intracranial or subarachnoid hemorrhage due to rupture of a cerebral
vessel.
In ICVA cerebral blood flow falls below normal and the nervous system can no longer
maintain aerobic respiration.
In HCVA, an aneurysm enlarges and presses on cranial nerves or brain tissue or dramatically
ruptures, causing subarachnoid hemorrhage.
Clinical manifestations occur as a result of the above process and may include; sudden
severe headache, visual disturbance, tinnitus, dizziness, numbness, weakness, of the face,
arm or leg and loss of consciousness, etc.
ASSESSMENT AND DIAGNOSIS
History taking - usually from relations
Physical and neurological examinations
CT scan
Lumbar puncture, if no evidence of increased
intracranial pressure
Radiological studies e.g. carotid angiography
GENERAL MANAGEMENT OF CVAMedical
Thrombolytic therapy – heparin
Analgesia
Symptomatic treatment
Bed rest
Surgical
Many patients with primary intracranial hemorrhage may not be treated surgically.
However, surgical evacuation of cerebral hemorrhage can be performed via
craniotomy. Less invasive procedures that could be performed include:
Endovascular treatment and
Aneurysm coiling
NURSING MANAGEMENT OF A PATIENT WITH CVA
Assessment – Assess for:
Level of consciousness
Motor and sensory dysfunction
Headache (if conscious)
Eye opening and papillary signs
Airway patency
Gag and cough reflex
Respiratory pattern and
Cardiovascular status
Problems / Nursing Diagnoses Impaired physical mobility
Disturbed sensory perception
Self-care deficit
Impaired verbal communication
Pain
Ineffective tissue perfusion etc.
Nursing Care Outcomes
These should be properly thought out to resolve the actual & potential
problems (diagnoses) identified above. A proper Nursing care plan must be
drawn to implement the following actions. THIS IS USUALLY BASED ON
PRACTICE AREA TOOLS & POLICIES.
Nursing InterventionImplement care based on problems identified e.g.
Improving mobility and preventing joint deformities
Enhancing self-care
Optimizing cerebral tissue perfusion
Managing sensory perception
Improving communication
Relieving pain and discomfort etc.
EVALUATION - Evaluation criteria may include;
Achievement of improved mobility
Demonstration of normal sensory perception
Achievement and maintenance of self-care status
Demonstrates normal speech pattern
Exhibits less feelings of pain
Demonstrate intact neurologic status
Demonstration of normal vital signs and respiratory patterns.
STROKE HEROES ACT FAST
CALL FOR
HELP
CONCLUSION
The anatomic and physiologic review of nervous system, and the general
assessment and diagnostic evaluation for neurologic disorders discussed in
this lecture will enhance our understanding of any form of deviation from the
norm.
The pathophysiology of CVA as discussed, including the management of
patient with altered level of consciousness and patient with CVA is to
reinforce our professional practice in this era of evidence based practice. All
cases that affects level of consciousness should be considered emergencies
unless proven otherwise. Finally, I humbly advocate that the nursing process
be used as framework for nursing care at all settings. This is our own
language, let’s develop and treasure it.
REFERENCE
Berman, A. Synder, S.J., Kozier, B. & Erb, G: (2008) Kozier & Erb’s Fundamentals of
Nursing: Concepts, Process, & Practice. N.J: Prentice Hall
Center for Disease Control (CDC), (2003),Mass Casualties. Available at:
http://www.bt.cdc.gov/masscasualties/pdf/glasgow-coma-scale.pdf
Eric H. Chudler, (2011), Neuroscience for Kids, University of Washington 1996-2011.
Available at: http://faculty.washington.edu/chudler/auto.html
Geralyn M. Caplan, (2013), Lecture notes on BIO 137 Anatomy & Physiology I.
Available at: http://legacy.owensboro.kctcs.edu/gcaplan/anat/notes/default.htm
Guyton, A.C., & Hall, J.E. (2006), Textbook of Medical Physiology. Philadelphia:
Saunders
NANDA-I (2007), Nursing Diagnoses: Definition & Classifications 2007 – 2008.
Philadelphia: NANDA International
Smeltzer, S.C. & Bare, G.B.G. (2004) Brunner & Suddarth’s Textbook of Medical -
Surgical Nursing. Philadelphia: Lippincott, Williams & Wilkins
NB: Images were linked through google image and video search, and further studiesof all presented above is hereby highly advocated.