722 SECTION VI Pediatric Critical Care Neurologic neurologic insult or risk for further injury Hyperthermia with the attendant increased cerebral metabolic demand should be treated aggressively whatev[.]
722 S E C T I O N V I Pediatric Critical Care: Neurologic neurologic insult or risk for further injury Hyperthermia with the attendant increased cerebral metabolic demand should be treated aggressively whatever the primary injury.32 General Physical Exam An accurate head circumference is essential in infants and young children and should be documented on admission This may serve as a baseline for following the development of hydrocephalus in the at-risk infant In older children, an abnormal (large or small) head circumference may be a previously overlooked sign of pathology In the infant, the open fontanelle should be palpated and the findings on the exam agreed on in a quiet, resting state A bulging fontanelle is an important finding of meningeal irritation or increased ICP Examination of skin for the cardinal features of the phakomatoses may identify café-au-lait spots characteristic of neurofibromatosis, or shagreen patches, hypopigmented macules and angiomyofibromas characteristic of tuberous sclerosis The physical findings associated with inflicted trauma may be subtle,33 including unusual patterns of bruising, blood in the oropharynx, and burn or belt marks34 (see Chapter 121) Importance of Observation in the Neurologic Exam The elements of the neurologic examination in the PICU comprise the same features of the neurologic exam for noncritically ill patients and are detailed in eTable 60.1 The assessment of mental status, cranial nerves, motor function, reflexes, sensation, and cerebellar function must be adapted to each patient, but the structure of the neurologic exam in the PICU is no different from the outpatient examination If possible, sedating drugs and paralytic agents should be reduced prior to the exam If this is not feasible, the exam must be interpreted in the context of these confounding factors The assessment of mental status begins with observation The examiner should first confirm the drugs used for sedation, if any, and recent changes in dosing It is not possible to give precise dose ranges for typical sedating agents associated with a mental status exam For commonly used agents in the PICU (benzodiazepines, opiates, dexmedetomidine), the effects of the drug on arousal and responsiveness will vary with the age of the patient, duration of exposure, nature of the neurologic insult, effect of other drugs on metabolism, and genetically determined ability to clear these drugs This complex set of interactions underscores the importance of experience in the examination of these patients to determine what is an acceptable level of arousal and the need for serial neurologic examinations The observations of the nurses and parents should first be solicited The examiner should enquire about evidence for changes in arousal or awareness, such as spontaneous eye opening, evidence of a sleep-wake cycle, change in activity, or response to interventions such as suctioning If family members are present, their observations of response to their presence or voice are important and may represent the first signs of awareness on the part of the patient It is appropriate to have a family member carry out part of the exam, asking the patient to follow commands, as young children are more likely to respond to their family in that circumstance than to a stranger The pattern of breathing rate and rhythm should be observed Specific patterns may help localize the site of neurologic dysfunction but not the mechanism involved (see eTable 60.1) The crescendodecrescendo pattern alternating with periods of apnea, characteristic of Cheyne-Stokes respiration, may be due to dysfunction either of the cerebral hemispheres, thalamus, or hypothalamus with preserved brainstem function, but can also be found in patients with congestive heart failure or primary respiratory disease Similarly, the sustained, deep breathing pattern of central neurogenic hyperventilation may be due to either structural injury to the midbrain, sepsis, pulmonary disease, or compensated metabolic acidosis The conventional neurologic examination proceeds from mental status, cranial nerves, motor (bulk, tone, and strength), reflexes, and sensation to cerebellar exam and gait In children, in the PICU in particular, the exam is often best performed out of sequence It is easier to assess tone and reflexes in the asleep, relaxed patient before waking the patient up to assess mental status While the exam is discussed in the standard order later, it may be more informative to begin the hands-on part of the exam with assessment of tone and reflexes Once awake and agitated, subtle asymmetries of tone and reflexes, which may be key findings of the exam, may be obscured First, the child is observed The state of arousal (awake, asleep), and responsiveness, (interactive, verbal, nonresponsive), position (tone and asymmetry of limb position), movement (purposeful, spontaneous, dystonic, choreic, asymmetry of movement) can all be reliably assessed by observation In a nonintubated, nonsedated patient, the examiner may proceed directly with a standard mental status exam adjusted for age In the young child who is able to cooperate, the specific cognitive and language skills expected for age can be assessed (eTable 60.2) Assessment of Level of Consciousness and Mental Status For children with depressed consciousness, the precise stimulus required to elicit a response and the nature of this response should be specified It is not helpful to describe the patient as “lethargic” or “obtunded.” First, the child is called by name to determine whether there is a response If this is not effective, the examiner may ask a family member to speak to the child Next, the stimulus is increased It is most helpful to describe the patient’s response to specific stimuli and to use the same stimuli for serial examinations The GCS score, while of limited use in preverbal children (Table 60.3) is a rapid, quantitative measure If the patient’s eyes open to voice, the response to commands is tested next This is discussed in more detail later, but the commands should be increased in complexity in one to two or three steps If there is no response to voice, a painful stimulus is applied Note that in patients with sensory deficits due to neuropathy, spinal cord, or CNS lesions or with focal limb weakness, the extremity or dermatome selected for testing should have intact sensory or motor function In the sedated or severely impaired patient, the response may comprise only increase in heart rate It is important that the stimulus and the specific response, rather than vague descriptors (“lethargic, drowsy, sleepy”) are documented, as this will be more helpful in assessing serial examinations The infusion rate of sedating drugs or recent administration of sedating drugs should be documented with this exam The assessment of higher cognitive function and the early recognition of compromise of cognitive function is a challenge at any time when evaluating young children In the ICU—where the 722.e1 eTABLE Approach to the Intensive Care Unit Neurologic Examination: Localization and Mechanism 60.1 Exam Finding Structural-Vascular Insult Toxic-Metabolic Consciousness Stays at same level or deteriorates Waxes and wanes; milder impairment Toxins may cause progressive decline Respiration Cheyne-Stokes (crescendo-decrescendo alternating with apnea): loss of cerebral, thalamic, or hypothalamic control of breathing Neurogenic hyperventilation (sustained, rapid, deep breathing): midbrain disease Gasping respiration (irregularly irregular): dysfunction of lower brainstem or medulla Cheyne-Stokes: congestive heart failure, primary respiratory disease Neurogenic hyperventilation: metabolic acidosis, sepsis, liver failure Gasping respiration: intoxication (opiates, barbiturate), hypothyroidism Fundoscopy Papilledema due to increased ICP Papilledema does not occur except in hypertensive encephalopathy, lead intoxication, hypoparathyroidism Eye position Versive deviation Stroke ipsilateral to direction of deviation Versive deviation Seizure contralateral to direction of deviation Pupil reactivity Retraction or convergence nystagmus Midbrain Ocular bobbing Pons Intranuclear ophthalmoplegia Pons or midbrain Oculomotor nerve palsy Midbrain or herniation Skew gaze Brainstem Small reactive Thalamus, hypothalamus Midposition, fixed Midbrain Pinpoint, reactive Pons Small, combined with ptosis Horners, lateral medulla, sympathetic chain Large, fixed Oculomotor nerve, tectum No extraocular movement with preserved pupil reactivity Toxin Small reactive Large, fixed Botulism, ophthalmic drops Eye movements If asymmetric, likely structural Oculomotor nerve palsy Midbrain or herniation syndrome Abducens nerve palsy Unreliable localization Internuclear ophthalmoplegia Midbrain or pons Dysconjugate or skew gaze Brainstem Absent vertical and retained horizontal movement Midbrain Absent horizontal and retained vertical movements Pons Roving more common with metabolic derangements Absence of all movement with intact pupil light reflex Adventitious movements Posturing; sign of herniation Myoclonus following severe cerebral ischemia Restlessness, tremor, spasm, myoclonus, chorea, akathisia Muscle tone Asymmetric; increased, normal or decreased Symmetric, normal or decreased 722.e2 eTABLE Age-Dependent Motor and Language Patterns 60.2 Age (mo) Motor Language 15 Walks alone, crawls up stairs Jargon; follows simple commands 18 Runs, sits on chair, walks up stairs with hand held 10 words; names pictures; identifies body parts 24 Runs well; walks up and down stairs Three-word sentences 30 Jumps Refers to self as “I” 36 Stands on one foot; goes up stairs with alternating feet Knows age and gender; counts objects 48 Hops on one foot; throws ball Tells a story 60 Skips Names colors; repeats 10-syllable sentences Modified from Behrman RE, et al, eds Nelson Textbook of Pediatrics 14th ed Philadelphia: Elsevier; 1994 CHAPTER 60 Neurologic Assessment and Monitoring result in almost instantaneous papilledema Sometimes, papilledema never develops despite prolonged severe elevations of ICP TABLE 60.3 Glasgow Coma Scale Activity Best Response Eye opening Spontaneous To command To pain None Verbal Oriented Confused Inappropriate words Incomprehensible sounds None Motor response Obeys commands Localizes pain Withdraws to pain Abnormal flexion to pain Abnormal extension None Total 723 Score 3–15 additional confounding factors of sedation, other organ dysfunction, sleep disturbance, and anxiety must be accounted for—this evaluation is somewhat more challenging Of course, this is usually the most important component of the exam, and the technologies used for neurologic monitoring in the ICU all serve the same goal of the bedside exam, of detecting compromised cerebral function to enable directed therapeutic intervention In the older, awake child, a complete mental status exam can be performed This must be adjusted for age (see eTable 60.2) but should include assessment of language (fluency and comprehension) and the ability to name, repeat, write, read, and respond to written commands Simple mathematical problems should be adjusted to the child’s age-dependent ability Praxis can be assessed quickly even in the PICU by demonstration of learned behaviors even in the young child (brush your teeth, brush your hair) Other components of the mental status exam—including memory, fund of knowledge, and reasoning—can be assessed by holding a conversation with the patient Most importantly, the examiner needs to have an appropriate index of suspicion for these subtle neurologic deficits of attention, memory, praxis, language comprehension, and reading comprehension, which may be the early signs of new neurologic injury This is particularly true for patients with metabolic (often liver or renal failure), infectious or iatrogenic (sedation, immunophilins) risk factors for CNS dysfunction and may easily be missed if not specifically investigated Again, serial examinations by examiners familiar with the patient’s exam while sedated are the key to reliable detection of new deficits of higher cortical function in the ICU Fundoscopic Examination Examination of the fundi may reveal hemorrhages or papilledema Hemorrhages indicate either acute subarachnoid or subdural hemorrhage, cranial trauma from a direct blow or shaking injury, or malignant hypertension Papilledema indicates raised ICP from any cause Usually, papilledema develops hours after the onset of the elevated ICP Acute severe increases, however, as with subarachnoid hemorrhage (SAH) from a ruptured saccular aneurysm, can Cranial Nerve Examination The pupillary reaction to light is abolished only by structural damage to the midbrain or third cranial nerve Loss of the pupillary reflexes is always an ominous finding Preservation of pupillary reflexes in the presence of deep coma suggests a metabolictoxic cause The interpretation of the patterns of pupil reactivity is summarized in eTable 60.1 Measurement of pupil size and light response is a quantifiable measure of brainstem and autonomic nervous system function Absence of pupil reactivity is a poor prognostic sign after TBI or cardiac arrest To provide a very precise measure of pupil size and speed of contraction and relaxation, a portable handheld device (pupillometer) illuminates the eye with an infrared light (850 nm) while acquiring images for analysis The data (pupil size, rate of contraction and relaxation) are stored on the device and can be downloaded to a computer In a study of healthy volunteers and adult patients with TBI and ICP monitors in place, a discrepancy in pupil size of more than 0.5 mm was associated with ICP above 20 mm Hg.35 Using the Neurological Pupil Index (algorithmic composite of measures of pupillary reactivity), a single-center study of 28 children with ICP monitored, identified an inverse relationship between increases in ICP and decreases in pupil reactivity.36 One of the limitations in the use of other neuromonitoring data in children is the lack of data on age and gender differences These normative data are now available for children and show greater constriction velocities and percentages in males.37 Eye movements are assessed first by observation and then elicited in the patient with depressed mental status with the doll’s head maneuver (oculocephalic response) or cold caloric stimulation (oculovestibular response; see eTable 60.1) In general, coma produced by metabolic dysfunction is initially associated with roving, dysconjugate movement and may progress to the cessation of movement Cold caloric stimulation will produce nystagmus with the rapid phase contralateral to the ear that has been stimulated This rapid phase is the equivalent of saccadic eye movements and indicates intact functioning of the cerebral cortex The ears are irrigated separately several minutes apart In comatose patients, the fast “corrective” phase of nystagmus is lost, and the eyes are tonically deflected to the side irrigated with cold water or away from the side irrigated with warm water These vestibuloocular responses are lost or disrupted in brainstem lesions Versive eye deviation is a common finding suspicious for seizures In this case, the eye deviation is contralateral to the hemisphere with the ictal focus Alternatively, stroke in the ipsilateral hemisphere may also produce versive eye deviation toward the side of the stroke An abnormal corneal reflex may indicate either fifth nerve afferent disease (ipsilateral stimulation results in neither a direct nor consensual eye blink) or seventh nerve efferent disease (ipsilateral stimulation results in a brisk consensual but no direct response) Unilateral weakness of eye closure, forehead movement, and mouth movement indicates peripheral seventh cranial nerve palsy, whereas failure to move only the mouth with preservation of upper face movements indicates a central corticospinal tract lesion rostral to the pons Facial weakness may be noted during grimacing while responses to painful stimuli are evaluated Voluntary pharyngeal and laryngeal control is tested by asking the patient to speak and say “Ah.” In the absence of voluntary movement, a hypoactive gag indicates medullary or vagal dysfunction and a 724 S E C T I O N V I Pediatric Critical Care: Neurologic hyperactive gag indicates interruption of corticospinal inhibition to the medulla In a comatose patient or one whose consciousness is rapidly sinking, one must quickly determine whether the patient is experiencing raised ICP Papilledema or third cranial nerve palsy is strong evidence of elevated ICP Approach to the Motor Exam In the comatose or obtunded patient, asymmetry of resting tone and spontaneous movement are simple signs of paresis, which can be detected by first observing the patient In children, this is particularly important as a subtle weakness may not be apparent once the child is more awake and uncooperative An externally rotated, partly flexed abducted leg may indicate an ipsilateral hemiparesis due to an upper motor neuron lesion Facial weakness should also be first evaluated by observation before attempting formal testing (often impossible or unreliable in young, anxious, or sedated children) Signs of facial weakness at rest may include a widened palpebral fissure, diminished nasolabial fold, or flattened corner of the mouth Next, the examiner should attend to the initial movement of the face, either spontaneously or in response to a noxious stimulus Subtle weakness may be apparent only in a delayed response to these stimuli Weakness may be due to lesions at any level of the neuraxis The goal of the examination of the weak patient is to identify the pattern of weakness as coming from the upper or lower motor neuron and thereby identify the most likely mechanisms The upper motor neuron (UMN) comprises the corticospinal tract and its neurons The corticospinal tract begins in the motor and premotor cortex anterior to the central sulcus, descends through the central white matter of the cerebral hemispheres, decussates in the lower medulla, and terminates on the anterior horn cells or interneurons closely associated with the anterior horn cells The innervation of muscles that control movement of the jaw, pharynx, larynx, upper half of the face, neck, thorax, and abdomen is derived from both cerebral hemispheres Consequently, unilateral cerebral lesions lead only to weakness of the contralateral limbs and lower face The lower motor neuron (LMN) is composed of the anterior horn cells, motor roots, peripheral nerves, pre- and postsynaptic components of the neuromuscular junction, and the muscles receiving this innervation Stereotyped reflex movements may be present despite spinal cord injury because these responses are coordinated by local spinal reflexes below the level of the lesion In contrast, movement is absent following injury to the LMN because it is the final common pathway producing muscle activity If the patient is not able to cooperate with a complete exam testing all muscle groups, in addition to observing for asymmetric posture, the observation of facial movement, testing for neck flexion, grip strength, pronator drift, and counting the duration (up to 10 seconds) that the patient can maintain a straight leg raise are efficient means of assessment A number of key findings on the pattern of weakness can distinguish between UMN and LMN injury, chronic and acute injury, and neuropathy and neuromuscular disorders—including ICU-acquired paresis, myasthenia gravis, and Guillain-Barré syndrome (GBS) Acute UMN lesions result in a hypotonic or flaccid pattern of weakness and may be associated with the Babinski sign in the legs In contrast, chronic UMN injury results in a hypertonic limb with associated hyperreflexia An LMN pattern of weakness is more likely to be associated with a decrease in muscle tone and bulk and decreased or absent reflexes In general, proximal weakness suggests a myopathic process, while a distal pattern of weakness suggests a neuropathy The precise incidence of ICU-acquired weakness (ICU-AW) is uncertain in children.38 In a study of the incidence of weakness in 830 critically ill children, only 1.7% had generalized weakness.39 This is lower than the incidence of ICU-AW in adults.40 Extensive data from adult studies have identified ICU-AW—manifesting as a variable combination of weakness, muscle atrophy, hyporeflexia, and sensory deficits—as a common cause of failure of extubation with a high incidence of long-term morbidity The contribution of the risk factors in adults (sepsis, hyperosmolarity, neuromuscular blockage, prolonged ventilation, and corticosteroids) to pediatric ICU-AW is not known ICU-AW is primarily a clinical diagnosis, although nerve conduction and electromyography studies may be confirmatory Management, particularly in children, is empiric but this disorder should be suspected in any critically ill child with diminished reflexes and new weakness or requiring reintubation without identification of other causes The two most common neuromuscular disorders that require intensive care in children are GBS and myasthenia gravis (MG; discussed in Chapter 68) For patients with known MG admitted to the ICU in crisis, it is essential to note the timing of anticholinesterase treatment and the timing of the neurologic exam in relation to each evaluation of strength In general, testing should be performed at the nadir of weakness prior to each treatment This is the only reliable way in which a decline in strength can be detected in these patients In contrast to GBS, the progression to respiratory failure in MG may be arrested by noninvasive ventilator support with bilevel positive airway pressure (BiPAP) Muscle fatigue in MG is reversible with a combination of anticholinesterase treatment and BiPAP, which may prevent the need for intubation In the case of GBS, patients who cannot walk unaided should be treated with intravenous immunoglobulin (IVIG).41 Neither GBS nor MG should alter pupil reactivity In this case, if the pupils are slow to react or not react at all in a weak infant, the diagnosis of botulism should be considered.42 Posturing due to increased ICP should be distinguished from abnormal movements, including chorea and dystonia Decorticate posturing consists of adduction and stiff extension of the legs, flexion and supination of the arms, and fisting of the hands This occurs when the midbrain and red nucleus control body posture without inhibition by the diencephalon, basal ganglia, and cerebral cortex Decerebrate posturing consists of stiff extension of legs, arms, trunk, and head with hyperpronation of lower arms and plantar flexion of the feet This indicates pontine and vestibular nucleus control of posture without inhibition from more rostral structures Lesions below the level of vestibular nuclei lead to flaccidity and abolition of all postures and movements These movements should be distinguished from dystonia or chorea, which may be seen as side effects of medications, the sequelae of basal ganglia injury, or metabolic or neurotransmitter disorders Reflexes Reflexes may be absent in critically ill children, wax and wane during the course of the day, or be elicited by some examiners but not others This variability can be diminished by performing the exam when the child is in a quiet, resting state and by focusing on key reflexes In general, the purpose of the exam is to determine whether there are changes in intensity (a reduction or increase), symmetry, or development of pathologic reflexes ... apnea): loss of cerebral, thalamic, or hypothalamic control of breathing Neurogenic hyperventilation (sustained, rapid, deep breathing): midbrain disease Gasping respiration (irregularly irregular):... organ dysfunction, sleep disturbance, and anxiety must be accounted for—this evaluation is somewhat more challenging Of course, this is usually the most important component of the exam, and the technologies... Myoclonus following severe cerebral ischemia Restlessness, tremor, spasm, myoclonus, chorea, akathisia Muscle tone Asymmetric; increased, normal or decreased Symmetric, normal or decreased 722.e2