Cerebellar ataxia is a coordination disorder of motor skills caused by pathology of the cerebellum. Its main manifestations include gait disorder, disproportionality and asinergia of movements, dysdiadochokinesis, handwriting changes by the type of sweeping macrography. Usually cerebellar ataxia is accompanied by chanted speech, intentional trembling, postural tremor of the head and trunk, muscle hypotension. Diagnosis is carried out using MRI, CT, MSCT, brain MAG, Dopplerography, analysis of cerebrospinal fluid; if necessary, genetic studies. Treatment and prognosis depend on the causal disease that caused the development of cerebellar symptoms.
General information
Cerebellar ataxia is a symptom complex that includes specific violations of static and dynamic motor skills of a person and is pathognomonic for any diseases of the cerebellum. The same type of movement coordination disorders occur both with congenital defects of the cerebellum and with a variety of pathological processes in the cerebellum: tumors, multiple sclerosis, strokes, inflammatory and degenerative changes, toxic or metabolic damage, compression from the outside, etc. The degree of their severity varies significantly depending on the localization and size of the affected area of the cerebellum.
The nature of the disease can be judged by the accompanying symptoms of ataxia, as well as the peculiarities of the occurrence and course of pathological changes. The latter was the basis for the classification, which is used in their practice by many specialists in the field of neurology. According to it, cerebellar ataxia is distinguished with an acute onset, with a subacute onset (from 7 days to several weeks), chronically progressive (developing over several months or years) and episodic (paroxysmal).
Causes
The most common cause of acute cerebellar ataxia is ischemic stroke caused by embolism or atherosclerotic occlusion of the cerebral arteries, including feeding the cerebellar tissues. Hemorrhagic stroke, traumatic damage to the cerebellum as a result of TBI or its compression by the resulting intracerebral hematoma is also possible. Acute cerebellar ataxia can develop with multiple sclerosis, Guillain syndrome, postinfectious cerebellitis and encephalitis, obstructive hydrocephalus, various acute intoxications and metabolic disorders.
Subacute cerebellar ataxia most often occurs as a symptom of an intracerebral tumor (astrocytoma, hemangioblastoma, medulloblastoma, ependymoma) located in the region of the cerebellum, or meningioma of the bridge-cerebellar angle. Its cause may be normotensive hydrocephalus due to subarachnoid hemorrhage, meningitis or brain surgery. Cerebellar ataxia with subacute onset is possible with an overdose of anticonvulsants, vitamin deficiency, endocrine disorders (hyperparathyroidism, hypothyroidism). It can also act as a paraneoplastic syndrome in malignant tumor processes of extracerebral localization (for example, lung cancer, ovarian cancer, non-Hodgkin’s lymphomas, etc.).
Chronically progressive cerebellar ataxia is often a consequence of alcoholism, etc. chronic intoxication (including substance abuse and poly-drug addiction), slow-growing tumors of the cerebellum, genetically determined cerebral degenerative and atrophic processes with damage to the tissues of the cerebellum or its pathways, severe Chiari abnormality. Among the genetically determined progressive cerebellar-type ataxias, Friedreich’s ataxia, non-Friedreich spinocerebellar ataxia, Pierre-Marie ataxia, Holmes cerebellar atrophy, olivopontocerebellar degeneration (OPCD) are the most well-known.
Cerebellar ataxia with a paroxysmal course can be hereditary and acquired. Among the causes of the latter are TIA, multiple sclerosis, intermittent obstruction of the cerebrospinal tract, transient compression in the occipital foramen.
Symptoms
Cerebellar-type ataxia is manifested by sweeping, uncertain asynergic movements and a characteristic shaky gait, during which the patient spreads his legs wide for greater stability. When trying to walk along one line, there is a significant swinging to the sides. Ataxic disorders increase with a sharp change in the direction of movement or a rapid start of walking after getting up from a chair. Sweeping movements are the result of a violation of their proportionality (dysmetry). An involuntary stop of the motor act is possible before its goal is achieved (hypometry), as well as an excessive amplitude of movements (hypermetry). Dysdiadochokinesis is observed — the inability of the patient to quickly perform opposite motor acts (for example, supination and pronation). Due to coordination disorders and dysmetry, a pathognomonic change in handwriting occurs for cerebellar-type ataxia: macrography, unevenness and sweep.
Static ataxia is most evident when the patient tries to get into the Romberg pose. For pathology of the cerebellar hemisphere, a deviation, and even a fall, towards the lesion is typical, with changes in its median structures (the worm), a fall is possible in any direction or backwards. Conducting a finger-nasal test reveals not only a miss, but also an intentional tremor accompanying ataxia — trembling of the tip of the finger, which increases when it approaches the nose. Testing the patient in the Romberg pose with open and closed eyes shows that visual control does not particularly affect the results of the tests. This feature of cerebellar ataxia helps to differentiate it from sensitive and vestibular ataxia, in which the lack of visual control leads to a significant aggravation of coordination disorders.
As a rule, cerebellar ataxia is accompanied by nystagmus and dysarthria. Speech has a specific “cerebellar” character: it loses its smoothness, slows down and becomes intermittent, accents are on every syllable, which makes speech resemble chanting. Often, cerebellar-type ataxia is observed against the background of muscle hypotension and a decrease in deep reflexes. When tendon reflexes are triggered, pendulum-like movements of the limb are possible. In some cases, titubation occurs — a low-frequency postural tremor of the trunk and head.
Diagnostics
Since the pathology of the cerebellum can have a very diverse etiology, specialists in various fields are involved in its diagnosis: traumatologists, neurosurgeons, oncologists, geneticists, endocrinologists. A thorough neurologist’s study of the neurological status makes it possible to determine not only the cerebellar nature of ataxia, but also the approximate area of the lesion. Thus, hemiataxy, the unilateral nature of coordination disorders and a decrease in muscle tone indicate pathology in the cerebellar hemisphere; about the pathological process in the cerebellar worm — the predominance of walking and balance disorders, their combination with cerebellar dysarthria and nystagmus.
In order to exclude vestibular disorders, a study of the vestibular analyzer is carried out: stabilography, vestibulometry, electronistagmography. If an infectious brain lesion is suspected, a blood test is performed for sterility, and PCR studies are performed. Lumbar puncture with examination of the obtained cerebrospinal fluid allows you to identify signs of hemorrhage, intracranial hypertension, inflammatory or tumor processes.
The main methods of diagnosing diseases underlying the pathology of the cerebellum are neuroimaging methods: CT, MSCT and MRI of the brain. They make it possible to detect tumors of the cerebellum, post-traumatic hematomas, congenital anomalies and degenerative changes of the cerebellum, its prolapse into the large occipital foramen and compression with displacement of neighboring anatomical formations. In the diagnosis of vascular ataxia, MRA and dopplerography of cerebral vessels are used.
Hereditary cerebellar ataxia is determined by the results of DNA diagnostics and genetic analysis. The risk of having a child with pathology in a family where cases of this disease have been noted can also be calculated.
Treatment
The treatment of a causal disease is fundamental. If cerebellar ataxia has an infectious and inflammatory genesis, it is necessary to prescribe antibacterial or antiviral therapy. If the cause lies in vascular disorders, then measures are taken to normalize blood circulation or stop cerebral bleeding. For this purpose, angioprotectors, thrombolytics, antiplatelet agents, vasodilators, anticoagulants are used in accordance with the indications. With ataxia of toxic origin, detoxification is performed: intensive infusion therapy in combination with the appointment of diuretics; in severe cases, hemosorption.
Hereditary ataxia does not yet have a radical treatment. Metabolic therapy is mainly carried out: vitamins B12, B6 and B1, ATP, meldonium, ginko biloba preparations, piracetam, etc. To improve the metabolism in skeletal muscles, increase its tone and strength, massage is recommended for patients.
Tumors of the cerebellum and posterior cranial fossa often require surgical treatment. The removal of the tumor should be as radical as possible. When the malignant nature of the tumor is established, a course of chemo- or radiotherapy treatment is additionally prescribed. For cerebellar ataxia caused by occlusion of the cerebrospinal tract and hydrocephalus, bypass surgery is used.
Prognosis and prevention
The prognosis depends entirely on the cause of cerebellar ataxia. Acute and subacute ataxia caused by vascular disorders, intoxication, inflammatory processes, with timely elimination of the causal factor (occlusion of the vessel, toxic effects, infection) and adequate treatment, can completely regress or partially persist in the form of residual phenomena. Chronically progressive, hereditary ataxias are characterized by an increasing aggravation of symptoms, leading to disability of the patient. Ataxias associated with tumor processes have the most unfavorable prognosis.
Prevention of injuries, development of vascular disorders (atherosclerosis, hypertension) and infection; compensation of endocrine and metabolic disorders; genetic counseling during pregnancy planning; timely treatment of pathology of the cerebrospinal fluid system, chronic cerebral ischemia, Chiari syndrome, processes of the posterior cranial fossa.