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Coma: Some Facts

The outcome of a patient can be associated with their best response in the first twenty-four hours after injury.
  • The outcome of a patient can be associated with their best response in the first twenty-four hours after injury. Using the Glasgow Coma Scale (3 to 15, with 3 being a person in a coma with the lowest possible score, and 15 being a normal appearing person) research shows that if the best scale is 3 to 4 after twenty four hours, 87% of those individuals will either die or remain in a vegetative state and only 7% will have a moderate disability or good recovery. In patients with a scale from 5 to 7, 53% will die or remain in a vegetative state, while 34% will have a moderate disability and/or good recovery. In patients with a Glasgow Coma Scale of 8 to 10, 27% will die or remain in a coma, while 68% will have a moderate disability and/or good recovery. In patients who have a scale from 11 to 15, only 7% will be expected to die or remain in a coma, while 87% would expect to have at least a moderate disability and/or good recovery (remembering again that this is not an exact science).
  • Most comas end with eye opening and regaining of consciousness, however 10% of patients who open their eyes fail to regain consciousness. (Sometimes called Apallic Syndrome). These patients do not usually respond to environmental stimuli.
  • There is a syndrome which occurs in children, who after waking from the coma, display delayed recovery of consciousness in response to the psychological stresses of being in the hospital, rather then continued biological cause.
  • Studies show that patients remaining in a vegetative state for at least one year after injury are unlikely to gain consciousness, although they may live for many years.
  • Patients over 40 years of age have a poorer rate of recovery than younger patients, post coma.
  • Absence of eye opening in the first thirty days after injury is indicative of a poor prognosis.
  • 90% of brain injured patients who are in a coma for one month or longer will fail to improve to a state better than severe disability. However, two thirds of patients who were in a coma for two weeks or less may make a moderate to good recovery.
  • SPECT Scan can be useful in examining the brain of a person in a coma to see if there are abnormalities in cerebral blood flow.
  • CT or MRI Scan showing swelling, midline shift, and mass lesions may be evidence of a more prolonged coma. Likewise, enlargement of the ventricular system (the open spaces in the folds of the brain) and cerebroatrophy found months after the injury are associated with poor results.
  • Apallic patients (open eyes, non-responsive) can benefit from rehabilitation involving "sensory stimulation." Studies indicate these types of programs are helpful for patients who are at the boundary of coma and wakefulness.
  • The common cause of coma is oxygen deprivation. Anoxia refers to a complete absence of available oxygen, while hypoxia describes someone who had available oxygen but at reduced levels for a period of time. Anoxemia describes when a person's blood supply (rather than lungs) lacks oxygen. Oxygen deprivation lasting longer than five to ten minutes can be fatal. Almost all persons surviving five minutes or more of complete oxygen depravation or 15 minutes of "substantial" hypoxia sustain permanent brain damage (J.N. Walton, 1994). Those who do not end up in a coma typically have impaired learning ability and retrieval problems. Visual defects are not uncommon. PET studies and CT scanning can show damage in the area of the cerebellum and basal ganglia in severely impaired patients.
  • Therapeutic Hypothermia (artificial cooling of the body) has been thought to improve outcome of patients with severe head injury. However, recent studies have been in conflict. A 2002 study from the Netherlands (Tolderman, K.H. 2002) used this method on 136 patients with were in a coma and had high inter-cranial pressure (ICP). Their findings were that artificial cooling can significantly improve survival and neurological outcome in patients with severe head injury, when used in a protocol with great attention to the prevention of side affects from cooling.
  • Another thing to remember is the general rule that regardless of the cause of damages, the more rapid the onset of the condition, the more severe and wide spread its effects will be. (Ajuriagurerra, 1960; A. Smith 1984). In other words, using a stroke as an example, if the person immediately drops into unconsciousness, the outcome would, on average, be worse than someone whose stoke developed over time.
  • Factors influencing outcome of severe head injury were accounted for in a recent study. A strong predictive factor of whether or not those with severe head injury would survive or not involve the pupils. 90% of patients who had bilaterally dilated pupils (not reacting to light) on admission died. 66% of the patients with bilaterally "constricted" pupils at the time of admission died. Only 20% of patients with severe head injury who had normal pupil reaction to light at time of admission died. Therefore, this aspect of outcome could be used to determine both mortality and outcome of coma.
  • There has been speculation that the presence of traumatic sub-arachnoid hemorrhage (tSh) on admission to the hospital predicted a poorer outcome than a patient without such a hemorrhage. A study (Servadei, F. 2002) supports the idea that death among patients with sub-arachnoid hemorrhage is related to the severity of the initial brain damage, rather than to the effects of delayed casospasms and secondary brain damage. The presence of such a hemorrhage on admission warrants a poorer outlook.
  • CT scans often fail to show brain stem lesions. Recent studies on MRI of severely brain injured coma patients show that death was closely linked to the presence of bilateral pontine lesions. Even severe destruction of the supratentorial white matter as shown on MRI was not related to increased death rates, as long as the brain stem itself is spared (Firshing, R. 2002).
  • Many patients with traumatic brain injury suffer defuse traumatic brain swelling (DTBS). This can lead to changes in the size of the brain ventricles (the open spaces within the brain). Doctors found a direct correlation between changes in the third ventricle and outcome. All of the things being equal, changes in that area of the brain due to swelling suggest a poorer outcome for that patient. The outcome of children fared much better than adults in this study.
  • Multimodal-early-onset-simulation (MEOS) in early rehabilitation on coma patients is found to be sensitive in identifying some predictions of favorable or unfavorable outcome. The data seems to support the hypothesis that the absence of any response to external stimuli is indicative of an unfavorable outcome. (The coma patients were followed two years after injury.) The comas lasted from 8 to 41 days. The average initial Glasgow Coma Scale was 6.6. Follow-up on 14 patients showed that one remained in a vegetative state, 2 exhibited severe neurological deficits and were dependant on care, 6 sustained major functional deficits but were able to return to perform the task of everyday life on their own. Two patients reached slightly higher levels then that, 2 patients returned to their former jobs).
  • A study from 2002 (Mosenthal, A.C. 2002) confirmed what was previously believed in regard to the outcome of the elderly with traumatic brain injury. The mortality rate from TBI is higher in the geriatric population at all levels of head injury. The outcome at the time of hospital discharge is worse.



"Coma" describes a patient whose eyes are continuously closed and who cannot be aroused to a wakeful state. However, another version of diminished consciousness exists, similar to coma, called "vegetative state." Vegetative state is similar to coma but the eyes are open and can briefly track objects or sounds. Many vegetative patients' limbs are spastic.

The possibility of recovery from vegetative state (VS) depends on how long the state lasts. Bricolo (1980) followed 34 patients with post traumatic VS who opened their eyes spontaneously within two weeks of injury and 74% of those eventually achieved a satisfactory outcome. Of those whose eyes opened between the second and fourth week, 32% improved while only 18% of patients who opened their eyes during the second month eventually recovered.


Author No. of Patients VS Duration of Period Follow-up Period No. of Recovered Patients Percent Recovery
Bricolo et. al 34 2 weeks 1 year 16 47.0
Bricolo et. al 69 1 month 1 year 11 31.8
Bricolo et. al 22 2 months 1 year 6 18.1
Sazbon & Groswasser 134 1 month 3-52 mos. 72 53.7
Levine et al. (a) 93 1 month 1 year 48 51.6
Braakman et al. (b) 140 1 month 1 year 59 42.1
Levy et al. 25 1 month 1 year 2 8.0
Sato et al. 216 >3 months 1 year 14 6.5
Nakazawa et al 1,556 >3 months 1 year 18 1.2
Okui 1,183 >3 months 1 year 14 1.2
Higashi et al 110 >3 months 5 years 8 7.2
(a) Report from U.S. Traumatic Coma Data Bank.
(b) Report from International Traumatic Coma Data Bank

Follow-up Results in 140 Patients Vegetative at 1 Month After Injury

Age at Injury Total Number of cases % Independent at 1 year
< 20 years 53 19
20-40 years 46 9
> 40 years 41 0
Sources: Data from Braakman et al. (1988) and Jennett and Braakman (1990), used with permission.

Unfortunately, under current analysis, 40% of comatose patients cannot be distinguished between vegetative state (VS) from minimally conscious state (MCS). New forms of MRI have dramatically improved the ability to predict outcome in coma. MRS, a non-evasive imaging technique that quantifies certain chemical compounds in parts of the brain, has been shown in subacute phases of recovery to predict unfavorable outcome at one year from TBI with a high rate of sensitivity and specificity. Another recent advance in MRI, called Diffuse Tensor Imaging (DTI), enables evaluation of white matter tissue integrity at the microscopic level. Regular use of these techniques in the future will give families additional objective data upon which to predict outcome and make decisions regarding treatment.