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Ataxia telangiectasia is also a progressive neurological disease. This section describes how the different parts of the body are affected.

The process of movements is a very complex phenomenon that involves many parts of the nervous system.

In Ataxia telangiectasia, the cerebellum is mainly affected, but not only.

 

Ataxia

In "Ataxia Telangiectasia," there is "Ataxia".

Ataxia is a balance disorder that is linked to a lack of coordination of orders coming from the cerebellum. There is a lack of fine coordination of voluntary movements.

 

Disorders

During voluntary movement, there is a usual balance between the agonist muscles (active) and antagonist (inhibitory).

In AT, there is a rebound effect: there is no brake in the movement, the subject is over the target due to a late braking action of antagonistic muscles. Ataxia is manifested primarily by troubles in gait, balance and standing, accuracy and movement guidance by sight.

These neurological disorders are exacerbated by fatigue, stress, infections and in maintaining unbalancedposture . Conversely, a appropriate sitting position allows to limit the magnitude of abnormal movements.

 

Thumbnail imageCommand centers

Ataxia in the OT is not related to muscle weakness or peripheral neuropathy (nerve damage).

Ataxia is also different from balance disorders and dizziness due to damage in vestibular centers (systems located in the inner ear, which measure the posture of a person in space).

Control and transmitting movements centers potentially affected in ataxia telangiectasia are:

  • The basal ganglia
  • The cerebellum
  • The brainstem

 



The basal ganglia

Thumbnail imageDepending on the country, they include the thalamus or not. (see diagram cons

All their functions are not yet known, but their role in motility is demonstrated, both for involuntary movements such as the unconscious maintenance of a posture, or for voluntary movements such as walking or talking.

The basal ganglia communicate with each other through chemicals, neurotransmitters. The harmony of the movement is the result of fine tuning between activating and inhibitory neurotransmitters.

They are also affected in other diseases such as Parkinson's, where, as in AT, there are problems of tone (rigidity) and unwanted movements.

The cerebellum

cervelet3The cerebellum is the center of the fine coordination of muscle movements and balance control: it controls the fine dosing to apply to the muscles for a given action.

When injured as in AT, in addition to impaired balance and rebound phenomenon described above, speech may also be affected.

For patients with AT, it is particularly Purkinje cells (see below) that are affected.

The information that emerges from the cerebellum is conveyed to the muscles through the spinal cord and peripheral nerves.

Thumbnail imagePurkinje cell

The Purkinje cell is a specific type of neuron in the cerebellum. It is a "communication" cell.

Neurons communicate with each other through synapses to form a network. The Purkinje cell is the central element of synaptic network of the cerebellum, that is to say the majority of neurons that make up the cerebellum is connected to the Purkinje cells.

To take one example, the Purkinje cell is a bit like an old phone system operator who was connected with all the lines of the network, receiving all communications and distributing them in the right place. In the modern era, it would be a switch in a computer network.

It is known that these cells are progressively damaged in ataxia telangiectasia, bringing with them a dysfunction of the cerebellum.


The brainstem

tronc-cerebral1The brain stem connects the base of the brain to the spinal cord. It controls among others basic involuntary functions of life such as breathing. It also develops reflexes orders of maintaining balance.

When injured, dysarthria can also appear (difficulty with speech, cf Speech) and / or dysphagia (difficulty in swallowing - see Swallowing)



Peripheral nerves

They transmit motor or sensory information from the spinal cord to muscles (motor) or to the sensitive sensors (hot, cold, pressure, position in space).

In AT, it seems that dysfunctions of peripheral nerves are revealed with age, which may result in some muscle weakness and sensory loss. But generally, central nervous system disorder masks this phenomenon.


Process in AT

In ataxia telangiectasia, the absence of the protein encoded by the ATM gene impacts, according to the procedure described in chapter "ATM: DNA controller", the regeneration of cells or their maintenance in good working condition.

In the central nervous system where neurons do not multiply, the absence of ATM protein might disrupt homeostasis, that is to say, nutritional support and environment of nerve cells. This is known as degeneration of nerves and nerve cells.

Thumbnail imageNevertheless, therapeutic approaches are followed. Among them, the role of growth factors. Following recent discoveries, they seem to impact the rate of degradation. Thus, the growth hormone GH and its mediator IGF-1 (cf Growth et Diabetes) appear to affect the production of myelin, the insulation of neurons playing the same role as an electrical wire insulation. And it has been shown that the absence of ATM protein disrupts the production and regulation of these molecules for growth.

A team of German researchers have noted a lengthening of life span and neurological and immunological improvement on laboratory AT mice who received growth hormone. Far from declaring victory, this discovery gives hope to delay the effects of the degeneration in AT, thus saving time.

In line with this idea, another German program has just begun on children with ataxia telangiectasia.

Another symptom of AT is the increasing difficulty for the person to use their look and follow a target.

This oculomotor disorder must be taken into account with adjustments in everyday life.

Telangiectasia in the eyes are a completely mild symptom, if not the aesthetic discomfort. They have nothing to do with neurological problems that can impair vision.

 

Oculomotor apraxia

Description
Normally, when a noise attracts attention to one side, the eyes are preceeding the head movement of a few tenths of seconds. Conversely, in AT, the head will turn first, then the eyes will follow, but in short jerks. Same thing when it comes to track an object or even fix it, which eventually cause problems, including learning in class to look up and decipher what is written on the blackboard, or even to read. However adaptations are possible.(cf Computer: a tool et For teachers)

Thumbnail imageAffected areas

In the brainstem are located coordination centers of lateral eye movements. These centers receive three types of information:

  • From the frontal lobe of the brain, the order to wear his eyes on an object (will)
  • From the occipital lobe, the order of tracking if the subject moves (vision)
  • Information from the organ of balance in the ear for coordinating body position and gaze

Unlike the first two, this latter function is not affected in AT.

Treatment
Oculomotor apraxia is different from strabismus which is due to impairment of oculomotor muscles.

On other forms of apraxia, treatments are possible, with satisfactory results, based on botulinum toxin injections of the same family as the much more publicized used to eliminate wrinkles ...

Télangiectasies

Although present more prominently in the eye, télangiectasias are also found on the body and have no connection with apraxia described above. That's why they are developed in chapter "Skin / mucous membranes".

Communication by speech and expression is also impaired in ataxia telangiectasia.

Talk is an effort to patients with AT, which increases their fatigue.

These patients need time to express themselves, so man has to be careful and do not stop at their facial expressions that rarely reflect their actual mood of the moment.



With swallowing which could have joined also this chapter, the degeneration of the cerebellum may cause difficulties in speech articulation and control of facial expressions in patients with AT.



Mechanism of speech

Talking consists in emitting a series of coded sounds understandable by others.

The code of speech, the language, is a purely cognitive mechanism connected to the brain as evidenced by the diversity of languages ??spoken on Earth.

Thumbnail imageHowever, produce sounds and reflect his emotions by his gestures and expressions is a neuromuscular phenomenon involving:

  • the brain
  • peripheral nerves
  • the throat
  • the mouth
  • the chest (breath)



The process of speech is as follows:

  • muscles of the chest (rib cage, diaphragm and abdomen) regulates the expiration to modulate the intensity of sound, its length and pauses between breaths
  • sound is produced during the passage of air through the larynx and vocal cords
  • articulation is ensured by the muscles of the mouth: the cheeks, tongue, lips and palate to punctuate the sounds.



Speaking difficulties

The interconnections between the different functions are numerous in the face (jaw , tongue and face mobility, absorption, swallowing, breathing, ...). When one or more systems are affected, many difficulties may occur. This is the case for Ataxia Telangiectasia but in this area too, difficulties are different among concerned people. The neurological disorder disturbs the smooth coordination of all muscles involved in the process of speech and expression of emotions in the face. In addition, due to lung infections, respiratory capacity of people with AT can be reduced. The combined effects of these factors are:

  • People with AT have gradually trouble to start their sentence: the thought is clear but the action does not follow. They need more time to speak, which may suggest that they are reluctant, that they do not have the knowledge or are indifferent.
  • Efforts are noticeable on the face and expressions do not necessarily reflect the meaning of the sentence.
  • Then, the flow of words can be very fast but then the sentence will be short.
  • Sometimes, even if known, some AT patients have trouble finding a word which can make discussions around a specific vocabulary difficult.
  • Articulation difficulties can make the words harder to understand.



Communication difficulties

Thumbnail imageConsequences are numerous and various:

  • On the physical level, people with AT have to provide huge efforts to speak, which may end by tiring and discouraging them to express themselves in society.
  • Communication attitudes and expressions are at least as important as speaking: having a hypotonic face not accompanying emotions with expressions that match is a handicap in communication.
  • The communication from AT patients may be prone to misinterpretation, especially at school.
  • Communication is essential in the social life of a person. Imagine having all your thought and not being able to express it spontaneously, without a significant effort and the risk of not being understood the first time! On the psychological level, frustration is the first feeling taking hold.



Solutions

The immediate solutions are simple to implement. They are:

  • Inform the whole family, teachers , friends ...
  • Be patient, allow time for the person with AT to speak and especially terminate, not wanting to help finish by completing the end of his sentences.
  • Maintain good lung capacity by a suitable work of physical therapy, sport activities and basic precautions to keep away from infections.
  • Handle the psychological aspect of this difficulty which, if not the worst on the single criterion of dangerousness, is paramount in the construction of children with AT.
  • Consult a SLP who may, at first, assess the disability and follow it and secondly, propose a number of techniques for improving articulation. qui pourra, dans un premier temps, évaluer ce handicap et en assurer un suivi et, dans un deuxième temps, proposer un certain nombre de techniques susceptibles d'améliorer l'articulation.

Over time, swallowing becomes a source of difficulties for people with AT.

In addition to efforts that feeding demand, the risks are choking and inadequate nutritional intake.

Adaptive techniques and rehabilitation can minimize these problems.

 

Feeding involves:

  • bringing food to mouth
  • swallowing

In the picture of the Ataxia Telangiectasia may appear swallowing disorders, that is to say, the ability to swallow food, liquids or even his own saliva. This difficulty is clearly part of neurodegenerative disorders (see "Body control") and appears only progressively.

Swallowing

Man swallows approximately 600 times per day. There are three phases in swallowing:

swallow3Phase 1 : in the mouth
Phase 1: in the mouth The oral stage is the preparation for swallowing. Mixed with saliva, food is crushed to be better swallowed.

Phase 2 : in the throat
When swallowing starts, a sequence of very fast muscle contractions (<1s) implements and involves:

  • the tongue/li>
  • the vault of the palate
  • the epiglottis
  • the pharynx
  • the larynx (vocal cords)
  • a muscle at the top of the esophagus

Phase 3 : in the esophagus
The esophagus carries food crushed and mixed with saliva to the stomach and it must empeach it to get back.

Problems by phases

Each phase is characterize by a particular problem but once again, they aren't necessarily simultaneous. They are:

Phase 0: before reaching the mouth

Being able to bring food to the mouth. What seems elementary quickly becomes a source of fatigue with a neurodegenerative syndrome. Some simple solutions can facilitate this step.

Phase 1 : in the mouth
Leaks from the mouth: during chewing, it may not be sealed by the lips and the ability to keep a piece of food which attempts to escape may be lost. Difficulty chewing: length to form a ball capable of being swallowed = fatigue.

Phase 2 : in th throat
Particularly among adolescents with AT: problems of coordination in the swallowing sequence. This leads to silent wrong ways without reflexes such as coughing or retching heart to clear the airway of food who want to intrude. Moreover, these body reflexes also give warning of a problem to the entourage who can react quickly...but in AT, on warnings! The wrong ways, ie the content of the mouth that goes to the lungs instead of the esophagus are favored, even dangerous, which can increase the ENT and pulmonary infections.

Phase 3 : In the esophagus
Stomach reflux: acid reflux is usually not pleasant, but in AT, the major risk is the wrong way with a very aggressive stomachal liquid. In the same way as gastroesophageal reflux disease in young children, the fact of introducing foreign objects into the path to the lungs can cause lung infections, still complicated for AT patients.

Risks

Swallowing mouth control problems can cause:

  • Respiratory infections
  • risk of suffocation by silent wrong ways
  • deficiencies in essential nutrients that were not absorbed in sufficient quantity
  • salivation sometimes important for children with AT, saliva escaping sometimes.

 

Treatment

This is a specialty ofSLP (Speech and Langage Pathologist to treat this problem. Looking at drugs, beta blockers have sometimes been used, but with mixed results.

Intellectual abilities are not affected in ataxia telangiectasia.

It is very important to let it know by everyone so that the child with AT can take its rightful place in the social life, especially at school.

The psychological impact of this aspect concerning integration and self-confidence must always be taken into account, and consideration by others is the main factor.

Ataxia Telangiectasia does not affect the intellect. One can even say that, by necessity and the will to seek to offset the difficulties by themselves, children with AT develop a unique form of intelligence.

The first consequence is that a child with AT is intellectually capable of following a regular school program and can aspire to higher education. It can, like everyone else, follow a conversation and participate, provided that he's given time to speak and people around make an effort to understand him when speech problems are emerging.

In countries where access and acceptance of disabled suffer a huge delay, the challenges lie in the consideration of the disabling symptoms of the disease, their impact on integration in schools and on learning techniques and traditional communication.

The main objective is therefore to seek and develop tools and resources needed around the patient with AT for his personality finds its rightful place in society. (See « Living with AT»).

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