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Word of the Week RETT’S SYNDROME
a pervasive developmental disorder affecting the gray matter of the brain, occurring exclusively in females and present from birth. Characterized by autistic behavior, ataxia, dementia, seizures, and loss of purposeful movements of the hands. QUADRANTANOPIA
defective vision or blindness in one fourth of the visual field. ACCOMMODATION REFLEX
the coordinated changes that occur when the eye adapts itself for near vision; the changes are constriction of the pupil, convergence of the eyes, and increased convexity of the lens. KYPHOSCOLIOSIS
the combination of kyphosis (backward curvature of the spine) and scoliosis (lateral curvature), as seen in Scheuermann disease. KERNIG SIGN
a sign of meningitis: in the supine position the patient can easily and completely extend the leg, whereas in the sitting posture or when lying with the thigh flexed upon the abdomen the leg cannot be completely extended without pain.
JAMAIS VU
the sensation that familiar surroundings are strangely unfamiliar; the illusion that one has never seen anything like that before.
OBTUNDATION
mental blunting with mild to moderate reduction in alertness and a diminished sensation of pain.
LUMBAR PUNCTURE HEADACHE
headache in the erect position, and relieved by recumbency, following lumbar puncture, due to lowering of intracranial pressure by leakage of cerebrospinal fluid through the needle tract.
LEPTOMENINGES
the two more delicate components of the meninges: the pia mater and arachnoid considered together; the pia-arachnoid
EATON-LAMBERT SYNDROME
a myasthenia-like syndrome in which the weakness usually affects the limbs but ocular and bulbar muscles are spared; often associated with oat-cell carcinoma of the lung.
HEMIBALLISMUS
violent motor restlessness of half of the body, most marked in the upper limbs
HEIDENHAIN SYNDROME
a rapidly progressive degenerative disease manifested by cortical blindness, presenile dementia, dysarthria, ataxia, athetoid movements, and generalized rigidity
EFFERENT NEURON
a neuron that conducts nerve impulses that originated at the center and are proceeding towards the periphery EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO)
a technique of providing respiratory support; the blood is circulated through an artificial lung consisting of two compartments separated by a gas-permeable membrane, with the blood on one side and the ventilating gas on the other. It was originally used exclusively in newborns but is now being used more and more in adults. CHEYNE-STOKES RESPIRATION
breathing characterized by rhythmic waxing and waning of the depth of respiration; the patient breathes deeply for a short time and then breathes very slightly or stops breathing altogether. The pattern occurs over and over, every 45 seconds to 3 minutes. Periodic breathing of this type is caused by disease affecting the respiratory centers, usually heart failure or brain damage. CEREBELLOPONTINE ANGLE SYNDROME
a syndrome caused by a tumor of the cerebellopontine angle or an acoustic tumor, characterized by hearing loss, subjective noises, ipsilateral cerebellar ataxia, and eventually ipsilateral impairment of function of the sixth and seventh cranial nerves accompanied by elevated intracranial pressure.
CEREBRAL PERFUSION PRESSURE
the mean arterial pressure minus the intracranial pressure, a measure of the adequacy of cerebral blood flow CARDIOVERSION
the delivery of a direct current countershock synchronized with the QRS complex to the myocardium in order to end tachydysrhythmias and restore sinoatrial control of the heart rhythm through depolarization of the entire myocardium. The depolarization interrupts reentry circuits, thus ending myocardial fibrillation and some other types of dysrhythmias. The electric shock can be delivered directly to the myocardium in an open chest procedure, or through externally applied paddles placed on the chest. VERTEBRAL LAMINA
either of the pair of broad plates of bone flaring out from the pedicles of the vertebral arches and fusing together at the midline to complete the dorsal part of the arch and provide a base for the spinous process of the vertebra. VERNIX CASEOSA
the thick white substance composed of sebum and desquamated epithelial cells that provides a protective covering for the skin of the fetus. In the full-term newborn, during the first two or three days of life there is a small amount of vernix caseosa in body creases and the hair. SLEEP PARALYSIS
paralysis occurring at awakening or sleep onset; it represents extension of the atonia of REM sleep into the waking state and is often seen in those suffering from narcolepsy or sleep apnea. STENOSIS
an abnormal narrowing or contraction of a body passage or opening; called also arctation, coarctation, and stricture RECEPTIVE APHASIA
inability to understand written, spoken, or tactile speech symbols; also called sensory aphasia or Wernicke's aphasia EMBOLIZATION
therapeutic introduction of a substance into a vessel in order to occlude it ELECTROCONVULSIVE THERAPY (ECT)
a treatment for mental disorders in which an electric current is used to produce convulsions. It is used primarily to treat depression or the depressive phase of bipolar disorder; it has also been used to treat some forms of schizophrenia and acute mania.
BRADYKINESIA
slowing down of a movement; gradual loss of spontaneous movement. This is a major symptom of Parkinson’s disease INHIBITORY POST-SYNAPTIC POTENTIAL (IPSP)
a hyperpolarizing potential recorded in a post-synaptic neuron when activated by an inhibitory neurotransmitter
SULCUS
anatomic nomenclature for a groove, trench, or furrow
CATAPLEXY
a condition, associated with narcolepsy; marked by abrupt attacks of muscular weakness and hypotonia triggered by an emotional stimulus, such as mirth, anger, or fear
WALLERIAN DEGENERATION
fatty degeneration of a nerve fiber that has been severed from its nutritive source
CONDUCTIVE HEARING LOSS
hearing loss caused by impaired transmission of sound waves through the external ear canal to the bones of the middle ear, usually because of a blockage of the external ear or dysfunction of the middle ear. Common causes include obstruction of the ear canal by earwax or a foreign object; perforation of the eardrum; otitis media; otosclerosis; and congenital malformations of the outer or middle ear.
CHRONIC
persisting for a long time; applied to a morbid state, designating one showing little change or extremely slow progression over a long period
IN VITRO
within a glass; phenomena that are observed in a test tub or artificial environment
CHOREA
a type of dyskinesia (abnormal movement) characterized by continuing, rapid, dance-like movements
EXCITATORY POST-SYNAPTIC POTENTIAL (EPSP)
a depolarizing potential recorded in a post-synaptic neuron when activated by an excitatory neurotransmitter
VERTEBROBASILAR INSUFFICIENCY
transient or intermittent ischemia of the brain stem and cerebellum due to stenosis, thrombosis, or other obstruction of the vertebral or basilar artery; this results in symptoms such as vertigo, diplopia, nystagmus, muscle weakness, and dysarthria
COPROLALIA
involuntary utterances of vulgar or obscene words; seen in Tourette’s syndrome VENTRICULAR TACHYCARDIA
an abnormally rapid ventricular rhythm with aberrant ventricular excitation, characterized by at least three consecutive ventricular complexes of more than 100 beats per minute
MAGNETOENCEPHALOGRAPHY (MEG)
a noninvasive imaging technique that measures the magnetic fields produced by electrical currents in the brain; MEG uses superconducting quantum interference devices (SQUIDs)
AUTOSOMAL RECESSIVE
two copies of an abnormal gene must be present for the disease or trait to develop
ACETABULUM
the cup-shaped cavity on the lateral surface of the hip bone. It holds the round head of the femur (thigh bone)
EPIDURAL HEMATOMA
a hematoma between the dura mater and the skull, usually caused by a heavy blow to the head that damages the upper surface of the dura mater. This type of hematoma is the result of rupture of a relatively large meningeal artery, with rapid leakage of blood that increases intracranial pressure, which can be fatal in a short period of time. Symptoms occur within a few hours after injury and may include sudden or gradual loss of consciousness, partial or full paralysis on the side opposite the injury, and dilation of the pupil of the eye on the same side as the injury.
ANTAGONIST
a substance that tends to modify the action of another; a drug that binds to a cellular receptor for a neurotransmitter or a drug blocking the action of a substance without producing any physiological effect itself
DEPOLARIZATION
changing the resting potential of a neuron to less negative, moving toward threshold
HIPPOS
abnormal exaggeration of the rhythmic contraction and dilation of the pupil; independent of changes in illumination or in fixation of the eyes
HETEROTOPIA
displacement of parts; displacement of gray matter, typically into the deep cerebral white matter
AKINESIA
absence or difficulty in producing body movements
IN VIVO
within the body; phenomena that are observable in a living organism
NEUROBLASTOMA
a malignant tumor derived from primitive ganglion cells usually arising in the autonomic nervous system or the adrenal medulla; affects mostly infants and children up to 10 years of age.
SUBARACHNOID SPACE
space between the arachnoid and pia mater (under the arachnoid and above the pia) in which cerebrospinal fluid (CSF) circulates
CAPACITANCE
the ability to store a charge. Capacitors block direct current but pass alternating current. The unit of capacitance is the farad
ANTIDROMIC
conduction of action potentials in the opposite direction, e.g., conduction of potentials toward the periphery in a sensory axon
ACTION TREMOR
rhythmic, involuntary movement of a limb when movement is initiated, e.g., when writing or lifting a cup
REM REBOUND
the phenomenon in which a person deprived of rapid eye movement (REM) sleep for a prolonged period will when permitted to sleep undisturbed compensate by having increased REM sleep
GLASGOW COMA SCALE
a clinical tool used to assess the degree of consciousness and neurological functioning - and therefore severity of brain injury - by testing motor responsiveness, verbal acuity, and eye opening
SCHWANN CELLS
cells that produce the myelin sheath around axons in the peripheral nervous system
SALT BRIDGE
when the conductive medium (paste, salt jelly…) between two electrodes has smeared and joined making the two electrodes record as one big electrode
PROXIMAL
closer to the center of the body; opposite of distal
ANEURYSM
a balloon-like sac in the wall of an artery, vein, or heart caused by a weakening of the wall by injury, disease, or abnormality present at birth
ANASTOMOSIS
a connection between two vessels; on opening created by surgical, traumatic, or pathological means between two normally separate spaces or organs HYPOCAPNIA
a state in which the level of carbon dioxide in the blood is lower than normal; can result from deep or rapid breathing BONE CONDUCTION
transmission of sound to inner ear is mediated by mechanical vibration of the cranial bones TEMPORAL DISPERSION
signals traveling at different rates in different portions of a nerve creating a “bumpy” looking picture on the EP or NCS computer screen CATHODE
the negative terminal of an electrolytic cell NEUROFIBROMATOSIS
a familial disorder characterized by developmental changes in the nervous system, muscles, bones, and skin GLIOBLASTOMA MULTIFORME
rapidly growing malignant glioma usually occurring in adults METASTATIC
spreading from other primary carcinomas within the body OCULOMOTOR
related to or causing movements of the eyeball CLUSTER HEADACHES
vascular headaches that occur in clusters, i.e., daily headaches for weeks or months before disappearing for months or years characterized by unilateral excruciating pain in and around one eye; more common in males than females APOPTOSIS
programmed cell death induced by specialized biochemical pathways, often serving a specific purpose in the development of the animal NECROSIS
cell death due to external factors, such as lack of oxygen or physical damage, that disrupt the normal biochemical processes in the cell GAMMA-AMINO BITYRIC ACID – GABA
an amino acid neurotransmitter whose primary function is to inhibit the firing of neurons MANIA
a mental disorder characterized by excessive excitement, exalted feelings, elevated mood, psychomotor overactivity, and overproduction of ideas HIPPOCAMPUS
a seahorse-shaped structure located within the brain and is part of the limbic system. Learning and memory formation are its major known functions RAREFACTION
the first major acoustic wave applies a negative pressure in front of the diaphragm and air goes away from the eardrum
ECTODERM
outermost embryonic layer from which skin, hair, nails, nerve, and brain tissue arise seizures triggered by something in the environment, such as flashing lights, certain types of music, or particular odors. Also known as environmental epilepsy INHIBITORY POSTSYNAPTIC POTENTIALS – IPSP
change in the membrane voltage of a postsynaptic neuron that makes it more difficult to fire an action potential RESTLESS LEG SYNDROME
condition that occurs shortly after bedtime in which the legs feel uncomfortable unless moved NODES OF RANVIER
regularly spaced, about one micrometer gap in the myelin sheath around an axon ORTHODROMIC RECORDING
the stimulus is distal and the recording site is proximal so the impulses travel in the same direction as naturally arising sensory impulses SOMNAMBULISM
a sleep disorder, a parasomnia, where the person rises out of bed and walks about or performs other complex motor behavior while asleep
ICP – INTRACRANIAL PRESSURE
the amount of pressure exerted inside the skull by brain tissue, blood, and cerebrospinal fluid
DELIRIUM
syndrome with the clinical picture of clouding of consciousness; changes in psychomotor activity; alterations in sleep, speech, and perception; and disorientation and memory impairment
FIBRILLATIONS
low amplitude, brief biphasic or triphasic potentials that result from the spontaneous activity of single muscle fibers that have lost their innervation.
PET – POSITRON EMISSION TOMOGRAPHY
imaging scan during which a small amount of radioactive glucose is injected and the scanner measures the activity or functional level of the brain by measuring its glucose
SARS - SEVERE ACQUIRED RESPIRATORY SYNDROME
severe form of pneumonia characterized by fever, coughing, difficulty breathing, and hypoxia caused by the SARS coronavirus
EMBOLISM
the sudden blocking of an artery by a clot or foreign material which has been brought to the site of the obstruction by the blood current
PAPILLEDEMA
edema (swelling) of the optic disk most commonly due to increased intracranial pressure; also called choked disk
SUBDURAL HEMATOMA
a collection of blood under the dura mater (the outermost meningeal covering of the brain and spinal cord)
DYSPHONIA
difficulty in speaking
SIGNAL-TO-NOISE RATIO
S/N ratio – the amplitude of the signal divided by the amplitude of the noise
LOGOCLONIA
spasmodic repetition of words or parts of words, particularly the end syllables, often occurring in Alzheimer’s disease
STEREOGNOSIS
the ability to have knowledge (gnosis) of the solidness (stereo) of an object using the sense of touch
MONTAGE
an organized combination of electrode derivations recording at the same time
GANGLION
a group of nerve cell bodies usually located outside the central nervous system; occasionally applied to certain nuclear groups within the brain or spinal cord such as the basal ganglia
WERNICKE’S APHASIA
Language disorder caused by damage to Wernicke’s area located in the temporal lobe of the dominant hemisphere. The disorder is characterized by fluent but meaningless speech and severe impairment of the ability to understand spoken or written words.
POLYMORPHIC
multiple frequencies that together create complex waveforms
MRSA
Methicillin-resistant Staphylococcus aureus – strain of Staphylococcus aureus that has become resistant to certain antibiotics
GAMMA FREQUENCY
above 30 Hz (unlimited in upper range); exact width of the gamma range is still being debated
HYPOTONIA
a condition of diminished tone of the skeletal muscles; diminished resistance of muscle to passive stretching
POSTICTAL
after a seizure. The EEG shows postictal slowing. The patient has postictal confusion
PLEDs - Periodic Lateralized Epileptiform Discharges
an EEG pattern that occurs in a variety of acute neurologic conditions, most often cerebral infarctions
HYPNAGOGIC HALLUCINATIONS
vivid often frightening, dreamlike experiences that occur while dozing, falling asleep or upon awakening
EPILEPTOGENSIS
the production or development of epilepsy
BATTLE’S SIGN
discoloration over the skin of the mastoid region of the skull seen with factures of the base of the skull
DEMENTIA a general loss of cognitive abilities, including impairment of memory as well as one or more of the following: aphasia, apraxia, agnosia, or disturbed planning, organizing, and abstract thinking abilities
PERIODICITY the distribution of patterns or elements in time; the appearance of a particular EEG activity at more or less regular intervals INTERNEURON
any neuron in a chain of neurons that is situated between a primary sensory neuron and the final motor neuron
PATHOPHYSIOLOGY
the functional changes that accompany a particular syndrome or disease
TODD’S PARESIS
CEREBRUM
the main portion of the brain occupying the upper part of the cranial cavity; its two hemispheres form the largest part of the central nervous system in humans.
ATTENUATION
reduction of amplitude of EEG activity resulting from decreased voltage; may be seen during painful stimulation while recording an EEG on a patient in coma
RETROGRADE AMNESIA inability to recall events that occurred before the actual onset or cause (e.g., head trauma) of memory loss
ACTIVE SLEEP sleep stage in a neonate characterized by rapid eye movement (REM), irregular respirations, loss of muscle tone, and a continuous EEG pattern GYRUS
one of the convolutions of the cerebral hemispheres caused by infolding of the cortex
SHORT TERM MEMORY memory that is lost within a brief period (from a few seconds to a maximum of about 30 minutes) unless reinforced
VERTEBRECTOMY excision of a vertebra
BRADYCARDIA slowness of the heartbeat as evidenced by slowing of the pulse rate to less than 60 beats per minute
PROGNOSIS a forecast as to the probable outcome of an attack of disease ROSTRAL
in human anatomy, toward the oral and nasal region
CONCEPTUAL AGE (CA) time in utero (gestational age) plus time since birth; infant born at 34 weeks gestational age who is 2 weeks old has a CA of 36 weeks.
ALIASING SPHENOIDAL ELECTRODES AGORAPHOBIA SUBDURAL HEMATOMA NEUROCYSTICERCOSIS MALIGNANT TRIGEMINAL NEURALGIA FLACCID THROMBOSIS RETICULAR ACTIVATING SYSTEM (RAS) NEUROPSYCHOLOGY ENCEPHALOMALACIA SETTING SUN SIGN ANGIOGRAPHY BURST SUPPRESSION BABINSKI’S REFLEX
dorsiflexion (upward flexion) of the big toe on stimulating the sole of the foot; normal in infants but in others a sign of a lesion in the central nervous system, particularly in the pyramidal tract. HEMIPLEGIA OHM ANOSMIA AXON
the process of a neuron by which impulses travel away from the cell body; at the terminal end of the axon impulses are transmitted to other neurons or to effector organs.
PHOTOPAROXYSMAL RESPONSE BLEPHAROSPASM
tonic spasm of the orbicularis oculi muscle producing more or less complete closure of the eyelids.
HERTZ CORPUS CALLOSUM
an arched mass of white matter found in the depths of the longitudinal fissure that connects the cerebral hemispheres.
AURA IDIOPATHIC CREUTZFELDT-JAKOB DISEASE PRION GLOSSOKINETIC POTENTIALS TRENDELENBURG'S POSITION EPINEPHRINE AUTOMATISM HYPOTHALAMUS PHOTOPHOBIA FAST FOURIER TRANSFORM (FFT) |