Contents
Hyperkinesis of organic origin
Hyperkinetic syndromes with predominant involvement of facial muscles
Facial paraspasm
The following forms of blepharospasm are distinguished:
- primary: blepharo-spasm-oromandibular dystonia syndrome (facial paraspasm, Mezha syndrome, Bruegel syndrome);
- secondary – in organic diseases of the brain (Parkinson’s disease, progressive supranuclear palsy, multiple system atrophy, multiple sclerosis, “dystonia plus” syndromes, vascular, inflammatory, metabolic and toxic (including neuroleptic) lesions of the nervous system;
- due to ophthalmological reasons;
- other forms (facial hemispasm, facial synkinesis, pain tic and other “peripheral” forms).
Primary (dystonic) blepharospasm is observed in the picture of facial paraspasm. Facial paraspasm is a peculiar form of idiopathic (primary) dystonia, described in the literature under different names: Mezha’s paraspasm, Bruegel’s syndrome, blepharospasm syndrome – oromandibular dystonia, cranial dystonia. Women get sick three times more often than men.
As a rule, the disease begins with blepharospasm and in such cases we are talking about focal dystonia with blepharospasm syndrome. Usually, after a few years, dystonia of the oral muscles occurs. The latter is called oromandibular dystonia, and the entire syndrome is designated as segmental dystonia with blepharospasm and oromandibular dystonia. However, the time interval between the appearance of blepharospasm and the onset of oromandibular dystonia sometimes covers many years (up to 20 years or more), so many patients simply do not live to see the generalized stage of paraspasm. In this regard, this blepharospasm syndrome can be legitimately considered both as a stage and as a form of facial paraspasm. In this case, isolated blepharospasm is sometimes called essential blepharospasm.
Much less commonly, the disease begins in the lower half of the face (“lower Bruegel syndrome”). As a rule, with this type of debut of Bruegel’s syndrome, dystonia does not subsequently generalize across the face, that is, blepharospasm does not join oromandibular dystonia, and at all subsequent stages of the disease this syndrome remains focal.
Facial paraspasm occurs most often in the 5th-6th decade of life. It is extremely rare that the disease develops in childhood. In typical cases, the disease begins with somewhat rapid blinking, which gradually becomes more frequent, followed by the appearance of tonic spasms of the orbicularis oculi muscle with squinting (blepharospasm). At the onset of the disease, in approximately 20% of cases, blepharospasm is unilateral or clearly asymmetrical. It is extremely rare that blepharospasm remains persistently one-sided during long-term observation. In the latter case, the differential diagnosis of Bruegel syndrome and facial hemispasm becomes relevant. The motor pattern of blepharospasm itself in these diseases is different, but a more reliable and simpler method in the differential diagnosis is to analyze the dynamics of hyperkinesis.
Having begun gradually, facial paraspasm then progresses very slowly, over 2-3 years, after which it acquires a stationary course. Rarely, in about 10% of patients, short-term remissions are possible.
Severe blepharospasm is manifested by extremely intense squinting and may be accompanied by facial hyperemia, dyspnea, straining and hand movements, indicating the patient’s unsuccessful attempts to overcome blepharospasm. Blepharospasm is characterized by corrective gestures (especially in the early stages of the disease) and paradoxical kinesias, which are very diverse. More often, blepharospasm stops during any oral activity (smoking, sucking candy, eating seeds, expressive speech, etc.), emotional activation (for example, during a doctor’s visit), after a night’s sleep, drinking alcohol, in the dark, when closing one eye and, especially, closing both eyes.
Blepharospasm has a pronounced stress-generating effect and, as the disease progresses, causes serious maladjustment due to the inability to use one’s vision in everyday life. This is accompanied by noticeable emotional, personal and dyssomnic disorders. Two thirds of patients with severe blepharospasm become “functionally blind” because they cannot use the function of vision, which itself is intact.
Like all other dystonic hyperkinesis, blepharospasm depends on the characteristics of postural innervation: it is almost always possible to find positions of the eyeballs in which blepharospasm stops. Usually it decreases or completely disappears with extreme abduction of the eyeballs during tracking movements. Patients note relief with half-lowered eyelids (writing, washing, knitting, communicating and moving with half-lowered eyes). Hyperkinesis often decreases in a sitting position and, as a rule, subsides in a lying position, which is typical to one degree or another for all forms of dystonia. Natural sunlight outdoors has the greatest provoking effect on blepharospasm.
The described phenomena are the reference points for the clinical diagnosis of dystonic hyperkinesis. Their value increases when several of the characteristic symptoms mentioned above are identified in the patient.
The differential diagnosis of blepharospasm should be carried out among the above-mentioned primary and secondary forms of blepharospasm. This list should only be supplemented with the syndrome of apraxia of eyelid opening, with which blepharospasm sometimes has to be differentiated. We must not forget, however, that apraxia of eyelid opening and blepharospasm can often coexist in the same patient.
Secondary forms of dystonic blepharospasm observed in the picture of various organic diseases of the brain (Parkinson’s disease, progressive supranuclear palsy, multiple system atrophy, multiple sclerosis, dystonia plus syndromes, vascular, inflammatory, metabolic and toxic, including neuroleptic, lesions of the nervous system ) carry all the clinical features of dystonic blepharospasm and are recognized, firstly, thanks to typical dynamic characteristics (corrective gestures and paradoxical kinesia, effects of night sleep, alcohol, changes in visual afferentation, etc.) and, secondly, by concomitant neurological symptoms that manifest the diseases listed above.
Blepharospasm due to ophthalmological reasons rarely causes diagnostic difficulties. These eye diseases (conjunctivitis, keratitis) are usually accompanied by pain and such patients immediately come to the attention of the ophthalmologist. Blepharospasm itself does not have any of the above properties of dystonic blepharospasm. The same applies to other “peripheral” forms of blepharospasm (for example, with hemispasm).
Oral hyperkinesis
The following forms of oral hyperkinesis are distinguished:
- tardive dyskinesia,
- other drug-induced oral hyperkinesis (cerucal, oral contraceptives, other drugs),
- spontaneous orofacial dyskinesia of the elderly,
- other forms (“lower” Bruegel syndrome, “galloping” tongue syndrome, “rabbit” syndrome, bruxism, “lingual” epilepsy, tongue myokymia and others).
Tardive dyskinesia is an iatrogenic, poorly curable, fairly common disease, which is a direct consequence of the widespread use of antipsychotics in the medical practice of doctors of various specialties. Violent movements in tardive dyskinesia usually begin in the muscles of the face and tongue. The most typical triad of pathological movements is the so-called bucco-lingual-masticatory (buccal-lingual-masticatory) syndrome.
Less commonly, the muscles of the trunk and limbs are involved in hyperkinesis.
Typically inconspicuous onset in the form of subtle movements of the tongue and motor restlessness in the perioral area. In more severe cases, irregular but almost constant movements of the tongue, lips and lower jaw are clearly visible. These movements often take the form of motor automatisms of licking, sucking, chewing with slurping, smacking, chewing and lapping movements, sometimes with lip slapping sounds, aspiration, grunting, puffing, moaning and other unarticulated vocalizations. Characterized by rolling and sticking out the tongue, as well as more complex grimaces, mainly in the lower half of the face. These dyskinesias can usually be voluntarily suppressed for a short period of time. For example, oral hyperkinesis stops when the patient brings food to the mouth while he is chewing, swallowing, or talking. Sometimes, against the background of oral hyperkinesis, mild hypomimia is detected. In the extremities, dyskinesia preferentially affects the distal parts (“piano fingers”) and can sometimes be observed on only one side.
The differential diagnosis of tardive dyskinesia requires, first of all, the exclusion of the so-called spontaneous orofacial dyskinesia of the elderly, stereotypy, and oral hyperkinesis in neurological and somatic diseases. The clinical manifestations of spontaneous orofacial dyskinesia are completely identical to those of tardive dyskinesia, which undoubtedly indicates the commonality of their pathogenetic mechanisms. At the same time, neuroleptic drugs are considered the most significant risk factor, allowing one to identify a predisposition to dyskinesia at any age.
The diagnostic criteria for tardive dyskinesia are the following:
At all stages of the disease, the tongue takes a very active part in the clinical manifestations of tardive dyskinesia: rhythmic or constant protrusion, forced pushing it out of the mouth; Patients are usually unable to hold their tongue out of their mouth for 30 seconds.
Discontinuation of antipsychotic drugs can lead to aggravation of the patient’s condition and the appearance of new dyskinetic symptoms. In some cases, their abolition leads to a decrease or disappearance of dyskinesia (sometimes after a period of temporary increase in hyperkinesis). In this regard, tardive dyskinesia is divided into reversible and irreversible or persistent. It is believed that the presence of symptoms of tardive dyskinesia 3 months after discontinuation of antipsychotics can be considered as a criterion for persistent dyskinesia. The issue of discontinuing antipsychotics should be decided strictly individually due to the risk of relapse of psychosis. A number of risk factors have been identified that predispose to the development of tardive dyskinesia: duration of treatment with antipsychotics, older age, gender (women are more often affected), long-term use of anticholinergics, previous organic brain damage, and a certain significance of genetic predisposition is also assumed.
Although tardive dyskinesia most often develops in adulthood and old age, it can appear in youth and even childhood. In addition to the clinical picture, an important diagnostic factor is to identify the connection between the appearance of dyskinesia and the use of a neuroleptic. Spontaneous orofacial dyskinesia of the elderly (oral masticator syndrome of the elderly, spontaneous orofacial dyskinesia) appears only in the elderly (usually people over 70 years of age) who have not received antipsychotics. It has been noted that spontaneous oral dyskinesia in the elderly is combined with essential tremor in a high percentage of cases (up to 50% and above).
The differential diagnosis of tardive dyskinesia should also be carried out with another neuroleptic phenomenon in the oral area – rabbit syndrome. The latter is manifested by rhythmic tremor of the perioral muscles, mainly the upper lip, sometimes involving the masticatory muscles (tremor of the lower jaw), with a frequency of about 5 per second. The tongue is usually not involved in hyperkinesis. Externally, the violent movements are similar to the movements of a rabbit’s mouth. This syndrome also develops during long-term treatment with antipsychotics, but unlike tardive dyskinesia, it responds to treatment with anticholinergics.
At the onset of the disease, tardive dyskinesia and spontaneous oral dyskinesia in the elderly sometimes have to be differentiated from the onset of Huntington’s chorea.
In severe cases, tardive dyskinesia is manifested by generalized choreic movements, less often by ballistic throws, dystonic spasms and postures. These cases require a differential diagnosis with a wider range of diseases (Huntington’s chorea, neuroacanthocytosis, hyperthyroidism, systemic lupus erythematosus, other causes of chorea).
There are other drug-induced or toxic forms of oral hyperkinesis (especially when using cerucal, oral contraceptives, alcohol), which in their clinical manifestations have features of dystonic hyperkinesis, but are associated with the intake of the above substances and are often paroxysmal (transient) in nature.
Other forms of oral hyperkinesis include quite rare syndromes: “lower” Bruegel syndrome (oromandibular dystonia), “galloping” tongue syndrome, the already mentioned “rabbit” syndrome, bruxism, etc.
Oromandibular dystonia (or “inferior Bruegel syndrome”) is difficult to diagnose in cases where it is the first and main manifestation of Bruegel syndrome. If it is combined with blepharospasm, the diagnosis usually does not cause difficulties. Oromandibular dystonia is characterized by the involvement in hyperkinesis of not only the muscles of the oral pole, but also the muscles of the tongue, diaphragm of the mouth, cheeks, chewing, cervical and even respiratory muscles. Involvement of the cervical muscles may be accompanied by manifestations of torticollis. In addition, a number of movements in the face and even in the trunk and limbs in such patients are not pathological in nature; they are completely voluntary and reflect the patient’s active attempts to resist muscle spasms.
Oromandibular dystonia is distinguished by the variety of its manifestations. In typical cases, it takes the form of one of three well-known options:
The lower version of Bruegel’s syndrome is often accompanied by difficulties in swallowing, chewing and articulation (spasmodic dysphonia and dysphagia).
The diagnosis of oromandibular dystonia is based on the same principles as the diagnosis of any other dystonic syndrome: mainly on the analysis of the dynamics of hyperkinesis (the relationship of its manifestations with postural loads, time of day, the effect of alcohol, corrective gestures and paradoxical kinesias, etc.), identification other dystonic syndromes, which in Bruegel syndrome occur in other parts of the body (outside the face) in 30–80% of patients.
There is often a situation where ill-fitting dentures lead to excessive motor activity in the oral area. This syndrome is more common in women aged 40–50 years, who are prone to neurotic reactions.
Episodic repetitive movements of the tongue (“lingual epilepsy”) are described in children with epilepsy (including during sleep; in patients after traumatic brain injury (without any changes in the EEG) in the form of undulating (3 per second) retractions and protrusions at the root tongue (“galloping tongue syndrome”), or rhythmic pushing it out of the mouth (a type of myoclonus) with a favorable course and outcome.
A syndrome of lingual dystonia after electrical trauma has been described; tongue myokymia after radiation therapy.
Bruxism is another frequently occurring hyperkinesis in the oral region. It is manifested by periodic stereotypical movements of the lower jaw with clenching and characteristic grinding of teeth during sleep. Bruxism is observed in healthy people (from 6 to 20% of the entire population) and is often combined with such phenomena as periodic movements of the limbs during sleep, sleep apnea, epilepsy, tardive dyskinesia, schizophrenia, mental retardation, post-traumatic stress disorder. A seemingly similar phenomenon during wakefulness is usually described as trismus.
Facial hemispasm
Facial hemispasm is characterized by stereotypical clinical manifestations, which facilitates its diagnosis.
The following forms of facial hemispasm are distinguished:
- idiopathic (primary);
- secondary (compression of the facial nerve by a tortuous artery, less often by a tumor, and even less often by other causes).
Hyperkinesis with facial hemispasm is paroxysmal in nature. Paroxysm consists of a series of short, rapid twitches, most noticeable in the orbicularis oculi muscle, which, layering on each other, turn into a tonic spasm, giving the patient a characteristic facial expression that cannot be confused with anything else. In this case, there is squinting or closing of the eyes, pulling up of the cheek and corner of the mouth, sometimes (with severe spasm) deviation of the tip of the nose towards the spasm, and often contraction of the muscles of the chin and platysma. Upon careful examination during paroxysm, large fasciculations and myoclonus with a noticeable tonic component are visible. In the interictal period, microsymptoms of increased muscle tone in the affected half of the face are revealed: a prominent and deepened nasolabial fold, often a slight shortening of the muscles of the lips, nose and chin on the ipsilateral sides of the face. Paradoxically, at the same time, subclinical signs of facial nerve insufficiency are revealed on the same side (less retraction of the corner of the mouth when grinning, the symptom of “eyelashes” when voluntarily closing the eyes). Paroxysms usually last from a few seconds to 1-3 minutes. Hundreds of attacks are observed throughout the day. It is important to note that, unlike other facial hyperkinesis (tics, facial paraspasm), patients with facial hemispasm can never demonstrate their hyperkinesis. It is not amenable to volitional control and is not accompanied by corrective gestures and paradoxical kinesias. There is a smaller dependence of the severity of hyperkinesis on the functional state of the brain than in many other forms. Voluntary squinting sometimes provokes hyperkinesis. The most significant is the state of emotional stress, leading to an increase in motor paroxysms, while at rest it disappears, although not for long. Periods free from hyperkinesis usually last no more than a few minutes. During sleep, hyperkinesis persists, but occurs much less frequently, which is objectified during an overnight polygraphic study.
In more than 90% of patients, hyperkinesis begins in the orbicularis oculi muscle, and in the vast majority of cases, from the muscles of the lower eyelid. Over the next few months or years (usually 1 – 3 years), other muscles innervated by the facial nerve are involved (up to the m. stapedius, which leads to the characteristic sound that the patient feels in the ear during a spasm), which are synchronously involved in motor paroxysm . Subsequently, a certain stabilization of the hyperkinetic syndrome is observed. There is no spontaneous recovery. An integral part of the clinical picture of facial hemispasm is a characteristic syndromic environment, occurring in 70–90% of cases: arterial hypertension (usually easily tolerated by patients), dissomnia disorders, emotional disturbances, moderate cephalgic syndrome of a mixed nature (tension headaches, vascular and cervicogenic headaches) . A rare but clinically significant syndrome is trigeminal neuralgia, which, according to the literature, occurs in approximately 5% of patients with facial hemispasm. Rare cases of bilateral facial hemispasm have been described. The second side of the face usually becomes involved after several months or years (up to 15 years), and in this case, attacks of hyperkinesis on the left and right sides of the face are never synchronous.
On the side of hemispasm, as a rule, subclinical but quite obvious permanent (background) symptoms of mild deficiency of the VII nerve are detected.
Emotional disorders, predominantly of an anxious and anxious-depressive nature, tend to worsen with the development in some cases of maladaptive psychopathological disorders up to severe depression with suicidal thoughts and actions.
Although most cases of facial hemispasm are idiopathic, these patients require careful examination to exclude symptomatic forms of hemispasm (compression lesions of the facial nerve as it exits the brain stem). The differential diagnosis of facial hemispasm with another unilateral facial hyperkinesis – postparalytic contracture – does not cause any particular difficulties, since the latter develops after neuropathy of the facial nerve. But it should be remembered that there is a so-called primary facial contracture, which is not preceded by paralysis, but which is nevertheless accompanied by mild, compared to hyperkinesis itself, clinical signs of damage to the facial nerve. This form is characterized by pathological synkinesis in the face, typical of postparalytic contractures.
At the onset of facial hemispasm, it may be necessary to differentiate it from facial myokymia. This is often a one-sided syndrome, manifested by small worm-like contractions of the muscles of the perioral or periorbital localization. It is not characterized by paroxysmality, its manifestations are practically independent of the functional state of the brain, and the presence of this syndrome always indicates a current organic lesion of the brain stem (usually multiple sclerosis or a tumor of the pons).
Rare cases of facial paraspasm manifest themselves in atypical forms in the form of unilateral blepharospasm and even unilateral Bruegel syndrome on the upper and lower half of the face. Formally, such hyperkinesis looks like hemispasm, since it involves one half of the face, however, in the first case, hyperkinesis has clinical and dynamic signs characteristic of dystonia, in the second – for facial hemispasm.
Differential diagnosis in such difficult cases is also recommended to include pathology of the temporomandibular joint, tetanus, partial epilepsy, tonic spasms in multiple sclerosis, hemimastic spasm, tetany, facial myokymia, labio-lingual spasm in hysteria.
Sometimes there is a need to differentiate from tics or psychogenic (“hysterical” in the old terminology) hyperkinesis in the face, which occurs as a facial hemispasm. Among other things, it is useful to remember here that only those muscles that are innervated by the facial nerve take part in the formation of facial hemispasm.
In case of significant diagnostic difficulties, overnight printing can play a decisive role. According to our data, in 100% of cases with facial hemispasm, night polygraphy reveals an EMG phenomenon that is pathognomonic for this disease in the form of paroxysmal, high-amplitude (over 200 μV) fasciculations occurring in the superficial stages of night sleep, grouped in packs of irregular duration and frequency. The paroxysm begins suddenly with maximum amplitudes and also ends abruptly. It is an EMG correlate of hyperkinesis and is specific for facial hemispasm.
Facial hyperkinesis, combined or occurring against the background of more common hyperkinesis and other neurological syndromes
- Idiopathic tics and Tourette’s syndrome.
- Generalized drug-induced dyskinesia (1-dopa, antidepressants and other drugs).
- Choreic hyperkinesis in the face (Huntington’s, Sydenham’s chorea, benign hereditary chorea, etc.).
- Facial myokymia (brain stem tumors, multiple sclerosis, etc.).
- Facial crampies.
- Facial hyperkinesis of epileptic nature.
It is necessary to emphasize once again that in a number of diseases, facial hyperkinesis can only be a stage or an integral part of a generalized hyperkinetic syndrome of various origins. So idiopathic tics, Tourette’s disease, Huntington’s chorea or Sydenham’s chorea, common cramps, many drug-induced dyskinesias (for example, associated with treatment with dopa-containing drugs), etc. at first they may manifest themselves only as facial dyskinesias. At the same time, a wide range of diseases are known in which facial hyperkinesis is immediately identified in the picture of a generalized hyperkinetic syndrome (myoclonic, choreic, dystonic or tic). Many of these diseases are accompanied by characteristic neurological and (or) somatic manifestations, which greatly facilitate diagnosis.
This group also includes facial hyperkinesis of an epileptic nature (opercular syndrome, facial convulsions, gaze deviations, “lingual” epilepsy, etc.). In this case, the differential diagnosis should be carried out in the context of all clinical and paraclinical manifestations of the disease.
Hyperkinetic syndromes in the facial area not associated with the participation of facial muscles
- Oculogyric dystonia (dystonic gaze deviation).
- Syndromes of excessive rhythmic activity in the extraocular muscles:
- opsoclonus,
- “nystagmus” eyelids,
- bobbing syndrome,
- dipping syndrome, e) “ping-pong” gaze syndrome,
- periodic alternating gaze deviation with dissociated head movements,
- periodic alternating nystagmus,
- cyclic oculomotor paralysis with spasms,
- periodic alternating asymmetric deviation,
- myokymia syndrome of the superior oblique muscle of the eye,
- Duane’s syndrome.
- Masticatory spasm (trismus). Hemimastic spasm.
Clinicians consider it advisable to include in this section the following (IV) group of hyperkinetic syndromes in the head and neck region of non-facial localization due to the importance of this problem for the practitioner. (In addition, some of these hyperkinesias are often combined with facial localization of dyskinesias)
Oculogyric dystonia (dystonic gaze deviation) is a characteristic symptom of postencephalitic parkinsonism and one of the early and characteristic signs of neuroleptic side effects (acute dystonia). Oculogyric crises can be an isolated dystonic phenomenon or combined with other dystonic syndromes (tongue protrusion, blepharospasm, etc.). Attacks of upward gaze deviation (more rarely, downward gaze deviation; even less often, lateral deviation or oblique gaze deviation) last from several minutes to several hours.
Syndromes of excessive rhythmic activity of the oculomotor muscles. They combine several characteristic phenomena. Opsoclonus is constant or periodic chaotic, irregular saccades in all directions: different frequencies, different amplitudes and different vector movements of the eyeballs are observed (“dancing eyes syndrome”). This is a rare syndrome indicating organic damage to the brainstem-cerebellar connections of various etiologies. Most cases of opsoclonus described in the literature relate to viral encephalitis. Other causes: tumors or vascular diseases of the cerebellum, multiple sclerosis, paraneoplastic syndrome. In children, 50% of all cases are associated with neuroblastoma.
“Nystagmus century” – a rare phenomenon manifested by a series of fast, rhythmic, upward jerk-like movements of the upper eyelid. It has been described in many diseases (multiple sclerosis, tumors, traumatic brain injury, Miller Fisher syndrome, alcoholic encephalopathy, etc.) and is caused by eye movements such as convergence or when moving the gaze. “Nystagmus of the eyelids” is considered a sign of damage to the midbrain tegmentum.
bobbing syndrome (ocular bobbing) is manifested by characteristic vertical movements of the eyes, which are sometimes called “floating movements”: with a frequency of 3-5 per minute, in most cases bilateral friendly, rapid deviations of the eyeballs downwards are observed, followed by their return back to the original position, but in a more slower pace than the downward movement. This ocular “swing” occurs when the eyes are open and is usually absent when the eyes are closed. In this case, bilateral horizontal gaze palsy is noted. The syndrome is characteristic of bilateral injuries of the pons (hemorrhage into the pons, glioma, traumatic damage to the pons; often observed in “locked-in” syndrome or coma). Atypical bobbing (with intact horizontal eye movements) has been described in obstructive hydrocephalus, metabolic encephalopathy, and pontine compression by cerebellar hematoma.
Dipping syndrome (ocular dipping) is the reverse syndrome of bobbing syndrome. The phenomenon is also manifested by characteristic vertical eye movements, but in the opposite rhythm: slow downward eye movements are observed, followed by a delay in the lowest position and then a rapid return to the middle position. Such cycles of ocular movements are observed with a frequency of several times per minute. The final phase of raising the eyeballs is sometimes accompanied by wandering eye movements in the horizontal direction. This syndrome has no topical significance and often develops with hypoxia (respiratory disorders, carbon monoxide poisoning, hanging, status epilepticus).
Ping-pong gaze syndrome (periodic alternating gaze) is observed in patients in a comatose state and is manifested by slow wandering movements of the eyeballs from one extreme position to another. Such repeated rhythmic horizontal conjugal eye movements are associated with bilateral hemispheric lesions (infarctions) with relative intactness of the brain stem.
Periodic alternating gaze deviation with dissociated head movements is a unique rare syndrome of cyclic disorders of eye movements, combined with contraversive head movements. Each cycle includes three phases: 1) friendly deviation of the eyes to the side with a simultaneous turn of the head in the opposite direction, lasting 1-2 minutes; 2) a period of “switching” lasting from 10 to 15 seconds, during which the head and eyes again acquire their original normal position and 3) a friendly deviation of the eyes to the other side with a compensatory contralateral turn of the face, also lasting 1-2 minutes. Then the cycle constantly repeats itself, stopping only in sleep. During the cycle, gaze paralysis is observed in the direction opposite to the direction of ocular deviation. In most of the reported cases, nonspecific involvement of the structures of the posterior cranial fossa is postulated.
Periodic alternating nystagmus can be congenital or acquired and also manifests itself in three phases. In the first phase, repeated repetitions are observed for 90-100 seconds. horizontal shocks of nystagmus, in which the eyes “beat” in one direction; the second phase of 5-10 seconds of “neutrality”, during which nystagmus may be absent or there is a pendulum-like nystagmus or downward nystagmus, and the third phase, also lasting 90 – 100 seconds, during which the eyes “hit” in the opposite direction. If the patient tries to look in the direction of the fast phase, the nystagmus becomes more severe. The syndrome is presumably based on bilateral damage to the paramedian reticular formation at the pontomesencephalic level.
Alternating oblique deviation (skew dewiation). Oblique deviation or Hertwig-Magendie syndrome (Hertwig-Magendiesche) is manifested by vertical divergence of the eyes of supranuclear origin. The degree of divergence may remain constant or depend on the direction of gaze. The syndrome is usually caused by acute damage to the brain stem. Sometimes this sign can be intermittent and then there is a periodic alternation of the side of the higher eye. The syndrome is associated with bilateral damage at the pretectal level (acute hydrocephalus, tumor, stroke and multiple sclerosis are the most common causes).