Apraxia is a disorder of the ability to perform sequential actions while maintaining the necessary amount of sensory and motor functions. Occurs when various parts of the cortex, subcortical nodes are affected. It is diagnosed according to neurological examination data, including specific neuropsychological tests. The cause of the detected disorders is determined using neuroimaging methods (MRI, CT). Treatment of apraxia depends on the etiology of the lesion, is carried out with the use of medication, neurosurgical, rehabilitation techniques.
Praxis — translated from the Greek “action”, in the medical sense — is the highest nervous function that provides the ability to perform purposeful sequential actions. Training in the skillful performance of complex motor acts occurs in childhood with the participation of various zones of the cortex and subcortical ganglia. Subsequently, frequently performed daily actions reach the level of automatism, are provided mainly by subcortical structures. The loss of acquired motor skills with the preservation of the motor sphere, normal muscle tone was called apraxia. The term was first proposed in 1871. A detailed description of the violation was made by the German physician Lipmann, who created the first classification of pathology at the beginning of the XX century.
Violations of praxis occur when various parts of the brain are damaged: the cortex, subcortical formations, nerve pathways that ensure their interaction. Most often, apraxia accompanies damage to the frontal-parietal cortical areas. Damaging etiofactors are:
- Brain tumors. Intracerebral neoplasms (glioma, astrocytoma, ganglioneuroblastoma), sprouting into the cortex, subcortical centers, have a damaging effect on the zones involved in ensuring praxis.
- Strokes. Hemorrhagic stroke (cerebral hemorrhage) occurs with a rupture in the wall of a cerebral vessel, ischemic — with thromboembolism, spasm of cerebral arteries.
- Traumatic brain injuries. Apraxia is caused by direct damage to the cerebral areas responsible for praxis, their secondary damage due to the formation of post-traumatic hematoma, edema, ischemia, inflammatory reaction.
- Infectious lesions. Encephalitis, meningoencephalitis of various etiologies, brain abscess with localization of inflammatory foci in the cortex, subcortical ganglia.
- Degenerative processes. Diseases accompanied by progressive cortical atrophy: dementia, Peak’s disease, Alzheimer’s, alcoholic encephalopathy, corticobasal degeneration. Caused by chronic cerebral ischemia, toxic damage (alcoholism), dysmetabolic disorders (diabetes mellitus), genetic factors.
Risk factors that increase the likelihood of developing praxis disorders include age over 60, hereditary predisposition, hypertension, a history of stroke, cardiovascular diseases, chronic alcoholism.
The mechanism of formation of complex movements organized in time and space is under study. It is known that the neurophysiological basis of sequential actions is provided by a wide network of interneuronal contacts of various anatomical and functional zones of both hemispheres. Friendly work of all departments of the system is necessary to perform long-established and new actions. The predominant role of the dominant hemisphere is observed in the implementation of complexly organized movements aimed at solving a new task that lies outside the usual behavior. Apraxia occurs when the function of individual parts of the system is impaired under the influence of the above etiological factors. The complex organization of the praxis system, the entry of various cerebral structures into it provides a wide variability of the clinical picture, the existence of numerous types of apraxia.
The division of praxis disorders proposed by Lipmann according to the level of failure in the chain of formation of sequential action is used in foreign neurology at the present time. According to this classification , apraxia is divided into:
- Ideomotor. It is manifested by difficulties in performing simple motor acts. It is observed when the parietal lobe is affected in the region of the supracranial and angular gyrus, premotor zone, communication routes between them, interhemispheric cortical and cortical-subcortical connections.
- Ideatory. It is associated with the difficulties of consistently performing complex actions with the correct execution of their individual parts. Specific areas of cerebral damage have not been identified. Ideatory apraxia occurs when the parietal, frontal lobes, subcortical structures are affected.
- Limbic-kinetic. It is characterized by a lack of dexterity and speed of subtle movements, visible mainly in the fingers of the hand. Occurs contralateral to the lesion. A number of authors associate the limbic-kinetic form with damage to the premotor cortex of the frontal lobe, violation of its connections with basal structures. Other researchers point to the lack of clear differences between this pathology and mild motor disorders (pyramidal insufficiency).
Domestic neurologists use the classification of the founder of Soviet neuropsychology A.R. Luria, which assumes the separation of violations of praxis by the mechanism of their occurrence. Accordingly, apraxia is divided into:
- Kinetic — disorder of the dynamics of the act of movement, violation of transitions between individual simple movements that form a single complex action. Apraxia is bilateral in nature, less pronounced on the side of the lesion.
- Kinesthetic — violation of subtle actions (buttoning, tying shoelaces) due to the loss of the ability to select the necessary movements.
- Spatial — difficulties in performing spatially-oriented actions (dressing, making the bed). A separate subspecies is constructive apraxia — the loss of the ability to create a whole from separate parts.
- Regulatory — difficulties in planning, controlling, mastering the implementation of new complex actions.
Since the complex mechanism of praxis is not precisely established, some modern authors criticize these classifications and suggest distinguishing the forms of apraxia taking into account specific functional disorders. According to this principle, apraxia of dressing, apraxia of walking, apraxia of manipulating objects, etc. are distinguished.
A single clinical symptom is a disorder of performing actions while maintaining the necessary volume of sensorimotor function. Patients have no sensitivity disorders, paresis, pronounced changes in muscle tone. Their limbs are capable of performing movements at the level of a healthy person. The action is not realized due to the loss of the sequence of movements. Apraxia can occur against the background of other disorders of higher nervous activity (agnosia, amnesia), cognitive decline.
Kinetic apraxia is characterized by a violation of the smooth transition between successive elements of action, the patient “getting stuck” on the performance of a separate motor element. Rude awkward movements are typical. The disorder concerns both new and habitual actions. With the kinesthetic form, the patient is unable to perform subtle finger movements (to fasten / unbutton buttons, sew, tie knots), to give the hands the position shown by the doctor, in the process of action he cannot choose the necessary position of the fingers. The lack of visual control aggravates the situation. The patient loses the ability to demonstrate an action without an object (without having a cup, to show the movements necessary to pour water into a cup).
Spatial apraxia is manifested by a disorder of the ideas “right / left”, “top / bottom”, combined with spatial agnosia. The patient cannot dress himself, assemble an object from parts, and when the dominant hemisphere is affected, it is difficult to write letters. Regulatory apraxia is characterized by the preservation of simple, habitual actions against the background of disrupted performance of new ones. Motor acts are characterized by a pattern. The implementation of a new action program (tasks to light a candle with a match) is accompanied by slipping into simple automated operations (for smokers — an attempt to light a candle like a cigarette), the execution of a separate fragment (ignition and extinguishing of a match).
Persistent apraxia leads to disability, the degree of which depends on the form of pathology. The patient turns out to be professionally incompetent, often incapable of self-care. Awareness of one’s own defect causes severe psychological discomfort, contributes to social maladaptation.
Due to the lack of a unified classification, an accurate understanding of the pathogenesis and morphological substrate, the identification of apraxia is not an easy task for a neurologist. Diagnosis is carried out against the background of exclusion of other mechanisms of motor disorders, determination of the nature of cerebral lesions. The examination of the patient includes:
- Neurological examination. It is aimed at assessing the sensitive, motor, cognitive sphere. It helps to detect concomitant focal symptoms (paresis, sensitivity disorders, extrapyramidal hyperkinesis, cerebellar ataxia, cranial nerve dysfunction, memory and thinking disorders). Violations of praxis can be combined with paresis, hypesthesia. In such cases, the diagnosis of “apraxia” is established if the existing motor disorders do not fit into the framework of these disorders.
- Neuropsychological tests. A number of tests are carried out in which the patient performs actions according to the instructions, copies the poses and movements of the doctor, makes a whole of parts, performs actions with one or more objects and without them. Individual tests are carried out with closed eyes. The analysis of the results includes an assessment of the number and nature of test execution errors.
- Neuroimaging. It is performed using CT, MRI brain. It allows you to diagnose the lesion: tumor, stroke zone, abscess, hematoma, inflammatory foci, atrophic changes.
It is necessary to differentiate apraxia from extrapyramidal disorders, pyramidal insufficiency, sensory ataxia, cerebellar disorders, agnosia. The formulation of the diagnosis should contain an indication of the underlying disease (trauma, stroke, encephalitis, Alzheimer’s disease, etc.).
Therapy is carried out in relation to the causal disease. According to the indications, pharmacotherapy, neurosurgical treatment, restorative techniques are used.
Drug therapy includes:
- Improvement of cerebral hemodynamics. Vascular therapy for acute and chronic ischemic lesions is performed with the use of vasodilators (vinpocetine), thrombolytic (heparin), improving microcirculation (pentoxifylline) agents. In case of hemorrhagic stroke, aminocaproic acid preparations and angioprotectors are administered.
- Neuroprotective therapy. It is aimed at increasing the resistance of neurons to hypoxia, dysmetabolic shifts in acute disorders of cerebral circulation, injuries, inflammatory processes.
- Nootropic therapy. Nootropics (piracetam, gamma-aminobutyric acid, ginkgo biloba) increase the activity of neurons, improve interneuronal interaction, promotes the restoration of cognitive functions.
- Etiotropic treatment of neuroinfections. According to the etiology, antibiotic therapy, antiviral, antimycotic treatment is carried out.
Neurosurgical interventions are performed according to indications in order to restore intracranial blood supply, remove intracranial hematoma, abscess, tumor. Operations are performed by neurosurgeons urgently or as planned. Rehabilitation therapy is based on special classes with a rehabilitologist, which allow improving cognitive abilities, partially compensating for praxis disorder, adapting the patient to the neurological deficit that has arisen.
Prognosis and prevention
Apraxia has a different prognosis, directly depending on the nature of the causal pathology. After a stroke, TBI, encephalitis, the degree of recovery depends on the severity of the lesion, the age of the patient, and the timeliness of providing qualified medical care. Inoperable tumor processes and progressive degenerative diseases have an unfavorable prognosis. Preventive measures consist in the prevention of head injuries, infections, carcinogenic effects; timely treatment of cardiovascular diseases, cerebrovascular pathology.