Startl - syndrome: causes, symptoms, diagnosis

The startle syndrome unites a large group of diseases characterized by an intensified startle reaction (startle - flinch) to unexpected external stimuli.

The start reaction (the "generalized motor activation reaction") is a universal component of the orienting reflex for mammals. Its latent period is less than 100 msec, and the duration is less than 1000 msec. For a physiological start-reaction, a habitual reaction is characteristic. As a benign phenomenon, the start-reaction occurs in 5-10% of the population.

The intensified start-reaction is a stereotyped response (flinching) to light, sound and other unexpected stimuli. The predominant element of this flinch is the generalized reaction of the bending of the head, trunk and extremities (though sometimes the extension reaction is observed). It, like the physiological start-up reaction in healthy people, is mediated mainly by the reticular formation of the brain stem (as well as the amygdala and the hippocampus), has an extremely wide receptive field and is caused by an increase in the excitability of spinal motor neurons. The start reaction is modulated by cortical mechanisms. The alarm state reinforces the start-reaction. The pathological (strengthened) start-reaction differs from its physiological by its severity.

An intensified startle reaction can also be a consequence of a variety of diseases affecting the nervous system. In this regard, it can be primary and secondary.

The main forms and causes of the start syndrome:

I. Physiological start-reaction of healthy people (shudder in response to light, sound and other unexpected stimuli).

II. Reinforced pathological reaction:

A. Primary forms:

1. Hyperexlexion.
2. Culturally caused syndromes, such as meryachit, lat, "jumping Frenchman from Maine" and others.

B. Secondary forms:

1. Non-progressive encephalopathies.
2. Startle-epilepsy.
3. High damage to the spinal cord and brain stem (stem reticular reflex myoclonus).
4. Malformatsiya Arnold-Chiari.
5. Occlusion of posterior thalamic artery.
6. Creutzfeldt-Jakob disease.
7. Myoclonic epilepsy.
8. The syndrome of a rigid person.
9. Tourette's syndrome.
10. Hyperthyroidism.
11. Hyperactive behavior.
12. Impaired mental function.
13. Iatrogenic forms (drug-induced).
14. Psychogenic diseases.

A. Primary forms of the startle syndrome

Primary forms include a benign reinforced startle reaction, startle diseases, startle-epilepsy and some so-called culture-mediated disorders (the pathophysiology of the latter remains poorly understood and their place in the classification may change).

Hyperexlexia is a sporadic (with a later onset) or (more often) hereditary disease with an autosomal dominant type of inheritance, characterized by an onset in early childhood, congenital muscular hypertension ("stiff-baby"), which gradually regresses with age, and the presence of pathological start-reactions. The latter are the dominant clinical symptom. In the same families, unfolded and less pronounced forms occur. Start-up reactions persist in contrast to muscle rigidity throughout life and often cause the patient to fall (sometimes with repeated fractures). A demonstrative start-reaction is a flinching at the point of the nose, which is not addictive. In this case, unlike start-epilepsy, consciousness is not violated. For patients with hyperexcplexion, enhanced nocturnal myoclonas are characteristic. It was suggested that hyperexpection is a reticular stimulus-sensitive (reflex) myoclonus. Often there is a good response to clonazepam.

Cultural-conditioned syndromes, which can be both family and sporadic, include such things as "lata", "peace", "jumping Frenchman from Maine", "imu", "mali-mali", "yaun", " "Hiccups" and others (there are more than 10 of them), which are described in different countries of the world, since the XV century.

The most studied are two forms: "lata" and "jumping Frenchman's syndrome from the state of Maine". They occur both in the form of family and sporadic forms. The main manifestations are pronounced start-up reactions in response to unexpected sensory (more often sound) stimuli, which are combined with such phenomena (not necessarily with all of them) as echolalia, echopraxia, coprolalia, and automatic execution of orders or movements that mimic the behavior of others. These syndromes are currently rare.

B. Secondary forms of the startle syndrome

Secondary forms occur with a large number of neurological and mental diseases. They include non-progressive encephalopathies (post-traumatic, posthypoxic, perinatal anoxia), degenerative diseases, high spinal cord injuries, Arnold Chiari syndrome, occlusion of the posterior thalamic artery, brain abscess, Chiari anomaly, Creutzfeldt-Jakob disease, myoclonic epilepsies, rigorous man syndrome, sarcoidosis , viral infections, multiple sclerosis, Tourette's syndrome, hyperthyroidism and "hyperadrenergic states", Tay-Sachs disease, some phakomotoses, paraneoplastic lesion brainwave, hyperactive behavior, delayed mental maturation and some other conditions. Reinforced starter reactions are also found in the picture of psychogenic neurotic diseases, especially in the presence of anxiety disorders.

A special variant of the secondary startle syndrome is "startle-epilepsy", which does not designate a nosological unit and unites several phenomena with epilepsies of different origin. This includes epileptic seizures, which are provoked by unexpected sensory stimuli ("stimulant-sensitive epilepsy"), causing startle. Such epileptic seizures are described in various forms of cerebral palsy, as well as in patients with Down syndrome, Sturge-Weber disease, and Lennox-Gastaut syndrome. Startle-induced epileptic seizures can be both partial and generalized and are observed in lesions of the frontal or parietal region. A good effect (especially in children) is provided by clonazepam and carbamazepine.