Neurological Glossary
Pacinian corpuscle
Largest of the skin receptors located deep in the dermis and responsible for sensation of vibration and deep pressure
Paediatrician
A doctor who specialises in the care of children and in their disorders and diseases.
Palsy
Paralysis of a muscle group
Papilledema
Swelling of nerve head usually but not always due to increased ICP
Parachute reflex
Protective reflex of normal infants (present by 7-9 months) in which both arms go out in front in response to the head being held down and pointed toward the floor
Paralysis
Loss of motor function in a body part
Paramedian pontine reticular formation (PPRF)
Collection of premotor neurons located in or near the abducens nucleus that drive horizontal gaze when excited by the cerebral cortex
Parameningeal
Adjacent to the meninges; includes nasal cavity, middle ear, paranasal sinuses, mastoid, infratemporal fossa, and pterygopalatine fossa
Paraphasia
speech error characterized by substitutions of letters (e.g., "bree" for "tree") or words (e.g., "house" for "tree")
Paraplegia
Impairment of legs only
Parasagittal
Sagittal section that is lateral to the midline
Parasomnia
Disorder in which abnormal behavior intrudes into the sleep process; includes somnambulism, night terrors, and bruxism
Parasympathetic nervous system
Part of the autonomic nervous system concerned with conservation and restoration of energy; its preganglionic fibres arise from the motor nuclei of cranial nerves III, VII, IX and X in the brainstem and from the second, third and fourth sacral segments of the spinal cord
Paratonia (gegenhalten)
Increased muscle tone that increases in proportion to the speed and strength with which the examiner tries to move the joint; indicative of extensive bihemispheric or bifrontal dysfunction
Parenchyma
tissue
Paresis
Reduced ability to activate motor neurons; weakness
Paresthesia
Skin sensation, such as burning, prickling, itching, or tingling, with no apparent physical cause
Parinaud�s syndrome (dorsal midbrain syndrome)
Syndrome characterized by a supranuclear palsy of vertical conjugate movements, convergence-retraction nystagmus, and light-near dissociation of the pupillary reflex; eyes may be forced downward; due to lesion of the dorsal midbrain including pressure on the it from hydrocephalus or increased intracranial pressure
Parkinson disease
Neurodegenerative disease characterized by resting tremor, bradykinesia/akinesia, rigidity, and postural instability due to loss of cells in the substantia nigra with striatal dopamine deficiency and residual Lewy bodies
Parkinsonism
Complex of symptoms including resting tremor, bradykinesia/akinesia, rigidity, and postural instability that are due to striatal dopamine deficiency or reduced function; may be seen in a variety of neurodegenerative disorders including idiopathic Parkinson disease, Lewy body dementia, corticobasal degeneration, progressive supranuclear palsy, multisystems atrophy
Parkinson plus syndromes
Primary neurodegenerative disorders associated with complex clinical presentations including parkinsonism that reflect degeneration in various neuronal systems in addition to the substantia nigra; parkinsonian features are characterized by symmetry of signs, truncal>appendicular signs, and lack of response to levodopa or dopamine agonists
Partial (focal) seizure
Seizure that starts in a single cortical region
Participation restrictions
Problems an individual may experience in their own involvement in life situations (e.g., inability to return to work).
Penumbra
Area surrounding the dense core of irreversibly damaged cells that has preserved ionic homeostasis and reduced neuronal electrical activity but that is capable of recovery
Pelvic Tilt
Position of pelvis � which can be normal or abnormal
Perception
Awareness and understanding of one's environment (e.g. awareness of touch, sights, sounds)
Perceptual neglect
Inability to distribute spatial attention to objects in the visual field
Perceptual skills
Ability to receive and distinguish information through the prime senses of vision, touch, taste, hearing and smell.
Periaqueductal gray
Tegmental gray matter surrounding the cerebral aqueduct within the midbrain that is important in the processing of pain
Perimetry
Visual field testing designed to determine the sensitivity of specific locations of peripheral and central vision
Perineurium
Connective tissue sheath surrounding a bundle of nerve fibers
Periodic limb movement disorder
Sleep disorder characterized by repetitive stereotyped movements during sleep, most commonly an extension of the big toe and dorsiflexion of the ankle; often associated with a partial arousal or awakening of which the patient is typically unaware
Peripheral nerve block injections
Injection of local anaesthetic in the vicinity of a peripheral nerve to anaesthetize the nerve's area of innervation and prevent pain signals from reaching the brain.
Peripheral nervous system
Nerve cell body, spinal nerve root, plexus, peripheral nerve, neuromuscular junction, and muscle
Perseveration
A persisting tendency to repeat actions or phrases of sentence. An ability to stop one activity and transfer to another.
Perisylvian plexus
Referring to structures around the Sylvian fissure; includes Wernicke's area in auditory association cortex and Broca's area in front of motor cortex
Perimysium
Connective tissue sheath surrounding a bundle of muscle fibres
Petit mal seizure
see absence seizure
Phonophobia
Abnormal intolerance to sound that commonly occurs in migraine and other headaches
Photophobia
Abnormal intolerance to light, usually associated with eye pain; characteristic of meningeal irritation, migraine, optic nerve disease, and ocular or retinal disorders
Physiologic tremor
Subtle low amplitude, high frequency tremor most easily observed in the hands that is present in healthy persons and most prominent during posture and action
Physiotherapist
A therapist who specialises in physical methods of treatment to promote healing and return to health and optimal functioning
Pia
Innermost layer of the meninges that is intimately applied to the surface of the brain parenchyma and spinal cord and separated from the arachnoid by the subarachnoid space
Pick�s disease
Form of frontotemporal dementia characterized by a slowly progressive deterioration of social skills and changes in personality in addition to impairment of intellect, memory, and language; defined pathologically by Pick bodies (rounded tau-posiotive inclusions similar to neurofibrillary tangles) and Pick cells (swollen or ballooned neurons) in a predominantly frontal location
Piedro Boots
Specialised footwear
Pincer grasp
Finger-thumb opposition
Pineal
Midline body attached to the posterior part of the third ventricle and lying between the superior colliculi, below the splenium of the corpus callosum; major site of melatonin biosynthesis
Pituitary apoplexy
Spontaneous hemorrhagic infarction of a typically large and nonfunctioning pituitary adenoma presenting with headache, nausea and vomiting, cranial nerve II, III, IV, or VI palsies, altered mental status, and hypopituitarism
Pituitary gland (hypophysis)
Endocrine organ lying ventral to the hypothalamus and optic chiasm; includes an anterior glandular lobe made up of hormone-secreting cells and a posterior neural lobe containing the terminals of neuropeptide-secreting, hypothalamic neurons
Placing (stepping) response
Normal neonatal reflex consisting of elevating the foot and moving it forward when its dorsal surface is touched; the infant will appear to attempt to stand or walk
Plantar response
Superficial (cutaneous) reflex elicited by applying a stimulus to the skin of the foot or leg; flexion (curling down) of all toes (�downgoing toe�) is a normal response, while extension of the great toe (�upgoing toe�) with fanning of the other toes is abnormal and signifies a lesion of the corticospinal tract. Many methods of eliciting the plantar reflex have been described, including the following:
Plegia
Inability to activate any motor neurons; paralysis
Polymyositis
Inflammatory muscle disease associated with primarily proximal limb weakness; considered to be an autoimmune disease of disordered cellular immunity and often associated with a specific collagen-vascular disease
Polysomnogram
Continuous and simultaneous recording of multiple physiological variables during sleep
Pons
Middle aspect of the brainstem, lying between the midbrain rostrally and the medulla caudally
POP
Plaster of Paris casts
Porencephaly
Cerebral hemispheric cyst that is usually the remnant of a destructive lesion (e.g., stroke or infection) or is due to abnormal brain development
Positive sharp wave
Spontaneous muscle activity seen on electromyography in association with denervation or irritable myopathy consisting of long action potentials with initial positive (down) wave followed by wide negative (up) wave
Positive symptom
Exaggeration of a physiological phenomenon; implies abnormal excessive (irritative�) discharges in gray matter or (e.g., seizure or hemifacial spasm) or chronic imbalance in complex integrated motor pathways (e.g., chorea)
Positron Emission Tomography (PET)
A sensitive medical imaging technique in which a pharmaceutical, marked or "labelled" with a radioactive substance, is injected into the patient to show how well cells are functioning. Useful for diagnosing brain disease, because brain tumours, strokes, and neuron-damaging diseases which cause dementia (such as Alzheimer's disease) all cause great changes in brain metabolism, which in turn causes easily detectable changes in PET scans.
Postdrome
Period following a migraine during which a person has impaired concentration, fatigue, or irritability
Posterior/Dorsal
Nearer the back of the body
Posterior cerebral artery
Paired arteries that arise from the top of the basilar artery; supply blood to the posterior areas of the brain, including the medial occipital lobes (visual cortex), the inferior temporal lobes, and thalamus
Posterior commissure
One of the three major groups of commissural fibres that crosses the midline of the epithalamus just dorsal to the point where the cerebral aqueduct opens into the third ventricle
Posterior communicating artery
Branch of the internal carotid artery that joins the middle cerebral artery (anterior circulation) to the posterior cerebral artery (posterior circulation); supplies thalamus, hypothalamus, optic chiasm, and mamillary bodies
Posterior cord syndrome
Spinal cord injury syndrome associated with damage to the posterior portion of the spinal cord resulting in bilateral loss of vibration /proprioception +/- bilateral weakness below the level of the lesion
Posterior fossa
Brainstem and cerebellum
Posterior horn (dorsal horn)
Gray matter in the back of the spinal cord that receives sensory information from the body through the dorsal root ganglia
Post-herpetic neuralgia
Condition following an acute varicella zoster infection (shingles) characterized by persistent pain (3 or more months) in the dermatomal distribution of the previous zoster rash
Postural instability
Loss of ability to make postural adjustments in response to perturbations, i.e., defect in righting reflex; common in Parkinson disease
Postural tremor
Tremor that occurs with the maintenance of a posture or position against gravity
Posture
Ability to stand upright automatically against gravity; controlled by the vestibulospinal, reticulospinal, and tectospinal pathways
Pott�s disease
Tuberculous involvement of the vertebral column with vertebral collapse
PMH
Past Medical History
PMLD
Profound and Multiple Learning Difficulties
Praxis
Ability to plan, time, sequence, and spatially organize skilled movements
Prefrontal cortex
Cortical region of the frontal lobe lying anterior to primary and premotor cortex; mediates various executive functions, with the dorsolateral division involved in working memory processes, planning, and decision making, and the ventromedial division involved in emotion and the organization of appropriate social behaviour
Premotor cortex
Cortical region (Brodmann's area 6) in the posterior frontal lobe anterior to the primary motor cortex involved in planning or programming of voluntary movements
Primary progressive
Clinical course of multiple sclerosis characterized from the beginning by progressive disease, with no plateaus or remissions, or an occasional plateau and very short-lived, minor improvements
Primary progressive aphasia
Progressive form of dementia characterized by global loss of language abilities and initial preservation of other cognitive functions; pathologically, there may be spongiform changes in the frontal and temporal lobes rather than Alzheimer-like changes
Primitive neuroepithelial tumor (PNET)
Tumor histologically similar to the medulloblastoma but located outside the posterior fossa
Prion
Proteinacious infectious agent responsible for various fatal brain diseases classified as spongiform encephalopathy
Prodrome
Premonitory phenomena occurring hours to days before headache onset in migraine consisting of psychological, neurological, or constitutional symptoms
Prognosis
Assessment of the future course and expected outcome of a patient's illness
Progressive multifocal leukoencephalopathy (PML)
Fatal demyelinating CNS disease of immunocompromised patients caused by reactivation of the JC papovavirus
Progressive supranuclear palsy (Steele-Richardson-Olszewski syndrome)
Parkinson plus syndrome characterized by predominantly axial rigidity, akinesia, supranuclear ophthalmoplegia (impairment of voluntary vertical gaze�downward more than upward), and pseudobulbar palsy
PROM
Passive range of Movement
Prone
Lying on tummy
Proprioception
Joint position sense
Proptosis (exophthalmos)
Abnormal protrusion of the eyeball
Prosencephalon
see forebrain
Prosody
Emotional content of language
Pseudoathetosis
Involuntary slow, writhing movements of a limb (usually the hand or fingers) occurring when the eyes are closed due to impaired proprioception. Unlike in athetosis, the movements are not present when the eyes are open because visual feedback provides the necessary information to know where the limb is in space
Pseudobulbar affect
Condition in which episodes of laughing and/or crying occur with no apparent precipitating event
Pseudobulbar palsy
Syndrome characterized by dysarthria, dysphagia, dysphonia, impairment of voluntary movements of tongue and facial muscles, and emotional lability; caused by diseases such as multiple sclerosis, motor neuron disease, and stroke that affect the motor fibers traveling from the cerebral cortex to the lower brainstem (i.e., corticobulbar tracts)
Pseudorosette
Spoke-wheel arrangement of cells with tapered cellular processes surrounding a blood vessel, creating a perivascular nuclear free zone; seen in most ependymomas and less commonly in other CNS tumors
Psychologist
A person qualified in the scientific study of the mind. A Clinical Psychologist is trained in the assessment and treatment of people with illness or impairment.
Ptosis
Eyelid droopiness
Pupillary light response
Contraction of the pupil on exposure of the retina to light; dependent on proper functioning of the optic and oculomotor nerves
Putamen
Largest and most lateral component of the basal ganglia
Pyramid
Prominent column of white matter on the ventromedial margin of the medulla containing axons of the corticospinal tract
Pyramidal tract
see corticospinal tract
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