Focal neurologic signs
Encyclopedia
Focal neurologic signs also known as focal neurological deficits or focal CNS signs are impairments of nerve
, spinal cord
, or brain
function that affects a specific region of the body, e.g. weakness in the left arm, the right leg, paresis
or plegia.
Focal neurological deficits may be caused by a variety of medical conditions such as head trauma , tumor
s or stroke
; or by various diseases such as meningitis
or encephalitis
or as a side effect of certain medications such as those used in anasthesia.
signs usually involve the motor system, and may include many special types of deficit, depending on which part of the frontal lobe is affected:
signs usually involve somatic sensation, and may include:
signs usually involve auditory sensation and memory, and may include:
signs usually involve visual sensation, and may include:
involves loss or damage to memory, and may include:
signs usually involve balance and coordination, and may include:
signs generally involve unilateral paralysis with contralateral loss of pain sensation
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
, spinal cord
Spinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
, or brain
Human brain
The human brain has the same general structure as the brains of other mammals, but is over three times larger than the brain of a typical mammal with an equivalent body size. Estimates for the number of neurons in the human brain range from 80 to 120 billion...
function that affects a specific region of the body, e.g. weakness in the left arm, the right leg, paresis
Paresis
Paresis is a condition typified by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it also can be used to describe the muscles of the eyes , the stomach , and also the vocal cords...
or plegia.
Focal neurological deficits may be caused by a variety of medical conditions such as head trauma , tumor
Tumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
s or stroke
Stroke
A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
; or by various diseases such as meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
or encephalitis
Encephalitis
Encephalitis is an acute inflammation of the brain. Encephalitis with meningitis is known as meningoencephalitis. Symptoms include headache, fever, confusion, drowsiness, and fatigue...
or as a side effect of certain medications such as those used in anasthesia.
Frontal lobe signs
Frontal lobeFrontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
signs usually involve the motor system, and may include many special types of deficit, depending on which part of the frontal lobe is affected:
- unsteadiness in walking
- muscular rigidity, resistance to passive movements of the limbs (hypertoniaHypertoniaHypertonia a condition marked by an abnormal increase in muscle tension and a reduced ability of a muscle to stretch. It is caused by lesions to upper motor neurons in the central nervous system, which carry information from the central nervous system to the muscles and control posture, muscle...
) - paralysis of a limb (monoparesisMonoplegiaIn medicine, monoplegia is a paralysis of a single limb, usually an arm. It is frequently associated with cerebral palsy. This is the mildest form of cerebral palsy, and individuals with it generally have a good prognosis for later life. It can also be used if just one muscle group or muscle is...
) or a larger area on one side of the body (hemiparesisHemiparesisHemiparesis is weakness on one side of the body. It is less severe than hemiplegia - the total paralysis of the arm, leg, and trunk on one side of the body. Thus, the patient can move the impaired side of his body, but with reduced muscular strength....
) - paralysis head and eye movements
- inability to express oneself linguistically, described as an expressive aphasiaExpressive aphasiaExpressive aphasia , also known as Broca's aphasia in clinical neuropsychology and agrammatic aphasia in cognitive neuropsychology, is caused by damage to or developmental issues in anterior regions of the brain, including the left posterior inferior frontal gyrus known as Broca's area...
(Broca's aphasia) - focal seizures which can spread to adjacent areas (Jacksonian seizureJacksonian seizureJacksonian seizure is associated with a form of epilepsy. They involve a progression of the location of the seizure in the brain, which leads to a "march" of the motor presentation of symptoms.-Presentation:...
) - grand mal or tonic-clonicSeizure typesThe numerous epileptic seizure types are most commonly defined and grouped according to the scheme proposed by the International League Against Epilepsy in 1981...
seizures - changes in personality such as disinhibition, inappropriate jocularity, rage without provocation; or loss of initiative and concern, apathy, akinetic mutismAkinetic mutismAkinetic mutism is a medical term describing patients who tend neither to speak nor move . It is the result of severe frontal lobe injury in which the pattern of inhibitory control is one of increasing passivity and gradually decreasing speech and motion.An example of a cause of this disorder...
, general retardation - "frontal release" signFrontal release signFrontal release signs are primitive reflexes traditionally held to be a sign of disorders that affect the frontal lobes. The appearance of such signs reflects the area of brain dysfunction rather than a specific disorder which may be diffuse such as a dementia, or localised such as a tumor.The only...
s, i.e. reappearance of primitive reflexes such as the snout reflexSnout reflexThe Snout reflex is a pouting or pursing of the lips that is elicited by light tapping of the closed lips near the midline. The contraction of the muscles causes the mouth to resemble a snout....
, the grasp reflex, and the palmar-mental reflex - unilateral loss of smell (anosmia)
Parietal lobe signs
Parietal lobeParietal lobe
The parietal lobe is a part of the Brain positioned above the occipital lobe and behind the frontal lobe.The parietal lobe integrates sensory information from different modalities, particularly determining spatial sense and navigation. For example, it comprises somatosensory cortex and the...
signs usually involve somatic sensation, and may include:
- impairment of tactile sensation
- impairment of proprioceptionProprioceptionProprioception , from Latin proprius, meaning "one's own" and perception, is the sense of the relative position of neighbouring parts of the body and strength of effort being employed in movement...
, i.e. postural sensation and sensation of passive movement - sensory and visual neglectHemispatial neglectHemispatial neglect, also called hemiagnosia, hemineglect, unilateral neglect, spatial neglect, unilateral visual inattention, hemi-inattention or neglect syndrome is a neuropsychological condition in which, after damage to one hemisphere of the brain, a deficit in attention to and awareness of...
syndromes, i.e. inability to pay attention to things in certain parts of the person's sensory or spatial environment. This can be as extreme as denial of a limb. - loss of ability to read, write or calculate (dyslexiaDyslexiaDyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...
, dysgraphiaDysgraphiaDysgraphia is a deficiency in the ability to write primarily in terms of handwriting, but also in terms of coherence. It occurs regardless of the ability to read and is not due to intellectual impairment...
, dyscalculiaDyscalculiaDyscalculia is a specific learning disability involving innate difficulty in learning or comprehending simple arithmetic. It is akin to dyslexia and includes difficulty in understanding numbers, learning how to manipulate numbers, learning maths facts, and a number of other related symptoms...
) - loss of ability to find a defined place (geographical agnosiaAgnosiaAgnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...
) - loss of ability to identify objects based on touch (astereognosia.AgnosiaAgnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...
)
Temporal lobe signs
Temporal lobeTemporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
signs usually involve auditory sensation and memory, and may include:
- deafness without damage to the structures of the ear, described as cortical deafness
- tinnitusTinnitusTinnitus |ringing]]") is the perception of sound within the human ear in the absence of corresponding external sound.Tinnitus is not a disease, but a symptom that can result from a wide range of underlying causes: abnormally loud sounds in the ear canal for even the briefest period , ear...
, auditory hallucinations - loss of ability to comprehend music or language, described as a sensory aphasiaReceptive aphasiaReceptive aphasia, also known as Wernicke’s aphasia, fluent aphasia, or sensory aphasia, is a type of aphasia traditionally associated with neurological damage to Wernicke’s area in the brain,...
(Wernicke's aphasia) - amnesiaAmnesiaAmnesia is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Memory appears to be stored in several parts of the limbic system of the brain, and any condition that interferes with the function of this system can cause amnesia...
, memory loss (affecting either long- or short-term memory or both) - other memory disturbances such as déjà vuDéjà vuDéjà vu is the experience of feeling sure that one has already witnessed or experienced a current situation, even though the exact circumstances of the prior encounter are uncertain and were perhaps imagined...
- complex, multimodal hallucinations
- complex partial seizuresSeizure typesThe numerous epileptic seizure types are most commonly defined and grouped according to the scheme proposed by the International League Against Epilepsy in 1981...
(temporal lobe epilepsy)
Occipital lobe signs
Occipital lobeOccipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
signs usually involve visual sensation, and may include:
- total loss of vision (cortical blindnessCortical blindnessCortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the visual area in the brain's occipital cortex. This damage is most often caused by loss of blood flow to the occipital cortex from either unilateral or bilateral posterior cerebral artery...
) - loss of vision with denial of the loss (Anton's syndrome)
- loss of vision on one side of the visual field of both eyes (homonymous hemianopsiaHomonymous hemianopsiaHemianopsia or hemianopia is visual field loss that respects the vertical midline, and usually affects both eyes, but can involve one eye only. Homonymous hemianopsia, or homonymous hemianopia occurs when there is hemianopic visual field loss on the same side of both eyes...
) - visual agnosiaVisual agnosiaVisual agnosia is the inability of the brain to make sense of or make use of some part of otherwise normal visual stimulus and is typified by the inability to recognize familiar objects or faces...
s, i.e. inability to recognize familiar objects, colors, or facesProsopagnosiaProsopagnosia is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact... - visual illusions such as micropsia (objects appear smaller) and macropsia (objects appear larger)
- visual hallucinationHallucinationA hallucination, in the broadest sense of the word, is a perception in the absence of a stimulus. In a stricter sense, hallucinations are defined as perceptions in a conscious and awake state in the absence of external stimuli which have qualities of real perception, in that they are vivid,...
s, displaying elementary forms, such as zig-zags and flashes, in one half of the visual field only for each eye. (In contrast, temporal lobe visual hallucinations display complex forms, and fill the entire visual field.)
Limbic Signs
Damage to the Limbic SystemLimbic system
The limbic system is a set of brain structures including the hippocampus, amygdala, anterior thalamic nuclei, septum, limbic cortex and fornix, which seemingly support a variety of functions including emotion, behavior, long term memory, and olfaction. The term "limbic" comes from the Latin...
involves loss or damage to memory, and may include:
- Loss or confusion of long-term memory prior to focal neuropathy (Retrograde amnesiaRetrograde amnesiaRetrograde amnesia is a loss of access to events that occurred, or information that was learned, before an injury or the onset of a disease....
) - Inability to form new memories (Anterograde amnesiaAnterograde amnesiaAnterograde amnesia is a loss of the ability to create new memories after the event that caused the amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. This is in contrast to retrograde amnesia, where memories...
) - Loss of, or reduced emotions (ApathyApathyApathy is a state of indifference, or the suppression of emotions such as concern, excitement, motivation and passion. An apathetic individual has an absence of interest in or concern about emotional, social, spiritual, philosophical or physical life.They may lack a sense of purpose or meaning in...
). - Loss of olfactory functions.
- Loss of decision making ability.
Cerebellar signs
CerebellarCerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
signs usually involve balance and coordination, and may include:
- unsteady and clumsy motion of the limbs or torso (ataxiaAtaxiaAtaxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
) - inability to coordinate fine motor activities (intention tremorIntention tremorIntention tremor, also known as cerebellar tremor, is a dyskinetic disorder characterized by a broad, course, and low frequency tremor. The amplitude of an intention tremor increases as an extremity approaches the endpoint of deliberate and visually guided movement...
), e.g. "past-pointing" (pointing beyond the finger in the finger-nose test) - inability to perform rapid alternating movements (dysdiadochokinesis), e.g. inability to rapidly flip the hands
- involuntary left-right eye movements (nystagmus)
Brainstem signs
Brainstem signs can involve a host of specific sensory and motor abnormalities, depending on which fiber tracts and cranial nerve nuclei are affected.Spinal cord signs
Spinal cordSpinal cord
The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
signs generally involve unilateral paralysis with contralateral loss of pain sensation