Focal neurologic signs also known as focal neurological deficits or focal CNS signs are impairments of

nerve A nerve is an enclosed, cable-like bundle of nerve fibers (called axons) in the peripheral nervous system. A nerve transmits electrical impulses. It is the basic unit of the peripheral nervous system. A nerve provides a common pathway for the ...

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

, or

brain The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special ...

function that affects a specific region of the body, e.g. weakness in the left arm, the right leg,

paresis In medicine, paresis () is a condition typified by a weakness of voluntary movement, or by partial loss of voluntary movement or by impaired movement. When used without qualifiers, it usually refers to the limbs, but it can also be used to desc ...

, or

plegia Paralysis (also known as plegia) is a loss of motor function in one or more muscles. Paralysis can also be accompanied by a loss of feeling (sensory loss) in the affected area if there is sensory damage. In the United States, roughly 1 in 5 ...

. Focal neurological deficits may be caused by a variety of medical conditions such as

head trauma A head injury is any injury that results in trauma to the skull or brain. The terms ''traumatic brain injury'' and ''head injury'' are often used interchangeably in the medical literature. Because head injuries cover such a broad scope of in ...

tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

s or stroke; or by various diseases such as

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion ...

encephalitis Encephalitis is inflammation of the Human brain, brain. The severity can be variable with symptoms including reduction or alteration in consciousness, headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hal ...

or as a side effect of certain medications such as those used in

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), a ...

. Neurological soft signs, are a group of non-focal neurologic signs.

Frontal lobe signs

Frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a groove b ...

signs usually involve the motor system and may include many special types of deficit, depending on which part of the frontal lobe is affected: * unsteady gait (unsteadiness in walking) * muscular rigidity, resistance to passive movements of the limbs ( hypertonia) * paralysis of a limb ( monoparesis) or a larger area on one side of the body (

hemiparesis Hemiparesis, or unilateral paresis, is weakness of one entire side of the body ('' hemi-'' means "half"). Hemiplegia is, in its most severe form, complete paralysis of half of the body. Hemiparesis and hemiplegia can be caused by different medi ...

) * paralysis head and eye movements * inability to express oneself linguistically, described as an

expressive aphasia Expressive aphasia, also known as Broca's aphasia, is a type of aphasia characterized by partial loss of the ability to produce language ( spoken, manual, or written), although comprehension generally remains intact. A person with expressive aph ...

(Broca's aphasia) *

focal seizure Focal seizures (also called partial seizures and localized seizures) are seizures which affect initially only one hemisphere of the brain. The brain is divided into two hemispheres, each consisting of four lobes – the frontal, temporal, parie ...

s that may spread to adjacent areas (

Jacksonian seizure Focal seizures (also called partial seizures and localized seizures) are seizures which affect initially only one hemisphere of the brain. The brain is divided into two hemispheres, each consisting of four lobes – the frontal, temporal, pari ...

) * grand mal or tonic-clonic seizures * changes in personality such as disinhibition, inappropriate jocularity, rage without provocation; or loss of initiative and concern, apathy,

akinetic mutism Akinetic mutism is a medical term describing patients tending neither to move ( akinesia) nor speak (mutism). Akinetic mutism was first described in 1941 as a mental state where patients lack the ability to move or speak. However, their eyes may f ...

, general retardation * "frontal release" signs, i.e. reappearance of primitive reflexes such as the snout reflex, the grasp reflex, and the palmar-mental reflex * unilateral loss of smell (anosmia)

Parietal lobe signs

Parietal lobe The parietal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The parietal lobe is positioned above the temporal lobe and behind the frontal lobe and central sulcus. The parietal lobe integrates sensory informa ...

signs usually involve somatic sensation, and may include: * impairment of tactile sensation * impairment of

proprioception Proprioception ( ), also referred to as kinaesthesia (or kinesthesia), is the sense of self-movement, force, and body position. It is sometimes described as the "sixth sense". Proprioception is mediated by proprioceptors, mechanosensory neurons ...

, i.e. postural sensation and sensation of passive movement * sensory and visual

neglect In the context of caregiving, neglect is a form of abuse where the perpetrator, who is responsible for caring for someone who is unable to care for themselves, fails to do so. It can be a result of carelessness, indifference, or unwillingness and ...

syndromes, i.e. inability to pay attention to things in certain parts of the person's sensory or spatial environment; this may be as extreme as denial of a limb * loss of ability to read, write, or calculate (

dyslexia Dyslexia, also known until the 1960s as word blindness, is a disorder characterized by reading below the expected level for one's age. Different people are affected to different degrees. Problems may include difficulties in spelling words, r ...

dysgraphia Dysgraphia is a learning disability of written expression, which affects the ability to write, primarily handwriting, but also coherence. It is a specific learning disability (SLD) as well as a transcription disability, meaning that it is a writ ...

dyscalculia Dyscalculia () is a disability resulting in difficulty learning or comprehending arithmetic, such as difficulty in understanding numbers, learning how to manipulate numbers, performing mathematical calculations, and learning facts in mathematics. ...

) * loss of ability to find a defined place (geographical

agnosia Agnosia is the inability to process sensory information. Often there 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. It is usually ...

) * loss of ability to identify objects based on touch ( astereognosia)

Temporal lobe signs

Temporal lobe The temporal lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The temporal lobe is located beneath the lateral fissure on both cerebral hemispheres of the mammalian brain. The temporal lobe is involved in proc ...

signs usually involve auditory sensation and memory, and may include: * deafness without damage to the structures of the ear, described as cortical deafness *

tinnitus Tinnitus is the perception of sound when no corresponding external sound is present. Nearly everyone experiences a faint "normal tinnitus" in a completely quiet room; but it is of concern only if it is bothersome, interferes with normal hearin ...

, auditory hallucinations * loss of ability to comprehend music or language, described as a sensory aphasia (Wernicke's aphasia) *

amnesia Amnesia is a deficit in memory caused by brain damage or disease,Gazzaniga, M., Ivry, R., & Mangun, G. (2009) Cognitive Neuroscience: The biology of the mind. New York: W.W. Norton & Company. but it can also be caused temporarily by the use ...

, memory loss (affecting either long- or short-term memory or both) * other memory disturbances, such as

déjà vu ''Déjà vu'' ( , ; "already seen") is a French loanword for the phenomenon of feeling as though one has lived through the present situation before.Schnider, Armin. (2008). ''The Confabulating Mind: How the Brain Creates Reality''. Oxford Univers ...

* complex, multimodal hallucinations * complex partial seizures (temporal lobe epilepsy)

Occipital lobe signs

Occipital lobe The occipital lobe is one of the four major lobes of the cerebral cortex in the brain of mammals. The name derives from its position at the back of the head, from the Latin ''ob'', "behind", and ''caput'', "head". The occipital lobe is the v ...

signs usually involve visual sensation, and may include: * total loss of vision ( cortical blindness) * loss of vision with denial of the loss (

Anton's syndrome Anton syndrome, also known as Anton's blindness and visual anosognosia, is a rare symptom of brain damage occurring in the occipital lobe. Those who have it are cortically blind, but affirm, often quite adamantly and in the face of clear evidenc ...

) * loss of vision on one side of the visual field of both eyes (

homonymous hemianopsia Hemianopsia, or hemianopia, is a visual field loss on the left or right side of the vertical midline. It can affect one eye but usually affects both eyes. Homonymous hemianopsia (or homonymous hemianopia) is hemianopic visual field loss on the sa ...

) *

visual agnosia Visual agnosia is an impairment in recognition of visually presented objects. It is not due to a deficit in vision (acuity, visual field, and scanning), language, memory, or intellect. While cortical blindness results from lesions to primary visual ...

s, i.e. inability to recognize familiar objects, colors, or faces * visual illusions such as micropsia (objects appear smaller) and macropsia (objects appear larger) * visual

hallucination A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combinati ...

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 system The limbic system, also known as the paleomammalian cortex, is a set of brain structures located on both sides of the thalamus, immediately beneath the medial temporal lobe of the cerebrum primarily in the forebrain.Schacter, Daniel L. 2012. ' ...

involves loss or damage to memory, and may include: * loss or confusion of long-term memory prior to focal neuropathy (

retrograde amnesia In neurology, retrograde amnesia (RA) is a loss of memory-access to events that occurred or information that was learned in the past. It is caused by an injury or the onset of a disease. It tends to negatively affect episodic, autobiographical, ...

) * inability to form new memories (

anterograde amnesia In neurology, anterograde amnesia is the inability to create new memories after the event that caused amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. ...

) * loss of, or reduced emotions (

apathy Apathy is a lack of feeling, emotion, interest, or concern about something. It is a state of indifference, or the suppression of emotions such as concern, excitement, motivation, or passion. An apathetic individual has an absence of inter ...

) * loss of olfactory functions * loss of decision-making ability

Cerebellar signs

Cerebellar The cerebellum (Latin for "little brain") is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. In humans, the cerebe ...

signs usually involve balance and coordination, and may include: *

cerebellar ataxia Cerebellar ataxia is a form of ataxia originating in the cerebellum. Non-progressive congenital ataxia (NPCA) is a classical presentation of cerebral ataxias. Cerebellar ataxia can occur as a result of many diseases and may present with symptoms ...

a gait with a broad base; the patient falters to the side of the lesion (

ataxia Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of t ...

) * inability to coordinate fine motor activities ( intention tremor), e.g. "past-pointing" (pointing beyond the finger in the finger-nose test) * inability to perform rapid alternating movements ( dysdiadochokinesia), e.g. inability to rapidly flip the hands * involuntary horizontal eye movements (

nystagmus Nystagmus is a condition of involuntary (or voluntary, in some cases) eye movement. Infants can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in reduced or limited vision. Due to the invol ...

) *

dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effectivel ...

, usually with bilateral lesions; the speech has a halting jerking quality (

scanning speech Scanning speech is a type of ataxic dysarthria in which spoken words are broken up into separate syllables, often separated by a noticeable pause, and spoken with varying force. The sentence "Walking is good exercise", for example, might be prono ...

or staccato speech)

Brainstem signs

Brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is ...

signs can involve a host of specific sensory and motor abnormalities, depending on which fiber tracts and

cranial nerve nuclei A cranial nerve nucleus is a collection of neurons ( gray matter) in the brain stem that is associated with one or more of the cranial nerves. Axons carrying information to and from the cranial nerves form a synapse first at these nuclei. Les ...

are affected.

Spinal cord signs

Spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spin ...

signs generally involve unilateral paralysis with contralateral loss of pain sensation.

Neurological soft signs

Neurological soft signs (NSS) are a group of minor non-focal neurological signs that include

synkinesis Synkinesis is a neurological symptom in which a voluntary muscle movement causes the simultaneous involuntary contraction of other muscles. An example might be smiling inducing an involuntary contraction of the eye muscles, causing a person to squ ...

. Other soft signs including clumsiness, and loss of fine motor movement are also commonly found in

schizophrenia Schizophrenia is a mental disorder characterized by continuous or relapsing episodes of psychosis. Major symptoms include hallucinations (typically hearing voices), delusions, and disorganized thinking. Other symptoms include social wi ...

. NSS likely reflect impairments in sensory integration, motor coordination, and the carrying out of complex motor tasks. When associated with schizophrenia the signs stop if clinical symptoms are effectively treated; and a consensus suggests that they may constitute a state marker for schizophrenia.

References

Essentials of Kumar and Clark's Clinical Medicine, 5th Edition. Saunders Elsevier, UK. 2012. page 725 {{DEFAULTSORT:Focal Neurologic Signs Symptoms and signs: Nervous system