APPENDIX A

Glossary of Terms

apraxia of eyelid opening—A medical condition where people have an inability to open the eyes voluntarily.

atypical parkinsonism—A group of neurological disorders that mimic Parkinson’s disease but do not respond to Parkinson’s medications.

basal ganglia—A structure within the brain that processes information responsible for initiating and guiding movement. Part of the extrapyramidal system.

bilateral stimulation—When a DBS system is placed only on both sides of the brain.

bipolar stimulation—A way of setting the stimulator so that one of the contacts on the lead is the active (or negative) contact, and the contact next to it is the positive contact. This decreases the amount of spread of electrical current and decreases side effects.

bradykinesia—A slowing of movement. This is the defining feature of Parkinson’s disease.

brainstem—The area of the central nervous system that connects the brain to the spinal cord. It is composed of the midbrain, pons, and medulla.

cerebellum—A brain structure that is responsible for coordinating movement.

cerebral cortex—The outermost layer of the brain containing nerve cells that are responsible for brain function.

computed tomography (CT)—A radiological procedure that uses X-rays and a computer to construct a series of pictures of tissues and organs of the body.

contracture—A permanent shortening of muscle, tendon, or scar tissue that produces a deformity, especially around a joint.

deep brain stimulator (DBS)—A device similar to a pacemaker for the heart that sends electrical signals to the brain and can improve the symptoms experienced by people with numerous neurological and psychiatric disorders.

diathermy—A medical treatment that delivers energy and heat within body tissues using high-frequency electric currents.  

dopamine—A chemical in the brain that is lost over time in Parkinson’s disease.

dyskinesias—Abnormal, involuntary movements of the body caused by Parkinson’s medication or DBS.

dystonia—A neurological disorder characterized by sustained contractions of muscles that cause twisting and other abnormal postures. This condition may affect any part of the body and can be generalized. Dystonias can also be primary, which means that they are either genetic or do not have another identifiable cause, or secondary, which means that they are due to something else, like a structural lesion in the brain.

electrocardiogram (EKG)—A recording of the electrical activity of the heart.

electrocautery—This is where an electrical current is used to stop bleeding vessels or tissues.

electroencephalogram (EEG)—A recording of the electrical activity of the brain.

essential tremor—A neurological disorder characterized by tremors of the hands, head, and voice. The tremors are worse when the hands are used and can cause significant embarrassment and disability.

extension—A wire that carries the electrical stimulation from the stimulator to the DBS lead.

extrapyramidal system—One of the motor systems of the brain that help shape and coordinate movement. This brain circuit breaks down our complex movements into sequences of simple ones.

Family Medical Leave Act—A federal law provides employees with up to 12 weeks of unpaid, job-protected leave per year.

frequency—One of the types of stimulation settings. The frequency refers to how many electrical pulses are delivered per second. Typical frequency settings for DBS are 130–185 Hz.

globus pallidus interna (GPi)—Part of the basal ganglia; this is one of the structures targeted for DBS. Placing a lead in this structure can help Parkinson’s disease and dystonia.

implantable pulse generator (IPG)—Also known as the stimulator or battery; it is a pacemaker-like device containing a battery that is the source of the electrical signals that eventually travel to the contacts in the DBS lead.

impulse control disorders—These are usually seen with Parkinson’s disease treatment. Some people develop strong urges that cannot be controlled. Common examples include pathologic gambling, hypersexuality, or compulsive shopping.

lead—The DBS lead is the portion of the DBS system that is located in the brain.

lead migration—A shifting of the DBS lead over time so that it is no longer where it was originally placed.

magnetic resonance imaging (MRI)—A method that uses magnetic fields to take clear and detailed pictures of the brain.

microelectrode recording—A technology that allows the neurosurgeon, often working with a neurologist or neurophysiologist, to measure the activity of brain cells during DBS surgery.

microlesioning effect—When individuals get a temporary improvement in their symptoms after DBS surgery, usually due to swelling in the brain.

monopolar stimulation—A way of setting the stimulator so that one of the contacts on the lead is the active (or negative) contact with the stimulator being the positive contact. This allows the electrical signals to spread out from the contact in a radial fashion.

motor fluctuations—A phenomenon seen in Parkinson’s disease where people go from feeling stiff and slow to normal, to moving excessively, with dyskinesias.

movement disorders—Neurological diseases that affect the ability to produce and control movements of the body.

movement disorder specialist—A neurologist who specializes in the care of people living with movement disorders such as Parkinson’s disease, essential tremor, or dystonia.

neurophysiologist—A person who specializes in the interpretation and recording of the electrical activity of the brain during DBS surgery.

neuropsychological examination (or neuropsychological evaluation)—A battery of tests that examine an individual’s cognitive (thinking and memory) function. This is usually done prior to DBS surgery and may take a few hours to complete.

neuropsychologist—A licensed psychologist who has completed postdoctoral training in the specialty of neuropsychology and has extensive knowledge of brain structures and brain function.

pallidotomy—A surgical procedure where the nerve cells in the globus pallidus are removed. This was used to help Parkinson’s disease.

Parkinson’s disease—A neurological disorder characterized by tremors that occur at rest, slowness of movements, and stiffness of the limbs and body. The symptoms are due to a loss of the dopamine-making cells in the brain.

primary motor cortex—The part of the cerebral cortex where all the nerve cells reside that carry signals to the voluntary muscles of the body, such as the face and limbs.

pulse width—This term refers to how wide each electrical pulse is. Typical pulse width settings for DBS are 60–90 µs.

pyramidal system—One of the motor systems of the brain; it is composed of cells that directly control the motor neurons (or nerve cells) of the spinal cord.

rigidity—Stiffness. One of the major symptoms of Parkinson’s disease.

speech-language pathologist—Someone who specializes in problems that affect communication.

stereotactic surgery—A form of surgery that makes use of a three-dimensional coordinate system to locate small targets inside the brain.

stimulator—A pacemaker-like device containing a battery that is the source of the electrical signals that eventually travel to the contacts in the DBS lead.

substantia nigra—A small region of the brain located in the midbrain that contains dopamine nerve cells. Loss of these cells is what causes Parkinson’s disease.

subthalamic nucleus (STN)—Part of the basal ganglia, the STN is one of the sites for DBS. Targeting this structure helps Parkinson’s disease.

tardive dystonia—A secondary dystonia that occurs after long-term exposure to antipsychotic agents or antinausea agents.

thalamotomy—A surgical procedure where the cells in the thalamus are removed. This procedure was often used to help tremor.

thalamus—One of the relay structures of the brain. All of the sensory input from the body goes through here.

tremor—A shaking of a part of a body that is rhythmic.

ultrasound—A medical procedure that uses high-frequency sound waves to produce images of organs, tissues, or blood flow inside the body.

Unified Parkinson Disease Rating Scale (UPDRS)—A commonly used rating scale that rates the severity of Parkinson’s symptoms.

unilateral stimulation—When a DBS system is placed only on one side of the brain.

ventralis intermedius (VIM) nucleus—One of the parts of the thalamus; this is where DBS leads are placed for tremor.

voltage—A measure of how strong an electrical pulse is. Typical voltage settings for DBS range from 1 to 4 V.

wearing off—The feeling people living with Parkinson’s get at the end of a medication cycle, typically slowness and stiffness.