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.