u Coma/Persistent Vegetative State
Codes R40.21- through R40.24- distinguish coma as scored on the Glasgow Coma Scale (GCS) to capture severity.
Definitions
Coma describes a deep state of unconsciousness in which patients are unable to move or respond to their environment. Coma may occur as a complication of an underlying illness or as a result of injuries, such as head trauma. Individuals in a coma lose their thinking abilities and awareness of their surroundings but retain non-cognitive function and normal sleep patterns.
The level of coma measured with the GCS is predictive of outcome. The longer patients remain in a coma, the poorer their chance of recovery and the greater the chance that they will enter a vegetative state.
It is rare for a coma to last longer than 2–4 weeks. The outcome for coma depends on the cause, severity, and site of the damage. People may emerge from coma with physical, intellectual, and psychological deficits. For those who remain in a coma for an extended period of time, the most common cause of death is infection, such as pneumonia.
Persistent vegetative state is 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 brain stem autonomic functions. These patients show no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli; show no evidence of language comprehension or expression; have bowel and bladder incontinence; and have variably preserved cranial-nerve and spinal reflexes.
Diagnostic criteria
A complete neurological assessment evaluating pupillary responses, ocular motility, eye deviation, spontaneous eye movements, fundal examination, and respiratory patterns must be conducted. Imaging is utilized to identify any structural intracranial disease, including edema and herniation.
The GCS arbitrarily defines coma as failing to open the eyes in response to a verbal command, performing no better than weak flexion, and uttering only unrecognizable sounds in response to pain. The scale is useful for objectively monitoring the clinical course of a patient demonstrating an alteration in consciousness, but it is not the sole diagnostic tool in defining coma.
The GCS scores the patient’s best response in each of three categories:
• E, eye opening response (1: none, 2: to pressure, 3: to sound, 4: spontaneous)
• V, verbal response (1: none, 2: incomprehensible speech, 3: inappropriate speech, 4: confused but able to answer questions, 5: oriented)
• M, motor response (1: none, 2: extension, 3: flexion, 4: withdrawal, 5: localization, 6: obeys commands)
Scores 2–5 in the motor response category represent the patient’s response to painful stimuli. The lowest score is E1/V1/M1 (3), while the highest score is E4/V5/M6 (15).
Provider Tips
The GCS is impacted in the intubated patient (there is an inability to obtain verbal response), so providers may use alternative scoring systems to manage and/or assess potential outcomes. The assessment will be based only on eye opening and motor scores, and the suffix T is added to the score to indicate the patient is intubated. The maximum GCS score is 10T and the minimum score is 2T in this population.