The glossary on this page is taken
from the following resources and appears in the book: Caring For Your
Child With Hydranencephaly. It is included here to help families with
some of the terms they may encounter when learning about their child's
Nervous System Diseases Health
Medical Terms Dictionary
apnea is a breathing disorder characterized by brief interruptions of
breathing during sleep. It owes its name to a Greek word, apnea, meaning
"want of breath."
There are two types of
sleep apnea: central and obstructive.
Central sleep apnea
occurs when the brain fails to send the appropriate signals to the
breathing muscles to initiate respirations.
apnea occurs when air cannot flow into or out of the person's nose
or mouth although efforts to breathe continue.
apnea is much more common than central sleep apnea. In obstructive sleep
apnea, the throat collapses during sleep causing the individual to snort
and gasp for breath. Hundreds of these episodes can occur every night
causing daytime sleepiness and, it is thought, increasing the risk of
hypertension (high blood pressure) and heart problems.
- wasting, shrinkage of muscle tissue or nerve tissue
An important neurologic test based, believe it or not, upon what the big
toe does when the sole of the foot is stimulated. If the big toe goes
up, that may mean trouble.
The Babinski reflex is
obtained by stimulating the external portion (the outside) of the sole.
The examiner begins the stimulation back at the heel and goes forward to
the base of the toes. There are diverse ways to elicit Babinski
response. A useful way that requires no special equipment is with firm
pressure from the examiner's thumb. Just stroke the sole firmly with the
thumb from back to front along the outside edge.
Care must be taken not
to overdo it. Too vigorous stimulation may cause withdrawal of the foot
or toe, which can be mistaken as a Babinski response.
The Babinski reflex is
characterized by extension of the great toe and also by fanning of the
Most newborn babies
are not neurologically mature and therefore show a Babinski response.
Upon stimulation of the sole, they extend the great toe . Many young
infants do this, too, and it is perfectly normal. However, in time
during infancy the Babinski response vanishes and, under normal
circumstances, should never return.
A Babinski response in
an older child or adult is abnormal. It is a sign of a problem in the
central nervous system (CNS), most likely in a part called the pyramidal
Asymmetry of the
Babinski response -- when it is present on one side but not the other --
is abnormal. It is a sign not merely of trouble but helps to lateralize
that trouble (tell which side of the CNS is involved).
The Babinski reflex is
known by a number of other names: the plantar response (because the sole
is the plantar surface of the foot), the toe or big toe sign or
phenomenon, the Babinski phenomenon or sign. (It is wrong to say that
the Babinski reflex is positive or negative; it is present or absent).
Babinski, despite the
Slavic sound of the name, was French: Joseph Francois Felix Babinski
(1857-1932). He will never be forgotten in medicine, thanks to the
reflex he found.
BAER (brainstem auditory evoked
of Central Nervous System, including pathway from brainstem
A series of structures located deep in the brain responsible for motor
- the protective membrane that separates circulating blood from brain
The slowing of motor movements due to dysfunction of the basal ganglia
and related structures.
- another term for stroke.
(computerized axial tomography):
structures within the body created by a computer that takes the data
from multiple X-ray images and turns them in pictures on a screen. The
CAT (computerized axial tomography) scan can reveal some soft-tissue and
other structures that cannot even be seen in conventional X-rays. Using
the same dosage of radiation as that of an ordinary X-ray machine, an
entire slice of the body can be made visible with about 100 times more
clarity with the CAT scan.
The "cuts" (tomograms)
for the CAT scan are usually made 5 or 10 mm apart. The CAT machine
rotates 180 degrees around the patient's body; hence, the term "axial."
The machine sends out a thin X-ray beam at 160 different points.
Crystals positioned at the opposite points of the beam pick up and
record the absorption rates of the varying thicknesses of tissue and
bone. The data are then relayed to a computer that turns the information
into a 2-dimensional cross-sectional image.
CAT scanning is
painless. Iodine-containing contrast material is sometimes used in CAT
scanning. If you are having a CAT scan and are allergic to iodine or
other radiocontrast materials, please notify your doctor and the
CAT scanning was
invented in 1972 by the British engineer Godfrey N. Hounsfield (later
Sir Godfrey) and the South African (later American) physicist Alan
Cormack. CAT scanning was already in general use by 1979, the year
Hounsfield and Cormack were awarded the Nobel Prize in Medicine or
Physiology for its development.
The CAT scan is also
known as the CT (computerized tomography) scan.
The portion of the brain in the back of the head between the cerebrum
and the brain stem. The cerebellum controls balance for walking and
standing and other complex motor functions.
A defect that results in weakness in the wall of a blood vessel that can
lead to bleeding in the brain.
- a brain attack that occurs when a wandering clot (embolus) or some
other particle forms in a blood vessel away from the brain -- usually in
The two halves of the cerebrum, the largest part of the brain.
- a type of stroke occurs when a defective artery in the brain bursts,
flooding the surrounding tissue with blood.
- the most common type of brain attack, it occurs when a blood clot
(thrombus) forms and blocks blood flow in an artery bringing blood to
part of the brain.
fluid: CSF. A
watery fluid, continuously produced and absorbed, which flows in the
ventricles (cavities) within the brain and around the surface of the
brain and spinal cord.
The CSF is produced by
the choroid plexus, a series of infolded blood vessels projecting into
the cerebral ventricles, and it is absorbed into the venous system.
If production exceedes
absorption, the CSF pressure rises and the result is hydrocephalus. This
can also occur if the CSF pathways are obstructed and CSF accumulates.
Disorders that affect the blood vessels that supply the brain that may
result in a stroke.
- consists of two parts (lobes), left and right, which form the largest
and most developed part of the brain; initiation and coordination of all
voluntary movement take place within the cerebrum. The basal ganglia are
located immediately below the cerebrum.
Central Nervous System:
Refers to the brain and the spinal cord.
The fluid that surrounds the brain and the spinal cord
- rapid, jerky, dance-like movement of the body.
Brisk increase in tone with involuntary movements that result in
dysfunction of the corticospinal tracts.
The state of unconsciousness in which patients lie unresponsive with the
- the outer layer of the cerebrum, densely packed with nerve cells.
The nervous system structures that
begin in the brain and travel to the motor neuron cell to innervate the
- a surgical procedure in which a supercooled probe is inserted into a
part of the brain called the thalamus in order to stop tremors.
Deep Tendon Reflexes: The
deep muscle stretch reflexes that are obtained by tapping on the tendons
(such as the "knee jerk").
An acquired loss of cognitive function that may affect language,
attention, memory, personality and abstract reasoning.
An inflammatory process that disrupts the myelin coating of nervous
- a chemical substance, a neurotransmitter, found in the brain that
regulates movement, balance, and walking.
- an involuntary movement including athetosis and chorea.
- difficulty in swallowing.
- a slow movement or extended spasm in a group of muscles.
- a protein, a chemical substance made by muscle fibers.
A diagnostic test to detect abnormalities of the heart using an
ultrasound probe to image the cardiac structures.
Swelling; fluid is retained resulting in swollen tissues.
(electroencephalography) The diagnostic test that is used to study the
brain wave activity. It is most useful to evaluate the seizure
- a "wandering" blood clot.
(electromyography/nerve conduction study) A test that is used to study
the nerves and muscles to help diagnose disorders that can affect them.
A small needle is placed in the muscle in the EMG. Electrical conduction
is studied in the NCV. The results are seen on an oscilloscope screen
and compared to normal values.
Inflammation or infection involving the brain.
- a brain disorder involving recurrent seizures; may also be called a
A series of electophysiologic tests that help to evaluate the function
of specific elements of the nervous system involved in Multiple
- any muscle that causes the straightening of a limb or other part.
- system consisting of nerve cells, nerve tracts and pathways that
connects the cerebral cortex, basal ganglia, thalamus, cerebellum,
reticular formation, and spinal neurons that is concerned with the
regulation of reflex movements such as balance and walking.
- any muscle that causes the bending of a limb or other body part.
A contrast agent that is given intravenously during MRI (magnetic
resonance imaging) to increase visualization of specific abnormalities.
- a cluster of nerve cells.
- the darker-colored tissues of the central nervous system; in the
brain, the gray matter includes the cerebral cortex, the thalamus, the
basal ganglia, and the outer layers of the cerebellum.
Hemiparesis: Weakness that
affects one side of the body.
Bleeding; (such as in brain hemorrhage)
Ischemia: Lack of blood
flow; (such as in ischemic stroke)
Lordosis - an exaggeration
of the forward curve of the lower part of the back, sometimes called
(also known as a spinal tap) A procedure that involves removing some of
the cerebrospinal fluid from the base of the spine. The physician will
first use a local anesthetic on the skin and soft tissues in the lower
back. Cerebrospinal fluid is obtained from the spinal area using a small
needle and a syringe.
A special radiology technique designed to image internal structures of
the body using magnetism, radio waves, and a computer to produce the
images of body structures. In magnetic resonance imaging (MRI), the
scanner is a tube surrounded by a giant circular magnet. The patient is
placed on a moveable bed that is inserted into the magnet. The magnet
creates a strong magnetic field that aligns the protons of hydrogen
atoms, which are then exposed to a beam of radio waves. This spins the
various protons of the body, and they produce a faint signal that is
detected by the receiver portion of the MRI scanner. A computer
processes the receiver information, and an image is produced. The image
and resolution is quite detailed and can detect tiny changes of
structures within the body.
MRI images tend to be
quite clear, particularly those of the soft tissue, brain and spinal
cord, abdomen and joints, and they may be superior to routine X-ray
images of such structures.
An MRI is painless and
has the advantage of avoiding x-ray radiation exposure. There are no
known risks of an MRI. The benefits of an MRI relate to its precise
accuracy in detecting structural abnormalities of the body.
Patients with heart
pacemakers, metal implants, or metal chips or clips in or around the
eyes cannot be scanned with MRI because of the effect of the magnet.
Metallic chips, materials, surgical clips, or foreign material
(artificial joints, metallic bone plates, or prosthetic devices, etc.)
can significantly distort the images obtained by the MRI scanner.
Similarly, patients with artificial heart valves, metallic ear implants,
bullet fragments, and chemotherapy or insulin pumps should also not have
Claustrophobia can be
a problem. For an MRI, patients lie in a closed area inside the magnetic
tube. Some patients experience a feeling of claustrophobia.
In 2003 the Nobel
Prize in Physiology or Medicine was awarded to the American Paul C.
Lauterbur (1929-) and the Briton Sir Peter Mansfield (1933-) "for their
discoveries concerning magnetic resonance imaging."
Usually refers to tumors that are cancerous; may refer to a disease
state that has a debilitating unremitting course.
Inflammation or infection of the meninges, which are the coverings of
Motor Neuron Cells:
The cells located in the spinal cord that give rise to the nerves that
supply the muscles.
MRI (magnetic resonance imaging):
A technique that utilizes the properties of magnetic fields to provide
images of the body
The outer lipid rich (fatty) layer that covers nerves and nervous system
pathways in the brain and spinal cord.
- jerking, involuntary movements of the arms and legs. May occur
normally during sleep.
A disease resulting in dysfunction of the muscles usually causing
weakness and atrophy.
Neurons: The nerve cells of
the brain that carry out neurological function.
- chemical substances that carry impulses from one nerve cell to
another; found in the space (synapse) that separates the transmitting
neuron's terminal (axon) from the receiving neuron's terminal
NPH: (normal pressure
hydrocephalus) Increase in
pressure within the ventricles of the brain, causing dementia, gait
difficulties and urinary incontinence.
The jerking "to and fro" movement of the eyes that occurs when disorders
affect the control of eye movement.
System: Refers to the nerves
and muscular structures
The lesion that occurs in the "white matter" of the brain due to
Used to describe medications or treatments that are preventative in the
treatment of disease.
Drooping of the eyelids due to weakness of the muscles responsible for
keeping the lids open.
Range Of Motion - the extent
that a joint will move from full extension to full flexion.
- a tremor of a limb that increases when the limb is at rest.
Stiffness in the limbs or body due to dysfunction of the basal ganglia
and related structures.
Seizure: The abnormal
electrical discharge of brain cells (neurons) that results in a
transient disturbance in brain function.
SEP (Somatosensory Evoked
of Central Nervous System, including pathway from the extremities.
An important neurotransmitter (communicates information chemically
between brain cells) that is involved in the pain disorders and
A disorder that results in apnea (cessation of breathing) during sleep
often due to obstruction of the upper airway.
stiffness of the body involving the limbs that results from dysfunction
of the corticospinal tracts.
Seizures that continue for more than twenty minutes without an
intervening period of responsiveness.
Bleeding in the area surrounding the brain, that is usually a result of
the rupturing of a cerebral aneurysm in the brain.
Sustention (Postural) Tremor
- a tremor of a limb that
increases when the limb is stretched.
- a tiny gap between the ends of nerve fibers across which nerve
impulses pass from one neuron to another; at the synapse, an impulse
causes the release of a neurotransmitter, which diffuses across the gap
and triggers an electrical impulse in the next neuron.
- a blood clot.
TIA: (Transient Ischemic Attack);
Neurological symptoms occur due to transient interruption of the blood
flow to the brain.
The involuntary turning of the neck to one side that can be seen in
disorders of the basal ganglia.
- a rhythmical shaking of a limb, head, mouth, tongue, or other part of
VER(Visual Evoked Responses):
Measures function of Central Nervous System, including the pathway from
Bones that make up the spinal column.
The lipid rich myelinated portion of the brain and spinal cord. Or:
nerve tissue that is paler in color than gray matter because it contains
nerve fibers with large amounts of insulating material (myelin). The
white matter does not contain nerve cells. In the brain, the white
matter lies within the gray layer of the cerebral cortex.