Oculomotor Apraxia: Symptoms, Treatment, and Possible Causes

Oculomotor apraxia is the inability to make horizontal eye movements voluntarily. or under a verbal order.

It was described by Cogan in 1952 and its etiology is unknown to this day. Let's see, in more detail, what this congenital disease consists of.

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What is oculomotor apraxia?

Oculomotor apraxia or apraxia of gaze can occur both in an acquired and congenital way.. This second form is an inherited disorder that affects the eye and is generally present from birth.

It consists of an alteration of brain function characterized by the inability to execute horizontal eye movements voluntarily, or under the verbal order of another person.

It is a condition, of still unknown causes, generally considered as a sporadic disorder, although there have been described cases with autosomal dominant inheritance (when a single copy of the gene allele is enough for the disease to manifest itself) express).

The patient suffering from oculomotor apraxia cannot voluntarily change the direction of gaze to the sides,

neither presents the rapid phase of vestibulo-ocular nor optokinetic reflexes (responsible for stabilizing the gaze to obtain clear images).

Causes

Although the causes responsible for the appearance of a condition such as oculomotor apraxia in newborn children have not yet been identified, it has been suggested that most of them could have developed Joubert syndrome, a genetically transmitted disorder.

This syndrome would cause partial metabolic alterations or developmental defects neurological, such as hypoplasia (incomplete development) of the cerebellar vermix, aplasia (absence of Development of hard body, gray matter heterotopias, Kallman syndrome or chromosomal abnormalities.

differential diagnosis

To establish an accurate diagnosis of oculomotor apraxia other causes should be ruled out, such as fixation defects and abnormal head movements: visual deficits due to eye problems, mobility disorders, spasms or psychomotor retardation.

Furthermore, the patient must maintain vertical saccadic movements (both volunteers and vestibulo-ocular and optokinetic reflexes). However, it should be noted that in acquired oculomotor apraxia, secondary to other central nervous system lesions, vertical movements are also affected.

main features

Cogan identified several key features characteristic of congenital oculomotor apraxia.

First of all, it highlights the sudden turn of the head in the direction of the object of fixation and deviation of the gaze to the opposite side, followed by a slow movement of the eyes towards the desired place.

are also given occasional twitching of gaze, and a movement of the head towards the object of fixation while the gaze remains fixed on the first position, followed by a closing of the eyelids and a subsequent slow movement of the eyes towards the new place of fixation.

On the other hand, there preservation of spontaneous eye movements and gaze in the vertical plane.

Finally, it is worth noting the alteration of the movements of attraction and, on occasions, of the movements that follow the gaze.

Type 2 oculomotor apraxia

One of the most studied oculomotor apraxias is type 2, caused by a mutation in the SETX gene. This apraxia is often accompanied by ataxia, which is the lack of muscle control or coordination of voluntary movements.

This type of apraxia is a characteristic symptom of Gaucher disease, a rare and degenerative condition, the result of the accumulation of certain fatty substances in organs such as the spleen or liver.

This disease usually causes early death in children who suffer from it, although in recent years it is carrying out an enzymatic treatment that replaces inactive enzymes with new ones to try to stop their Advance. In the most serious cases, a bone marrow transplant is usually needed.

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Treatment

Some health professionals recommend vision therapy to deal with a condition such as oculomotor apraxia and the consequences that derive from its condition.

In this type of therapy non-surgical visual exercises are performed, personalized and prepared by a behavioral optometrist, always under the supervision of a specialist ophthalmologist in the field.

It seems that there is evidence that the problem improves over the years if the exercises are executed correctly and during the specified time.

However, it has also been suggested that this disease has no cure and that the only solution is to adopt compensatory measures for the person to adapt to their new disability situation.

Other types of apraxias

Oculomotor apraxia is a specific type of apraxia that involves difficulties in eye movement, but there are other types of apraxias with symptoms that generate another series of complications similar in nature. We will see, below, what they are:

1. Ideomotor apraxia

Ideomotor apraxia is the most common apraxia of all and is characterized by the fact that people who suffer from it cannot copy movements or perform everyday gestures, such as waving or nodding.

Patients suffering from ideomotor apraxia are able to describe the steps to follow to carry out an action specific, but have severe difficulties in carrying out said action or in imagining that they are carrying it out. cape.

2. construction apraxia

This type of apraxia is the second most common. People with Construction Apraxia are unable to carry out motor actions that involve spatial organization; for example, they cannot make a picture, shapes with blocks, or make a face with a face.

3. ideational apraxia

Ideatory apraxia is a type of apraxia characterized by the difficulty to carry out complex actions that require some type of planning, such as sending an email or making food.

Patients with ideational apraxia generally produce incoherent, inappropriate and disorganized gestures.

4. Apraxia of speech

Apraxia of speech is characterized by the inability to reproduce necessary motor sequences with the mouth in order to speak intelligibly. This apraxia It can be suffered by both adults and children of learning to speak age, although in child patients this disorder is often called dyspraxia.

5. Kinetic limb apraxia

People who suffer from this type of apraxia have a deficit in the fluid movement of the extremities, both upper and lower. They also suffer a loss of dexterity or ability to perform both fine and precise movements. with the hands and fingers (fine motor skills) and movements with the arms and legs (fine motor skills). gross).

6. orofacial apraxia

In orofacial apraxia there is a manifest inability to properly control the muscles of the face, tongue, and throat, and therefore, problems chewing, swallowing, sticking out the tongue, etc.

This incapacity manifests itself when the person performs voluntary movements on purpose -and not involuntary-, that is, it only occurs when a movement is executed after having thought and planned it carefully. anteriority.

Bibliographic references:

• Gulias-Cañizo, R., Sánchez-Huerta, V., Rubio-Lezama, M. (2005). Congenital oculomotor apraxia: report of a case. Rev Mex Ophthalmol.