Gaze disturbance

All eye movements in humans are normally binocular and integrated with the visual system to ensure the perception of three-dimensional space. Both eyes function as a single unit and move in such a way as to ensure the stability of the gaze on a moving object and to ensure the stabilization of the visual image on the retina. This requires constant integration of afferent flows from visual, vestibular, proprioceptive, tonic cervical and (to a lesser extent) somatosensory stimuli. The oculomotor system is also influenced by the hemispheric motor control systems, basal ganglia and cerebellum. In addition, the state of consciousness and the level of wakefulness are important for the normal functioning of this system.

Impairments of gaze movements depend on the location, size, severity and type of damage. Hemispheric damage may manifest itself as both irritative phenomena (tonic gaze deviation, epileptic nystagmus) and paralytic ones (paralysis of conjugate movements, i.e. gaze paralysis). The same can be said about damage to the basal ganglia, which can manifest itself as oculogyric crises, on the one hand, and gaze paresis, on the other (for example, in progressive supranuclear palsy). Damage to the mesencephalon can lead to disturbances of vertical gaze (defect of upward gaze, defect of downward gaze, a combination of both), characteristic forms of nystagmus, disturbances of conjugate eye movements and crossed syndromes. Damage to the pons is characterized by defects of conjugate movements, syndromes of the medial longitudinal fasciculus and crossed syndromes. Processes in the medulla oblongata region can manifest themselves in visual phenomena only by nystagmus.

I. Associated (conjugate) gaze palsies.

A. Horizontal gaze paralysis

1. Frontal lesions (glance phenomena of irritation and paralysis)

1. Acute stroke (and other diseases)
2. Epileptogenic lesions (causing epileptic seizures)

2. Bridge (pontine) damage

1. Acute cerebrovascular accidents
2. Paraneoplastic syndrome

B. Vertical gaze paralysis

I. Paralysis of upward gaze

1. Midbrain tumor
2. Hydrocephalus
3. Shunt dysfunction in hydrocephalus
4. Hemorrhagic or ischemic infarction of the thalamus or midbrain
5. Hypoxia
6. Multiple sclerosis
7. Traumatic brain injury
8. Lipidoses
9. Wilson-Konovalov disease
10. Drug intoxication
11. .Whipple's disease
12. Syphilis
13. Tuberculosis
14. Limitation of upward gaze in Parkinson's disease
15. Limitation of upward gaze and vitamin B12 deficiency
16. Syndromes that mimic upward gaze palsy: Lambert-Eaton syndrome and Fisher syndrome

2. Downward gaze paralysis

1. Cerebral infarctions
2. Progressive supranuclear palsy
3. Niemann-Pick disease
4. Hexosaminidase A deficiency in adults
5. OPTSA
6. Ataxia-telangiectasia
7. Wilson's disease Konovalov
8. Huntington's chorea
9. Whipple's disease
10. Parkinson's disease (rare)
11. Hallervorden-Spatz disease
12. Diffuse Lewy Body Disease

II. Non-conjugate gaze palsies

A. Horizontal gaze

1. Posterior longitudinal fasciculus syndrome or internuclear ophthalmoplegia syndrome:

Unilateral internuclear ophthalmoplegia

1. Ischemic infarction of the brainstem
2. Wernicke's encephalopathy
3. Traumatic brain injury
4. Encephalitis
5. AIDS
6. Neurosyphilis
7. Tumor
8. Arnold-Chiari malformation
9. Hydrocephalus
10. Arteriovenous malformation
11. Metabolic disorders
12. Syringobulbia
13. Radiation encephalopathy
14. Progressive supranuclear palsy
15. Hepatic encephalopathy
16. Pernicious anemia
17. Drug intoxication

Bilateral internuclear ophthalmoplegia

1. Multiple sclerosis
2. Ischemic infarctions of the brainstem
3. Paraneplastic encephalomyelopathy

Syndromes that can mimic internuclear ophthalmoplegia

1. Myasthenia
2. Thyroid orbitopathy
3. Orbital pseudotumor
4. Partial paralysis of the oculomotor nerve
5. Miller Fisher syndrome
6. Penicillin-induced pseudointernuclear ophthalmoplegia
7. Surgical trauma of the medial rectus muscle of the eye
8. Myotonic dystrophy
9. Long-standing exotropia.

One and a half syndrome

1. Ischemic or hemorrhagic cerebral infarction
2. Multiple sclerosis
3. Brain tumor
4. Pseudo-one-and-a-half syndrome in myasthenia gravis

V. Vertical gaze

1. Monocular elevation paresis
2. Vertical one and a half syndrome
3. Oblique deviation

III. Syndromes of spontaneous rhythmic gaze disorders

1. Oculogyric crises
   • Economo's encephalitis
   • Traumatic brain injury
   • Neurosyphilis
   • Multiple sclerosis
   • Ataxia-telangiectasia
   • Rett syndrome
   • Brainstem encephalitis
   • Glioma of the third ventricle
   • Striocapsular infarction
   • Drug intoxication
2. Periodic alternating gaze
3. Ping-Pong Gaze Syndrome
4. Periodic alternating gaze deviation
5. Repeated divergence
6. Ocular bobbing
7. Ocular dipping
8. Pretectal pseudobobbing
9. Vertical ocular myoclonus
10. Alternating oblique deviation
11. Psychogenic gaze deviations.

IV. Congenital oculomotor apraxia.

I. Associated (concomitant) gaze palsies.

A. Paralysis of horizontal gaze.

Localization of lesions responsible for horizontal gaze palsy: frontopontine connections, mesencephalic reticular formation, pontine reticular formation (and the nucleus of the sixth cranial nerve).

Unilateral limitation of voluntary gaze to one side is usually due to contralateral frontal (but also contralateral parietal or occipital) or ipsilateral pontine damage. Weakness or paralysis of contralateral consensual abduction may be transient, lasting a few hours (e.g., postictal) or may persist for days or weeks, as in stroke. Limitation of eye movements is horizontal and in the direction opposite the side of the injury.

Frontal lesions. (Most often acute lesions with transient gaze disturbances): tumor, stroke, craniocerebral trauma or infection. All of them can cause such an irritative phenomenon as concomitant deviation of the eyes to the side opposite to the affected hemisphere (the patient looks away from the lesion).

Stroke: in the acute phase, the patient “looks at the lesion” due to the preserved function of the opposite center of turning the eyes and head to the side and, on the contrary, paralysis of turning the eyes and head in the ipsilateral hemisphere (paretic phenomenon).

Epileptogenic frontal (as well as parietal, occipital and temporal) lesions are manifested by transient deviation of the eyes and head to the contralateral side (the patient looks away from the lesion). Ipsiversive deviations of the eyes and head are also possible. Paralysis or weakness of horizontal conjugate eye movements of hemispheric origin are rarely encountered as an isolated phenomenon. They are almost always accompanied by other signs of hemispheric dysfunction (concomitant hemiparesis or hemiplegia).

Bridge (pontine) injuries (the patient “looks at hemiparesis”):

• Stroke is the most common cause of the above-mentioned concomitant deviation of the eyes.
• Paraneoplastic syndrome (depression of horizontal eye movements without hemiparesis) is a much rarer syndrome.

In patients over 50 years of age, the most common cause of horizontal gaze palsy is cerebrovascular disease (ischemic or hemorrhagic). In the subacute development of these gaze disorders in patients under 50 years of age, multiple sclerosis must be excluded. Congenital syndrome is usually caused by Moebius syndrome. Other causes of acquired horizontal gaze disorders include systemic lupus erythematosus, syphilis, Wernicke's encephalopathy. Myasthenia, as already mentioned, can simulate gaze disorders. In the differential diagnosis of the causes of horizontal gaze palsy (paresis), MRI and cerebrospinal fluid examination are used.

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B. Vertical gaze paralysis.

Unilateral hemispheric lesions do not in themselves cause vertical gaze palsy. If the latter is detected, it is usually due to hidden additional or bilateral brainstem damage.

Extensive bilateral hemispheric lesions may cause gaze palsy in both horizontal and vertical directions. There are reports that bilateral hemispheric lesions may impair eye movements in all directions.

Severe damage to the oral parts of the pons tegmentum causes paresis of both horizontal and vertical gaze. As a rule, these patients are in a coma.

Upward gaze palsy. The syndrome is characteristic of pretectal lesions involving the posterior commissure and is referred to as Parinaud's syndrome, Sylvian aqueduct syndrome, pretectal syndrome, dorsal midbrain syndrome, and Koerber-Salus-Elschnig syndrome. Retraction of the upper eyelids may be observed simultaneously. If the process extends ventrally involving the nucleus of the third (oculomotor) nerve, bilateral ptosis occurs. Sometimes a "skew deviation" develops with the eye on the side of the lesion being higher. In children with hydrocephalus, a sign of midbrain compression is tonic downward gaze deviation with retraction of the upper eyelids - the "setting sun" syndrome.

Main causes: tumor (the most common cause, especially pituitary tumor and metastatic tumors); hydrocephalus (especially with dilation of the third ventricle and aqueduct, leading to deformation of the posterior commissure); shunt dysfunction in hydrocephalus; hemorrhagic or ischemic infarction of the thalamus or midbrain; hypoxia; multiple sclerosis; craniocerebral trauma; neurosurgical (stereotactic) trauma; lipidoses; Wilson-Konovalov disease; drug intoxication (barbiturates, carbamazepine, neuroleptics); Whipple's disease; syphilis; tuberculosis; limited upward gaze in Parkinson's disease and (rarely) in vitamin B12 deficiency; Wernicke's encephalopathy; syndromes mimicking paresis of upward gaze: Lambert-Eaton syndrome and Fisher syndrome.

Downward gaze palsy. Isolated downward gaze palsy is rare. If this syndrome develops, it makes reading, eating, and walking on an inclined surface difficult. The syndrome is observed with bilateral lesions at the mesencephalic-diencephalic junction with involvement of the area lying between the Sylvian aqueduct and the red nucleus. Pseudoptosis (relaxation of the levator m.) may be observed when attempting to shift the gaze downward.

Main causes: infarctions (in most cases bilateral) in the basin of the paramedian thalamomesencephalic artery (a branch of the posterior cerebral artery) - the most common cause of acute downward gaze palsy.

Causes of progressive limitation of downward gaze: progressive supranuclear palsy; Niemann-Pick disease; adult hexosaminidase-A deficiency; OPCA; ataxia-telangiectasia; Wilson-Konovalov disease; Huntington's chorea; Whipple disease; Parkinson's disease (rare); Hallerwoden-Spatz disease (rare); diffuse Lewy body disease.

Paralysis of downward gaze also significantly complicates walking and, therefore, contributes to the genesis of dysbasia, which in almost all of the above diseases is complex (polyfactorial).

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II. Non-conjugate gaze palsies

A. Horizontal gaze.

Posterior longitudinal fasciculus syndrome or internuclear ophthalmoplegia syndrome.

Clinically, the syndrome is characterized by weakness of the adduction muscle of the eye on the side of the lesion of the posterior longitudinal fasciculus and contralateral monocular nystagmus with abduction of the other eye. Convergence, however, is preserved. Sometimes patients complain of diplopia (caused by oblique deviation) or oscillopsia. In the absence of the latter, patients usually do not present complaints. Internuclear ophthalmoplegia is often accompanied by oblique deviation with the higher eye on the side of the lesion. It may also be combined with ipsilateral downward nystagmus and contralateral torsional nystagmus.

Let us recall the main causes of unilateral internuclear ophthalmoplegia:

Ischemic brainstem infarction; Wernicke encephalopathy; traumatic brain injury; encephalitis; AIDS; neurosyphilis; tumor; Arnold-Chiari malformation; hydrocephalus; arteriovenous malformation; metabolic disorders (eg, Fabry disease, abetolipoproteinemia); syringobulbia; radiation encephalopathy; progressive supranuclear palsy; hepatic encephalopathy; pernicious anemia; drug intoxication (diphenin, amitriptyline, phenothiazines, tricyclic antidepressants, obzidan, lithium, narcotics, barbiturates).

The main causes of bilateral internuclear ophthalmoplegia are: multiple sclerosis; ischemic infarctions of the brain stem; paraneoplastic encephalomyelopathy.

Syndromes that can mimic internuclear ophthalmoplegia (pseudomonuclear ophthalmoplegia): myasthenia gravis; thyroid orbitopathy; orbital pseudotumor; other infiltrative lesions of the external extraocular muscles (tumor, amyloidosis, etc.); partial paralysis of the oculomotor nerve; Miller Fisher syndrome (sometimes true internuclear ophthalmoplegia is also observed); penicillin-induced pseudointernuclear ophthalmoplegia; surgical trauma of the medial rectus muscle of the eye; myotonic dystrophy; neuromyotonia of the lateral rectus muscle of the eyeball.

Bilateral internuclear ophthalmoplegia is usually observed with straight ahead gaze. Cases where internuclear ophthalmoplegia is combined with lateral abduction of both eyes are termed WEВINO syndrome (wall-eyed bilateral internuclear ophthalmoplegia). Convergence is often impossible. This syndrome is observed in midbrain lesions involving both posterior longitudinal fasciculi. A similar unilateral syndrome has been described (WEMINO syndrome; wall-eyed monocular internuclear ophthalmoplegia), where, as in the bilateral syndrome, divergence of the visual axes (exotropia) is also observed.

Internuclear ophthalmoplegia of abduction has also been described. Unilateral or bilateral internuclear ophthalmoplegia of abduction (so-called posterior internuclear ophthalmoplegia) is sometimes accompanied by nystagmus when the contralateral eye is adducted. This syndrome has been described in cases of ipsilateral damage to the oral parts of the pons or mesencephalon.

One-and-a-half syndrome is characterized by concomitant gaze palsy to one side (one part of the syndrome) and weakness of the adductor muscle when looking to the other side (the "half" of the syndrome compared to the first part). Here, only the abduction of one eye is preserved in the horizontal plane, which also exhibits nystagmus during such abduction. Vertical movements and convergence are preserved. The syndrome is caused by unilateral damage to the inferior part of the pontine tegmentum with ipsilateral involvement of the paramedian reticular formation of the pons, the nucleus of the abducens nerve, and adjacent fibers of the posterior longitudinal fasciculus on this side (on the side of complete horizontal gaze palsy).

Main causes: multiple sclerosis (the most common cause in people under 50); ischemic or hemorrhagic cerebral infarction (the most common cause in people over 50); tumor of the lower pons; pseudo-one-and-a-half syndrome in myasthenia.

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V. Vertical gaze

Monocular elevation paresis ("double elevator palsy") is characterized by limited elevation of one eye and may occur with supranuclear pretectal lesions on the side contralateral or ipsilateral to the paretic eye, which interrupt the fibers from the posterior longitudinal fasciculus to the superior rectus muscle and the oblique inferior muscle. Double elevator palsy may present with asymmetric paresis of upward gaze, which clinically appears as monocular elevation paresis on the side of the more severely affected eye (thus there is no true monocular elevator palsy). Other causes: paresis of the extraocular muscles; fibrositis or myositis of these muscles; myasthenia gravis; dysthyroid orbitopathy; muscle tumor; orbital bone fracture.

Vertical one-and-a-half syndrome - vertical gaze palsy and monocular paresis of downward gaze on the side of the lesion or contralateral to the lesion - has been described in thalamomesencephalic infarctions. Bell's phenomenon and all types of horizontal eye movements are preserved.

Skew Deviation. Although vertical eye alignment disturbances may be caused by damage to the ocular motor nerves or muscles (e.g., myasthenia gravis), the term skew deviation is reserved for vertical eye alignment disturbances caused by supranuclear disorders. Unlike other types of acquired vertical strabismus (e.g., superior oblique palsy, thyroid ophthalmopathy, myasthenia gravis), skew deviation is a condition in which the eyes are not usually rotated. Skew deviation occurs when peripheral or central lesions cause an imbalance in otolith signals and may accompany pathological processes at different levels of the brainstem (from the mesencephalon to the medulla or cerebellum). Rarely, increased intracranial pressure, Fisher syndrome, or hepatic coma may cause skew deviation.

If the oblique deviation varies with different gaze positions, this usually indicates a lesion of the medulla oblongata. Lesions of the peripheral vestibular organ may cause oblique deviation, with the contralateral eye positioned higher than the ipsilateral one. Lateral pontomedullary lesions involving the vestibular nuclei may result in oblique deviation with the lower eye on the side of the lesion. In contrast, the eye on the side of the lesion of the posterior longitudinal fasciculus is positioned higher.

III. Syndromes of spontaneous rhythmic gaze disorders

Oculogyric crises.

Oculogyric crises are episodic concomitant deviations of the eyes (usually directed upward and laterally, rarely downward or strictly laterally). These crises may be accompanied by other dystonic phenomena (blepharospasm, tongue protrusion, torticollis, etc.).

Main causes: drug intoxication (neuroleptics, lithium, tetrabenazine, carbamazepine); Economo encephalitis; traumatic brain injury; neurosyphilis; multiple sclerosis; ataxia-telangiectasia; Rett syndrome; brainstem encephalitis; third ventricular glioma; striatocapsular infarction.

Periodic alternating gaze.

Periodic alternating gaze (periodic alternating gaze deviation with dissociated head movements) is a complex cyclic three-phase syndrome:

1. concomitant lateral deviation of the eyes, usually with compensatory rotation of the head to the opposite side, lasting 1-2 minutes;
2. phase of switching to the initial position (10-15 seconds) and
3. phase of concomitant deviation of the eyes to the other side with compensatory head rotation lasting from 1 to 2 minutes.

Almost all of the described cases are represented by processes in the posterior cranial fossa (spinocerebellar degeneration, cerebellar medulloblastoma, Arnold-Chiari malformation, cerebellar dysgenesia, etc.).

Ping-pong gaze syndrome.

Ping-pong syndrome (in a patient in a coma) is a periodic concomitant deviation of the eyes from one extreme position to another; the duration of each cycle is 2.5-8 seconds. The syndrome usually reflects bilateral cerebral infarction with an intact brainstem, but has also been described in cases of hemorrhage in the posterior cranial fossa, basal ganglia infarction, hydrocephalus, MAO inhibitor overdose, and in patients in metabolic coma. It has no prognostic value.

Periodic alternating gaze deviation. Periodic alternating gaze deviation differs from the gaze ping-pong syndrome and occurs not only in comatose patients, but also (more often) in awake patients: alternating horizontal concomitant gaze deviation lasting from 1 to 2 minutes in each direction is observed. It occurs in patients with structural damage to the cerebellum and brainstem (Arnold-Chiari malformation, medulloblastoma), but has also been described in comatose patients with hepatic encephalopathy.

Repeated divergence.

Repetitive divergence is a rare phenomenon in patients in metabolic coma. In the resting phase, the eyes are in a mid-position or slightly diverged. In the next phase, they slowly diverge, then remain in a position of complete divergence for a short period, and finally return quickly to the original position before starting a new cycle. The movements are synchronous in both eyes.

Ocular bobbing.

Ocular bobbing (eye float syndrome) is a periodic rapid concomitant downward deviation of the eyes from the mid-position followed by their slow return to the initial mid-position in patients in a coma. The syndrome is mainly characteristic (but not pathognomonic) of pons damage (hemorrhage, tumor, infarction, central pontine myelinolysis). It has also been described in processes in the posterior cranial fossa (ruptured aneurysm or hemorrhage in the cerebellum), diffuse encephalopathies. Monocular bobbing and, rarely, nonconsensual bobbing on one side or the other are possible.

Ocular dipping.

Ocular dipping is a slow downward deviation of the eyes from a mid-position followed by a rapid return to the original position. It has been described in anoxic coma and after prolonged status epilepticus. It is thought to reflect diffuse brain dysfunction rather than any structural damage.

Pretectal pseudobobbing.

Pretectal pseudobobbing in coma has been described in acute hydrocephalus and consists of arrhythmic, repetitive downward and upward eye movements in a "V-pattern".

Vertical ocular myoclonus.Vertical ocular myoclonus - pendulum-like

Isolated vertical eye movements with a frequency of 2 per second in patients with locked-in syndrome or in coma after a stroke in the pons. These movements are usually accompanied by myoclonus of the soft palate.

Alternating oblique deviation. Alternating oblique deviation in coma is an intermittent lowering of one eye and raising of the other. The phase of changing the position of the eyeballs lasts from 10 to 30 seconds, and the phase of maintaining the new position - from 30 to 60 seconds. The syndrome is characteristic of pretectal injuries, including acute hydrocephalus, tumor, stroke, multiple sclerosis, traumatic brain injury, lithium intoxication, Wernicke's encephalopathy, tentorial herniation, spinocerebellar degeneration. Often reflects the severity of the process and in certain situations indicates the need for urgent neurosurgical intervention.

Psychogenic gaze deviations.

Psychogenic deviations of gaze (in any direction) are usually observed in the picture of a pseudo-seizure or psychogenic areactivity (“hysterical hibernation” - according to the old terminology) and are always combined with other demonstrative manifestations, the recognition of which helps in correct diagnosis.

Tonic upward gaze deviation (forced upward gaze) is a rare phenomenon observed in comatose patients and should be distinguished from oculogyric crises, petit mal seizures, and psychogenic coma. Comatose patients with persistent upward gaze deviation usually have diffuse hypoxic brain damage (hypotension, cardiac arrest, heat stroke) involving the cerebral hemispheres and cerebellum with a relatively intact brainstem. Some of these patients subsequently develop myoclonic hyperkinesia and marked downstroke nystagmus. Rarely, tonic upward gaze deviation may be psychogenic, in which case it is observed in the context of other motor conversion disorders.

Tonic downward gaze deviation (forced downward gaze) is observed in patients in a comatose state after hemorrhage in the medial thalamus, in acute obstructive hydrocephalus, severe metabolic or hypoxic encephalopathy, or after massive subarachnoid hemorrhage. In this case, the eyes may sometimes be converged, as when looking at one's own nose. A similar phenomenon may be observed in psychogenic coma (pseudocoma).

IV. Congenital ocular motor apraxia

Congenital ocular motor apraxia or Cogan syndrome is characterized by a congenital lack of ability for lateral gaze movements and is manifested by abnormal eye and head movements when attempting to voluntarily change the position of the eyes during lateral tracking movements.

This rare phenomenon has also been described in ataxia-telangiectasia; agenesis of the corpus callosum; Huntington's chorea, Niemann-Pick disease.

Other syndromes of excessive rhythmic activity in the oculomotor muscles (opsoclonus, "eyelid nystagmus", alternating nystagmus and other unusual types of nystagmus, cyclic oculomotor palsy with spasms, superior oblique myokymia syndrome, ocular tilt reaction) are not mentioned here, since they do not relate to gaze disorders.