Glossary

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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).

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

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.

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.

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. 

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.

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.

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.