Ataxias

At the base of an ataxic type symptomatology there may be damage to structures of the central or peripheral nervous system. Depending on the location of the lesion we can distinguish three main forms of ataxia:

Cerebellar ataxia (In principle, 2011). E’ a’ “central ataxia” (from injury to the central nervous system) due to lesions of the cerebellum or spino-cerebellar tracts (nerve pathways that connect the spinal cord with the cerebellum). The cerebellum plays a vital role in coordination of muscle movements. In order for it to play this role, it is essential that it receives, through the spino-thalamic pathways of the spinal cord, information from the rest of the body, necessary to work out the coordination of movements. Depending on the area involved, we can distinguish, broadly, a vermian cerebellar syndrome which mainly affects walking and maintaining an upright position (astasia cerebellare), it's a hemispheric cerebellar syndrome which occurs mainly at the level of the limbs ipsilateral to the lesion.

In cerebellar ataxia it is possible to find:

  • Ataxic cerebellar gait: is characterized by an enlargement of the support base (legs apart) and arms outstretched as a balance to maintain balance. The steps are of irregular amplitude and the patient has difficulty following a straight line path without lateral deviations and continuous regaining of the trajectory. In some cases, very serious, there is the impossibility of dembulating without support.
  • Asynergy or dysynergy. It is an alteration of the correct temporal sequences of muscle activation which leads to a lack of fluidity of movement. We often talk, in this case, of “breakdown of movement”, to underline its fragmented character. In the neurological examination, asynergy is evaluated with the index-nose test, the calcaneus-knee test, the proof of Babinski's synergy and the asynergy test of gait.
  • Disymmetry: inability to physically reach a target with a body district on the first shot (mano, foot) because we go further (hypermetry) or stop before its position (ipometria). We talk about braditelecinesia when the reaching movement shows a slowdown in the final phase. It is evaluated with index-nose and calcaneus-knee tests.
  • Adiadocokinesia: inability to perform alternating rapid movements. One of the best known tests for evaluating addocokinesia is the puppet test.
  • Nistagmo cerebellare (bidirectional)
  • Disartria. It consists in the alteration of the production of verbal language. There are several types of dysarthria. In the case of cerebellar ataxia this phenomenon is due to the alteration of the muscle activation sequence (asynergy). Characteristic of cerebellar dysarthria is “explosive word”, or pronounced in a disruptive way.
  • Disgrafia: it is the manifestation of asynergy and asymmetry in writing, which is extremely irregular.
  • Intentional tremor. It appears during the execution of the movements and is due to asynergy.
  • Postural tonic deviations of one or both upper limbs outwards or upwards.
  • Muscle hypotonia (ipotono cerebellare). It can be global or limited to one hemilate if the lesion has compromised a cerebellar hemisphere.
  • Other possible symptoms I'm: incoordination of eye movements, incontinence, difficulty swallowing

Sensory ataxia (In principle, 2011). It can be peripheral or central, depending on the level of the lesion, and it is due to a deficit of profound sensitivity. The injury may be due to peripheral neuropathies (bilateral and limited to the lower limbs in polyneuropathies) or impaired central nervous system in the spinal cord, of the thalamus or parietal lobe. It mainly manifests itself with:

  • Astasia sensitiva: difficulty maintaining an upright position, with loss of balance in all directions, which gets worse when the eyes are closed.
  • Ataxic sensitive gait. It is described as a gait with “step by parade” why patients walk “throwing” the legs forward and letting them fall heavily off the heel, to then bring the load to the tip of the foot. The gait of walking worsens considerably, with deviations in all directions, if the patient is asked to walk with his eyes closed.
  • Postural tonic deviations of one or both upper limbs outwards or upwards.
  • Deficit in deep feelings.

Vestibular ataxia (In principle, 2011). E’ a peripheral ataxia whose main feature is a balance disorder. It has the following clinical features:

  • Astasia vestibolare which worsens when the eyes are closed with loss of balance towards the injured side of the labyrinth.
  • Ataxic vestibular gait. It consists of a lateropulsion (lateral motor deviation) towards the injured side of the labyrinth, if the patient walks with his eyes closed. Rotation in the direction of the injured labyrinth while walking on the spot with eyes closed. Star running (if the patient is asked to go back and forth in a straight line, with closed eyes, in every change of direction of travel he will deviate towards the side of the damaged labyrinth. The resulting path will look like a star)
  • Postural tonic deviations. In the index deviation test, patients show a deviation of both indexes towards the side of the injured labyrinth.
  • Vestibular nystagmus: if manifested (rapid phase of nystagmus) towards the injured side of the labyrinth.
  • Dizziness

ETHIOPATHOGENESIS OF ATAXIA (Fazio-Loeb, 2019)

Ataxias can be due to several causes:

vascular or traumatic etiopathogenesis (ischemic or hemorrhagic stroke, emorragie sub-aracnoidee, aneurysm, head injuries etc.) for damage to those structures of the central nervous system, which we have already mentioned, whose impairment can lead to ataxic type symptoms: cerebellum, parietal lobe, thunderstorm, front, spinal cord;

autoimmune diseases; multiple sclerosis and other less known diseases.

toxic; it may be due to chronic alcoholism, medications, drugs (cocaine, heroin, phencyclidine, methadone), metal poisoning (mercury, lead, manganese, copper, aluminum, bismuth, thallium), from insecticides / pesticides and other substances.

Infectious; rubella, measles, varicella, mumps, poliovirus, mononucleosi, herpes simplex, legionella, toxoplasma, mycobacterium tubercolare, pathologies from prions etc.

deficiency pathologies; vitamin B1 deficiency; vitamin E deficiency.

hereditary genetic causes. The main hereditary ataxias are Friedreich's ataxia, spinocerebellar ataxias, telangiectatic ataxia, episodic cerebellar ataxias:

  • ATAXIA OF FRIEDRICH (Cambier, 2013). It is a’cerebellar ataxia autosomal recessive (the disease is only transmitted if both chromosomes contain the gene, transmitted by the two parents, present the pathological variant. If only one is passed on, the person who inherited it will be a healthy carrier and will be able to pass the gene on to their offspring.) each manifests them (rapid phase of nystagmus) towards the injured side of the labyrinth. The gene in question is called FRDA and encodes the mitochondrial protein fratassina. The disease is more serious the more the genetic code of the FRDA genes present on the two inherited chromosomes is altered. The severity of the frataxin impairment also affects the age of onset of the disease, which appears to be earlier in the most severe cases. The disease involves the establishment of degenerative processes that can involve: structures that carry information to the cerebellum, like the spino-cerebellar bundles (that conduct bodily information related to proprioceptive sensitivity, tactile…) e the piramidali life (carriers of information from the motor cerebral cortex); the cerebellum; the brain stem. Clinically, the predominant symptomatology is of the cerebellar type (with ataxic cerebellar gait and cerebellar dysarthria characterized by “explosive word”) and can also include areflexia, proprioceptive deficits, hollow foot, scoliosis but also a Babinski sign (due to impairment of the pyramidal pathways). In some cases, associations with heart disease are found, diabetes, Amyotrophy of Charcot-Marie-Tooth. A clinical picture comparable to that of Friedreich's disease may be due to a genetic deficiency of vitamin E. In this case it is possible to intervene by administering the missing vitamin.
  • ATASSIE SPINOCEREBELLARI (SCA) (Cambier, 2013). They are a group of autosomal dominant ataxias (only one copy of the defective gene is inherited to transmit the disease). They are due to mutations of different genes present in different points of our genome and more than thirty variants have been identified. The symptoms vary according to the different forms. The onset occurs on average between 30 e i 40 years of age.
  • TELEANGECTASIC ATAXIA (or Louis-Bar syndrome) (Cambier, 2013). E’ an autosomal recessive cerebellar ataxia due to the mutation of a gene involved in DNA repair mechanisms, present on the chromosome 11. Clinical symptoms begin in childhood. It involves the typical symptoms of cerebellar ataxia (due to atrophy of the cerebellar cortex), early and progressive onset, in association with conjunctival and cutaneous manifestations (telangiectasie) which can begin later, even after years. Telangiectasias are due to direct connection between veins and arteries without the intermediation of terminal capillaries and can also occur at the level of internal organs. Epistaxis is often present (nosebleeds) sporadic recurring. The presence of athetotic movements and apraxia of the oculomotor muscles is frequently found (that, in this clinical picture, it is expressed slowly in lateral and vertical eye movements. Furthermore, when the patient turns his head his gaze does not follow the rotation simultaneously, as is usually the case, but regains frontal vision with a long delay).
  • ATROFIE CEREBELLARI EPISODICHE (Cambier, 2013). It is an autosomal dominant group of inherited genetic disorders. Of the seven variants identified to date, the most common are two. The EA-1, which involves the appearance of episodes of short duration (a minute or two) of dysarthria and cerebellar ataxic type symptoms, due to a genetic defect in a potassium cell channel protein; the EA-2, which occurs with episodes of longer duration, from a few hours to a few days, characterized by cerebellar ataxia, disartria, vertigo and nystagmus. This second variant is due to an alteration of a potassium channel protein. The symptoms are triggered by stress and fatigue.

Rehabilitation

The cornerstone of the rehabilitation of ataxias are the exercises for balance and proprioceptive exercises. Among the first we find the rhythmic stabilizations of the Kabat method. It is an isometric reinforcement and co-contraction technique that, as its name also says, has the goal of giving stability to the different body districts. For the proprioceptive exercises the reference method of excellence is the Perfect but the application of the NeuroMuscular taping for its positive influence on proprioception. There are also other aspects not to be overlooked and underestimated in this pathology including the joint one. Problems with coordination and balance subject the joints to repeated stress, therefore it is good practice to consider also performing a joint treatment. The rehabilitation of ataxias, such as the rehabilitation of all pathologies, however, it must be tailor-made for each patient after careful evaluation.

BIBLIOGRAPHY

Fazio-Loeb neurology, 2019. Universe Publishing Company

Neurology. Jean Cambier, Maurice Masson, Catherine Masson, Henri Dehen. 2013. Edra Masson publisher.

The neurological examination. Normal and Pathological Pictures. Prencipe M., Piccin publisher 2011.