Neurological assessment

Anatomic and Physiologic Overview The nervous system consists of two divisions:

the central nervous system (CNS) including the brain and spinal cord

peripheral nervous system, which includes cranial and spinal nerves.

The peripheral nervous system can be further divided into the somatic, or voluntary, nervous system, and the autonomic, or involuntary, nervous system.

The function of the nervous system is control of all motor, sensory, autonomic, cognitive, and behavioral activities.

The nervous system has approximately 10 million sensory neurons that send information about the internal and external environment to the brain and 500,000 motor neurons that control the muscles and glands.

The brain itself contains more than 100 billion cells that link the motor and sensory pathways, monitor the body's processes, respond to the internal and external environment, maintain homeostasis, and direct all psychological, biologic, and physical activity through complex chemical and electrical messages

Anatomy of the Nervous System Cells of the Nervous System The basic functional unit of the brain is the

neuron It is composed of a cell body, a dendrite, and an axon.

The axon is a long projection that carries impulses away from the cell body. Nerve cell bodies occurring in clusters are called ganglia or nuclei.

Neurotransmitters Neurotransmitters communicate messages

from one neuron to another or from a neuron to a specific target tissue .

(In fact, probably all brain functions are modulated through neurotransmitter receptor site activity, including memory and other cognitive processes

Many neurologic disorders are due, at least in part, to an imbalance in neurotransmitters—that is :

an increase in gamma-aminobutyric acid (GABA) in alcohol withdrawal seizures

(a decrease in dopamine in Parkinson's disease and a decrease in acetylcholine in myasthenia gravis

The Central Nervous System

Brain The brain is divided into three major areas:

the cerebrum, the brain stem, and the cerebellum.

The cerebrum is composed of two hemispheres, the thalamus, the hypothalamus, and the basal ganglia.

Each hemisphere has four lobes: parietal, occipital, temporal, & frontal. The

cerebral lobes control complex problem-solving; value judgments; language;emotions; interpretation of visual images; & interpretation of touch, pressure,temperature, & position sense.

Each hemisphere sends and receives impulses from the opposite sides of the body

and consists of four lobes "frontal, parietal, temporal and occipital". The lobes are

composed of a substance known as gray matter, which mediates higher-level-functions such as memory, perception, communication,

and initiation of voluntary movements.

The brain stem includes the midbrain, pons, medulla, Is a major sensory and motor pathway for impulses running to and from the cerebrum. Regulates body functions such as respiration, auditory and visual reflexes, swallowing.

The cerebellum is located under the cerebrum and behind the brain stem).

contains the major motor and sensory pathways. It controls smooth, coordinated muscle movements and helps to maintain equilibrium.

The brain accounts for approximately 2% of the total body weight; in an average young adult, the brain weighs approximately 1,400 g whereas in an average elderly person, the brain weighs proximately 1,200g

The meninges (fibrous connective tissues that cover the brain and spinal cord) provide protection, support, and nourishment to the brain and spinal cord. The layers of the meninges are the dura, arachnoid, and pia mater .

Cerebrospinal Fluid

CSF, a clear and colorless fluid with a specific gravity of 1.007, is produced in the ventricles and is circulated around the brain and the spinal cord through the ventricular system. There are four ventricles: the right and left lateral and the third and fourth ventricles

CSF is produced in the choroid plexus of the lateral, third, and fourth ventricles. The ventricular and subarachnoid system contains approximately 150 mL of fluid; each lateral ventricle normally contains 25 mL of CSF .

The composition of CSF is similar to other extracellular fluids (such as blood plasma), but the concentrations of the various constituents are different.

The laboratory report of CSF analysis usually contains information on color, specific gravity, protein count, white blood cell count, glucose, and other electrolyte levels Normal CSF contains a minimal number of white blood cells and no red blood cells .

Cerebral Circulation The cerebral circulation receives

approximately 15% of the cardiac output, or 750 mL per minute. The brain does not store nutrients and has a high metabolic demand that requires the high blood flow.

The brain's blood pathway is unique because it flows against gravity; its arteries fill from below, and the veins drain from above.

In contrast to other organs that may tolerate decreases in blood flow because of their good collateral circulation, the brain has poor collateral blood flow, which may result in irreversible tissue damage when blood flow is occluded for even short time periods

Spinal Cord The spinal cord is located in the vertebral

canal and extends from the medulla oblongata to the first lumbar vertebra,and serving as the connection between the brain and the periphery.

Approximately 45 cm (18 in) long and about the thickness of a finger,

The spinal cord is an H-shaped structure with nerve cell bodies (gray matter) surrounded by ascending and descending tracts (white matter)

The spinal cord conducts sensory impulses up ascending tracts to the brain, conducts motor impulses down descending tracts to neurons that stimulate glands and muscles throughout the body, and is responsible for simple reflex activity. Reflex activity involves various neural structures.

Peripheral Nervous System

The peripheral nervous system consists of 12 pairs of cranial nerves and 31 pairs of spinal

nerves These nerves are categorized as two types of

fibers: somatic and autonomic. autonomic nervous system mediates unconsciousness, or

involuntary activities.  

Spinal Nerve The spinal cord is composed of 31 pairs of

spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. Each spinal nerve has a ventral root and a dorsal root

Autonomic Nervous System The autonomic nervous system regulates the

activities of internal organs such as the heart, lungs, blood vessels, digestive organs, and glands. Maintenance and restoration of internal homeostasis is largely the responsibility of the autonomic nervous system.

There are two major divisions: the sympathetic nervous system, with predominantly excitatory responses, most notably the “fight or flight” response .

and the parasympathetic nervous system, which controls mostly visceral functions.

Assessment: The Neurologic Examination Health History An important aspect of the neurologic

assessment is the history of the present illness. The initial interview provides an excellent opportunity to systematically explore the patient's current condition and related events while simultaneously observing overall appearance, mental status, posture, movement, and affect.

Neurologic disease may be stable or progressive, characterized by symptom-free periods as well as fluctuations in symptoms

The nurse should be aware of any history of trauma or falls that may have involved the head or spinal cord. Questions regarding the use of alcohol, medications, and illicit drugs are also relevant.

The history-taking portion of the neurologic assessment is critical and, in many cases of neurologic disease, leads to an accurate diagnosis. .

Neurological assessment

The Glasgow Coma Scale Best Eye-Opening Response Score Spontaneously 4 To speech 3 To pain 2 No response 1 Best Motor Response Score Obeys commands 6 Localizes stimuli: attempt to remove noxious stimuli 5

Withdrawal from stimulus :to avoid noxious stimuli 4 Abnormal flexion (decorticate) 3 Abnormal extension (decerebrate) 2 No response - flaccid 1

The Glasgow Coma Scale

Best Verbal Response Score Oriented 5 Confused conversation: 4Answer not appropriate to question

Inappropriate words: disorganized ,random speech 3 Incomprehensible sounds 2 No response 1

A total score of 3 to 8 suggests severe impairment, 9 to 12 suggests moderate impairment, and 13 to 15 suggests mild impairment.

Categories of consciousness

Alert (full consciousness): normal Awake: may sleep more than usual or be somewhat confused

on first awakening, but fully oriented when Aroused.

Confused :pt disoriented to time and place put usually oriented to person ,with impaired judgment and decision making.

Delirious: pt disoriented to time and place and person with loss of contact with reality and often has auditory or visual hallucination.

Lethargic: drowsy but follows simple commands when stimulated, in which the pt needs an increased stimulus to be awakened.

Comatose: may have no response to any stimulus.

Clinical Manifestations

Pain is considered an unpleasant sensory perception and emotional experience associated with actual or potential tissue damage or described in terms of such damage

Seizures are the result of abnormal paroxysmal discharges in the cerebral cortex, which then manifest as an alteration in sensation, behavior, movement, perception, or consciousness

Dizziness and Vertigo Dizziness is an abnormal sensation of

imbalance or movement.. About 50% of all patients with dizziness have vertigo, which is defined as an illusion of movement, usually rotation . Vertigo is usually a manifestation of vestibular dysfunction. It can be so severe as to result in disorientation, loss of equilibrium (staggering), and nausea and vomiting.

Visual Disturbances Lesions of the eye itself (eg, cataract),

lesions along the pathway (eg, tumor), or lesions in the visual cortex (from stroke) interfere with normal visual acuity. Abnormalities of eye movement can also compromise vision by causing diplopia or double vision.

Weakness Weakness, specifically muscle weakness, is

a common manifestation of neurologic disease.

Abnormal Sensation Numbness, abnormal sensation, or loss of

sensation is a neurologic manifestation of both central and peripheral nervous system disease

Diagnostic Evaluation

Computed Tomography Scanning (CT). The images provide cross-sectional views of the brain, with distinguishing differences in tissue densities of the skull, cortex, subcortical structures, and ventricles.

Magnetic Resonance Imaging (MRI) uses a powerful magnetic field (Can be performed through magnetic waves which stimulates nuclei of the atoms in the body ) to obtain images of different areas of the body

An MRI scan can be performed with or without a contrast agent and can identify a cerebral abnormality earlier and more clearly than other diagnostic tests .

It is used to detect CNS tumors, infectious problem of the CNS

allowing the clinician to monitor a tumor's response to treatment. It is particularly useful in the diagnosis of multiple sclerosis .

Cerebral angiography1-conventional angiography. For diagnosis of cerebral

aneurysm,, vasospasm, carotid artery disease.

*Complication: cerebral embolus, hemorrhage or hematoma at the site of catheter insertion,vasospasm, thrombosis, allergic reaction.

Electrophysiology studies

·        Electroencephalogram( EEG)*It is a recording of electrical impulses

generated by brain.

*Purpose include detection of area of abnormal electrical activity.

     

lumber puncture(LP)

*A lumbar puncture (spinal tap) is carried out by inserting a needle into the lumbar subarachnoid space .

The purpose of lumber puncture is to obtain CSF sample for analysis ( subarachnoid hemorrhage and infection).

*It is performed by insertion of 20 –22 gauge needle into the subarachnoid space at L3-L4 or L4 -L5 level by putting patient in lateral recumbent position .

Usually, specimens are obtained for cell count, culture, and glucose and protein testing. The specimens should be sent to the laboratory immediately because changes will take place and alter the result .

Post–Lumbar Puncture Headache*Bed rest after procedure is very important to

prevent headache also preventing CSF. analgesic agents, and hydration. Occasionally, Other Complications of Lumbar Puncture

Herniation of the intracranial contents results from shifting of tissue from one compartment of the brain to another, spinal epidural abscess, spinal epidural hematoma

Intracranial pressure (ICP) :

The main components inside the cranium are: - brain tissue (80%), blood (10%), and cerebrospinal fluid (CSF (10%). So that any increase in the size of brain tissue or increase in the volume of the CSF or problem in the blood vessel (E.g. bleeding into the cranium) will cause increase in the ICP.

 The normal ICP in patients should be less than 15mm Hg.

The effect of increase in ICP will cause neurological deficit (sensory, motor, level of consciousness) or other problem such as seizure so that it is important in some patient to monitor ICP.

Cerebral blood flow The normal cerebral blood flow (CBF) is 50ml / 100g

of brain tissue.

Although brain makes up to 2% of the body weight but it required 15% to 20 % of the resting cardiac output and 15% of the total body’s oxygen demands.

·   

Assessment and diagnosis

The main signs and symptoms of increased in ICP:

1-    Decreased in the level of consciousness. 2-    Cushing’s triad (bradycardia, systolic

hypertension, and bradypnea). 3-    Diminished brain stem reflexes. 4-    Papilledema. 5-    Decerebrate (extension to pain). 6-    Decorticate (flexion to pain).

7-    Unequal pupil size. 8-    Projectile vomiting. 9-    Decreased pupillary reaction to light. 10-  Altered breathing pattern. 11- Headache.

Medical and Nursing management

1-positioning and other nursing activities:

A-Elevation of the bed up to 30 degree will help to decrease ICP by encouraging the venous return.

B-Positions that should be avoided are (trendelenberg, prone, extreme flexion of the hip

2- hyperventilation: - The rational to hyperventilate patient with high ICP

is to reduce the Paco2 from its normal range (35-40mm Hg) to a range between 25 and 30 mmHg.wich lead to cerebral arteries vasoconstriction which lead to decrease in the CBF and increase in the venous return.

Also prolonged hyperventilation will lead to ischemia and infarction, so that the new trend is to maintain Paco2 in the lower side of the normal (35 ± 2 cm Hg).

4-    Blood pressure control: - Maintenance of arterial blood pressure in the high

normal range is essential in head injured patients.

Sedation is required to control blood pressure in the initial phase.

   If sedative fail to control blood pressure, antihypertensive should be administered (e.g.nitroprusside and nitroglycerin), also we will use B- blockers (e.g. labetalol or metoprolol) may be used to overcome the effect of vasodilation of antihypertensive agent.

3- temperature control: Cerebral metabolic rate increases 7% per degree

centigrade of increase in the body temperature.

Fever should be avoided and treated aggressively when occurred by using antipyretic and cooling device until the cause of fever to be determined

Hypothermia 32to 35-degree C will decrease the ICP

5-   Seizure control: - The prophylactic use of anticonvulsant is

important in controlling the cerebral metabolic needs.

The usual medication to be used are phenytoin and Phenobarbital also lorazepam as a short and fast acting.

7-Cerebrospinal fluid drainage

8- diuretic

a-Osmotic diuretic. The widely used medication is mannitol (it will

improve perfusion to ischemic areas of the brain and decrease intracerebral edema that caused by the injury by its osmotic effect.

Side effect: electrolyte imbalance

Nonosmotic diuretic: - The most widely used is furosemide

Maintain euvolemic state to maintain and optimize cerebral perfusion.

9- control of metabolic demand: There are some noxious stimuli that lead to increase

ICP: pain, presence of end tracheal tube, coughing suctioning, repositioning, bathing.

There are many agent are used to decrease metabolic demand : benzodiazepines( midazolam. Lorazepam), sedative – hypnotic (propofol), opioid narcotic (phentanyl and morphine), and neuromuscular blocking agents (atracurium and vecuronium)

Stroke

Is a descriptive term for the onset of acute neurological deficit

persisting for more than 24 hours and caused by interruption of blood flow to the brain.

 

Ischemic Stroke

An ischemic stroke, cerebrovascular accident (CVA), or “brain attack” is a sudden loss of function resulting from disruption of the blood supply to a part of the brain.

Modifiable risk factors for ischemic stroke include

Hypertension atrial fibrillation hyperlipidemia obesity smoking diabetes

Clinical Manifestations

Numbness or weakness of the face, arm, or leg, especially on one side of the body

Confusion or change in mental status Trouble speaking or understanding speech Visual disturbances Difficulty walking, dizziness, or loss of

balance or coordination Sudden severe headache

Motor, sensory, cranial nerve, cognitive, and other functions may be disrupted

Motor Loss hemiplegia (paralysis of one side of the

body) caused by a lesion of the opposite side of the brain. Hemiparesis, or weakness of one side of the body, is another sign.

Communication Loss

Other brain functions affected by stroke are language and communication. In fact, stroke is the most common cause of aphasia.

Dysarthria (difficulty in speaking), caused by paralysis of the muscles responsible for producing speech

Dysphasia (impaired speech) or aphasia (loss of speech), which can be expressive aphasia, receptive aphasia, or global (mixed) aphasia

Apraxia (inability to perform a previously

learned action) Visual-perceptual dysfunctions.

hemianopsia (loss of half of the visual field) Sensory Loss Agnosias are deficits in the ability to

recognize previously familiar objects perceived by one or more of the senses.

Assessment and Diagnosis

·   1- The characteristics signs of an ischemic stroke is a sudden onset of focal neurologic signs persisting for more than 24 hours.

·   2- Presence of hemiparesis, aphasia, hemanopsia.

·   3-Change in level of consciousness usually occur with brainstem or cerebellar involvement ,seizure, hypoxia, hemorrhage, increased ICP.

4-Brain CT without contrast. 5- ECG, chest X-ray, continuous cardiac monitoring, arterial blood gases.

Assessment and Diagnostic Findings Any patient with neurologic deficits needs a

careful history and a complete physical and neurologic examination.

The characteristics signs of an ischemic stroke is a sudden onset of focal neurologic signs persisting for more than 24 hours

- Presence of hemiparesis, aphasia, hemanopsia.

 -Change in level of consciousness usually occur with brainstem or cerebellar involvement ,seizure ,hypoxia, increased ICP.

Initial assessment focuses on airway patency, which may be compromised by loss of gag or cough reflexes and altered respiratory pattern; cardiovascular status (including blood pressure, cardiac rhythm and rate) and gross neurologic deficits

Patients may present to the acute care facility with temporary neurologic symptoms.

A transient ischemic attack (TIA) is a neurologic deficit lasting less than 24 hours, with most episodes resolving in less than 1 hour

. A TIA is manifested by a sudden loss of motor, sensory, or visual function. The symptoms result from temporary ischemia (impairment of blood flow) to a specific region of the brain.

A TIA may serve as a warning of impending stroke. Lack of evaluation and treatment of a patient who has experienced previous TIAs may result in a stroke and irreversible deficits

The initial diagnostic test for a stroke is a noncontrast (CT) scan performed emergently to determine if the event is ischemic or hemorrhagic .

A 12-lead (ECG) and a carotid ultrasound are standard tests

Medical Management

·      

· *Thrombolytic agent( rt-PA)which is given intravenously is recommended within 3 hours of onset of ischemic stroke, also age should be greater than 18 years old according to the national institute of neurologic disorders and stroke( NINDS).

·    * The recommended dose is 0.9 mg / Kg up to the maximum dose of 90 mg, 10% of the dose is administered as an initial intravenous bolus over 1 minute, the remaining 90% is administered by intravenous infusion over 60 minute.

·   * Patient who receive thrombolytic therapy for stroke should not receive aspirin, heparin, warfarin, ticlodipine for at least 24 hours after treatment.

Patients who have experienced a TIA or stroke should have medical management for secondary prevention.

Platelet-inhibiting medications, including aspirin, clopidogrel (Plavix), and ticlopidine (Ticlid), decrease the incidence of cerebral infarction in patients who have experienced TIAs and stroke from suspected embolic or thrombotic causes .

Therapy for Patients With Ischemic Stroke Not Receiving t-PA Other treatments may include anticoagulant

administration (IV heparin or low-molecular-weight heparin).

Interventions during this period include measures to reduce ICP, such as administering an osmotic diuretic (eg, mannitol), maintaining the partial pressure of carbon dioxide (PaCO2) within the range of 30 to 35 mm Hg, and positioning to avoid hypoxia

·       ·  *Blood pressure in some cases must not be lowered because it will affect the cerebral perfusion pressure.

·     * antihypertensive therapy is considered only if the diastolic blood pressure is greater than 120 mmHg or the systolic BP is greater than 220mmHg.

·     * Blood pressure should be 180/105 mmHg to prevent intracranial hemorrhage.

·     * Intravenous labetalol and nitroprusside is used to achieve BP control.

·      * Treatment should include controlling cerebral edema or seizure activity. but prophylaxis for these complication is not recommended.

Hemorrhagic Stroke

Hemorrhagic strokes account for 15% to 20% of cerebrovascular disorders and are primarily caused by intracranial or subarachnoid hemorrhage. Hemorrhagic strokes are caused by bleeding into the brain tissue, the ventricles, or the subarachnoid space .

 Intracerebral hemorrhage

·    *Is a bleeding directly into the brain tissue. ·    * It will destroys cerebral tissue causes cerebral edema, and increaseICP. *Causes include .    1- the most important cause is hypertension    2- rupture of AVM or aneurysm. .    3-. rupture of small artery.    4-patients who receive anticoagulant or thrombolytic therapy..     5-coagulation disorders..     6-drug abuse.     7-hemorrhage into cerebral infarct or brain tumor 

An intracerebral hemorrhage (ICH) is bleeding within brain tissue.

An ICH may be associated with other brain injuries, particularly contusions .

Assessment and Diagnostic Findings Any patient with suspected stroke should

undergo a CT scan to determine the type of stroke, the size and location of the hematoma, and the presence or absence of ventricular blood and hydrocephalus.

CT scan and cerebral angiography confirm the diagnosis of an intracranial aneurysm or AVM

Clinical Manifestations

Clinical Manifestations The patient with a hemorrhagic stroke can

present with a wide variety of neurologic deficits, similar to the patient with ischemic stroke.

     Medical Management

1. airway , breathing, and circulation.

2. reduction of blood pressure is necessary to decrease ongoing bleeding, but lowering blood pressure too much or too rapid may compromise cerebral perfusion pressure(CPP).

3. MAP should be below 130 mmHg in patients with a history of hypertension, and 110 mmHg after surgical treatment of ICH.

4. if there is increase in ICP, recommended therapy is mannitol, hyperventilation, neuromuscular blockade with sedation.

. steroids are avoided.surgery is required in patient with

hydrocephalus associated with cerebellar hemorrhage that compress brain stem or young patient with moderate or large hemorrhage with clinical deterioration

Subarachnoid hemorrhage

it is the bleeding into the subarachnoid space( CSF circulation).

causes of subarachnoid hemorrhage:- 1-  rupture of cerebral aneurysm. 2-  Arteriovenous malformation. 3-  Trauma. Risk factors: hypertension, smoking,

alcohol abuse , and stimulants use.

Subarachnoid hemorrhage

Traumatic subarachnoid hemorrhage (SAH) is caused by bleeding into the subarachnoid space.

Etiology

Cerebral aneurysm rupture account 85% of subarachnoid hemorrhage. Also 90% of aneurysms are congenital.

Rupture of cerebral aneurysm occur during the fifth and sixth decades of life.

arteriovenous malformation(AVM) rupture is responsible for less than 10% of subarachnoid hemorrhage.

AVM are congenital tangled mass of arterial and venous blood vessels that shunts blood directly from the arterial

side into the venous side

Assessment and diagnosis

1-HEADACHE( “ WORST HEADACHE IN MY LIFE”)

2-BRIEF LOSS OF CONSCIOUSNESS. 3-NAUSEA AND VOMITING 4-FOCAL NEUROLOGICAL DEFICIT. 5-STIFF NECK 6-PHTOPHOBIA

DIAGNOSTIC TESTS

1- CT scan initially done to verify diagnosis. 2- lumbar puncture to take CSF sample for

analysis if the CT scan is negative. 3- magnetic resonance angiogram(MRA)and

magnetic resonance venogram(MRV). 4- catheterization cerebral angiography.

Medical management

the goal of treatment is preservation neurological function.

Airway management and ventilatory assistance may be necessary.

Venticulostomy is performed to control ICP if the patients develop deterioration in the level of consciousness with hydrocephalus.

Control of blood pressure by maintaining systolic blood pressure no greater than 150mmHg and prevent hypotension.

prophylactic anticonvulsants must be prescribed.

Maintain normal blood volume by giving intravenous fluid to expand blood volume to prevent vasospasm, and maintain adequate cerebral perfusion.

Nimodipine: cause vasodilatation of cerebral vessel , in doses 60 mg every 4 hours for 21 days