Symptoms of damage to the parietal lobes

The temporal lobe is separated from the frontal by the central groove, from the temporal by the lateral groove, from the occipital by the imaginary line drawn from the upper edge of the parieto-occipital furrow to the lower edge of the cerebral hemisphere. On the outer surface of the parietal lobe there is a vertical postcentral gyrus and two horizontal lobes - the upper and the lower lobes, separated by a vertical furrow. The part of the lower parietal lobule located above the posterior part of the lateral sulcus is called the marginal (supramarginal) gyrus, and the part surrounding the ascending process of the upper temporal sulcus is the angular (angular) gyrus.

In the parietal lobes and postcentral convolutions, the afferent pathways of cutaneous and deep sensitivity terminate. Here, analysis and synthesis of perceptions from receptors of surface tissues and organs of motion are carried out. When these anatomical structures are damaged, sensitivity, spatial orientation and regulation of targeted movements are disturbed.

Anesthesia (or hypesthesia) of painful, thermal, tactile sensitivity, violations of joint-muscular sensation appear with lesions of postcentral convolutions. Most of the postcentral gyrus is occupied by the projection of the face, head, hand and fingers.

Astereregnosis is the unrecognition of objects when they feel them with their eyes closed. Patients describe individual properties of objects (for example, rough, with rounded corners, cold, etc.), but can not synthesize the image of the object. This symptom occurs with foci in the upper parietal lobe, next to the postcentral gyrus. When the latter is affected, especially in its middle part, all kinds of sensitivity for the upper limb drop out, so the patient is deprived of the opportunity not only to recognize the object, but also to describe its various properties (false asteroognosis).

Apraxia (disorder of complex actions with preservation of elementary movements) arises as a result of a lesion of the parietal lobe of the dominant hemisphere (in right-handers - the left hemisphere) and is detected with the functioning of the limbs (usually the upper limbs). Foci in the marginal gyrus (gyrus supramarginalis) cause apraxia due to the loss of kinesthetic images of actions (kinesthetic or ideator apraxia), and angular gyrus lesions (gyrus angularis) are associated with the disintegration of spatial orientation of the actions (spatial or constructive apraxia).

Patognomonichnym symptom in the defeat of the parietal lobe is a violation of the body scheme. This is expressed by the unrecognized or distorted perception of parts of his body (autopagnosia): the patients confuse the right half of the body with the left, can not correctly show the fingers of the hand when calling them by the doctor. Less common is the so-called pseudopolymelia - a sense of superfluous limb or other part of the body. Another type of disorder of the body scheme is anosognosia - the failure to recognize the manifestations of its disease (the patient, for example, claims to move his paralyzed left upper limb). We note that disorders of the body scheme are usually observed in lesions of the non-dominant hemisphere (right-handed - in right-handed people).

When the parietal lobe is affected in the region that borders on the occipital and temporal lobes (fields 37 and 39 are young in phylogenetic relation to education), the symptoms of disturbance of higher nervous activity are combined. Thus, the exclusion of the posterior part of the left angular convolution is accompanied by a triad of symptoms: finger agnosia (the patient can not call the fingers fingers), acalculia (account disorder), and violation of right-left orientation (Gerstman's syndrome). These disorders can be joined by alexia and the symptoms of amnestic aphasia.

The destruction of the deep sections of the parietal lobe results in a lower-quadrant hemianopsia.

Symptoms of irritation of the postcentral gyrus and parietal lobe manifest themselves paroxysms of paresthesia - various skin sensations in the form of crawling, itching, burning, electric current (sensory Jackson attacks). These sensations arise spontaneously. With foci in the postcentral gyrus, paresthesia usually occurs in limited areas of the body's covers (more often on the face, upper limb). Skin paresthesia before epileptic seizures is called somatosensory aura. Irritation of the parietal lobe posteriorly from the postcentral gyrus causes paresthesia immediately on the entire opposite half of the body.

Syndromes of local injuries of parietal lobes

I. Postcentral convolution

1. Elementary somatosensory disorders
   • Contralateral depression of sensitivity (a stereotype, a muscular-articulate feeling, tactile, painful, temperature, vibrational sensitivity)
   • Contralateral pain, paresthesia

II. The medial departments (cuneus)

1. Transcortical sensory aphasia (dominant hemisphere)

III. Lateral sections (upper and lower parietal lobules)

1. Dominant hemisphere
   • Dark apraxia
   • Finger agnosia
   • Acalculia
   • Right-Left Disorientation
   • Literalism
   • Alexia with agraea
   • Conducting aphasia
2. Non-dominant hemisphere
   • Anosognosia
   • Autopagnosia
   • Spatial disorientation
   • Hemicree neglect
   • Constructive apraxia
   • Apraxia dressing

IV. Epileptic phenomena, characteristic of parietal localization of epileptic focus.

Lesions of the parietal lobe are accompanied by various variants of agnosia, apraxia and spatial disorientation.

In addition to what has been said, many other neurological syndromes associated with parietal localization of brain damage have been repeatedly described in the literature. A rare syndrome is parietal ataxia. It develops in the defeat of those parts of the parietal lobe into which proprioceptive, vestibular and visual sensory flows converge, and is manifested by the decomposition of movements, hyper- and hypometry, and tremor.

Often also describe the atrophy of the muscles (especially the arms and shoulder girdle) on the opposite half of the body, which sometimes precedes the paresis with slowly flowing pathological processes.

Dark lesions in the first three years of life are sometimes accompanied by a lag in the growth of bones and muscles in the opposite half of the body.

Manual and oral apraxia, hypokinesia, echopraxia, paratonia (gegenhalten) are described.

Variants of thalamic syndrome sometimes develop with parietal damage. In processes in the posterior parts of the parietal lobe, visual disturbances may appear in the form of visual field defects. One-sided visual neglect (neglect or inattention) can be observed without a visual field defect. Violations of visual perception (metamorphopsia) can occur in both bilateral and unilateral lesions (more often on the right). There are separate indications of the possibility of the appearance of violations of follow-up movements of the eyes and optokinetic nystagmus, a nebulous decrease in intelligence, mental blindness, finger agnosia (in the picture of Gerstman's syndrome), disorientation of the spatial orientation (the posterior parts of the parietal lobe play a special role in visual-spatial focus, visual attention to this or that place of the surrounding space). The phenomenon of "perfect indifference" is also described in the syndrome of hemispheric ignoring, deterioration in the recognition of emotional vocalization, and depression.

I. Postcentral gyrus.

Lesions of this region are manifested by well-known somatotopically organized contralateral disorders of sensitivity (disturbances of stereognosis and muscular-articular sensation, tactile, painful, temperature, vibrational hypesthesia) and contralateral paresthesias and pains.

II. Medial parts of the parietal lobe (precuneus)

The medial parts of the parietal lobe (precuneus) face the interhemispheric fissure. Lesions of this region in the left (dominant by speech) hemisphere can be manifested transcortical sensory aphasia.

III. Lateral sections (upper and lower parietal lobes).

The defeat of the dominant (left) parietal lobe, especially gyrus supramarginalis, is manifested by the typical parietal apraxia observed in both hands. The patient loses the skills of habitual actions and expressed cases becomes completely helpless in dealing with this or that subject.

Finger agnosia inability to recognize or name individual fingers both in itself and in another person - most often caused by damage to gyrus angularis or the nearby zone of the left (dominant) hemisphere. Akalkuliya (inability to perform simple counting operations) is described in case of damage to various parts of the cerebral hemispheres, including lesions of the left parietal lobe. Sometimes the patient confuses the right side with the left (right-left disorientation). With the defeat of the angular convolution (gyrus angularis), there is an alexia - the loss of the ability to recognize written signs; the patient loses the ability to understand what was written. At the same time, the ability of writing is also violated, that is, it develops alexia with agraphia. Here, agrarianism is not so rough as when the second frontal gyrus is affected. Finally, the defeat of the parietal lobe of the left hemisphere can lead to the appearance of symptoms of conduction aphasia.

Pathological processes in the parietal lobe of the non-dominant hemisphere (for example, a stroke) can be manifested by anosognosia, in which the patient does not realize his defect, most often paralysis. A more rare form of agnosia is autotopagnosy - a distorted perception or non-recognition of parts of one's own body. In this case, there are symptoms of a distorted body scheme ("hemideperation"), a difficult orientation in parts of the body, a sense of having false limbs (pseudomelia). A violation of spatial orientation is possible. The patient, for example, begins to experience difficulties in any actions that require orientation in space: the patient is not able to describe the way from home to work, can not navigate in a simple plan of the terrain or in terms of his own room. The most noticeable symptom of damage to the inferior parietal lobule of the non-dominant (right) hemisphere is hemispheric contralateral ignoring (neglect): a distinct tendency to ignore events and objects in one half of space contralateral to the damaged hemisphere. The patient may not notice the doctor if the latter is standing by the bed on the side opposite to the hemispheric damage. The patient ignores the words on the left side of the page; trying to find the center of the horizontal line, he points to it, significantly shifting to the right, etc. Perhaps the emergence of constructive apraxia, when the patient loses the ability to perform even elementary actions that require clear spatial coordinates. Described apraksiya dressing with a lesion of the right parietal lobe.

The pathological focus in the lower parietal lobule is sometimes manifested by the tendency not to use a hand contralateral to damage, even if it is not paralyzed; she finds embarrassment when performing manual tasks.

Neurological syndromes of the parietal lobe can be summarized in another way:

Any (right or left) parietal lobe.

1. Contralateral hemihypesthesia, a violation of the sense of discrimination (with the defeat of the posterior central gyrus).
2. Hemispheric neglect.
3. Changes in the size and mobility of the contralateral limb, including muscle volume and lag in children.
4. Pseudothalamic syndrome
5. Disturbance of follow-up movements of the eyes and optokinetic nystagmus (with parietal associative cortical lesion and deep white matter).
6. Metamorphopsia.
7. Constructive apraxia
8. Parietal ataxia (the retrograde area).

Non-dominant (right) parietal lobe.

1. Constructive apraxia
2. Spatial disorientation
3. Deterioration of speech information recognition
4. Affective disorders.
5. Unilateral spatial disregard.
6. Apraxia dressing.
7. Attention disorders, confusion.
8. Anosognosia and autopagnosia

Dominant (left) parietal lobe.

1. Aphasia
2. Dyslexia
3. Agra.
4. Manual apraxia
5. Constructive apraxia.

Both parietal lobes (simultaneous defeat of both parietal lobes).

1. Visual agnosia.
2. Balint (strongalint) syndrome (develops in the defeat of the parieto-occipital region of both hemispheres) - a patient with normal visual acuity can simultaneously perceive only one subject; apraxia).
3. Rude visual and spatial disorientation.
4. Rough constructive apraxia.
5. Autopopognosy.
6. Bilateral heavy ideomotor apraxia.

IV. Epileptic paroxysmal phenomena, characteristic for parietal localization of epileptic focus.

Sensory areas. Primary sensory area.

1. Paresthesia, numbness, rarely - pain in the opposite half of the body (especially in the hand, forearm or face).
2. Jacksonian touch march
3. Bilateral paresthesias in the legs (paracentral lobe).
4. Taste aura (the lower Rolandic region, islet).
5. Paresthesia in the tongue (numbness, tension, cooling, tingling)
6. Abdominal aura.
7. Bilateral facial paresthesia
8. Genital paresthesia (paracentral lobe)

Secondary sensory area.

1. Bilateral bilateral (without involving the face) paresthesia, sometimes painful.

Additional sensory area.

1. Bilateral paresthesias in the extremities.

Posterior and parietal-occipital region.

1. Hallucinations.
2. Metamorphopsia (mainly in the defeat of the non-dominant hemisphere).
3. Photopsy.
4. Macropses or micropsions.
5. Dizziness (this symptom may be due to the involvement of temporal lobe structures in the discharge).

Speech symptoms.

1. Ictal aphasia
2. Stop speech

Non-dominant parietal lobe.

1. Ignoring the opposite half of the body (asomatognosia).

Poorly localized phenomena.

1. Intraabdominal paresthesia
2. Dizziness.

[1], [2], [3], [4], [5]