Glossary: Commonly Used Terms Found in Medical Literature — Q-Z

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Qualitative Analysis:  Research that looks at subjective information that is hard to
quantify, such as opinions, patterns, themes, and impressions.  It is different than
quantitative analysis that instead focuses on numbers (e.g. test results).

Quantitative Analysis:  Research that focuses on numbers.

Rapid Eye Movement (REM): The rapid, periodic, jerky movement of the eyes during certain stages of the sleep cycle when dreaming takes place.

Range of motion (ROM): The extent of a joint's free movement. The normal ROM of the elbow, for instance, carries the forearm through a half-circle. Passive ROM is tested while the limb is relaxed. Active ROM is movement controlled by the patient.

Receptor: A molecule on a neuron that receives a neurotransmitter. Reception of the neurotransmitter causes changes in the neuron which increase or decrease its likelihood of "firing," or sending its own signal to other neurons. Dopamine receptors are located on corpus striatum neurons, and on nigral cells.

Reduced penetrance: Reduced expression of a genetic disorder. The term penetrance refers to the frequency with which a specific genetic mutation produces its typical effect in those with the genetic abnormality. For example, if fewer than 100 percent of individuals who inherit a gene mutation for an autosomal dominant disorder develop the disease, the specific trait is said to have "reduced penetrance."

Reeling gait: characterized by irregular and uncertain steps. Control of the legs and trunk (the part of the body below the head, not including the arms and legs) is greatly impaired.

Reflex: Involuntary, predictable response to a particular stimulus.

Refractory: Resistant to or not readily yielding to treatment.

REM sleep: The period of sleep that is associated with dreaming, rapid eye movements (REM), and certain involuntary muscle movements.

Remittence: a temporary improvement of symptoms, without the symptoms completely going away.

Resonance: 1. The intensification and enriching of a musical tone by supplementary vibration 2. A quality imparted to voiced sounds. 3. The sound elicited on percussion of the chest.

Respiration: 1. A single complete act of breathing. 2. Fundamental process of life, in which oxygen is used to fuel the human body. 3. The physical and chemical processes by which an organism supplies its cells and tissues with the oxygen needed for metabolism and relieves them of the carbon dioxide formed in energy-producing reactions.

Restless legs syndrome (RLS): A neurologic movement disorder characterized by unusual, uncomfortable sensations (paresthesias/dysesthesias) deep within the calves and/or thighs, resulting in an irresistible urge to move the legs, and motor restlessness in response to or in an effort to alleviate discomfort. In some patients, the arms may also be affected. Symptoms become obvious or worse during periods of relaxation or inactivity; occur most frequently during the evening or the early part of the night; and may be temporarily relieved by voluntary movements of the affected area. Most patients experience associated sleep disturbances, including difficulties drifting off to and remaining asleep. RLS is also often associated with periodic limb movements of sleep (PLMS) or repeated, stereotypic, upward extension of the great toe and foot, potentially followed by flexion of the knee, hip, or ankle. Episodes of PLMS typically occur during periods of lighter (i.e., non-REM) sleep.

Restorative sleep: A refreshing sleep, i.e., receiving a sufficient amount of rest to feel refreshed and to engage in the activities of daily living without experiencing excessive daytime sleepiness (EDS).

Retina: The nerve-rich membrane that forms the innermost region of the eye. As light passes through other areas of the eye (including the cornea, pupil, and lens), it is bent or refracted to focus on the retina, which contains nerve cells that respond to light (photoreceptors). Images formed on the retina are converted into nerve impulses that are transmitted to the brain via the optic nerve (second cranial nerve).

Retroperitoneal fibosis: mass or abnormal tissue in the abdomen.

Reye syndrome: A potentially life-threatening disease characterized by sudden inflammation and swelling of the brain (acute encephalopathy) and rapid fat accumulation within certain internal organs (viscera), particularly the liver, occurring subsequent to certain viral infections, such as chickenpox or upper respiratory tract infections (e.g., influenza B). Reye syndrome primarily occurs in children and adolescents, although it has sometimes been reported during infancy or young adulthood. About a week after the onset of a viral infection, patients may develop uncontrollable vomiting, followed by a rapid onset of listlessness, confusion, and memory loss, a state of unconsciousness (coma), seizures, and/or other findings, potentially leading to life-threatening complications. Evidence suggests that the use of aspirin-containing preparations (salicylates) as a treatment for particular viral infections plays a role in the development of Reye syndrome. Therefore, experts advise that such medications be avoided for the treatment of viral infections during infancy, childhood, adolescence, and young adulthood.

Rhythmical myoclonus: Involuntary, shock-like contractions or spasms of a muscle or muscle group that occur in a rhythmical pattern. This usually occurs as a result of a lesion in the central nervous system.

Rigidity: 1. Hardness, inflexibility, or stiffness. Rigidity occurs due to increased tone (tension) in muscles near a joint that are in a shortened state (known as agonist muscles) and muscles that work to oppose such shortening (known as antagonist muscles). Muscle rigidity is often seen in Parkinson's disease (a type of brain disease resulting in motor impairments). May be a symptom of a neurologic movement disorder such as Parkinson's disease. 2. A personality aspect that is resistance to change. Rigity comes from the Latin word "rigere" which means "to be stiff."

Rule out: means to eliminate as a possibility. For example, a doctor may have a patient's blood pressure tested to rule out high blood pressure. That is, the doctor wants to know if the results from the test will eliminate the possibility that the patient has high blood pressure.

Saccadic: means jerky. An example would be saccadic eye movements, which are extremely fast, small, jerky voluntary eye movements to redirect the line of sight, allowing the eyes to fix on a still object as the head turns or the person moves.

Salicylates: Medications derived from salicylic acid, including aspirin (acetylsalicylic acid). Such compounds have anti-inflammatory, pain-relieving (analgesic), and fever-reducing (antipyretic) activities. Salicylates act to reduce the production of certain hormone-like chemicals known as prostaglandins that may have varying actions, potentially leading to inflammatory effects, increased pain sensitivity, fever, etc. Prolonged aspirin use may damage the stomach or intestinal lining, causing peptic ulcers and bleeding from the digestive tract. (Peptic ulcers are well-defined, raw areas where the mucous membrane lining the stomach, esophagus, or upper region of the small intestine has been eroded by acidic digestive [i.e., gastric] juices.) In addition, excessive intake of salicylates may lead to salicylate toxicity, characterized by rapid breathing, irritability, vomiting, and other findings.

Sandhoff's disease: A neurodegenerative metabolic disorder that is characterized by symptoms and findings similar to those associated with Tay-Sachs disease as well as possible, moderate enlargement of the liver and spleen (hepatosplenomegaly). Sandhoff's disease is a lysosomal storage disease in which deficiency of the enzymes hexosaminidase A and B results in an abnormal accumulation of certain fats (i.e., gangliosides) in particular tissues of the body. The disorder is transmitted as an autosomal recessive trait and affects only non-Jewish individuals (as opposed to Tay-Sachs disease, which primarily occurs in individuals of Ashkenazi Jewish ancestry).

Seizures: Episodes of uncontrolled electrical activity in the brain. These abnormal electrical disturbances may lead to involuntary jerking, spasms, or rhythmic contraction and relaxation of certain muscle groups and impaired control of involuntary functions such as breathing or bladder or bowel control. There may also be loss of consciousness or sensory or behavioral abnormalities.

Sensorimotor: Pertaining to both the sensory and motor aspects of a bodily function.

Sensory apraxia means the same thing as ideational apraxia - a disturbance of voluntary movement in which a person misuses objects because he/she has difficulty identifying the concept or purpose behind the objects.

Sensory ataxia: an impairment of one's sense of position. Sensory ataxia is characterized by striking the ground forcibly with the bottom of the foot as well as a stiff fling of the leg. This type of ataxia is seen in multiple sclerosis.

Sequelae: Plural of sequela, which is any abnormal condition that occurs subsequent to and/or is caused by disease, injury, or treatment.

Serotonin (3-[2-aminoethyl]-5-indolol): A vasoconstrictor found in many tissues of the body that is present in relatively high concentrations in portions of the central nervous system (e.g., hypothalamus, basal ganglia, etc.). Serotonin functions as a neurotransmitter, regulating the delivery of messages between nerve cells (neurons). This neurotransmitter is thought to play some role in regulating consciousness and mood states. Serotonin is also present in other tissues of the body such as the intestines and blood platelets.

Sialorrhea: Excess production of saliva, or increased retention of saliva in the mouth, due to difficulty swallowing.

Side effect: An effect of a drug that is not the main or intended effect. Side effects may be of no concern, or they may be bothersome or even dangerous, in which case they may limit the upper dose a patient can tolerate. Side effects are also called adverse effects.

Single photon emission computed tomography (SPECT): A noninvasive scanning procedure during which a radioactive substance known as a radionuclide is introduced into the body to help evaluate the function and structure of certain organs or tissues. The amount of the substance taken up by particular tissues may depend upon the amount of blood flow within such regions. For example, absence of radionuclide uptake in a targeted region may indicate a lack of blood flow in certain areas. Following intravenous administration of the radioactive compound, a specialized rotating camera detects the radiation emanating from the radionuclides in the form of particles known as protons. The recorded images may produce colorized, horizontal and vertical cross sections and be reconstructed by computer to create three-dimensional images. By evaluating the blood supply to particular tissues, SPECT may be particularly helpful in detecting certain changes within the central nervous system or the heart.

Sinus bradycardia: an abnormally slow heart rate (i.e., of less than 60 beats per minute).

Sleep latency: The interval of time between "settling in" to go to sleep and the onset of sleep.

Sleep maintenance: Once asleep, the ability to remain asleep.

Somnolence: Sleepiness, the state of feeling drowsy, ready to fall asleep.

Spasmodic dysphonia (SD): A manifestation of dystonia. SD involves the muscles of the larynx and surrounding muscles and therefore involves speech. In individuals with SD, speech in blocked by intermittent spasms of the voice box (larynx).

Spasmodic torticollis (ST): A form of dystonia involving the muscles of the neck, and therefore called "cervical dystonia." As a result of the abnormal involuntary contractions of the neck muscles, the head may be rotated, tilted, flexed, extended, or any combination of these postures. The movements may be quick, sustained, or patterned and, therefore, may be associated with tremor.

Spasmolytic: Antispasmodic; referring to agents that may eliminate or relieve spasms, typically of involuntary (i.e., smooth) muscle, such as within the arteries, the intestine, the ring-shaped muscles around certain natural openings or passages (sphincters), the bladder, the muscular tubes that carry urine from the kidneys to the bladder (ureters), etc.

Spastic gait: an abnormal type of gait (way of walking) in which the legs are weak and stiff, and in which there is no flexing at the knee and ankle. With each step, the leg rotates away from the body, then towards it, forming a half circle. The toes may also drag while walking. Sometimes the legs cross while the person walks, causing a scissor-like gait.

Spasticity: a condition in which there is increased tension in muscles that resist the force of gravity (the natural force that pulls objects downwards) and increased resistance to stretch. Spasticity is usually associated with decreased reflexes when the skin is stimulated but increased reflexes when deep body structures, such as tendons, are stimulated. Tendons are groups of fibers that attach muscles to a bone. In this context, fibers refer to the long cells that make up muscles. Spasticity usually involves the tendon extensors of the legs, and the flexors of the arms. Extensors are tendons that move body parts outwards, whereas flexors are tendons that move body parts inwards.

In slight spasticity, gross movements may be coordinated smoothly, but combined movements are impossible or appear uncoordinated. In moderate spasticity, movements require great effort and a lack of coordination is present. Many people with spasticity experience weakness.

Spinal cord: The cylindrical structure of nerve tissue that, together with the brain, comprises the central nervous system. The spinal cord is an extension of the medulla oblongata--which is part of the lowest region of the brain (brainstem)--and is contained within a central canal in the spinal column. The spinal cord and the brain are surrounded by a protective, 3-layered membrane (meninges). Cerebrospinal fluid (CSF) flows through the cavities (ventricles) of the brain, the spinal cord's central canal, and the space between the middle and inner layers of the meninges (subarachnoid space). The spinal cord consists of an inner core of gray matter and surrounding areas of white matter, composed of bundles of myelinated nerve fibers (axons) known as spinal tracts. These include ascending tracts that carry sensory impulses up the spinal cord to the brain and descending tracts that transmit motor impulses from the brain down the spinal cord. Nerves emerge from both sides of the spinal cord (i.e., spinal nerves) through the narrow gaps (foramina) between bones of the spinal column (vertebrae). The spinal nerves, which are attached to the spinal cord by specialized nerve bundles (spinal nerve roots), contain both motor and sensory neurons.

Sporadically: Occurring intermittently, randomly, or in isolation.

SSRIs: Selective serotonin reuptake inhibitors. Drugs belonging to this class are antidepressant agents that selectively inhibit the absorption of serotonin at certain nerve membranes (e.g., presynaptic neuronal membranes). These drugs increase the concentration of serotonin within the central nervous system and enhance serotonin's neurotransmission activities.

Staged DBS:  Unilateral DBS followed by a staged contralateral procedure.

Status post: means following or after.

Stereoagnosis: see astereognosis.

Stereotactic: refers to use of precise coordinates to identify deep structures of the brain. The coordinates may be obtained by fitting a patient's head with a special frame and taking a CT or MRI scan. The position of the brain structures relative to the frame permits fine localization of the deep brain structures. Stereotactic methods are used during brain surgery for tremor, Parkinson's disease, and dystonia. These brain structures are located with precise, three-dimensional coordinates.

Stereotypic: Inappropriate, persistent repetition of particular bodily postures, actions, or speech patterns. These are typically involuntary, rhythmic, coordinated, and purposeless movements, postures, or vocalizations that may appear ritualistic or purposeful in nature. Stereotypies may be associated with a variety of neurologic and behavioral disorders, such as Tourette syndrome, obsessive-compulsive disorders, Rett syndrome, restless legs syndrome, schizophrenia, and autism.

Stereotypical: Conforming to a repetitive pattern as in repetition of particular movements or gestures.

Stress incontinence: Involuntary leakage of urine from the bladder with intense muscle activity (e.g. laughing, coughing, and sneezing).

Stretch reflex: Contraction of a muscle stimulated by rapid stretching.

Stretch-loop circuits: Pathways of electrical impulses along specific nerve fibers (alpha motoneurons) that result in a "stretch" reflex in a muscle.

Striatum: Anatomical structures deep within the brain – composed of the caudate nucleus, putamen, and globus pallidus. It is an area of the brain that controls movement and balance. It is connected to and receives signals from the substantia nigra.

Subjective: 1. Relating to, proceeding from, or taking place within an individual’s mind, emotions, etc. 2. Originating from or influenced by one’s personal interests, prejudices, emotions, etc. 3. Of the mind or emotions only. (As opposed to objective).

Subglottis: The area below the glottis, which are thin strips of muscle inside the throat that produce sound by moving slightly as air travels over them.

Substantia nigra: A dark band of gray matter deep within the brain where cells manufacture the neurotransmitter dopamine for movement control. Degeneration of cells in this region may lead to a neurologic movement disorder such as Parkinson's disease.

Sydenham's chorea: A usually self-limited condition in which chorea develops in association with an inflammatory disease caused by certain strains of streptococci bacteria. This disease, known as rheumatic fever, is characterized by the sudden onset of fever and joint pain, with subsequent inflammation of the heart (carditis), chest pain, skin rash, and other symptoms. If rheumatic fever involves the nervous system, Sydenham’s chorea may develop. This condition commonly affects children aged 5 to 15 or women during pregnancy. Sydenham's chorea involves involuntary, uncontrollable, jerky movements that gradually worsen in severity, potentially affecting arm movements, the manner of walking (gait), and speech. In most patients, the condition spontaneously resolves in weeks or months.

Sympathetic nervous system: Part of the nervous system that along with the parasympathetic nervous system forms the autonomic nervous system (ANS). The ANS regulates the functioning of involuntary structures, such as the glands, smooth muscle, and heart. The sympathetic nervous system regulates certain involuntary responses during times of strong emotion, such as fear or anger; exercise; or other forms of stress. These responses, sometimes referred to as the "fright-or-flight response," include widening of the pupils; increased heart and breathing rates; constriction of most blood vessels, raising blood pressure; widening of those blood vessels that supply skeletal muscles; and reduction in the rate of peristalsis.

Synapse: The junction between two neurons or between a neuron and an effector organ. As a nerve impulse reaches a synapse, the terminal or end of the "presynaptic" neuron's axon releases neurotransmitters, which diffuse across the gap and bind to receptors of the "postsynaptic" neuron or the effector organ (i.e., muscle or gland). As the electrical impulse is conducted across the gap, electrical changes are triggered that serve to continue or hinder transmission of the impulse.

Syndrome: a group of signs and symptoms that occur together and have a common cause, representing a certain disease or inherited abnormality. A sign is clear evidence of disease that can be measured or seen (unlike a symptom), such as a fever or a rash.

Synthesis: The formation of a complex chemical compound through the union of simpler substances.

Tachycardia: a rapid heart rate.

Tardive dyskinesia: a complication of the long-term use of antipsychotic medications. Moreover, it is a movement disorder that may result from extended therapy with certain antipsychotic medications such as haloperidol. The condition is characterized by involuntary, rhythmic movements of the face, jaw, mouth, and tongue, such as lip pursing, chewing movements, or protrusion of the tongue. Facial movements are sometimes accompanied by involuntary, jerky or writhing motions (choreoathetoid movements) of the trunk, arms, and legs. In some patients, symptoms discontinue months or years after withdrawal of antipsychotic therapy. However, in others, the condition may not be reversible.

Tardive dystonia: A form of tardive dyskinesia characterized by chronic dystonia due to administration of medications that block dopamine D2 receptors (dopamine receptor antagonists), such as certain antipsychotic agents. (Dopamine receptors are molecules on the surfaces of receiving nerve cells that are sensitive to stimulation by dopamine, a neurotransmitter that controls movement and balance. Several types of dopamine receptors have been identified, including D1, D2, and D3.) Dystonia is a neurologic movement disorder characterized by sustained muscle contractions that often result in repetitive twisting motions or unusual postures or positions. Tardive dystonia is the most common form of secondary dystonia--i.e., dystonia that results from certain environmental factors or "insults" that affect the brain. In adults, tardive dystonia often initially affects facial or neck muscles. Dystonia may remain limited to such regions or extend to affect adjacent muscles of the trunk and arms. Children are more likely to be affected by generalized dystonia that involves muscles of the trunk and legs.

Tay-Sachs disease: A progressive neurodegenerative metabolic disorder that belongs to a group of diseases called lysosomal storage diseases. Also known as GM2 gangliosidosis type I or infantile type, Tay-Sachs disease results from deficiency of the enzyme hexosaminidase A, which leads to an abnormal accumulation of certain fats (i.e., gangliosides) in particular tissues, particularly nerve cells of the brain. An autosomal recessive disorder, Tay-Sachs disease primarily affects individuals of northeastern European Jewish (Ashkenazi Jewish) ancestry. Symptom onset typically begins from about 3 to 6 months of age. Associated symptoms may include an exaggerated startle response, increasing listlessness, loss of previously acquired skills (psychomotor regression), severely diminished muscle tone (hypotonia), and the development of characteristic, cherry-red circular areas within the middle layers of the eyes (Tay's sign). With disease progression, affected infants and children may develop increasing muscle stiffness or rigidity; seizures; sudden, involuntary, "shock-like" contractions of multiple muscle groups in response to certain stimuli (generalized, stimuli-sensitive myoclonus); enlargement of the brain (metabolic megalencephaly); deafness; blindness; and dementia. Life-threatening complications may develop between 2 to 5 years of age.

Tendon: A tough fibrous cord of tissue that attaches muscle to bone (or other structures of the body).

Teratogenic: Possessing the ability to disrupt normal fetal development and causing fetal abnormalities.

Thalamic syndrome: a condition in which the body becomes oversensitive to pain as a result of damage to a sensory relay station in the brain known as the thalamus. Dysesthesia, which refers to feeling pain or uncomfortable sensations after being touched by an ordinary stimulus or even in the absence of stimulation, can occur during thalamic syndrome. Thalamic syndrome can lead to continuing crude pain in the arms and/or legs. The pain in thalamic syndrome can be made worse with hot and cold temperature, emotional distress, and even music.

Thalamotomy: Destruction of a selected portion of the thalamus (a structure deep within the brain) for the relief of pain, involuntary movements, seizures, and, rarely, emotional disturbances.

Thalamus: An area of the brain consisting of 2 relatively large masses of gray matter. The thalamus relays information from most sensory organs to the outer region of the cerebrum or cerebral cortex; receives and processes messages from the body concerning heat, cold, pain, pressure, and touch; and influences motor activity of the cerebral cortex.

Tics: Involuntary, compulsive, stereotypic muscle movements or vocalizations that abruptly interrupt normal motor activities. These repetitive, purposeless motions (motor tics) or utterances (vocal tics) may be simple or complex in nature; may be temporarily suppressed; and are often preceded by a "foreboding" sensation or urge that is temporarily relieved following their execution. Simple tics include abrupt, isolated movements, such as repeated facial twitching, blinking, or shoulder shrugging, and simple sounds, including grunting, throat clearing, or sighing. Complex tics may involve more sustained, complex movements, such as deep knee bending or leg kicking, or complex vocalizations, including repeating another person's words or phrases (echolalia) or, rarely, explosive cursing (coprolalia). Tourette syndrome is defined as the presence of multiple motor and vocal tics for at least one year, changes in the nature of the tics (e.g., complexity, severity, anatomical location) during the course of the disorder, and symptom onset before age 21.

Tone: Resistance or tension in a muscle when a limb or other body part is moved passively and in a relaxed state about a joint. A state of muscle tension balanced by partial contraction or alternate contraction and relaxation.

Toxic metabolites: Potentially harmful substances formed as the result of normal body functions.

Transient: Temporary; transitory; not lasting or enduring.

Tremor: Rhythmic, involuntary, oscillatory (or to-and-fro) movements of a body part.

Tropical spastic paraparesis (HTLV-1-associated myelopathy): A rare disorder characterized by slowly progressive weakness (paraparesis), stiffness (rigidity), and spasticity of the leg muscles due to infection with the human T-cell lymphotropic virus-1 (HTLV-1). Modes of transmission include sexual contact, mother-to-child transmission (e.g., via breastfeeding), and blood transfusion.

Unilateral: Affecting, pertaining to, or confined to one side only.

Unverricht-Lundborg's disease (Baltic myoclonic epilepsy): A form of progressive myoclonic encephalopathy (PME) characterized by the development of repeated seizures or episodes of uncontrolled electrical activity of the brain (epilepsy); sudden, "shock-like" muscle contractions that may be induced by voluntary movements or in response to certain external stimuli (action or reflex myoclonus); and eventual impairment of coordination, postural instability, and other associated findings (i.e., cerebellar ataxia). Although mental deterioration may also be associated with the disorder, it is typically milder than that seen with Lafora's disease (another form of PME). Unverricht-Lundborg's disease is thought to be inherited as an autosomal recessive trait. Symptom onset typically begins from about age 6 to 13. The disorder is slowly progressive; however, the degree of disease progression and disability may be extremely variable among affected family members.

Upper motor neurons: neurons (nerve cells) in the motor cortex (an area of the brain located in middle, top part of the brain) that help make up the following nerve tracts (paths): corticospinal tracts (paths from the brain to the spine) and corticobulbar tracts (paths from the top part of brain to the lower part of the brain called the brain stem, which looks like a bulb). The brainstem is an area in the lower part of the brain that connects it with the spinal cord. This area of the brain controls many functions crucial for life to continue. Unlike upper motor neurons, lower motor neurons send messages to the skeletal muscles.

Urge incontinence: involuntary leakage of urine from the bladder when one needs to urinate.

Variable expressivity: Varying manifestation of a genetic trait. The term "expressivity" refers to the degree to which a hereditary trait appears in an individual. Thus, in individuals with a gene mutation for an autosomal dominant disorder that has variable expressivity, the specific characteristics that are manifested may vary in range and degree from mild to severe.

Vascular: Pertaining to or containing blood vessels.

Vasoconstrictor: A chemical substance whose actions result in the narrowing of blood vessels.

Vasodilator: A chemical substance whose actions cause an increase in the diameter of blood vessels.

Vasomotor: Pertaining to the muscles and nerves that control blood vessel diameter, thereby regulating or modulating blood pressure.

Ventral intermediate (VIM) nucleus: A specific region of the thalamus. This area of the brain is involved in the control of movement and is the "target" area for thalamotomy and deep brain stimulation when treating patients with tremor.

Vermis: 1. A worm. 2. Any structure or part in the body that resembles a worm in shape.

Vermis of the Cerebellum: The cerebellar vermis is a narrow, worm shaped structure in between both sides of the cerebellum. The cerebellum is an area in the back, bottom part of the brain that plays an important role in movement and coordination. There is a top portion of the vermis and a bottom portion. The top portion is called the superior cerebellar vermis and the bottom portion is called the inferior cerebellar vermis. The bottom portion is sunken between the two sides of the cerebellum.

Ventricle: A normal cavity, as of the brain or heart.

Virulent: Referring to or characterized by virulence or the degree to which an invading microorganism, such as a bacterium or virus, is able to produce disease. Measures of virulence may be based upon the microorganism's ability to invade bodily tissues and the severity of the disease produced.

Viscersa: a term used to describe all of the organs inside of the body. It is typically used to refer to all of the organs inside of the belly. Viscera is plural of viscus, a term for any organ inside of the body. Viscera is also known as vitals.

Wearing off phenomenon: A phenomenon experienced by individuals that take levodopa.  Typically this phenomenon is felt when one’s medication is towards the end of its efficacy per dose (e.g. it wears off).  This phenomenon often increases in frequency the longer one takes levodopa.

White matter: Bundles of myelinated nerve fibers or axons. These nerve fibers have a creamy white appearance due to myelin, a whitish substance that primarily contains fats and proteins. Myelin forms a protective, insulating sheath around certain axons, functioning as an electrical insulator and ensuring efficient nerve conduction. The breakdown, destruction, or loss of myelin from a nerve or nerves (demyelination), such as seen in certain neurodegenerative diseases, results in impaired nerve impulse transmission.

Within normal limits: means that everything is okay. In other words, it is normal or within the limits of what is considered normal.

Wilson disease: a genetic disorder that causes excessive copper accumulation in the liver or brain. Without prompt, appropriate treatment, the disorder may result in progressive liver disease, degenerative changes of the brain, psychiatric abnormalities, and other symptoms. Neurologic findings may include tremor; involuntary, rapid, jerky movements combined with relatively slow, writhing movements (choreoathetosis); impaired muscle tone and sustained muscle contractions, producing repetitive movements and abnormal posturing; increasingly slurred speech; and difficulties swallowing. Some patients may also experience increasing irritability, anxiety, severe depression, unusual behaviors, or other psychiatric problems.

Zeitgeist: a term used to describe the trend of opinions, morals, thoughts, unquestioned assumptions, and other influences on an individual that are understood to be part of a certain culture, science, or art at any point in time.

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