Definitions

Consciousness is the spontaneously occurring state of awareness of self and environment. Consciousness has two dimensions – wakefulness and awareness [Multi-Society Task Force on the Persistent Vegetative State, 1994]. Normal consciousness requires arousal, an independent, autonomic-vegetative brain function subserved by ascending stimuli – emanating from pontine tegmentum, posterior hypothalamus, and thalamus – that activate mechanisms inducing wakefulness. Awareness is subserved by cerebral cortical neurons and their reciprocal projections to and from the major subcortical nuclei. Awareness requires wakefulness, but wakefulness can be present without awareness.

In preterm and term newborns and in infants, consciousness may require a more operational definition. Crying when uncomfortable or hungry at least suggests awareness of self, and visual alertness or soothing to an auditory stimulus (such as parent’s voice) suggests environmental awareness. The presence of an appropriate socially responsive smile in the younger infant is a clear marker of consciousness and awareness. The bilateral absence of the cerebral cortex, as in anencephaly or severe hydranencephaly, may make realistic assessment of consciousness impractical.

Clouding of consciousness is the minimal reduction of wakefulness or awareness wherein the main difficulty is attention or vigilance. Clouding of consciousness is distinguished from daydreaming, in that the child cannot be easily stimulated to normal consciousness. It is also distinguished from the inattention of attention-deficit hyperactivity disorder by failure to improve with one-to-one confrontation or removal of distractions.

Confusion is the state of impaired ability to think and reason clearly at a developmentally and intellectually appropriate level. Confused children have persistent difficulty with orientation, simple cognitive processing, and acquisition of new memory. Normal suggestibility and anxiety in younger children may be misleading when assessing confusion. In newborns, infants, and younger children, clouding of consciousness and confusion are difficult to assess and are not of practical value. In the older child or adolescent, confusion may be an important indicator of drug ingestion, toxin exposure, or severity of concussion. Other definitions of impairment of consciousness states may be divided into the following categories:

impairment of consciousness with activated mental state

impairment of consciousness with reduced mental state

impairment of consciousness along the continuum of coma–vegetative state–minimally conscious state and related conditions.

Vegetative State, Minimally Conscious State, and Related Conditions

Table 73-1 lists several of the major neurologic conditions that the clinician must be capable of differentiating from coma. This table was modified from the report issued by the Multi-Society Task Force on the Persistent Vegetative State [1994] and more recent work that is defining the concept of the minimally conscious state [American Congress of Rehabilitation Medicine, 1995; Giacino et al., 1997]. The principal neurologic conditions in which there may be overlap of clinical findings on examination that should be differentiated from coma are discussed in the next sections.

Table 73-1 Severe Disorders of Consciousness and Related Conditions

Vegetative State

The vegetative state can be described as a condition of complete unawareness of the self and the environment, accompanied by sleep–wake cycles with either complete or partial preservation of hypothalamic and brainstem autonomic (vegetative) functions [Zeman, 1997; Monti et al., 2010]. Criteria to diagnose the vegetative state have been recommended for adults and children by the Multi-Society Task Force on Persistent Vegetative State and are listed in Box 73-1. Children in a vegetative state lack evidence of self-awareness or recognition of external stimuli. Rather than being in a state of “eyes-closed” coma, they remain unconscious but have irregular periods of wakefulness alternating with periods of sleeping. Vegetative patients demonstrate a variety of sounds, emotional expressions, and body movements, and they may smile or shed tears. They have inconsistent head- and eye-turning movements to sounds and inconsistent, nonpurposeful trunk and limb movements. The most objective sign is lack of sustained visual fixation or visual tracking.

Box 73-1 Criteria for the Diagnosis of the Vegetative State

No evidence of awareness of themselves or their environment; they are incapable of interacting with others

No evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli

No evidence of language comprehension or expression

Intermittent wakefulness manifested by the presence of sleep–wake cycles

Sufficiently preserved hypothalamic and brainstem autonomic functions to survive if given medical and nursing care

Bowel and bladder incontinence

Variably preserved cranial nerve (pupillary, oculocephalic, corneal, oculovestibular, gag) and spinal reflexes

It is estimated that there are about 4000–10,000 children in a vegetative state in the United States [Ashwal, 1996] and about 100,000 worldwide [Ashwal, 2005]. The etiology of the vegetative state in children can be classified into the following three broad groups of disorders:

1. acute traumatic and nontraumatic brain injuries

2. metabolic and degenerative disorders affecting the nervous system

3. developmental malformations.

The percentage of children having these etiologies of the vegetative state is as follows: acute traumatic and nontraumatic injuries (30 percent), perinatal insults (17.7 percent), chromosomal disorders or congenital malformations (13.0 percent), infections (10.3 percent), and unknown causes (28 percent) [Ashwal et al., 1994].

The most common causes of acute brain injury leading to the vegetative state in children are head trauma and hypoxic-ischemic encephalopathies [Adams et al., 2000]. Severe traumatic brain injury in children is often due to nonaccidental trauma but also occurs after a motor vehicle crash, particularly when infant restraints have not been used or when a pedestrian versus motor vehicle crash occurs. Hypoxic-ischemic injuries after cardiorespiratory arrest occur at birth, after episodes of near-miss sudden infant death syndrome or near-drowning, and after other acute life-threatening episodes, including shock due to systemic trauma or infection.

The clinical course of evolution to a vegetative state after an acute injury usually begins with eyes-closed coma for several days to weeks, followed by the appearance of sleep–wake cycles. Gillies and Seshia retrospectively determined that the transition from eyes-closed coma to the vegetative state averaged 8.6 ± 1.7 days in 17 children aged 1 month to 6 years [Gillies and Seshia, 1980]. Other responses, such as decorticate and decerebrate posturing (1.7 days), roving eye movements (1.8 days), and eye blinking (3.3 days), appeared earlier than sleep–wake cycles [Gillies and Seshia, 1980].

The progression of many metabolic and degenerative nervous system disorders in children may result in an irreversible vegetative state. In contrast to patients who become vegetative within several weeks after an acute injury, patients with metabolic or degenerative diseases slowly evolve to a vegetative state over several months or years. Severe congenital central nervous system (CNS) malformations can also result in a vegetative state. At birth, anencephaly is the only malformation in which an infant can be diagnosed as being in a vegetative state because of the absence of the cerebral cortex. Other malformations, such as hydranencephaly, may result in a vegetative state but, because of the limitations of the neurologic examination in assessing higher cortical functions and in differentiating voluntary from involuntary responses until about 3–6 months of age, it is recommended that such infants not be diagnosed as being vegetative until there is certainty about the diagnosis.

Diagnosis of the vegetative state is made clinically [AAN Quality Standards Subcommittee, 1995]. There are no confirmatory laboratory tests, in contrast to establishing the diagnosis of brain death. However, the absence of cortical (scalp-recorded) potentials of the somatosensory-evoked response to median nerve stimulation has been associated with the vegetative state in some studies [Beca et al., 1995; Frank et al., 1985]. Neuroimaging studies usually demonstrate diffuse or multifocal cerebral disease involving the gray and white matter or major CNS malformations [Ashwal, 1996]. In patients with traumatic and nontraumatic brain injury, serial imaging studies may demonstrate progressive atrophy. PET studies may demonstrate significant global reductions of cerebral glucose metabolism in infants [Larsen et al., 1993]. Proton magnetic resonance spectroscopy measurement of increased cerebral lactate in newborns, infants, and children with nervous system disease is associated with severe disability, survival in the vegetative state, or death [Ashwal et al., 1997].

Issues have been raised for several of the disorders of consciousness with regard to the diagnostic accuracy of the clinical assessment versus the use of advanced imaging or neurophysiological methods to assess such severely affected patients [McKinney and Giacino, 2008; Owen and Coleman, 2007; Giacino et al., 2009; Gawryluk et al., 2010]. In addition, several recent studies in adult patients thought to be in a vegetative state have raised considerable interest, as investigations with fMRI have shown evidence of awareness and presumably some level of higher cortical function [Owen and Coleman, 2008]. In addition, deep brain stimulation in minimally conscious-state patients [Schiff et al., 2009] has resulted in clinical improvement and has raised additional issues as to the role of functional imaging in evaluating vegetative state patients and also in potentially new approaches to treatment.

Recovery from the vegetative state in children depends on the etiology and is reviewed in more detail in the Multi-Society Task Force on the Persistent Vegetative State report [1994]. In children with severe closed-head injuries who were vegetative 1 month after injury, follow-up at 1 year found that 29 percent remained in a vegetative state, 9 percent had died, and 62 percent recovered consciousness. Recoveries after 12 months were not reported, although one study found that 2 of 40 children with traumatic brain injury began to recover after 1 year in a vegetative state [Kriel et al., 1993]. In contrast, children in a nontraumatic vegetative state have a much poorer potential for recovery than those in a traumatic vegetative state. At 1 year, most children remained in a vegetative state (65 percent) or died (22 percent); only 13 percent demonstrated recovery, usually to a severe disability. It was based on these data and consensus opinion that the Task Force came to the conclusions that, in children (as well as in adults), the vegetative state could be judged permanent 12 months after traumatic brain injury and 3 months after nontraumatic injury. The chance for recovery after these time periods was exceedingly low, and the patient almost always progressed to a severe disability. This perspective has received general acceptance, although concerns have been raised about the certainty of diagnosis and whether there is a greater potential for patients to recover than previously realized [Giacino et al., 1997; Jennett, 1997].

It is important to identify children who are in a vegetative state correctly because of the implications for continued care, family expectations, and the need for rehabilitation. Specialty programs for coma recovery are usually directed at patients who are severely disabled or are in a minimally conscious or vegetative state. Management issues are confounded by a lack of understanding of expected recovery patterns, terminology inconsistency, lack of or inappropriate use of outcome measures, and inadequate knowledge concerning medical management based on scientifically sound practices for this special patient population [Zasler et al., 1991]. Children in a vegetative state have been reported to have a considerably shorter than normal life expectancy [Ashwal et al., 1994]. Children in a vegetative state who are younger than 1 year of age had a median survival of 2.6 years, whereas the median survival of children aged 2–6 years was 5.2 years. In children 7–18 years of age, the reported median survival was 7 years.

Minimally Conscious State

The minimally conscious state has been defined as a condition of severely altered consciousness in which the person demonstrates minimal but definite behavioral evidence of self- or environmental awareness [Giacino et al., 1997]. Recovery from coma depends on the cause of coma, extent of brain injury, and ability of injured areas to recover or of uninjured areas to assume the functions of injured areas. Not all comatose patients recover rapidly or completely. A variety of terms have been used to define these states, and there is often confusion between recovery states and prognostic categories. The term minimally conscious state has been proposed to describe those patients who were in coma or a vegetative state and who begin to demonstrate minimal signs of awareness. The term minimally conscious state may also be used to describe patients with degenerative disorders who are no longer functionally interactive but are not in the vegetative state. Patients in a minimally conscious state are able to do the following:

1. follow simple commands

2. gesture or verbally give “yes” or “no” responses (regardless of accuracy)

3. verbalize intelligibly

4. perform movements or affective behaviors, which are not attributable to reflexive activity, in contingent relation to relevant environmental stimuli.

Criteria to diagnose the minimally conscious state are shown in Box 73-2 [Giacino et al., 2002].

Box 73-2 Diagnostic Criteria for the Minimally Conscious State

Simple command following

Gestural or verbal yes-no responses (regardless of accuracy)

Intelligible verbalization

Purposeful behavior, including movements or effective behaviors that occur in contingent relation to relevant environmental stimuli and are not due to reflexive activity. Some behavioral examples of qualifying purposeful behaviors include the following:

Appropriate smiling or crying in response to the linguistic or visual content of emotional but not to neutral topics or stimuli

Vocalizations or gestures that occur in direct response to the linguistic content of questions

Reaching for objects that demonstrates a clear relationship between object location and direction of reach

Touching or holding objects in a manner that accommodates the size and shape of the object

Pursuit eye movement or sustained fixation that occurs in direct response to moving or salient stimuli

(Adapted from Giacino JT et al. The minimally conscious state. Definition and diagnostic criteria. Neurology 2002;58:349.)

Children in the minimally conscious state are usually victims of acquired brain injury (traumatic and nontraumatic), neurodegenerative and neurometabolic disorders, or congenital or developmental disorders [Ashwal, 2003]. Based on limited literature on this disorder in adults [Giacino and Kalmar, 2005], it is possible that such children, depending on the etiology of the insult, may have a better potential for neurologic recovery and a longer life expectancy than children in the vegetative state. In a study of 5075 children aged 3–15 years in a vegetative state or minimally conscious state, 564 were in the vegetative state, 705 in the minimally conscious state and immobile, and 3806 in the minimally conscious state and mobile. The 8-year survival rates were 63 percent for vegetative state, 65 percent for immobile minimally conscious state, and 81 percent for mobile minimally conscious state. Thus, presence of consciousness was not a critical variable in determining life expectancy in this study, and mobility was more important than consciousness in predicting survival [Strauss et al., 2000].

Locked-In Syndrome

The locked-in syndrome refers to a condition in which patients retain consciousness and cognition but are unable to move or communicate because of severe paralysis. This condition is a result of diseases involving the descending corticospinal and corticobulbar pathways at or below the pons or of severe involvement of the peripheral nervous system. By definition, patients in coma or a vegetative state are unconscious and differ from patients in a locked-in syndrome, who retain awareness, although this difference may be difficult to determine. The locked-in syndrome is quite rare in children [Habre et al., 1996; Scott et al., 1997]. Some patients with this condition can establish limited communication using eye movements.

Akinetic Mutism

Akinetic mutism is a rare condition consisting of pathologically slowed or nearly absent bodily movement, accompanied by a similar loss of speech [Plum and Posner, 1982]. The original description of this condition in 1941 was in an adolescent with symptoms of intermittent depressed states of consciousness secondary to a craniopharyngioma [Cairns et al., 1941]. Since then, akinetic mutism has been seen with bacterial and viral CNS infections, other tumors of the nervous system, and hydrocephalus, and occasionally as a postoperative phenomenon, especially with posterior fossa and cerebellar tumors [Lin et al., 1997; Melton et al., 1991]. Wakefulness and self-awareness are usually preserved in most patients, but the level of mental function is reduced. The condition characteristically accompanies gradually developing or subacute, bilateral damage to the paramedian mesencephalon, basal diencephalon, or inferior frontal lobes. The long-term outlook for children with akinetic mutism is unknown because few patients with this disorder have been reported. It is most likely related to the etiology and severity of the associated disease.

Brain Death

Brain death describes the permanent absence of all brain functions, including those of the brainstem [Task Force for the Determination of Brain Death in Children, 1987; Nakagawa et al., 2011]. Brain-dead patients are irreversibly comatose and apneic, and they have absent brainstem reflexes, including the loss of all cranial nerve functions. The appearance of brain death can be imitated by deep anesthesia, sedative overdose, or severe hypothermia. Patients who are brain-dead differ from patients who are in a coma, in that comatose patients usually have preserved brainstem functions and some degree of respiratory drive. Guidelines for the diagnosis of brain death in infants and children were originally published in 1987 and were recently revised in 2011; they are reviewed in greater detail in Chapter 79. A useful algorithm for distinguishing among brain death, vegetative state, locked-in syndrome, and higher-order consciousness is presented in Figure 73-1 [Ashwal and Cranford, 2002].

Fig. 73-1 An algorithm useful for distinguishing among brain death, vegetative state, locked-in syndrome, and higher-order consciousness.

MCS, minimally conscious state.

(From Ashwal S, Cranford R. The minimally conscious state in children. Semin Pediatr Neurol 2002;9:19.)

Consciousness Rating Scales

Several behavior rating scales have been developed because of the difficulty with imprecise use of terminology and because of the need for a truly reproducible assessment of consciousness with good inter-rater reliability [Kirkham et al., 2008]. Although typically referred to as coma scales, these scales have value in assessing consciousness alterations other than coma.

The best known and most widely used is the Glasgow Coma Scale, which yields a score of 3–15, based on best response to stimuli in the following three categories: eye opening, verbal response, and motor response (Table 73-2) [Teasdale and Jennett, 1974]. In its original form, the Glasgow Coma Scale was not developmentally suitable for assessment of newborns, infants, and younger children, and a variety of alternate scales have been proposed [Duncan et al., 1981; Hahn et al., 1988; Raimondi and Hirschauer, 1984; Reilly et al., 1988; Rubenstein, 1994; Simpson et al., 1991; Simpson and Reilly, 1982]. An ideal pediatric modification of the Glasgow Coma Scale would meet the following criteria:

The Pediatric Coma Scale [Reilly et al., 1988; Simpson et al., 1991; Simpson and Reilly, 1982] makes minor changes in the verbal scale of the Glasgow Coma Scale and redefines the “best” score based on developmental and age-appropriate norms (Table 73-3). It has the advantage of prospective evaluation and inter-rater reliability and the disadvantage of different maximum scores based on age, thus making outcome prediction and comparison difficult to study using the Glasgow Coma Scale.

Table 73-3 Pediatric Coma Scale

The Children’s Coma Scale redefines intracategory criteria and the “maximum” score, and changes the eye-opening category to “ocular response” [Raimondi and Hirschauer, 1984]. The Children’s Coma Scale meritoriously included pupillary reflexes, extraocular movements, and apnea in its categories, and is therefore substantially different from the Glasgow Coma Scale and requires different training and forms to be used (Table 73-4).

Table 73-4 Children’s Coma Scale

The Glasgow Coma Scale – Modified for Children maintains the same categories as the Glasgow Coma Scale and the same maximum and minimum scores, while allowing developmental and age-appropriate scoring [Hahn et al., 1988; Rubenstein, 1994]. It does, however, equate spontaneous movement with following commands to achieve 6 points in the best motor response category to allow inclusion of infants and young children (see Table 73-2). None the less, the Glasgow Coma Scale – Modified for Children allows the best direct comparison with the Glasgow Coma Scale for scoring of consciousness impairment and assessment of outcome.

The Glasgow Coma Scale and its modifications for children are useful for evaluating and quantifying the continuum from consciousness to coma more objectively, and for allowing serial reassessment that meaningfully reflects the state of the patient at a particular moment in time with good inter-rater reliability. The scores also allow a relatively large amount of information to be conveyed quickly and concisely, with minimal need to remember cumbersome definitions or to write long descriptions. Their ease of use makes them even more valuable in the critical care and emergency department settings. The Glasgow Coma Scale and its pediatric modifications do not take into account the important brainstem reflexes, such as pupillary reactivity or oculocephalic, oculovestibular, or corneal reflexes. These should be a routine part of the assessment of the patient with impaired consciousness [Narayan et al., 1981].

The sum of the Glasgow Coma Scale may convey less useful information than the ocular, motor, and verbal responses individually [Teasdale et al., 1983]. In a study of 270 children aged 2 months to 12 years with acute nontraumatic coma, multivariate analysis suggests that the ocular and motor response scores, and not the total score, were predictors of short-term survival. Additionally, the absence of one or more brainstem reflexes (oculocephalic, oculovestibular, or pupillary reactivity) predicted short-term adverse outcomes [Nayana Prabha et al., 2003].

In children, the Glasgow Coma Scale motor subscore has equal predictive value with the full scale score and is more easily and reliably obtained [Van de Voorde, 2008]. In a retrospective study of 130 children 3 months to 16 years old admitted for traumatic brain injury, the motor response of the Glasgow Coma Scale predicted outcome as well as the full Glasgow Coma Scale, had a more linear relationship to mortality, and was easier to collect accurately [Fortune and Shann, 2010]. Multiple studies have shown the value of the motor subscore of the Glasgow Coma Scale and the additive value of brainstem reflex data in predicting outcome in children with traumatic and nontraumatic coma.

The Full Outline of Unresponsiveness (FOUR) Score Coma Scale (Table 73-5) was created to address these areas of weakness in the use of the Glasgow Coma Scale and its derivatives [Wijdicks et al., 2005]. The FOUR Score is divided into four categories (eye response, motor response, brainstem reflexes, and respiration), each with a maximum score of four (range 0–4). By providing a measure of consciousness that does not require patient vocalization, assessment of motor function, evaluation of brainstem reflexes at the mesencephalic, pontine, and medullary levels, and observation of respiration, the FOUR Score improves upon the Glasgow Coma Scale and incorporates other important features of the neurologic exam. Addition of this neurologic scoring system allows recognition of brain death, the vegetative state, the locked-in syndrome, and progressive changes seen in herniation syndromes [Wijdicks, 2006].

Table 73-5 “FOUR” Score Coma Scale

(From Wijdicks E et al. Validation of a new Coma Scale: The FOUR Score. Annals of Neurology 2005;58[4]:584–593.)

In adults, the FOUR Score has excellent inter-rater reliability when performed by nurses or physicians, and is suitable for use in neurosurgical and medical critical care and in the emergency department [Wolf, 2007; Akavipat, 2009; Stead, 2009; Fischer et al., 2010]. In a study of 60 children (ages 2–18 years) admitted for traumatic and nontraumatic injuries, the inter-rater reliability of the Glasgow Coma Scale was good and that of the FOUR Score was excellent [Cohen, 2009]. Both the FOUR Score and the Glasgow Coma Scale were predictive of in-hospital mortality and poor outcome at the conclusion of hospitalization.

The FOUR Score Coma Scale has comparable predictive value and inter-rater reliability to the Glasgow Coma Scale and is easier to use. Further studies in children will be necessary to determine the role of the FOUR Score in prediction of long-term outcome.The FOUR Score, however, may not adequately distinguish the vegetative state from the minimally conscious state when compared to the Coma Recovery Scale – Revised score [Schnakers et al., 2006]. This distinction may be more important in chronic critical care and acute and chronic rehabilitation settings than in the acute critical care setting. The Coma Recovery Scale – Revised is more complex than the FOUR Score Coma Scale, requires more training to use, and is more appropriately employed as an outcome measure [Giacino et al., 2004].

Pathophysiology

Consciousness is the result of the complex interplay between the cerebral cortex and the ascending reticular-activating system. The ascending reticular-activating system is a somewhat diffuse and widely circumscribed group of neurons that lie in the reticular formation of the brain that extends from the lower medulla to the midbrain and diencephalon [Moruzzi and Magoun, 1949; Plum and Posner, 1982]. Coma is produced by diseases or conditions that cause bilateral cerebral cortical dysfunction, ascending reticular-activating system dysfunction, or both. Pathologically, these can be subdivided as follows [Adams et al., 1982; Gennarelli et al., 1982; Plum and Posner, 1982]:

Metabolic, toxic, or infectious encephalopathies that diffusely affect the cerebral hemispheres, the ascending reticular-activating system, or both

Supratentorial mass lesions that compress or displace the diencephalon or brainstem

Subtentorial mass or destructive lesions that compress or damage the ascending reticular-activating system

Traumatic, hypoxic-ischemic, or metabolic axonal injury that affects both cerebral hemispheres, the ascending reticular-activating system, or their interconnections.

Impairment of consciousness results from partial disruptions of neuronal function in these same areas. Prolonged coma after severe traumatic brain injury may be due to traumatic axonal injury or diffuse axonal injury without severe injury to the cortex or ascending reticular-activating system. This finding explains why patients with traumatic brain injury have a better potential for recovery than patients with hypoxic-ischemic injury.

Etiologies

A more relevant and practical classification for the etiology of impairment of consciousness and coma in children produces three distinct but overlapping categories:

Box 73-3 Etiologies of Impaired Consciousness and Coma

Infectious or Inflammatory

A Infectious

Bacterial meningitis

Viral encephalitis

Rickettsial infection

Protozoan infection

Helminth infestation

B Inflammatory

Sepsis-associated encephalopathy

Vasculitis, collagen vascular disorders

Demyelination

Acute disseminated encephalomyelitis

Multiple sclerosis

Structural

A Traumatic

Concussion

Cerebral contusion

Epidural hematoma or effusion

Intracerebral hematoma

Diffuse axonal injury

Abusive head trauma

B Neoplasms

C Vascular Disease

Cerebral infarction

Thrombosis

Embolism

Venous sinus thrombosis

Cerebral hemorrhage

Subarachnoid hemorrhage

Arteriovenous malformation

Aneurysm

Congenital abnormality or dysplasia of vascular supply

Trauma to carotid or vertebral arteries in the neck

D Focal Infection

Abscess

Cerebritis

E. Hydrocephalus

Metabolic, Nutritional, or Toxic

A Hypoxic-Ischemic Encephalopathy

Shock

Cardiac or pulmonary failure

Near-drowning

Carbon monoxide poisoning

Cyanide poisoning

Strangulation

B Metabolic Disorders

Sarcoidosis

Hypoglycemia

Fluid and electrolyte imbalance

Endocrine disorders

With acidosis

Diabetic ketoacidosis

Aminoacidemias

Organic acidemias

With hyperammonemia

Hepatic encephalopathy

Urea cycle disorders

Disorders of fatty acid metabolism

Reye’s syndrome

Valproic acid encephalopathy

Uremia

Porphyria

Mitochondrial disorders

Leigh’s syndrome

C Nutritional

Thiamine deficiency

Niacin or nicotinic acid deficiency

Pyridoxine dependency

Folate and B₁₂ deficiency

D Exogenous Toxins and Poisons

Alcohol intoxication

Over-the-counter medications

Prescription medications (oral and ophthalmic)

Herbal treatments

Heavy-metal poisoning

Mushroom and plant intoxication

Illegal drugs

Industrial agents

E. Hypertensive Encephalopathy

F. Burn Encephalopathy

Bacterial, viral, rickettsial, or protozoan infections of the CNS may cause conscious alteration by direct involvement of brain parenchyma, interference with blood flow, production of cerebral edema with resulting increased intracranial pressure, and increasing metabolic activity beyond metabolic substrate availability. Viral infections are more likely to involve brain parenchyma (encephalitis). The meningitis produced by bacterial infections may produce injury as a result of large blood vessel occlusion, microvascular inflammation, or disturbance of cerebral autoregulation. Cerebral edema, focal mass or abscess, and hydrocephalus as a result of intracranial infection may produce injury by reducing cerebral blood flow or leading to herniation.

Structural causes of consciousness impairment or coma include intracranial neoplasm, infectious space-occupying lesion (abscess, tuberculoma), nonaccidental and accidental trauma, cerebral infarction or hemorrhage, and hydrocephalus. These conditions are described in detail in other chapters.

Metabolic and toxic causes of impaired consciousness or coma include hypoxic-ischemic injury (focal or generalized), electrolyte abnormality, endocrinopathy, hepatic or renal failure, and inherited disorders, including organic and aminoacidurias, urea cycle disorders, mitochondrial disorders, and porphyria. Paroxysmal disorders, such as uncontrolled seizures, nonconvulsive status epilepticus, or migraine, may produce changes in consciousness that may be episodic. The diagnosis, pathophysiology, and treatment of specific disorders are reviewed elsewhere in this book.

There may be considerable overlap between these categories, and it is always necessary to consider combined causes of impaired consciousness and coma. Disorders that produce abnormalities of osmolality, such as hyponatremia, hypernatremia, and diabetic ketoacidosis, may also lead to structural complications, such as intracranial hemorrhage or stroke as a consequence of sinovenous thrombosis. Both have been reported as rare complications of diabetic ketoacidosis [Atlluru, 1986]. Cerebral edema may complicate treatment of ketoacidosis, causing alterations of consciousness or herniation [Green et al., 1990].

Children with psychiatric disorders, such as conversion, panic, or anxiety disorders, may present with neurologic symptoms including genuine or apparent impairment of consciousness. Symptoms may include dizziness, hyperventilation, paresthesias, agitation, or restlessness. The episodic and paroxysmal nature of these episodes and the complete recovery between episodes should suggest the diagnosis [Herskowitz, 1986].

Nutritional causes of alteration of consciousness or coma are relatively uncommon in the United States but represent a significant problem in other areas of the world. These are reviewed in Chapter 103. Wernicke’s encephalopathy is related to a deficiency of thiamine. In addition to consciousness alteration, patients may have eye-movement abnormalities, ataxia, and deep tendon reflex changes. Wernicke’s encephalopathy has been reported in children and adolescents as a result of systemic malignancy and because of thiamine deficiency in total parenteral nutrition, and it may occur related to anorexia nervosa, acquired immunodeficiency syndrome (AIDS), and prolonged fasting [Bruck et al., 1991; Hahn et al., 1998; Nautiyal et al., 2004; Pihko et al., 1989; Salas-Salvado et al., 2000; Vasconcelos et al., 1999].

Niacin or nicotinic acid deficiency (pellagra), with the typical features of mental changes, dermatitis, and diarrhea, is rarely seen in the United States. However, disorders of the synthetic pathway from tryptophan to niacin or nicotinic acid or impaired intestinal absorption of tryptophan in Hartnup’s disease may produce symptoms in children or adolescents [Clayton et al., 1991; Freundlich et al., 1981].

Evaluation

The clinical approach to impairment of consciousness must be comprehensive and systematic. It is especially important to evaluate the evolution of symptoms and to interview any potential witnesses to the onset of symptoms. Not all patients with impairment of consciousness progress to coma, but early recognition of the progression and intervention often yields better outcome. Coma is a medical and neurologic emergency requiring immediate consideration of key issues, including immediate life support, identification of the cause of coma, and institution of specific therapy. These critical issues will be reviewed in sequence, but all have immediate importance and significance in the comatose child. The approach to the child with impaired consciousness but not coma is similar but may be modified, based on the evaluation of symptoms and clinical need.

Brain Herniation

Within the skull are unique dural reflections that divide the intracranial contents into compartments. The falx cerebri lies between the cerebral hemispheres, and the tentorium cerebelli separates anterior fossa structures (cerebral hemispheres and diencephalon) from posterior structures (brainstem and cerebellum). The opening in the tentorium through which the midbrain passes is called the tentorial notch. Excised dura is leathery and malleable, but the dural reflections, in vivo, are relatively rigid and firm. Focal or generalized lesions, which produce mass effect or increased intracranial pressure, may produce one of the three brain herniation syndromes based on squeezing of brain structures over or through the tentorium or through the foramen magnum. It is extremely important to recognize early signs and symptoms of these herniation syndromes so that urgent and appropriate intervention can be provided.

Diagnostic Testing

All patients with significant impairment of consciousness or coma should have immediate blood glucose finger stick determination by Chemstrip or Dextrostix, and should have blood drawn for a chemistry profile, complete blood count, and arterial blood gas analysis. The blood chemistry profile should minimally include glucose, sodium, potassium, blood urea nitrogen, calcium, magnesium, and ammonia. Hypoglycemia, derangements of osmolality (hyponatremia, hypernatremia), and ketoacidosis are important causes of mental status change in children. Uremia with encephalopathy may be seen in patients with acute renal failure with evolution over hours to days. It may also be the presenting feature in the hemolytic-uremic syndrome. Disorders of calcium metabolism may impair consciousness and cause peripheral symptoms. Abnormalities of calcium or magnesium may precipitate unexpected seizures, especially in infants and young children. Hyperammonemia may alter consciousness, particularly in conjunction with hepatotoxicity resulting from valproic acid or other agents, Reye’s syndrome, inborn errors of metabolism, or other disorders. A complete blood count assists in determining the presence of infection, anemia, or toxin exposure, such as lead poisoning. A urine specimen should be sent for toxicology screening (see Chapter 100). An expanded plasma toxicology screen that looks for unknown toxins by gas chromatography may be useful, as the urine screen mainly looks for drugs of abuse. Arterial blood gas determination is necessary, as is pulse oximetry. Blood gas analysis is important for assessing adequacy of oxygenation, as well as CO₂ removal.

When infection is suspected, blood and urine cultures should be obtained.

Additional blood and urine studies, which may be worth obtaining when the patient is first seen but are not usually immediately available, include urine and blood specimens for amino and organic acid disorders, thyroid function studies, plasma cortisol, free fatty acid, very long chain fatty acids and total and free carnitine levels, comprehensive drug testing, and screening for disorders of porphyrin metabolism.

Lumbar puncture should be performed when there is a suggestion of infection of the CNS, with or without fever. Depending on the clinical findings and evaluation, CT needs to be performed before the lumbar puncture. When medically stable, all patients in coma and most, if not all, patients with impairment of consciousness of undetermined etiology should have a CT performed as rapidly as possible. In children with closed-head injury, CT or preferably MRI may be critical in identifying the specific cause of impaired loss of consciousness [Ashwal and Holshouser, 1997]. MRI is also invaluable in identifying evidence of herpes simplex encephalitis or an acute demyelinating process, such as acute disseminated encephalomyelitis.

The EEG is essential to diagnose clinically inapparent status epilepticus (i.e., nonconvulsive status epilepticus). Certain EEG patterns, such as periodic lateralized epileptiform discharges, may suggest herpes simplex encephalitis, especially in the setting of a febrile illness [Misra and Kalita, 1998]. In addition, the EEG is useful in the serial re-assessment and evaluation of patients in status epilepticus or persistent coma, as well as in patients requiring pharmacologic paralysis or sedation.

Treatment

Treatment of the child with impaired consciousness or coma requires scrupulous attention to certain basic principles while definitive diagnostic tests are obtained and therapy initiated. Specific etiologies of many individual causes of disordered consciousness are listed in Box 73-3 and are reviewed by specific diagnostic category in other sections of this book. The following principles of management are similar in most patients and are outlined in Box 73-4.

Box 73-4 Treatment Goals for Patients with Impaired Consciousness and Coma

Ensure oxygenation

Maintain circulation

Give glucose

Correct acid–base and electrolyte imbalance

Consider specific antidotes

Reduce increased intracranial pressure

Stop seizures

Treat infection

Adjust body temperature

Manage agitation

Monitoring of the Comatose Patient

After initiation of treatment, it is necessary to re-evaluate serially the patient’s condition and effectiveness of intervention. The neurologic examination is the gold standard for evaluation and re-evaluation, but often is significantly modified by iatrogenic intervention, such as mechanical ventilation, sedation, and paralysis. Many clinical neurophysiology monitors are available to improve critical care monitoring; some are in more widespread use than others. All clinical neurophysiology monitors are used in one or more of the following situations:

as an extension of the neurologic examination to identify nonconvulsive status epilepticus or EEG patterns that suggest a diagnosis, and to evaluate the integrity of certain neural pathways

to improve assessment of the neurologic condition of patients who are sedated, or sedated and paralyzed, and on mechanical ventilation

to assist in assessment of availability of metabolic substrate critical to maintain brain integrity and function

to evaluate treatment effect in status epilepticus

to improve outcome assessment.

Traditionally, the EEG has been used to identify presence of or risk for seizures, and has additive value in that certain patterns may suggest specific pathology, such as triphasic waves in metabolic causes of coma and periodic lateralized epileptiform discharges in focal injury and infection. EEG reactivity to sensory stimulation is considered a favorable sign in coma recovery [Young, 2000]. EEG has the advantage of ready availability in most centers and is usually definitive in the evaluation for on-going seizures. However, there is no universal agreement about criteria to diagnose nonconvulsive status epilepticus in obtunded or comatose patients [Brenner, 2002]. Other drawbacks to the use of long-term EEG monitoring include technical training necessary to apply and maintain the electrode–scalp interface, specialized training necessary for interpretation, and EEG susceptibility to artifact in the critical care setting. Processed derivations of EEG activity, therefore, have been successfully used to monitor brain activity.

The Bispectral Index monitor is a recorder that uses processed EEG data to measure sedation depth on a scale from 0 to 100 (0, coma; 40–60, general anesthesia; 60–90, sedated; 100, awake). The Bispectral Index monitor is useful in monitoring depth of sedation during conscious sedation [Agrawal et al., 2004] and neurologic status in critically ill unsedated patients [Gilbert et al., 2001]. It is also easily applied to children in critical care settings, and has been used to monitor children in barbiturate coma, sedation to assist mechanical ventilation, and procedural sedation, and to evaluate sedation effects of multiple medications [Grindstaff and Tobias, 2004]. Although the Bispectral Index Scale does not have the monitoring power of a full-montage EEG, it has the advantage of easier electrode application and more ready interpretation. In a study of 16 patients between 10 and 192 months of age with consciousness alteration, who were admitted to a pediatric intensive care unit, the Bispectral Index Scale correlated well with the Glasgow Coma Scale [Hsia et al., 2004]. Amplitude-integrated EEG is an alternative methodology that has been used for the evaluation of the neonate but is now being used in older children and adults to assess the severity of neurologic injury [Scheuer and Wilson, 2004; ter Horst et al., 2004].

Sensory-evoked potentials allow assessment of the integrity of visual, auditory, and somatosensory pathways in the unconscious patient. Somatosensory-evoked potentials have been especially valuable because their neural pathways extend from brainstem through thalamus and subcortical white matter to cortex. Somatosensory-evoked potentials are relatively resistant to sedation effect and are useful in predicting outcome in comatose patients. Visual-evoked potentials have not been as valuable as somatosensory-evoked potentials for outcome prediction in comatose children [Shewman, 2000a, b; Taylor and Farrell, 1989]. Brainstem auditory-evoked potentials are valuable for monitoring brainstem function but do not predict cortical function [Shewman, 2000a, b]. The presence of normal brainstem auditory-evoked potentials with abnormal somatosensory-evoked potentials is seen in patients who are in a vegetative state [Frank et al., 1985]. Middle latency auditory-evoked potentials have cortical representation and have been shown to improve coma outcome prediction in adults, although they may be less resistant to environmental artifact and sedation than somatosensory-evoked potentials. Event-related potentials (auditory P300 response) may assist in evaluating severity of injury and may correlate with closed-head injury outcome in adults [Fischer et al., 2004; Keren et al., 1998; Litscher, 1995; Logi et al., 2003].

Motor-evoked potentials have limited value in evaluation of the comatose patient and have not been studied in children for this purpose. Adult studies have found that electrically elicited, but not magnetoelectrically elicited, motor-evoked potentials may predict postcoma pyramidal motor deficit but do not allow prediction of severity of motor deficit. Motor-evoked potentials do not have the predictive value of somatosensory-evoked potentials for coma outcome. Motor-evoked potentials may be valuable in evaluating clinical deterioration in the acute phase of coma [Rohde et al., 1999; Zentner and Rohde, 1992, 1994].

Measurement of cerebral blood flow is a direct way to determine delivery of essential metabolic substrate to the brain but is not useful for continuous monitoring. Brain-tissue PO₂ measurement, however, is suitable for continuous monitoring. In 25 patients older than 16 years with severe traumatic brain injury (Glascow Coma Scale value less than 8), it was found that intraparenchymal brain PO₂ favorably compared with stable xenon CT for measurement of cerebral blood flow and allowed continuous monitoring of this critical substrate [Doppenberg et al., 1998]. Another study of 22 severe head-injury patients aged 11–52 years found that continuous monitoring of partial pressure of brain-tissue oxygen was practical and safe, allowed monitoring of ischemia on a continuous basis, allowed demonstration of abnormalities of oxygen autoregulatory mechanisms, and was superior to jugular oximetry [Van Santbrink et al., 1996]. Low brain-tissue PO₂, as a measure of cerebral hypoxia, is predictive of poor neurologic outcome and is an important independent measurement parameter in adults with severe traumatic brain injury [Bardt et al., 1998]. Monitoring of brain tissue PO₂ may also allow early detection of critical and potentially irreversible worsening, and allow measurement of intervention effect on a continuous basis. This is exemplified in a case report of a 15-year-old patient with severe traumatic brain injury and uncontrollable intracranial hypertension, who developed bilateral fixed and dilated pupils and critically low brain-tissue PO₂ on the third day after injury; this patient who underwent bilateral decompressive craniotomy with immediate normalization of intracranial pressure and complete recovery of brain-tissue PO₂ to the normal level [Kiening et al., 1997].

Local sampling of energy substrates by microdialysis during ischemia is feasible and allows measurement of glucose, lactate, pyruvate, and glutamate in brain tissue serially over time. Glucose concentration closely follows brain-tissue PO₂, lactate concentration significantly increases when brain-tissue O₂ falls below critical level, and glutamate is significantly elevated with very low brain-tissue PO₂ levels in adult head-trauma patients [Hlatky et al., 2004]. Microdialysis measurements have thus far only been applied in children for monitoring of severe traumatic brain injury. In one study of nine children aged 2–14 years, a low glutamine to glutamate ratio was associated with increased morbidity [Tolias et al., 2002].

Near-infrared spectroscopy (NIRS) noninvasively monitors brain-tissue oxygenation by measuring the distinct absorption spectra of oxygenated and deoxygenated hemoglobin in the frontal cortex. NIRS compares favorably to brain-tissue PO₂ monitoring in adults with severe traumatic brain injury or aneurysmal subarachnoid hemorrhage [Brawanski et al., 2002]. Additionally, in a study of 43 children monitored after corrective surgery for noncyanotic congenital heart defects, noninvasive measurement of the cerebral tissue oxygenation index by NIRS correlated with central venous oxygen saturation measured with a catheter placed in the right atrium [Nagdyman et al., 2004]. At least one commercially available device for NIRS monitoring is approved by the U.S. Food and Drug Administration for children [Andropoulos et al., 2004], and has been used extensively to monitor brain-tissue oxygenation during surgery for congenital heart disease. In a study of 26 infants and children having heart surgery with bypass and deep hypothermic circulatory arrest, low cerebrovascular hemoglobin oxygen saturation was associated with postoperative neurologic complications in 3 children (1 with seizure and 2 with prolonged coma) [Kurth et al., 1995].

Cerebral oxygenation measured by NIRS has been found to be valuable in two pediatric patients (ages 4 months and 16 years) being monitored for seizures in the pediatric intensive care unit and the epilepsy monitoring unit, and demonstrated preictal increase in cerebral oxygenation and suggested perfusion–metabolism mismatch during seizure activity. Thus, the monitoring of cerebral oxygenation by NIRS has value in the critical care setting for continuous monitoring of dynamic changes in cerebral oxygenation in relation to changes in metabolic need [Adelson et al., 1999]. None the less, use of NIRS to monitor brain-tissue oxygenation has not been studied extensively in children, except in surgery for congenital heart defects, and a recent study in children indicated poor agreement between two commercially available cerebral oximeters using NIRS [Dullenkopf et al., 2003].

Transcranial Doppler ultrasonography measures real-time cerebral blood flow velocity and is useful for monitoring middle cerebral artery flow velocity transcranially in all ages and through the anterior fontanel in infants. Transcranial Doppler has been used in pediatric cardiac surgery to evaluate cerebrovascular response to cardiopulmonary bypass, hypothermia, and deep hypothermia circulatory arrest [Andropoulos et al., 2004]. It has also been used to evaluate detectable cerebral perfusion threshold in low-flow cardiopulmonary bypass in neonates [Zimmerman et al., 1997]. It is important to note, however, that cerebral blood flow velocity depends on vessel diameter and is not the same measurement as cerebral blood flow, which depends on cerebral vascular resistance and varies with temperature, CO₂ pressure, cerebral perfusion pressure, and bypass flow. Therefore, cerebral blood flow velocity may correlate best with cerebral blood flow in deep hypothermia when autoregulation is lost and blood vessel diameter does not change.

Brain-tissue PO₂ monitoring and microdialysis to evaluate energy substrates are complementary, and both monitoring probes require neurosurgical installation into brain parenchyma. Therefore, they are primarily used clinically to evaluate and monitor victims of severe traumatic brain injury. NIRS and transcranial Doppler are currently used to monitor brain oxygenation in children during and after cardiac surgery. The devices are small and relatively portable, and can be used in the pediatric critical care environment safely, effectively, and continuously. Their ultimate value in monitoring of children in coma and guiding therapeutic interventions has yet to be delineated. However, in a prospective study of 250 patients undergoing pediatric cardiac surgery, it was found that interventions based on neurophysiologic monitoring (EEG, transcranial Doppler, NIRS) appeared to decrease the incidence of postoperative neurologic sequelae and reduce length of stay [Austin et al., 1997].

Outcome Measurement

When consciousness is impaired, outcome is related to the etiology of the insult and rapid identification and treatment of the underlying cause. Early appropriate treatment may prevent further deterioration of the mental state and injury to the nervous system and improve outcome. Outcome studies in childhood coma are available for traumatic and nontraumatic causes, and typically emphasize predictive value of signs and symptoms at the time of initial medical intervention. These studies are described in detail in Chapters 74–76.

A commonly used and widely accepted measurement of outcome after severe closed-head injury is the Glasgow Outcome Scale [Jennett and Bond, 1975]. The Glasgow Outcome Scale has the following five broad outcome categories:

The Glasgow Outcome Scale heavily emphasizes functional independence in mobility, transportation, and self-care. Significant functional improvement can be seen within the first three categories. The Glasgow Outcome Scale is limited in its ability to quantify impairments related to social skills and emotional and cognitive dysfunction; it does not take into account special issues of injury and recovery during the developmental period.

Early studies using the Glasgow Outcome Scale as an outcome measure after closed-head injury reported that patients advance to the highest functional level by 6 months after injury [Jennett et al., 1976, 1979; Jennett and Bond, 1975; Lange-Cossack et al., 1981]. Meaningful recovery, however, may occur for months to years after injury [Mahoney et al., 1981, 1983]. Because there may be significant functional improvement within the three highest Glasgow Outcome Scale categories (i.e., good recovery, moderate disability, and severe disability) and because long-term improvement is possible, especially when injury occurs during early childhood, alternative outcome scales have been developed.

Another scoring system, the Pediatric Cerebral Performance Category Scale, was published by Fiser in 1992 and is a modified form of the Glasgow Outcome Scale. This six-point outcome scoring system was validated in 1469 pediatric patients suffering acute CNS injuries. It has also been correlated with neuropsychological test scores [Fiser et al., 2000]. The score includes the following outcomes:

This scale has been used in outcome prediction studies after acute brain injury in children who were acutely evaluated with proton MR spectroscopy [Ashwal et al., 2000; Brenner et al., 2003; Holshouser et al., 1997]. In a prospective study of 53 children less than 3 years old with severe brain injury or hypoxic-ischemic encephalopathy, the Glasgow Outcome Scale indicated good recovery in 46 percent of 50 children with known outcome [Robertson et al., 2002]. However, only 16 percent had average or above-average scores on both the mental and motor developmental sections of the Bayley Scales of Infant Development II at 18–36 months of age. Thus, a commonly used developmental assessment tool, the Bayley Scales of Infant Development II, provides a greater distinction between normal and delayed development than does the good recovery level of the Glasgow Outcome Scale [Robertson et al., 2002].

Another scoring system, also adapted from the adult Glasgow Outcome Scale, that was developed for evaluating children with traumatic brain injury and likely has wider usage is the King’s Outcome Scale for Childhood Head Injury (KOSCHI) [Crouchman et al., 2001]. The KOSCHI expands the five-category Glasgow Outcome Scale to provide increased sensitivity at the milder end of the disability range (Table 73-6). The Glasgow Outcome Scale category of “persistent vegetative state” was replaced by “vegetative.” “Good recovery” was allocated two categories, in acknowledgment of the long-term importance of relatively minor sequelae in a developing child. The scale is easy to use and reliable, and is very helpful in differentiating children with milder outcomes into subcategories. Although studies have suggested limited value when it is used at the time of hospital discharge in predicting outcome [Calvert et al., 2008], it remains a practical and straightfoward method to classify outcomes.

Table 73-6 King’s Outcome Scale for Childhood Head Injury (KOSCHI)

(From Crouchman M et al. A practical outcome scale for paediatric head injury. Arch Dis Child 2001;84:120–124.)

The Disability Rating Scale consists of eight items divided into four categories:

The Disability Rating Scale is a more sensitive measure of improvement during inpatient rehabilitation than the Glasgow Outcome Scale [Hall et al., 1985], and is suitable for use in adolescents and some older children.

The Functional Independence Measure and its pediatric counterpart, the Wee Functional Independence Measure (WeeFIM), further refine outcome assessment using six items and 18 categories [Data Management Service of the Uniform Data System of Medical Rehabilitation and the Center for Functional Assessment Research, 1989]. The WeeFIM items and categories are as follows:

The WeeFIM has good inter-rater reliability and allows serial assessment throughout the pediatric age range.

The Pediatric Evaluation of Disabilities Inventory measures both capability and performance of multiple functional activities in three areas

The Pediatric Evaluation of Disabilities Inventory is designed for use from 6 months to 7 years of age, but is appropriate for older children whose functional level is within the intended age range. Specialized derivations of the Pediatric Evaluation of Disabilities Inventory specific to acquired brain injury do not improve the assessment value of the generic inventory, although further refinement may allow better functional recovery scoring in acquired brain injury [Kothari et al., 2003]. Pediatric Evaluation of Disabilities Inventory score change of about 11 percent has been found clinically meaningful during inpatient rehabilitation in a cohort of 53 children aged 1–19 years [Iyer et al., 2003].

The WeeFIM and the Pediatric Evaluation of Disabilities Inventory are sensitive measures of functional outcome and are suitable for inpatient rehabilitation monitoring and long-term outpatient follow-up. They are two of the most commonly used functional outcome measures in children [Ziviani et al., 2001], and are superior to the Glasgow Outcome Scale and its pediatric variants for assessment of long-term functional improvement in children across more relevant domains of recovery.

The School Functional Assessment was developed to measure performance of functional tasks that are important for participation in an elementary school level program (kindergarten through grade 6). The School Functional Assessment evaluates:

The School Functional Assessment provides for further functional assessment of short-term and long-term outcome more specific to the educational setting and may allow prediction of specialized school needs before discharge from inpatient rehabilitation.

The Barthel Index is commonly used as a prognostic indicator in adult clinical stroke trials [Huybrechts et al., 2007]. It has functional disability categories (Table 73-7) that lend themselves to use in children who are emerging from coma, but it has not been studied in detail [Mahoney et al., 1965; Jöhnk et al., 1999].

Table 73-7 Barthel Score

(From Mahoney and Barthel: Functional evaluation: the Barthel Index, MD State Med J 14:2, 1965; Jöhnk K et al. Assessment of sensorimotor functions after traumatic brain injury (TBI) in childhood – Methodological aspects. Restor Neurol Neurosci 1999;14[2–3]:143.)

Other standardized measures used to assess intellectual, cognitive, language, and behavioral development in children without injury are useful in evaluating and assessing outcomes in children after severe acquired brain injury. In children old enough and cooperative enough, neuropsychologic testing is the most sensitive and specific way to measure and monitor change in these domains. Valuable reviews of these issues are available [Fletcher et al., 2001; Hannay and Sherer, 1996; Levin, 1994; Ylvisaker et al., 1990]. In a retrospective analysis of 83 children aged 1–18 years admitted to hospital after head injury, 70 percent had severe head injury and 13 died. Forty-five patients had at least one cognitive assessment, and 17 were evaluated with intelligence testing less than 4 months after injury, 5–15 months after injury, and 16–38 months after injury. Continued improvement in cognitive functioning was seen at 16–38 months’ follow-up assessment [Campbell et al., 2004]. This improvement underscores the fact that continued cognitive recovery may progress for years and that more long-term studies are necessary.

Prognosis

Conclusions

Altered states of consciousness in pediatric patients are urgent situations, and coma is a medical emergency requiring rapid and organized intervention. Basic life support needs, evaluation of the history and physical examination, and specific laboratory and neurodiagnostic tests are of paramount importance and should proceed simultaneously in the emergency department. Specific diagnoses must be treated appropriately, but there are key general principles to management of impaired consciousness and coma that apply in all situations.

The outcome for children with coma is substantially better than for adults and may be affected by the speed and appropriateness of intervention. Even with the best and most appropriate care, some children die, some survive on mechanical ventilation and become brain-dead, and some survive beyond mechanical ventilation and have minimal consciousness or severe disability, or remain in a vegetative state. Decisions concerning basic life sustenance, type and location of care, and need for rehabilitation should take into consideration the type of injury, time from injury, recovery potential, family wishes, and appropriate ethical guidelines and standards [Michelson and Ashwal, 2004; Ashwal and Cranford, 2002].

References

The complete list of references for this chapter is available online at www.expertconsult.com.

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