Sometimes a person has a reflex deviation of the apples of the eye to one side. This anomaly, which occurs when the patient tries to turn their head vertically or horizontally, is called an oculocephalic reflex.
Oculocephalic reflex is caused by quickly turning and briefly holding the patient’s head to the right, then to the left, and unbending and bending the neck. In this case, the eyes deviate in the opposite direction (for example, when turning the head to the left, the eyes deviate to the right). This reflex can be investigated only in the absence of an injury to the cervical spine. In patients with severe traumatic brain injury, the head can only be turned in the horizontal plane.
The normal oculocephalic reflex reflects the safety of the labyrinths, neck proprioceptors, vestibular nuclei, and their connections with the nuclei of the oculomotor nerves, the medial longitudinal fascicle. If, when turning the head, the eyeballs remain in the same position, then the damage is localized at the level of the nuclei of the abducens nerves, vestibular nuclei, and their connections. If, when turning the head, abduction of the eye is preserved, but adduction is disturbed, then the lesion is located at the level of the medial longitudinal bundle, which carries out connections between the nuclei of the abducens oculomotor nerves. Asymmetric uncomfortable eye deviation and uncomfortable eye movements in assessing the oculocephalic reflex indicate structural damage to the brain stem and are often called doll’s eyes.
This phenomenon is observed in newborns. In most cases, a strange symptom manifests itself in those children who were born prematurely. Also, this phenomenon is diagnosed with metabolic disorders and all kinds of intoxications.
Physiological Functions of the Eccentric Gaze Fixation
The value lies in that it allows you to fix the gaze on a stationary object and provide a projection of the gaze fixation point on the retina in the zone of best vision during head movements or acceleration.
- In a healthy, awake person, the oculocephalic reflex can be arbitrarily suppressed due to the influences of the cerebral cortex on the stem structures.
- If this reflex is disturbed, patients cannot read since they cannot stabilize their gaze during a small physiological tremor of the head.
- The activity of stem structures is associated not only with the mechanisms of the gaze, but also the mechanisms of its stable fixation, i.e., stable gaze retention due to active suppression of eyeball movements. It is essential to ensure the stability of the gaze in an eccentric position of the eyes.
- The mechanisms of keeping the horizontal gaze are realized with the participation of the vestibular nuclei, vestibulocerebellum, and the nucleus praepositus Hypo-glossy, which lies in the bottom of the fourth ventricle between the nucleus of the hypoglossal nerve, located more caudally, and the nucleus of the abducens nerve, located rostral.
- The mechanisms for maintaining the vertical gaze are realized with the participation of the Cajal interstitial nucleus.
The Mechanism of Occurrence of the Oculocephalic Reflex
The emergence of this reflex is explained as follows.
- Normally, rotation of the head leads to displacement of the endolymph in the semicircular canals in the direction opposite to this rotation. In this case, in one labyrinth, an endolymph current arises towards the ampulla of the horizontal semicircular canal and in the other labyrinth in the direction from the ampulla of the canal.
- There is an increase in irritation of the receptors of one and a decrease in irritation of the receptors of the opposite vestibular apparatus, i.e., imbalance of impulses coming to the vestibular nuclei.
- When the vestibular nuclei are irritated on one side, the information is immediately transmitted to the contralateral nucleus of the abducens nerve in the Varolievy pons, from where impulses through the medial longitudinal bundle reach the nucleus of the oculomotor nerve in the midbrain on the side of the irritated vestibular apparatus. This provides asynchronous contraction of the lateral rectus muscle of the eye opposite to the irritated labyrinth and the medial rectus muscle of the eye of the same name, which ultimately leads to a slow, friendly deviation of the eyes in the direction opposite to the direction of head rotation for oculocephalic reflex.
In other words, the rotational movement of the head to the left leads to an increase in the frequency of discharges in the left vestibular nerve, increased excitation of the left vestibular nucleus, excitation of neurons in the nucleus of the right abducens nerve, and reflex abduction of the right eyeball due to contraction of the lateral rectus muscle of the right eye. Simultaneous turn of the left eye to the right occurs due to the transmission of excitation through the medial longitudinal bundle to the motor nucleus of the left oculomotor nerve and contraction of the medial rectus muscle of the left eye.
Diagnosis of Oculocephalic Reflex or the Doll’s Eyes
Eccentric gaze fixation disorders can manifest as nystagmus and saccades/oscillations. A significant difference concerns the initial movement that takes the visual line away from the object in question. Such an initial movement that takes the eye away from the target, with nystagmus, is a slow drift, and with saccadic oscillation, a rapid movement of the eyeball.
Clinical diagnosis of disorders of the eye movement system requires a series of tests while finding out the cause of such disorders is a comprehensive clinical and neurological study.
Dr. Cantelli first described the oculocephalic reflex. Medical specialists are deciphering the essence of the oculocephalic reflex thanks to the research already available. Everything depends on the state of the investigated person. The following is taken into account:
- The patient is conscious.
- The patient is in a coma.
- Development of a coma against the background of 1 lesion of the cortex.
- Violation of the cortex against the background of 2-fold deformation of the pons.
The procedure should be carried out quickly. In no case should such manipulations be carried out if there is a suspicion of damage to the cervical spine.
- If reflex deviations of the eyeballs of the examined person occur in the direction opposite to turning the head, a positive doll’s eyes reflex is diagnosed.
- If the doctor suspects damage to the stem structures, a negative test result is diagnosed.
Oculocephalic Reflex in People in Coma
When a person is in a severe coma, the doctor should put them on their back. Then the examiner performs the following manipulations:
- carries out passive turns of the subject’s head in the vertical direction;
- carries out passive turns of the subject’s head in the horizontal direction.
If the patient is in a coma and the presence of an anomaly is not observed, then the doctor diagnoses inorganic damage to the brain stem structures. It is important to consider that a negative oculocephalic reflex is a norm when awake because an effort of will can suppress it. If a person is in a coma, then the functions of the brain trunk are preserved. At the same time, as a result of turning the head to one side (this phenomenon is called mechanical irritation), the eyeballs (combined) move in a completely different direction.
The eyes of a patient who is currently in a coma cannot be fixed on the midline. The opposite is observed if the main function of the brain stem is impaired.
When a fatal outcome occurs, it is easy to draw a parallel with a trunk lesion. In this case, the eyes become lifeless, as if drawn and are fixed strictly along the middle line.
If the person under study is not in a coma, then they have a high degree of activity in the cerebral cortex of the GM. This activity helps to suppress and arrest the doll’s eyes reflex. At the same time, the person’s eyes look straight ahead.
If the patient is in a severe coma and the presence of an anomaly is not observed, then the doctor diagnoses inorganic damage to the brain stem structures. It is important to consider that a negative oculocephalic reflex is a norm when awake because an effort of will can suppress it.
Treatment of Oculocephalic Reflex
Eccentric gaze fixation appears in adults when the correct diagnosis was not made in childhood, or the necessary treatment was lacking. Therapy begins with identifying the cause of the change in the functioning of the eye system.
Adults require an increased course of treatment, as the struggle for a healthy eye is often difficult. The therapy is carried out using special devices that activate the functions of the eye.
- Video-computer vision correction shows excellent results.
- A course of physiotherapy equipment is prescribed by a doctor to treat eccentric gaze fixation in children and adults, based on medical indicators.
- Treatment by occlusion is the most ancient but effective method. The occluder can be in the form of a bandage for small children, a shutter in glasses, a sticker on the glass. The neglect of the case regulates the duration of wearing the occluder. It can be periodic or constant and is corrected as visual acuity indicators improve.
If you have oculocephalic reflex or symptoms that may be causing it, you should see your doctor right away. The doctor will be able to correctly diagnose and prescribe treatment.
- What disease can cause a reflex deviation of the apples of the eye to one side?
This anomaly, which occurs when the patient tries to turn their head vertically or horizontally, is called an oculocephalic reflex.
- What do positive doll’s eyes mean?
If the reflex in the eyes is not impaired, they demonstrate a conjugate movement in the direction opposite to the movement of the head; however, if the reflex is impaired (negative doll head maneuver), the eyes remain stationary.
- How does the vestibular-ocular reflex work?
This reflex uses information from the inner ear to create eye movements that help stabilize the gaze. This reflex helps to focus when walking.
- What is the normal oculocephalic reflex?
Most often it is a reflex that helps the eye movement while the head is moving in the opposite direction. It is possible to establish the absence of this reflex when the eyes move in the same direction as the head.