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

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 sp ...

, or

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

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. 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 inju ...

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 or encephalitis or as a side effect of certain medications such as those used in anesthesia. 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 be ...

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 Hypertonia is a term sometimes used synonymously with spasticity and rigidity in the literature surrounding damage to the central nervous system, namely upper motor neuron lesions. Impaired ability of damaged motor neurons to regulate descending ...

) * paralysis of a limb (

monoparesis Monoplegia is paralysis of a single limb, usually an arm. Common symptoms associated with monoplegic patients are weakness, numbness, and pain in the affected limb. Monoplegia is a type of paralysis that falls under hemiplegia. While hemiplegia i ...

) 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 apha ...

(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) * 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, general retardation * "frontal release" signs, i.e. reappearance of primitive reflexes such as the

snout reflex The Snout reflex (also orbicularis oris reflex) or a "Pout" 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. This 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 an ...

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, dysgraphia,

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 Astereognosis (or tactile agnosia if only one hand is affected) is the inability to identify an object by active touch of the hands without other sensory input, such as visual or sensory information. An individual with astereognosis is unable to i ...

)

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 pro ...

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

cortical deafness Cortical deafness is a rare form of sensorineural hearing loss caused by damage to the primary auditory cortex. Cortical deafness is an auditory disorder where the patient is unable to hear sounds but has no apparent damage to the anatomy of the e ...

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, also known as receptive aphasia, sensory aphasia or posterior aphasia, is a type of aphasia in which individuals have difficulty understanding written and spoken language. Patients with Wernicke's aphasia demonstrate fluent ...

(Wernicke's aphasia) * amnesia, 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 vi ...

signs usually involve visual sensation, and may include: * total loss of vision (

cortical blindness Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the brain's occipital cortex. Cortical blindness can be acquired or congenital, and may also be transient in certain instances. Acquired cortic ...

) * 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 hemianopsia) *

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 The face is the front of an animal's head that features the eyes, nose and mouth, and through which animals express many of their emotions. The face is crucial for human identity, and damage such as scarring or developmental deformities may affe ...

* 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 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 intere ...

) * 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 cereb ...

signs usually involve balance and coordination, and may include: * cerebellar ataxia 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 ...

) * 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 Dysdiadochokinesia (DDK) is the medical term for an impaired ability to perform rapid, alternating movements (i.e., diadochokinesia). Complete inability is called adiadochokinesia. The term is from Greek ''δυς'' ''dys'' "bad", ''διάδοχο� ...

), 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 effectively ...

, usually with bilateral lesions; the speech has a halting jerking quality ( scanning speech or staccato speech)

Brainstem signs

Brainstem 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. Lesions ...

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 sp ...

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. 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 wit ...

. 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