In a field that is constantly evolving, using the correct terms is critical. Below, we have provided a list of terms that are commonly used – often incorrectly – with appropriate definitions. One goal of CASBI is to create a common language used across the fields of neurology and neuroethics. Using a term correctly when either speaking with other professionals or with patients’ families is incredibly important. Whether needed to convey accurate diagnoses or assist a family in making significant decisions, using the right words the right way is key.

Behavioral Measures

Coma Recovery Scale (CRS-R)

The Coma Recovery Scale -Revised (CRS-R) was developed by Joseph Giacino and colleagues in 2004 as an attempt to resolve the original CRS’s psychometric characteristics and respond to changes in diagnostic parameters – mainly dealing with the development of MCS criteria. The revised scale is comprised of 6 subscales (auditory, visual, motor, oromotor, communication, and arousal) with a total of 23 items, with the lowest scores representing reflexive activities and higher scores indicating more integrated behaviors that suggest higher levels of cognitive function.

Disability Rating Scale (DRS)

The Disability Rating Scale (DRS) was developed by Michael Rappaport and colleagues in 1977 to correlate levels of disability with evoked brain potentials and chart the progress of patients who fall in the midrange spectrum of recovery, generally described as being in MCS. The DRS is broken into four categories as evidenced by specific constituent behaviors: arousability, awareness and responsivity  (eye opening, verbalization, motor response); cognitive ability for self-care activities (feeding, toileting, grooming); dependence  on others (level of functioning) and psychosocial adaptability (employability).  Each item gets its own score, with a zero indicating normal functioning, with a possible total of 29, which indicates the lowest level of functioning.

Glasgow Coma Scale (GCS)

The Glasgow Coma Scale (GCS) is the perennial assessment tool, developed by Graham Teasdale and Bryan Jennett in 1974, from which most others evolved. The GCS is used in the acute care setting and is divided into three categories: motor response, verbal response, and eye opening. The highest possible score is a 15, which indicates a normal level of functioning. A score under 8 indicates coma. 

Glasgow Outcome Scale (GOS)

The Glasgow Outcome Scale (GOS) was developed by Bryan Jennett and Michael Bond in 1975 and to be used to assess acute injury and predict outcomes. There are five functional categories of the GOS: death, the persistent vegetative state, severely disabled (conscious but disabled), moderately disabled (but independent), and good recovery. Scoring is from 1 to 5, with a one indicating the ability to return to work, and a five indicating death.

Care settings/terms

Acute care

Acute care is health care provided to patients experiencing an illness or health problem either of a short-term or emergency nature. It usually refers to the care the patient receives at a hospital just after their initial injury. One goal of acute care is to stabilize the patient for discharge as soon as safely possible, which often occurs too early with brain injury patients. Acute care is the opposite of chronic care.

Chronic care

Chronic care is care that is required by patients with a long term illness or injury. In patients with severe brain injury, this care is often delivered in a nursing home. In this setting, rehabilitative services are generally either limited or not available.


Neuro-rehab is an intensive form of rehabilitation in a facility or program that focuses on the needs of patients with brain injury. The goal of neuro-rehab programs is to help the patient achieve the highest level of independent functioning possible. Neuro-rehab generally occurs after the acute care stage and is time limited.

Nursing home

A nursing home is a facility that houses patients with chronic conditions who require nursing care. Nursing homes are often associated with elderly patients whose health is declining. Many severely brain injured patients end up in nursing homes, which are often not equipped to fully meet their needs.

Occupational therapy (OT)

Occupational therapy (OT) is a goal oriented therapy aimed at developing, improving, or maintaining daily living activities. OT often involves adapting a task or teaching a new way to perform a task based on the needs and limitations of the patient.  OT is generally discontinued when improvement is not shown (see medical necessity), which is problematic for patients with severe brain injury who have unclear trajectories and might be improving cognitively but not showing overt behavioral improvements.

Physical therapy (PT)

Physical therapy (PT) is a rehabilitative service aimed at improving a patient’s mobility, motor function, reduce pain, and prevent disability. PT is generally discontinued when improvement is not shown (see medical necessity), which is problematic for patients with severe brain injury who have unclear trajectories and might be improving cognitively but not showing overt behavioral improvements.

Skilled nursing facility (SNF)

A skilled nursing facility (SNF) is a nursing home certified to participate in, and be reimbursed by, Medicare. Skilled nursing care by registered nurses and doctors is administered. SNFs often have more programs available than nursing homes, such as speech and occupational therapy.

Speech therapy

Speech therapy is a rehabilitative service aimed at improving a patient’s ability to communicate. In severe brain injury, speech therapy might deal with cognitive impairments that affect speech and/or motor impairments that make speech difficult. Speech therapy is generally discontinued when improvement is not shown (see medical necessity), which is problematic for patients with severe brain injury who have unclear trajectories and might be improving cognitively but not showing overt behavioral improvements.

Sub-acute care/rehab

Sub-acute care and rehab are levels of care that that fall between acute care and long-term care. Both focus on achieving specified measurable outcomes, using an interdisciplinary approach, and on providing care in an efficient and low-cost manner. Both sub-acute care and rehab are goal oriented and time limited and are generally not long enough to show results with patients with severe brain injury.


Withdrawal occurs when a decision has been made to discontinue a treatment or life-sustaining measures. This allows the underlying disease to naturally progress. Withdrawal is ethically and legally considered the same as withholding.

Decisions/Ethics terminology

Advance directive

An advance directive is a document or oral statement that outlines what an individual would like to be done in various situations in the event of illness. If it specifies a proxy or HCA, it provides substantive and procedural moral authority to the designated agent.


Assent is obtained when a patient is able to participate in decision-making but cannot legally provide his/her own consent. Assent is the patient’s agreement to a decision regarding his/her care, and should be obtained whenever possible.

Best interests

Best interests are used to make decisions for patients based on what the average person would want in light of the benefits and burdens of the proposed treatment options, when there is no advance directive and prior wishes are unknown.

Do-Not-Resuscitate (DNR)

Do-Not-Resuscitate (DNR) is an order to not perform cardio-pulmonary resuscitation in the event of a cardiac arrest. DNR pertains only to the last minutes of life. DNR should not be confused with the idea of ‘do not treat.’ Any DNR discussion should also include goals of care and plans for events leading up to an arrest, such as respiratory decompensation and intubation.

Informed consent

Informed consent is a process that involves a dialogue with a patient or surrogate to inform him/her about a treatment, procedure, or research study that is being proposed. The patient or representative must fully understand what is involved, must have any questions answered, and must agree without coercion as to whether or not to proceed.

Medical necessity

Medical necessity is the basis upon which care is paid for by Medicare. This is based on what the insurer deems reasonable and necessary to treat or diagnose an illness or injury. Reasonable and necessary refers to questions of amount, frequency, duration and efficacy of the proposed treatments, and is generally correlated with length of recovery. In severe brain injury, making these determinations is incredibly difficult where the natural history is not fully predictable. This often leads to patients having therapy discontinued prematurely.

Prior wishes

Prior wishes are expressed preferences by a person as to what they would like done in various situations should they become ill and not be able to make their own decisions. These wishes can be expressed in conversation and used to help make decisions for the patient.

Proxy/Health Care Agent (HCA)

A proxy or health care agent (HCA) is someone that a patient explicitly designates to make decisions about medical treatment if the patient should lose their capacity to do so.

Substituted judgment

Substituted judgment is used when there is no advance directive and prior wishes are unknown. The surrogate considers the patient’s values and life experiences in making a decision about what the patient would want.

Surrogate/Legally authorized representative (LAR)

A surrogate or legally authorized representative (LAR) is the person who becomes decision-maker for a patient in the absence of an explicitly designated health care agent. Status is determined by a state law hierarchy of persons to contact, typically referred to as the next of kin.  This can be an unmarried partner or close friend.


Withholding occurs when a treatment or life-sustaining therapy is never started for a patient, and is ethically and legally considered the same as withdrawal of care.

Diagnostic/Descriptive Categories

Cognitive motor dissociation (CMD)

Cognitive motor dissociation (CMD) has been proposed to label the group of patients who appear to no signs of awareness at all (consistent with vegetative state) or very limited non-reflexive movements such as eye-tracking (consistent with minimally conscious state) yet demonstrate language comprehension and higher-level mental function using non-invasive assessment with research tools. Such research tools include functional magnetic resonance imaging and electroencephalography have been adapted to identify hidden mental function using specialized analysis techniques.


Coma is a state of unarousable unresponsiveness. In coma, the eyes are closed and motor function consists of reflex and postural responses only. Coma rarely lasts longer than 4 weeks.

Confusional State (CS)

Confusional State (CS) is a state of impaired consciousness with preserved functional object use and/or consistent communication. CS patients may exhibit disorientation and fluctuating levels of impairment.


Emergence from MCS to MCS-E occurs when a patient can consistently demonstrate reliable communication or functional object use.

Locked-in state (LIS)

Locked-in state (LIS) is not a disorder of consciousness, but a state of complete or almost complete loss of motor output. LIS has the misleading appearance of a disorder of consciousness due to a lack of motor output. Communication via brain-computer interface, EEG, functional brain imaging, autonomic responses, or subtle eye movements is sometimes possible. An individual in LIS is not cognitively impaired.

Minimally Conscious State (MCS)

Minimally Conscious State (MCS) is a state showing intermittent or inconsistent evidence of consciousness. In MCS, patients might show intermittent or inconsistent verbal output, object use, response to verbal command, or purposeful communicative gestures (such as eye movements).

Non-behavioral MCS

Non-behavioral MCS is a state where the patient is minimally conscious, but cannot exhibit evidence of cognition behaviorally due to severe motor impairment. Nonbehavioral MCS can sometimes be identified using neuroimaging techniques providing evidence of appropriate activation in response to stimuli.

Vegetative State (VS)

Vegetative State (VS) is a state of intermittent arousal without evidence of consciousness. In VS, there is spontaneous cycling through eyes-closed and eyes-open states, spontaneous eye and limb movements without evidence of goal-oriented behavior or sensory responsiveness. Persistent Vegetative State and Permanent Vegetative State are terms that should be avoided as they are generally confused. Instead, language related to type of injury (i.e. anoxic or traumatic) and duration is more appropriate.

Medical terms

Acquired brain injury (ABI)

An acquired brain injury occurs when the brain is damaged due to a discrete event, and not as a result of a genetic or congenital disorder.

Anoxic brain injury

An anoxic brain injury occurs when oxygen to the brain is completely, but temporarily, cut off.

Brain death

Brain death is an irreversible cessation of function of all cells in the brain and brainstem.

Disorders of consciousness (DOCs)

Disorders of consciousness (DOCs) are medical conditions in which an individual’s consciousness is temporarily or permanently compromised. This includes coma, the vegetative state, and minimally conscious state. DOCs can have various causes, such as anoxic or traumatic injuries.

Hypoxic brain injury

A hypoxic brain injury occurs when there is a period of low level oxygenation in the brain.


A stroke occurs when there is a disturbance of blood flow to the brain. There are two categories of stroke: ischemic and hemorrhagic.

An ischemic stroke occurs when blood flow to part(s) of the brain is decreased, damaging tissue in the associated area(s). Ischemia is a focal injury, which means that the injury is limited to the location where the stroke occurred.

A hemorrhagic stroke occurs when there is bleeding within the skull, caused by a ruptured blood vessel. This can be due either to trauma or to a non-traumatic event, such as an aneurism.  A hemorrhage is a focal injury, which means that the injury is limited to the location where the stroke occurred.

Traumatic brain injury (TBI)

 A traumatic brain injury (TBI) occurs when an external force damages part(s) of the brain.


Assistive device

An assistive device is developed to assist, adapt and rehabilitate individuals with disabilities. Assistive devices promote greater independence by enabling the disabled to perform tasks that formerly either required great effort or were impossible to accomplish.

Brain Computer Interface (BCI)

Brain Computer Interface (BCI) work seeks to develop and evaluate signal processing methods that extract signal features from the brain, classify them and otherwise translate brain signals into device commands. Brain signals can be acquired either invasively or non-invasively. Applications of BCI technology include providing a means to repair or enhance human perception, affect, action, and cognition. 

Deep Brain Stimulation (DBS)

Deep Brain Stimulation (DBS) seeks to alter brain function through the use of electrical, magnetic, radiowave, or focally targeted pharmacological injection. The goal of deep brain stimulation is to modulate the brain and behavior through stimulation of neural structures below the cerebral cortex. To date, 3 patients with TBI have had DBS surgery using electrodes implanted by our group and colleagues.

Electroencephalogram (EEG)

Electroencephalogram (EEG) is a direct measure of electrical voltage fluctuations produced by the summation of synchronized activity of dendritic inhibitory and excitatory post-synaptic membrane potentials of thousands or millions of neurons that have similar spatial orientation. EEG is recorded from the surface of the scalp via multiple electrodes and can be used to determine different global and local functional states of the brain, i.e. wakefulness, drowsiness and stages of sleep, defined by the frequency content and localization of certain waveforms. Alteration from expected 'normal' waveforms can be used to detect dysfunctions of brain activity, i.e. loss of function, altered function or tendency for seizures. In our lab, we use continuous EEG recordings and analyze the presence of normal or abnormal brain activity. All recordings are visually screened and quantitative measures, such as spectral analysis (i.e. frequency content), coherence (measure of synchronicity) and similar techniques are applied to the EEG signals during awake and sleeping resting states and during paradigms testing language and music processing, command following, and mental imagery.

Functional-MRI (fMRI)

Functional-MRI (fMRI) is a functional neuroimaging procedure using MRI technology and scanners. fMRI measures brain activity by detecting associated changes in blood flow, due to the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. fMRI uses the change in magnetization between oxygen-rich and oxygen-poor blood as its basic measure. This measure is frequently corrupted by noise from various sources, so statistical procedures are used to extract the underlying signal. The strength of the resulting brain activation can be presented graphically by color-coding. We use fMRI to measure large-scale functional brain connectivity and to assess potential cognitive capacities that would escape us using behavioral testing alone.

Magnetic Resonance Imaging (MRI)

Magnetic Resonance Imaging (MRI) is a structural imaging technique that is used to visualize the internal structures of the body in detail. MRI creates images of the human body that are far more detailed than X-rays. MRI provides good contrast between the different soft tissues of the body, which makes it especially useful in imaging the brain. A patient lies in an MRI scanner, which has a large, powerful magnet. The magnetic field is used to align some of the atomic nuclei in the body, and radio frequency magnetic fields are applied to systematically alter this alignment. This causes the nuclei to produce a rotating magnetic field that is detectable by the scanner. Information from this magnetic field is used to construct an image of the scanned area of the body. Unlike CT scans or traditional X-rays, MRI does not use ionizing or radiation. We use MRI to obtain a detailed picture of global brain atrophy and structural lesions in the brain.


Neuroimaging includes the use of various techniques to either directly or indirectly image the structure, function, or pharmacology of the brain. It is a relatively new discipline within medicine and neuroscience. Neuroimaging falls into two broad categories: Structural imaging, which deals with the structure of the brain and the diagnosis of intracranial disease (such as tumor) and injury, and functional imaging, which is used to diagnose metabolic diseases/lesions and their effect on the function of the brain. Functional imaging enables, for example, the processing of information by centers in the brain to be visualized directly. Such processing causes the involved areas of the brain to increase metabolism or blood flow, which is captured on the scan. Together, we use structural and functional neuroimaging to obtain a more complete picture of the brain than either category of neuroimaging would provide alone.

Positron Emission Tomography (PET)

Positron Emission Tomography (PET) is a nuclear medical imaging technique that produces a three-dimensional image of functional processes in the brain. The PET device detects pairs of gamma rays emitted indirectly by a tracer, which is introduced into the body on a biologically active molecule. A CT scan is also acquired during the PET scan.


Fludeoxyglucose PET (FDG-PET) is the most common type of PET, which uses biologically active molecule called [18F]FDG, an analogue of glucose. The concentration of [18F]FDG indicates tissue metabolic activity. We use this technique to measure the different patterns of glucose metabolism in the brain along the recovery process from severe brain injury and to evaluate longitudinal changes in individual cases.

Raclopride PET is another kind of PET that uses a ligand that specifically binds to a subclass of dopamine receptors of the brain. [11C]raclopride-PET evaluates the bioavailability of dopamine-2 like receptors within the striatum and extrastriatal structures of the brain. Analysis of the acquired signal allows quantification of the status of the dopaminergic system at the postsynaptic level. In addition, when [11C]raclopride-PET is combined with a single dose of amphetamine, a compound that blocks the reuptake of dopamine from the synaptic cleft, it is possible to quantify the dopaminergic presynaptic response. We use this technique to measure the presynaptic and postsynaptic status of the dopaminergic system in patients with severe brain injury with the aim to improve current therapeutic approaches.

X-ray computed tomography (CAT scan/CT)

X-ray computed tomography (CAT scan/CT) is a technology that uses computer-processed x-rays to produce tomographic images (or virtual 'slices') of specific areas of the brain. Digital geometry processing is used to generate a three-dimensional image of the inside of the brain from a large series of two-dimensional radiographic images.  We combine data from CT scans and PET scans (both are acquired with the same scanner during the same session) to compute correction factors for the computation of metabolic values obtained in PET.

Weill Cornell Medicine Consortium for the Advanced Study of Brain Injury 520 East 70th Street New York, NY