Cerebral Dysfunction

Chapter 45


Cerebral Dysfunction


Marilyn J. Hockenberry




Cerebral Dysfunction


Most of the information about the status of the brain is obtained by indirect measurements. Some of these measurements are discussed elsewhere in relation to numerous aspects of child care (e.g., as part of assessments of health [Chapter 29], newborn status [Chapter 24], intellectual disability [Chapter 37], hypoxic injury [cerebral palsy, Chapter 49], and attainment of developmental milestones at each stage of development). Because increased intracranial pressure (ICP) and altered states of consciousness have such prominent places in neurologic dysfunction, they are described here, followed by techniques for neurologic assessment and diagnostic tests.



Increased Intracranial Pressure


The brain, tightly enclosed in the solid bony cranium, is well protected but highly vulnerable to pressure that may accumulate within the enclosure (Fig. 45-1). The total volume of the cranium—brain (80%), cerebrospinal fluid (CSF) (10%), and blood (10%)—must remain approximately the same at all times. A change in the proportional volume of one of these components (e.g., increase or decrease in intracranial blood) must be accompanied by a compensatory change in another. In this way the volume and pressure normally remain constant. Examples of compensatory changes are reduction in blood volume, decrease in CSF production, increase in CSF absorption, or shrinkage of brain mass by displacement of intracellular and extracellular fluid. Children with open fontanels compensate by skull expansion and widened sutures. However, at any age the capacity for spatial compensation is limited. An increase in ICP may be caused by tumors or other space-occupying lesions, accumulation of fluid within the ventricular system, bleeding, or edema of cerebral tissues. When compensation is exhausted, any further increase in the volume of the cranium results in a rapid rise in ICP.



Early signs and symptoms of increased ICP are often subtle and assume many patterns (Box 45-1). As pressure increases, signs and symptoms become more pronounced, and the level of consciousness (LOC) deteriorates.




Altered States of Consciousness


Consciousness implies awareness (i.e., the ability to respond to sensory stimuli and have subjective experiences). There are two components of consciousness: alertness, an arousal-waking state, including the ability to respond to stimuli; and cognitive power, including the ability to process stimuli and produce verbal and motor responses.


An altered state of consciousness usually refers to varying states of unconsciousness that may be momentary or extend for hours, for days, or indefinitely. Unconsciousness is depressed cerebral function (i.e., the inability to respond to sensory stimuli and have subjective experiences). Coma is defined as a state of unconsciousness from which the patient cannot be aroused even with powerful stimuli.



Levels of Consciousness


Assessment of LOC remains the earliest indicator of improvement or deterioration in neurologic status. LOC is determined by observations of the child’s responses to the environment. When it is being assessed in young children, it is often useful to have a parent present to help elicit a desired response. An infant or child may not respond in an unfamiliar environment or to unfamiliar voices. Children older than 3 years of age should be able to give their name, although they may not be cognizant of place or time. Other diagnostic tests such as motor activity, reflexes, and vital signs vary more and do not necessarily directly parallel the depth of the comatose state. The most consistently used terms are described in Box 45-2.




Coma Assessment


Several scales have been devised in an attempt to standardize the description and interpretation of the degree of depressed consciousness. The most popular of these is the Glasgow Coma Scale (GCS), which consists of a three-part assessment: eye opening, verbal response, and motor response (Fig. 45-2). Numeric values of 1 through 5 are assigned to the levels of response in each category. The sum of these numeric values provides an objective measure of the patient’s LOC. A person with an unaltered LOC would score the highest, 15; a score of 8 or below is generally accepted as a definition of coma; and the lowest score, 3, indicates deep coma. A decrease in the GCS score indicates a deterioration of the patient’s condition. In 1987 major medical and legal societies developed specific guidelines for the determination of brain death among children of all ages (Mathur, Peterson, Stadtier, et al., 2008).




General Aspects


Children younger than 2 years of age require special evaluation because they are unable to respond to directions designed to elicit specific neurologic responses. Early neurologic responses in infants are primarily reflexive; these responses are gradually replaced by meaningful movement in the characteristic cephalocaudal direction of development. This evidence of progressive maturation reflects more extensive myelinization and changes in neurochemical and electrophysiologic properties.


Most information about infants and small children is gained by observing their spontaneous and elicited reflex responses as they develop increasingly complex motor skills and by eliciting progressively sophisticated communicative and adaptive behaviors. Delay or deviation from expected milestones helps identify high-risk children. Persistence or reappearance of reflexes that normally disappear indicates a pathologic condition. In evaluating an infant or young child, it is also important to obtain the pregnancy and delivery history to determine the possible impact of intrauterine environmental influences known to affect the orderly maturation of the central nervous system (CNS). These influences include maternal infections, cigarette or alcohol consumption, drug use, toxin exposure, trauma, and metabolic insults.


General aspects of assessment that provide clues to the etiology of dysfunction include the following:



Family history—Sometimes offers clues regarding possible genetic disorders with neurologic manifestations.


Health history—May provide valuable clues regarding the cause of dysfunction. Information should include Apgar scores, age of developmental milestones, trauma or injuries, acute and chronic illnesses, encounters with animals or insects, and ingestion or inhalation of neurotoxic substances.


Physical evaluation of infants—Includes assessment of:




Neurologic Examination


The purpose of the neurologic examination is to establish an accurate, objective baseline of neurologic information. It is essential that the neurologic examination be documented in a fashion that can be reproduced by others. This allows for a comparison of the findings so the observer can detect subtle changes in the neurologic status that might not otherwise be evident. Descriptions of behaviors should be simple, objective, and easily interpreted: “Drowsy but awake and conversationally rational/oriented”; “Sleepy but arousable with vigorous physical stimuli. Pressure to nail base of right hand results in upper-extremity flexion/lower-extremity extension.”



Vital Signs


Pulse, respiration, and blood pressure provide information regarding the adequacy of circulation and the possible underlying cause of altered consciousness. Autonomic activity is most intensively disturbed in cases of deep coma or brainstem lesions.


Body temperature is often elevated, and sometimes the elevation may be extreme. High temperature is most frequently a sign of an acute infectious process or heat stroke but may also be caused by ingestion of some drugs (especially salicylates, alcohol, and barbiturates) or intracranial bleeding, especially subarachnoid hemorrhage. Hypothalamic involvement may cause elevated or decreased temperature. Coma of a toxic origin may produce hypothermia.


The pulse varies and may be rapid, slow and bounding, or feeble. Blood pressure may be normal, elevated, or very low. The Cushing reflex, or pressor response, causes a slowing of the pulse and an increase in blood pressure and is uncommon in children; when it occurs it is a very late sign of ICP. Medications may affect the vital signs. For assessment purposes actual changes in pulse and blood pressure are more important than the direction of the change.


Respirations are often slow, deep, and irregular. Slow, deep breathing is often seen in the heavy sleep caused by sedatives, after seizures, or in cerebral infections. Slow, shallow breathing may result from sedatives or opioids (narcotics). Hyperventilation (deep and rapid respirations) is usually a result of metabolic acidosis or abnormal stimulation of the respiratory center in the medulla caused by salicylate poisoning, hepatic coma, or Reye’s syndrome (RS).


Breathing patterns have been described with a number of terms (e.g., apneustic, cluster, ataxic, Cheyne-Stokes). However, it is better to describe what is being observed rather than placing a label on it because the traditional terms are often used and interpreted incorrectly. Periodic or irregular breathing is an ominous sign of brainstem (especially medullary) dysfunction that often precedes complete apnea. The odor of the breath may provide additional clues (e.g., the fruity, acetone odor of ketosis; the foul odor of uremia; the fetid odor of hepatic failure; or the odor of alcohol).




Eyes


Pupil size and reactivity are assessed (Fig. 45-3; see also Fig. 45-2). Pinpoint pupils are commonly observed in poisoning such as opiate or barbiturate poisoning and in brainstem dysfunction. Widely dilated and reactive pupils are often seen after seizures and may involve only one side. Dilated pupils may also be caused by eye trauma. Widely dilated and fixed pupils suggest paralysis of cranial nerve III secondary to pressure from herniation of the brain through the tentorium. A unilateral fixed pupil usually suggests a lesion on the same side. If pupils are fixed bilaterally for more than 5 minutes, brainstem damage is usually implied. Dilated and nonreactive pupils are also seen in hypothermia, anoxia, ischemia, poisoning with atropine-like substances, or prior instillation of mydriatic drugs.




The description of eye movements should indicate whether one or both eyes are involved and how the reaction was elicited. The parents should be asked about preexisting strabismus, which causes the eyes to appear normal under compromise. Posttraumatic strabismus indicates cranial nerve VI damage.


Special tests, usually performed by qualified persons, include:








Motor Function


Observing spontaneous activity, gait, and response to painful stimuli provides clues to the location and extent of cerebral dysfunction. Even subtle movements (e.g., the outward rotation of a hip) should be noted, and the child observed for other signs. Asymmetric movements of the limbs or absence of movement suggests paralysis. In hemiplegia the affected limb lies in external rotation and falls uncontrollably when lifted and allowed to drop. In patients with cerebellum abnormalities heel-to-toe walking is difficult. Patients with cerebellar ataxia have an unsteady, broad-based gait. All motor functions should be described rather than labeled.


In the deeper comatose states there is little or no spontaneous movement, and the musculature tends to be flaccid. There is considerable variability in the motor behavior in lesser degrees of coma. For example, the child may be relatively immobile or restless and hyperkinetic; muscle tone may be increased or decreased. Tremors, twitching, and spasms of muscles are common observations. The patient may display purposeless movements. Combative or negativistic behavior is common. Hyperactivity is more common in toxic states than in cases of increased ICP. Seizures are common in children and may be present from any cause. Any repetitive or seizure movements should be described precisely.



Posturing


Primitive postural reflexes emerge as cortical control over motor function is lost in brain dysfunction. These reflexes are evident in posturing and motor movements directly related to the area of the brain involved. Posturing reflects a balance between the lower exciting and the higher inhibiting influences and strong muscles overcoming weaker ones. Decorticate or flexion posturing (Fig. 45-4, A) is seen with severe dysfunction of the cerebral cortex or lesions to corticospinal tracts above the brainstem. Typical posturing includes rigid flexion with the arms held tightly to the body; flexed elbows, wrists, and fingers; plantar flexed feet; legs extended and internally rotated; and possibly the presence of fine tremors or intense stiffness. Decerebrate posture or extension posturing (see Fig. 45-4, B) is a sign of dysfunction at the level of the midbrain or lesions to the brainstem. It is characterized by rigid extension and pronation of the arms and legs, flexed wrists and fingers, a clenched jaw, an extended neck, and possibly an arched back. Unilateral decerebrate posture is often caused by tentorial herniation.



Posturing may not be evident when the child is quiet but can usually be elicited by applying painful stimuli such as a blunt object pressed on the base of the nail. Nurses should avoid applying thumb pressure to the supraorbital region of the frontal bone (risk of orbital damage). Noxious stimuli (e.g., suctioning) elicits a response, as may turning or touching. When the nurse is describing posturing, the stimulus needed to provoke the response is as important as the reaction.



Reflexes


Testing of some reflexes may be of limited value. In general the corneal, pupillary, muscle-stretch, superficial, and plantar reflexes tend to be absent in deep coma. The state of reflexes varies in lighter grades of unconsciousness and depends on the underlying pathologic process and the location of the lesion. Absence of corneal reflexes and presence of a tonic neck reflex are associated with severe brain damage. The Babinski reflex (see Extremities, Chapter 29) may be of value if it is found to be present consistently in children older than 18 months. A positive Babinski reflex is significant in assessment of pyramidal tract lesions when it is unilateral and associated with other pyramidal signs.




Special Diagnostic Procedures


Numerous diagnostic procedures are used for the assessment of cerebral function. Laboratory tests that may help delineate the cause of unconsciousness include blood glucose, urea nitrogen, and electrolyte (pH, sodium, potassium, chloride, calcium, and bicarbonate) tests; blood ammonia levels; clotting studies, hematocrit, and a complete blood count; liver function tests; blood cultures if there is fever; and urine toxicology screen and blood lead levels if clinically indicated.


An electroencephalogram (EEG) may provide important information. For example, generalized random, slow activity suggests suppressed cortical function; and localized slow activity suggests a space-occupying issue such as a hematoma, tumor, or infectious process. A flat tracing is one of the criteria used as evidence of brain death.


Examination of spinal fluid is performed when toxic encephalopathy or infection is suspected. Lumbar puncture ordinarily is delayed if intracranial hemorrhage is suspected and is contraindicated in the presence of ICP because of the potential for tentorial herniation.


Auditory and visual evoked potentials are sometimes used in neurologic evaluation of infants and very young children. Visual evoked potentials are useful in evaluating visual abnormalities from the retina to the visual cortex, and brainstem auditory evoked potentials are useful for assessing hearing acuity and brainstem function. Both are particularly useful for detecting demyelinating disease and neoplasms.


Highly sophisticated tests are carried out with specialized equipment. Two imaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI), assist in diagnosis by scanning both soft tissues and solid matter. Most of these tests are outlined in Table 45-1. Because such tests can be threatening to children, the nurse needs to prepare patients for them and provide support and reassurance during them (see Preparation for Diagnostic and Therapeutic Procedures, Chapter 39). Children who are old enough to understand require careful explanation of the procedure, reason for it, what they will experience, and how they can help. School-age children usually appreciate a more detailed description of why contrast material is injected. The importance of lying still for tests needs to be stressed. Children unfamiliar with the machines can be shown a picture beforehand.



TABLE 45-1


NEUROLOGIC DIAGNOSTIC PROCEDURES











































































TEST DESCRIPTION PURPOSE COMMENTS
LP Spinal needle is inserted between L3-L4 or L4-L5 vertebral spaces into subarachnoid space; CSF pressure is measured, and sample is collected. Diagnostic—Measures spinal fluid pressure, obtains CSF for laboratory analysis
Therapeutic—Injection of medication
Contraindicated in patients with increased ICP or infected skin over puncture site.
Subdural tap Needle is inserted into anterior fontanel or coronal suture (midline to pupil). Helps rule out subdural effusions
Removes CSF to relieve pressure
Place infant in semi-erect position after subdural tap to minimize leakage from site; prevent child from crying if possible. Check site frequently for evidence of leakage.
Ventricular puncture Needle is inserted into lateral ventricle via coronal suture (midline to pupil). Removes CSF to relieve pressure Risk of intracerebral or ventricular hemorrhage.
EEG EEG records changes in electrical potential of brain.
Electrodes are placed at various points to assess electrical function in a particular area.
Impulses are recorded by electromagnetic pen or digitally.
Detects spikes, or bursts of electrical activity that indicate the potential for seizures
Used to determine brain death
Patient should remain quiet during procedure; may require sedation.
Minimize external stimuli during procedure.
Nuclear brain scan Radioisotope is injected intravenously and then counted and recorded after fixed time intervals.
Radioisotope accumulates in areas where blood-brain barrier is defective.
Identifies focal brain lesions (e.g., tumors, abscesses)
Positive uptake of material with encephalitis and subdural hematoma
Visualizes CSF pathways
Requires IV access; patient may require sedation.
In normal children or noncommunicating hydrocephalus, no retrograde filling of ventricles occurs.
Areas of concentrated uptake of material are termed hot spots.
Endocephalography Pulses of ultrasonic waves are beamed through head; echoes from reflecting surfaces are recorded graphically. Identifies shifts in midline structures from their normal positions as a result of intracranial lesions
May show ventricular dilation
Simple, safe, rapid procedure.
Fontanel must be patent.
RTUS Similar to CT but uses ultrasound instead of ionizing radiation. Allows high-resolution anatomic visualization in variety of imaging planes Produces images similar to CT scan.
Especially useful in neonatal CNS problems.
Anterior fontanel must be patent.
Radiography Skull films are taken from different views—lateral, posterolateral, axial (submentoventricular), half-axial. Shows fractures, dislocations, spreading suture lines, craniosynostosis
Shows degenerative changes, bone erosion, calcifications
Simple, noninvasive procedure.
CT scan Pinpoint x-ray beam is directed on horizontal or vertical plane to provide series of images that are fed into computer and assembled in image displayed on video screen.
CT uses ionizing radiation.
Visualizes horizontal and vertical cross section of brain in three planes (axial, coronal, sagittal)
Distinguishes density of various intracranial tissues and structures—congenital abnormalities, hemorrhage, tumors, demyelinating and inflammatory processes, calcification
Requires IV access if contrast agent is used.
Patient may require sedation.
Rapid.
MRI MRI produces radiofrequency emissions from elements (e.g., hydrogen, phosphorus), which are converted to visual images by computer. Permits visualization of morphologic feature of target structures
Permits tissue discrimination unavailable with many techniques
MRI is noninvasive procedure except when IV contrast agent is used.
No exposure to radiation occurs.
Patient may require sedation.
Parent or attendant can remain in room with child.
MRI does not visualize bone detail or calcifications.
No metal can be present in scanner.
PET PET involves IV injection of positron-emitting radionucleotide; local concentrations are detected and transformed into visual display by computer. Detects and measures blood volume and flow in brain, metabolic activity, and biochemical changes within tissue Requires lengthy period of immobility.
Minimum exposure to radiation occurs.
Patient may require sedation.
DSA Contrast dye is injected intravenously; computer “subtracts” all tissues without contrast medium, leaving clear image of contrast medium in vessels studied. Visualizes vasculature of target tissue
Visualizes finite vascular abnormalities
Safe alternative to angiography.
Patient must remain still during procedure; may require sedation.
SPECT Involves IV injection of photon-emitting radionuclide; radionuclides are absorbed by healthy tissue at different rate than by diseased or necrotic tissue; data are transferred to computer that converts image to film. Provides information regarding blood flow to tissues; analyzing blood flow to organ may help determine how well it is functioning Requires lengthy period of immobility.
Minimum exposure to radiation occurs.
Patient may require sedation.


image


CNS, Central nervous system; CSF, cerebrospinal fluid; CT, computed tomography; DSA, digital subtraction angiography; EEG, electroencephalography; ICP, intracranial pressure; IV, intravenous; LP, lumbar puncture; MRI, magnetic resonance imaging; PET, positron emission tomography; RTUS, real-time ultrasonography; SPECT, single-photon emission computed tomography.


Although radiographic examinations are not painful, the appearance of the machinery is often so frightening that the child protests because of anxiety. This is especially true of CT and MRI, both of which require that the child’s head be placed within a special immobilizing device. Chin and cheek pads are sometimes used to prevent the slightest head movement, and straps are applied to the body to prevent a slight change in body position. The nurse can explain these events to a frightened child by comparing them to an astronaut’s preparation for a space flight. It is important to emphasize to the child that at no time is the procedure painful.


The nurse should not expect cooperation from a young child. Sedation may be required. Many different agents are currently used for sedation of children undergoing neurologic diagnostic procedures. Chloral hydrate, pentobarbital, or benzodiazepines have been used for decades as short-term sedative agents and remain safe methods of pediatric outpatient sedation (Mason, 2008). Chloral hydrate and pentobarbital have no analgesic proprieties but can provide successful sedation for nonpainful procedures such as CT and MRI (Mason, 2008). In recent years propofol has been used as a sedation agent for diagnostic procedures because of its short induction and recovery time, but this medication should be used with caution because it can cause respiratory depression and apnea with little warning (Machata, Willschke, Kabon, et al., 2008; Mason, 2008). (See Pain Management, Chapter 30.)


Physical preparation for the diagnostic test may involve administration of a sedative. If so, children should be helped through the preparation and administration and assured that someone will remain with them (if possible). Children need continual support and reinforcement during procedures in which they remain conscious. Vital signs and physiologic responses to the procedure are monitored throughout. Many diagnostic procedures performed on an outpatient basis require sedation, and children need recovery time and observation. The nurse should review written instructions with parents if the child is discharged after a procedure. Children who have undergone a procedure with a general anesthetic require postanesthesia care, including positioning, to prevent aspiration of secretions and frequent assessment of the vital signs and LOC. In addition, other neurologic functions such as pupillary responses, motor strength, and movement are tested at regular intervals. Any surgical wound resulting from the test is checked for bleeding, CSF leakage, and other complications. Children who undergo repeated subdural taps should have their hematocrit monitored to detect excessive blood loss from the procedure.



Nursing Care of the Unconscious Child


The unconscious child requires nursing attention, with observation, recording, and evaluation of changes in objective signs. These observations provide valuable information regarding the patient’s progress. Often they serve as a guide to the diagnosis and treatment. Therefore careful and detailed observations are essential for the patient’s welfare. In addition, vital functions must be maintained, and complications prevented through conscientious and meticulous nursing care. The outcome of unconsciousness may be early and complete recovery, death within a few hours or days, persistent and permanent unconsciousness, or recovery with varying degrees of residual mental or physical disability. The outcome and recovery of the unconscious child may depend on the level of nursing care and observational skills.


Emergency measures are directed toward ensuring a patent airway, breathing, and circulation; stabilizing the spine when indicated; treating shock; and reducing ICP if present. Delayed treatment often leads to increased damage. As soon as emergency measures have been implemented, and in many cases concurrently, therapies for specific causes are begun. Because nursing care is closely related to medical management, both are considered here.


Continual observation of LOC, pupillary reaction, and vital signs is essential to manage CNS disorders. Regular assessment of neurologic status is an essential part of nursing comatose children. The assessment frequency depends on the cause of unconsciousness, the LOC, and the progression of cerebral involvement. Intervals may be as short as every 15 minutes or as long as every 2 hours. Significant alterations must be reported immediately.


Vital signs provide important information about the status of the unconscious child. Hypothalamic and brainstem disorders may affect the patient’s thermoregulation; thus frequent monitoring is needed. The temperature is taken every 2 to 4 hours, depending on the patient’s condition. Hypothermia is defined as a core body temperature less than 35° C (95° F). EEG slowing is noted at 30° C, and loss of pupillary light reflex is lost at 28° C (Young, 2009). Hyperthermia is defined as a core body temperature greater than 38.5° C (101.3° F); and temperatures greater than 42° C can cause EEG slowing, seizures, and encephalopathy (Young, 2009).


The neurologic examination is performed periodically and includes evaluating pupillary abnormalities, brainstem function, LOC, and motor response (Sharma, Kochar, Sankhyan, et al., 2010). Pupils are observed for their size, symmetry, and reaction to light. Signs of meningeal irritation such as nuchal rigidity are also assessed. The presence of the oculovestibular response, corneal (blink) response, and cough and gag reflexes is evaluated. Aspects of LOC assessment include response to vocal commands, resistance to care, and response to painful stimuli. Spontaneous movement, changes in muscle tone or strength, and body position are noted. Seizure activity is described according to the duration and body areas involved.


Pain management for the comatose child requires astute nursing observation and management. Responses to pain include motor reactions such as increased agitation or posturing; facial changes such as grimaces; and physiologic reactions such as tachycardia, tachypnea, diaphoresis, or hypertension (Schnakers and Zasler, 2007). Because these findings may not be specific for pain, the nurse should observe for their appearance during times of induced or suspected pain and their disappearance after the end of the inciting procedure or the administration of analgesia. A pain assessment record should be used to document indications of pain and the effectiveness of interventions (see Pain Assessment, Chapter 30).


The use of opioids such as morphine to relieve pain is controversial because they may mask signs of altered consciousness or depress respirations. However, unrelieved pain activates the stress response, which can elevate ICP. To block the stress response, some authorities advocate the use of analgesics; sedatives; and in some cases paralyzing agents via continuous intravenous (IV) infusion. A frequently used combination is fentanyl, midazolam, and vecuronium (Norcuron). If there are concerns about assessing the LOC or respiratory depression, naloxone (Narcan) can be used to reverse the opioid effects. Regardless of which drugs are used, adequate dosage and regular administration are essential to provide optimal pain relief (see Pain Management, Chapter 30).


Other measures to relieve discomfort include providing a quiet, dimly lit environment; limiting visitors; preventing any sudden, jarring movement such as banging into the bed; and preventing an increase in ICP. The last is most effectively achieved by proper positioning and prevention of straining such as during coughing, vomiting, suctioning, and defecating.




Respiratory Management


Respiratory effectiveness is the primary concern in the care of the unconscious child, and establishing an adequate airway is always the first priority. Carbon dioxide has a potent vasodilating effect and increases cerebral blood flow (CBF) and ICP. Cerebral hypoxia that lasts longer than 4 minutes nearly always causes irreversible brain damage.


Children in lighter states of coma may be able to cough and swallow; but those in deeper states are unable to handle secretions, which tend to pool in the throat and pharynx. Dysfunction of cranial nerves IX and X places the child at risk for aspiration and cardiac arrest; therefore the child is positioned to prevent aspiration of secretions, and the stomach is emptied to reduce the likelihood of vomiting. In infants blockage of air passages from secretions can happen in seconds. In addition, upper airway obstruction from laryngospasm is a frequent complication in comatose children.


An oral airway can be used for children who have a temporary loss of consciousness such as after a contusion, seizure, or anesthesia. For children who remain unconscious for a longer time, a nasotracheal or orotracheal tube is inserted to maintain the open airway and facilitate removal of secretions. Endotracheal intubation should be considered in children with a GCS score of less than 8, evidence of herniation, apnea, or inability to maintain an airway (Sankhyan, Raju, Sharma, et al., 2010). A tracheostomy is performed in cases in which laryngoscopy for introduction of an endotracheal tube would be difficult or for a child who needs long-term ventilatory support. Suctioning is used only as needed to clear the airway, exerting care to prevent increasing ICP. Respiratory status is observed and evaluated regularly. Signs of respiratory distress may be an indication for ventilatory assistance.


When the respiratory center is involved, mechanical ventilation is usually indicated (see Chapter 39). Blood gas analysis is performed regularly, and oxygen is administered as indicated. Moderately severe hypoxia and respiratory acidosis are often present but not always evident from clinical manifestations. Hyperventilation frequently accompanies unconsciousness and may lead to respiratory alkalosis, or it may represent the attempt by the body to compensate for metabolic acidosis. Therefore blood gas and pH determinations are essential guides for therapy. Chest physiotherapy is carried out on a regular basis, and the child’s position is changed at least every 2 hours to prevent pulmonary complications.



Intracranial Pressure Monitoring


An acute rise in ICP can cause secondary brain injury (Singhi and Tiwari, 2009), and management of the child with increased ICP is a complex and important task. ICP monitoring is used to guide therapy to reduce ICP and provides information on intracranial compliance, cerebrovascular status, and cerebral perfusion (Sankhyan, Raju, Sharma, et al., 2010). Nonetheless ICP monitoring is an invasive procedure that has associated risks, including infection, hemorrhage, malfunction, and obstruction (Singhi and Tiwari, 2009). Indications for inserting an ICP monitor are as follows:



Four major types of ICP monitors are:



Direct ventricular pressure measurement with an intraventricular catheter remains the gold standard of ICP monitoring (Singhi and Tiwari, 2009). Subarachnoid and epidural monitoring can be used when a catheter cannot be cannulated in the ventricle, but they often must be replaced after several days because of measurement drift (Singhi and Tiwari, 2009). Transducers for both ventricular and subarachnoid monitoring should be set up without the use of a flush device.


Placement of the intraventricular catheter and subarachnoid bolt occurs through a burr hole in the skull. The intraventricular method involves introduction of a catheter into the lateral ventricle on the nondominant side, if known. The subarachnoid bolt involves placement of a bolt in the subarachnoid space, and the epidural sensor involves placement of a sensor between the dura and the skull. The intraventricular catheter has the advantage of providing a means for recalibration when measurement drift occurs, but both the catheter and the bolt can be used for therapeutic CSF drainage to reduce pressure. A drainage bag attached to the system is kept at the level of the ventricles and can be lowered to decrease ICP (see Critical Thinking Case Study).





Placement of the subarachnoid bolt is not adjusted by anyone except the neurosurgeon who placed the device. The neurosurgeon is notified if a satisfactory waveform on the ICP monitoring is not observed.


An epidural sensor provides a readout of the ICP with a stopcock assembly and transducer. Although less invasive, ICP measurements may be inconsistent. In infants a fontanel transducer can be used to detect impulses from a pressure sensor and convert them to electrical energy. The electrical energy is then converted to visible waves or numeric readings on an oscilloscope. ICP measurement from the anterior fontanel is noninvasive but may prove to be inaccurate if the equipment is poorly placed or recalibrated inconsistently.


ICP can be increased by instilling solutions; therefore antibiotics are administered systemically if a positive CSF culture is obtained. CSF is a body fluid; therefore Standard Precautions are implemented according to hospital policy (see Infection Control, Chapter 39).


Nurses caring for patients with intracranial monitoring devices must be acquainted with the system, assist with insertion, interpret the monitor readings, and be able to distinguish between danger signals and mechanical dysfunction.


For sustained ICP elevations greater than 20 to 25 mm Hg, several medical measures are available. Osmotic diuretics may provide rapid relief in emergency situations. Although their effect is transient, lasting only about 6 hours, they can be lifesaving in emergencies. These substances are rapidly excreted by the kidneys and carry with them large quantities of sodium and water. Mannitol (or sometimes urea) administered intravenously is the drug most frequently used for rapid reduction and can lower ICP in 1 to 5 minutes. The infusion is generally given slowly but may be pushed rapidly in cases of herniation or impending herniation. Hypertonic saline in concentrations of 3% to 23% has been shown to reduce ICP by its osmotic force and can be beneficial for hypovolemic and hypotensive patients by increasing intravascular volume and blood pressure (Singhi and Tiwari, 2009). Adrenocorticosteroids are not recommended for cerebral edema secondary to head trauma. Paco2 should be maintained at 25 to 30 mm Hg to produce vasoconstriction, which reduces CSF, thereby decreasing ICP; but this effect is sustained only 11 to 20 hours because the CSF equilibrates to the new Paco2 level (Singhi and Tiwari, 2009).



Nursing Activities


In cases of high levels of increased ICP, procedures tend to trigger reactive pressure waves in many patients. For example, increased intrathoracic or abdominal pressure is transmitted to the cranium. Particular care should be taken in positioning these patients to avoid neck vein compression, which may further increase ICP by interfering with venous return.


The child can be propped to one side or the other, and the use of an alternating-pressure mattress reduces the chance of prolonged pressure to vulnerable areas. Frequent clinical assessment of the child cannot be replaced by an ICP monitoring device.



It is important to avoid activities that may increase ICP by causing pain or emotional stress. Gentle range-of-motion exercises can be carried out but should not be performed vigorously. Nontherapeutic touch can cause an increase in ICP. Any disturbing procedures to be performed should be scheduled to take advantage of therapies such as osmotherapy and sedation that reduce ICP. Efforts are taken to minimize or eliminate environmental noise. Assessment and intervention to relieve pain are important nursing functions to decrease ICP. Individualizing nursing activities and minimizing environmental stimuli by decreasing elective procedures help control ICP (Sankhyan, Raju, Sharma, et al., 2010).




Nutrition and Hydration


In the unconscious child fluids and calories are supplied initially by the IV route (see Chapter 39). An IV infusion is started early, and the type of fluid administered is determined by the patient’s general condition. Fluid therapy requires careful monitoring and adjustment based on neurologic signs and electrolyte determinations. The goal of fluid therapy is euvolemia. Often comatose children are unable to cope with the same amounts of fluid they can tolerate when they are healthy, and overhydration must be avoided to prevent fatal cerebral edema. When cerebral edema is a threat, fluids may be restricted to reduce the chance of fluid overload. Skin and mucous membranes are examined for signs of dehydration. Observation for signs of altered fluid balance related to abnormal pituitary secretions is a part of nursing care.


Long-term nutrition is provided with a balanced formula via a nasogastric or gastrostomy tube. Most children have continuous feedings; but, if bolus feedings are used, the tube is rinsed with water after each feeding. Avoid overfeeding to prevent vomiting and the risk of aspiration.



Altered Pituitary Secretion


An altered ability to handle fluid loads is attributed in part to the syndrome of inappropriate antidiuretic hormone secretion (SIADH) and diabetes insipidus (DI) resulting from hypothalamic dysfunction (see Chapter 46). SIADH frequently accompanies CNS diseases such as head injury, meningitis, encephalitis, brain abscess, brain tumor, and subarachnoid hemorrhage. In patients with SIADH, scant quantities of urine are excreted, electrolyte analysis reveals hyponatremia and hyposmolality, and manifestations of overhydration are evident. It is important to evaluate all parameters because the reduced urinary output might be erroneously interpreted as a sign of dehydration. The treatment of SIADH consists of restriction of fluids until serum electrolytes and osmolality return to normal levels.


DI may occur after intracranial trauma. In DI there are large amounts of diluted urine and the accompanying danger of dehydration. Adequate replacement of fluids is essential, and observation of electrolyte balance is necessary to detect signs of hypernatremia and hyperosmolality. Exogenous vasopressin may be administered.



Medications


The cause of unconsciousness determines specific drug therapies. Children with infectious processes are given antibiotics appropriate to the disease and the infecting organism. Corticosteroids are prescribed for inflammatory conditions and edema. Cerebral edema is an indication for osmotherapy. Sedatives or antiepileptics are prescribed for seizure activity (see p. 1449).


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Sep 16, 2016 | Posted by in NURSING | Comments Off on Cerebral Dysfunction
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