Infants and young children have a limited repertory (store house) of behavioural responses, making it difficult to detect and quantify the states of altered sensorium. A detailed, directed history and thorough physical examination is mandatory in arriving at the diagnosis and the underlying aetiology.
Since an accurate initial evaluation is critical to the management and the ultimate outcome in a child with coma, consistent and practical methods of describing various states of impaired consciousness in children are needed. The Glasgow Coma Scale (GCS), though effective and widely accepted, has its limitations in clinical practice because of the varied verbal and motor responses in children at different ages.
Several modifications of the Glasgow Coma Scale have come into existence, which are in use for gauging deterioration or improvement in acute stages of coma in children.
Consciousness is a state of normal cerebral activity in which the patient is able to respond to internal changes and to changes in the external environment. Maintenance of consciousness requires an intact and functioning reticular activating system and an adequate volume of functional hemispheres. Alterations in consciousness are apparent as a decrease in spontaneous activity or in the response to environmental stimuli. The term “altered sensorium” lacks precision and is applicable to all states where it is certain that normal sensorium is not present.
Definition of certain terms used in relation to altered sensorium
Sleep: Sleep is a normal variation in consciousness. The sleeping child is easily aroused and is then responsive to stimuli, questions and directions.
Drowsiness: the patient appears to be in normal sleep but can not be easily awakened. Once awake such patients tend to fall asleep despite attempts to continue conversation or clinical examination. There is disorientation and higher intellectual functions are impaired.
Stupor: defined as a state of impaired consciousness from which a child can be aroused only by vigorous and repeated stimuli. The child slips back into unresponsiveness after a few mumbled words. The superficial and deep tendon reflexes are preserved.
Confusional state: there is an inability to think with customary speed and clarity. Response to environmental stimuli is inappropriate and the patient is irritable, excitable and easily distracted.
Delirium: the American Psychiatric Association defines delirium as:
Illusions: misinterpretations of actual sensory stimuli.
Hallucinations: perceptions of sensory stimuli that are not present e.g. hearing voices, music or sound, seeing objects, animals, people, insects etc. Delusions : incorrect beliefs that cannot be changed by evidence or reason. Coma : condition in which a patient is unreasonable and unresponsive to all external stimuli.
Akinetic mutism or Coma vigile: patient has a blank staring look and appears to be awake but is unresponsive by way of movement and speech. This state may precede coma or occur during the course of recovery.
Prolonged Coma: when a patient is in coma for longer than 2 weeks.
Persistent vegetative state: this is the end stage of severe and extensive brain damage and has the following features :
Reflexes such as blinking, swallowing, chewing and gag are intact.
Brain death: this is a state of coma in which the brain has ceased to function completely, but pulmonary and cardiac functions can still be maintained by artificial means for hours to few days.
In children, systems for describing patients with impaired consciousness are not consistent. Moreover, infants and young children have a restricted repertoire of experience and behavioural responses. Therefore, the detection of and quantitation of alterations of consciousness are much more difficult.