Balance disorders/PGS

Introduction
Balance means the ability to maintain the position of the body and its parts in space. It depends on constant afferentation from the somatosensory, vestibular and visual systems, on the processing of this information in the brainstem, cerebellum, basal ganglia and some parts of the cortex. Dysfunction of any of these areas of the nervous system leads to a relatively specific balance disorder that can be distinguished by a careful history and clinical examination.

The history of balance disorders must include the following information:


 * type of balance disorder, ameliorating and aggravating factors
 * moments of provocation and the beginning of a feeling of instability (acute, gradual)
 * duration of progression (minutes, days, months, years)
 * course (continuous, progressive, episodic), in case of episodic, the duration of the attack
 * accompanying symptoms (vegetative, auditory, other neurological)
 * history of internal and psychiatric comorbidities and used medication

Already from the anamnesis and clinical examination it is possible to distinguish:


 * 1) vertigo, which indicates a lesion of the vestibular system
 * 2) ataxia caused by lesions of the cerebellum, proprioceptive pathways or the vestibular system
 * 3) stability disorders caused by lesions of the basal ganglia, frontal cortex or their connections
 * 4) non-specific or pre-synopal states of a feeling of imbalance, which are usually caused by cardiovascular, metabolic or vegetative causes.

Tonic deviations
They are also a reflection of static vestibular imbalance. In vertigo of peripheral origin, their direction is identical to the slow component of nystagmus (they are directed towards the weaker vestibular apparatus), therefore the peripheral vestibular syndrome is sometimes called harmonic.Hautant's testis performed sitting with the back supported, eyes closed and the upper limbs on the forearms. The deviation of the limbs to the side in 30 seconds is monitored. Deviation of standing from the vertical has a similar cause. It is true that the patient tends to fall behind the weaker labyrinth (ear), so the direction of the fall changes when the head is turned. There is also deviation from a straight direction when walking. A more sensitive test is the Unterberger test, when the patient is allowed to march in place with forearms and eyes closed for at least 30 seconds. With vestibular asymmetry, we observe a deviation of more than 45°. Central vestibular syndrome causes tonic deviations and falls without lateral predilection, and is therefore sometimes called dysharmonic.

Associated auditory or trunk symptoms
We examine the hearing as an orientation by rubbing the fingers gradually over both ears of the patient. Hearing impairment associated with vertigo suggests its peripheral origin. From the trunk symptoms, we will examine oculomotor skills, the function of other cranial nerves, the cerebellum and long motor and sensory pathways. The finding of trunk symptoms along with vertigo is indicative of its central origin.

Special exams
In milder unilateral vestibular lesions that do not cause spontateous nystagmus, we examine the so-called dynamic vestibular function using the head-impulse test, which consists of passive head movements in the planes of the semicircular canals while visual fixation of one point. Impairment of the vestibulo-ocular reflex manifests itself in insufficient compensatory movement of the bulbs against head movement when moving the head towards the affected labyrinth, which must be compensated by a compensatory saccade.

A very sensitive test for a unilateral vestibular disorder is the caloric test – injection of warm and cold water into the ear canal, which induces nystagmus, the intensity of which is recorded on both sides and subsequently compared. If positional vertigo is suspected, we perform positional tests – Dix-Hallpike maneuver – during which we turn the patient's head to a 45-degree angle and quickly place him in this way with his head over the bed, we monitor the development of vertigo and nystagmus, which typically comes with a latency of several seconds and up to a minute fade away. We also perform the test with the head facing forward and turned 45 degrees to the other side.

Audiometry
It objectivies hearing impairment, the presence of which indicates a peripheral disability.

Stem evoked potentials
They objectify the impairment of the vestibular pathway.

CT scan of the brain
We indicate for central and post-traumatic vestivular syndrome. It will help rule out serious lesions of the inner ear, lesions of the cerebellum (malacia, hemorrhage, atrophy), can show older trunk malacia, tumor of the pontine angle and diffuse ischemic lesions.

MRI of the brain
It is more accurate in the diagnosis of multiple sclerosis, trunk malacia and tumors of the pons.

Liquor
It is necessary to examine if an inflammatory cause or multiplr.

X-ray of the cervical spine
It will show degenerative changes when cervicogenic imbalance is suspected. However, the examination has little informative value, as the finding of degenerative changes does not mean confirmation of a causal connection with a balance disorder.

Sonography of cerebral arteries
demonstrates hemodynamic disorders or congenital abnormalities of the brainstem.

Tab. 1: Distinguishing between peripheral and central vestibular syndrome

Ataxia
Ataxia is dyscoordination or clumsiness of movements that is not the result of muscle weakness. This is a failure of the plan, measurement and monitoring of the trajectory of movements. It can affect eye movements, speech, limbs, trunk, standing and walking and is caused by lesions of the vestibular apparatus, cerebellum or proprioceptive pathways.

Clinical examination
Taxi is examined on the upper limbs with the finger-nose test, when we let the patient alternately touch his nose with his index finger and our finger, whose position we change, then we examine the finger-nose test with closed eyes. On the lower extremities, we examine the taxi with the heel-knee test, where the patient touches the heel of the knee of the other lower extremity without visual control and then slowly moves the heel down the lower leg. Trunk ataxia is investigated by standing stability test, first with slightly straddled (stance I), then supine (stance II) and finally standing supine with closed eyes (stance III). We evaluate deviations to the sides (titubation), possibly if there is a tendency to fall in a certain direction.

CT scan of the brain
which can show atrophy or structural lesions of the cerebellum (tumor, malacia, hemorrhage, atrophy).

MRI of the brain
which is more accurate in depicting cerebellitis and multiple sclerosis (MS).

Copper metabolism screening
an ophthalmological examination focused on the detection of the Keyser-Fleyscher ring must be performed in patients younger than 45 years to rule out Wilson's disease.

Genetic testing
indicated for suspected spinocerebellar ataxia, Friedreich ataxia or Wilson's disease.

Paraneoplastic antibodies
(anti-Yo) when paraneoplastic involvement is suspected.

Examination of the cerebrospinal fluid
to rule out an inflammatory cause and MS and vitamin E level.

Auxiliary examination methods in sensory ataxia
The causes of sensory ataxia are numerous and can be located in the peripheral nerves (neuropathy) or in the long pathways of the spinal cord, especially the posterior cords that carry proprioceptive information (myelopathy). The following will help in the diagnosis: EMG to confirm axonal or demyelinating lesions of the peripheral nervous system.

Liquor
to rule out chronic immune demyelinating polyneuropathy and infectious causes.

Paraneoplastic antibodies
(anti-Hu) when paraneoplastic involvement is suspected.

MRI of the spinal cord
it shows atrophy or structural involvement of the posterior cords (compression by tumorous masses, multiple sclerosis, vascular malformation, spinal cord ischemia, vasculitis).

Further, the search for the cause of polyneuropathy (vitamin B12 level, blood glucose, TSH) will help.

Porucha stability při lézi frontálních drah, bazálních ganglií a jejich spojů
je způsobena především ztrátou posturálních reflexů a poruchou iniciace pohybů – zejména chůze. Posturální reflexy vyšetřujeme pull-testem, kdy hodnotíme schopnost pacienta vyrovnat vychýlení z rovnováhy postrčením dozadu. Fyziologickou odpovědí je pokrčení kolen. Pečlivě vyšetřujeme rovněž chůzi a přítomnost dalších příznaků Parkinsonského syndromu (akineza, rigidita, třes). Poruchou stability tohoto typu se blíže zabývá kapitola – Parkinsonské syndromy.

Z pomocných vyšetření pomohou zejména zobrazovací metody (CT, MRI mozku), které mohou odlišit strukturální abnormity v oblasti bazálních ganglií, multiinfarktové postižení bílé hmoty (morbus Binswanger) a normotenzní hydrocefalus.

Presyncopal states and non-specific feelings of imbalance
(emptiness in the head, uncertainty, feeling as if on water) do not have a vestibular character and can be caused by an insufficient supply of oxygen and nutrients to the brain in cardiovascular, hematological or metabolic disorders, or by abnormal processing of sensory inputs or by abnormal experiencing of internal states in psychiatric disorders. It is always necessary to remember that disorders of the cardiovascular system can also cause central vestibular syndrome, especially in older patients in the field of atherosclerotic changes in the vertebrobasilar and river bed and branches of the circle of Willis.

If a presyncopal state is suspected, it is necessary to perform an ECG, examination, measure blood pressure while lying down and after standing, perform a biochemical examination (glycemia, mineralogram, renal parameters, TSH, inflammatory markers) and a blood count.

Sonography of cerebral arteries can demonstrate bilateral hemodynamically significant carotid stenosis or diffuse atherosclerotic changes in the vertebrobasilar basin.

The above examinations must also be performed in case of central vestibular syndrome!

We will perform an EMG if tetanic syndrome is suspectd, as well as an examination level of Mg and Ca.

Disorders of the peripheral vestibular system (both acute and chronic)
If peripheral vestibular syndrome is suspected, consultation with an ENT specialist is necessary.

Benign paroxysmal positional vertigo
It is a very common cause of peripheral vestibular syndrome. There is a history of repeated attacks of vertigo of the peripheral type, lasting less than 1 minute, induced by a change in the position of the head. They typically appear with a latency of several seconds after lying down and after verticalization. Patients also complain of slight instability when walking. The cause is the release of calcium carbonate crystals from the otolith system and their travel into the semicircular canals (most often into the back), which leads to irritation of the hair cells when moving the head. It occurs most often in the 6th decade, more in women, the risk factor is head trauma and previous viral labyrinthitis. We establish the diagnosis using the Dix-Hallpike position test. The therapy of choice is positioning maneuvers (Semont's or Epley's), during which the crystals move from the semicircular canals to the utricle, where they do not cause problems. Epley maneuver - YouTube presentation (English)

Acute inflammatory vestibulopathy
In the case of viral vestibular neuronitis (neurolabyrintitis) vertigo develops within a few hours, reaches its maximum in about 24 hours and then gradually subsides, but complete adjustment only occurs within 1–3 months. In about 50% of cases, it is preceded by a viral disease, sometimes it occurs epidemically in families. It is not accompanied by significant hearing impairment. This benign entity must be differentiated from zoster oticus, which is caused by the varicella-zoster virus. It usually starts with an earache, followed by the seeding of a vesicular eruption in the area of ​​the external auditory canal and on the eardrum (sometimes it can only be seen otoscopically - in case of suspicion, an ENT examination is necessary). At any time during the course, damage to the VII and VIII cranial nerves can occur, which can be irreversible. Also borreliosis in stage II. can cause disorders of the cranial nerves, typically a bilateral lesion of VII. nerve, less often lesions of the oculomotor or vestibulocochlear nerve. The diagnosis of herpes zoster and borreliosis is confirmed by a positive cerebrospinal fluid examination (cytoprotein association with mononuclear pleocytosis, detection of the pathogen microscopically or by PCR, detection of specific antibodies). Bacterial labyrinthitis is rare today and can be a complication of otitis media or osteomastoiditis. It usually has a rapidly developing severe course. In the anamnesis, it is possible to find pain in the area of ​​the ear or mastoid process. The diagnosis is confirmed by an otoscopic examination and/or a CT pyramid.

Etiology and clinical course
It is caused by an increase in pressure in the endolymphatic system, which leads to repeated ruptures of the membrane separating the peri- and endolymphatic space. It is manifested by repeated attacks of vertigo, a feeling of fullness in the affected ear, fluctuating hearing impairment and tinnitus, which typically last several minutes to hours. The disease occurs more often in women, between the ages of 30 and 50. a year. Attacks occur at irregular intervals of a week to several years, the hearing impairment is usually reversible in the early stages, later remains a residue in the form of hearing impairment in the low-frequency area demonstrable by audiometry. Over 20 years of disease duration, up to 20% of patients may have bilateral impairment of hearing and vestibular function.

Meniere 's syndrome is a set of symptoms similar to Meniere's disease, but with a known etiology affecting the permeability of blood vessels. The most common are degenerative diseases of the cervical spine, endocrinological diseases, allergic reactions, infections.

Clinical course
A triad is typical: tinnitus, rotational vertigo, hearing loss. Symptoms are typically unilateral. Accompanying symptoms such as nausea, vomitus, balance disorders may appear. Attacks last minutes, hours, occasionally even days. They fade away slowly. Repeated seizures can lead to hearing loss.

Diagnostics
We establish the diagnosis based on:


 * history of at least two typical attacks (dg. cannot be reliably determined after the first attack),
 * proof of a shift in the hearing threshold by 10 dB in 2 different frequencies during at least one examination ,
 * by ruling out another cause.

diff. dg.
vestibular schwannoma Multiple sclerosis circulatory disorders of the CNS CVS disease

Therapy
Therapy consists of dietary measures – reducing salt in the diet, limiting smoking and caffeine, as well as pharmacotherapy with diuretics or betahistine. In late stages, local endolymphatic application of gentamicin is considered. Vestibular rehabilitation is appropriate.

Posttraumatic Vertigo
Dizziness after head trauma is very common and can occur as a result of damage to the peripheral vestibular apparatus, contusion of the trunk or injury to the cervical spine. Post- traumatic vertigo must be examined with a brain CT scan, which will show a possible fracture of the pyramid with possible consequences of tears in the membranous labyrinth or laceration of the vestibular nerve. We always think of a base fracture when hemorrhagic or cerebrospinal fluid otorhea is found. Labyrinth contusion often follows sharp blunt blows to the ear region. In the pathophysiology, microhemorrhages and damage to hair cells, which are not visible on CT brain, are most likely to be used. Contusions of the labyrinth are often associated with perforation of the tympanic membrane. Perilymphatic fistula it can occur with fractures of the base, but also with blunt trauma with a sudden change in the pressure of the cerebrospinal fluid and subsequent leakage of perilymph from the inner ear, as well as with barotrauma, strong noise or increased abdominal pressure. The development is sudden and is usually accompanied by a loud popping sound in the ear. The most common vertigo following an injury is benign positional vertigo, which occurs with a certain latency. It is important to distinguish non-vestibular dizziness within the post-concussion syndrome, which includes dizziness, headache, irritability, impaired concentration and forgetfulness, and also within the whiplash injury of the cervical spine caused by sudden sharp flexion and extension of the spine, most often in car accidents, which causes pain in the cervical spine and head. It is also important to differentiate central vertigo at trunk contusion with ischemic or hemorrhagic changes. The diagnostic method of choice in this case is MRI.

Tumors of the pontine angle
They are mostly benign and grow very slowly. In 80% of cases it is a vestibular schwannoma (previously a statoacoustic neuroma), in the remaining cases it is most often a meningioma or cholesteatoma. A neurinoma is usually first manifested by unilateral hearing loss or tinnitus, gradually adding a balance disorder, which tends to have a non-specific character. In an advanced stage, other cranial nerves passing through the pontine angle ( trigeminus, n. facialis ) are affected. In diagnosis, MRI takes precedence. The therapy is surgical, preferably open surgery, an alternative is stereotactic gamma knife operation. Since schwannoma it grows very slowly, we choose a conservative procedure - observation - for older patients and smaller tumors.

Toxické vestibulopatie
Alkohol při akutní ebrietě může vyvolat cerebellární i vestibulární ataxii s vertigem a nystagmem. Při nálezu nystagmu po úrazu v ebrietě je však nejprve nutno vyloučit závažnější příčinu tohoto stavu. Rovněž aminoglykosidy, salicyláty, chinin, chinidin a cis-platina jsou vestibulotoxické.

Lékové intoxikace
Cerebellární syndrom, někdy doprovázený i zmateností, může být vyvolaný intoxikací alkoholem, sedativy-hypnotiky, jako jsou benzodiazepiny či barbituráty nebo antikonvulzivy – typicky fenytoinem či carbamazepinem. Intoxikace může vzniknout i omylem, záměnou slabší za silnější dávku léku (např. Rivotril 0.5&thinsp;mg za 2&thinsp;mg balení). Hladiny těchto látek je možné stanovit v plazmě a/nebo v moči, což má význam v potvrzení suspekce na intoxikaci.

Infekční onemocnění
Akutně vzniklý mozečkový syndrom může být vzácně způsoben infekční příčinou – virovou encefalitidou (varicella, příušnice, lymfocytární choriomeningitis) či bakteriálním abscesem. Pozor – absces je kontraindikací lumbální punkce, diagnostikuje se výhradně zobrazovacími metodami! Vzácně může mít také autoimunitní příčinu a následovat virové onemocnění nebo vakcinaci.

Roztroušená skleróza
Akutní vertigo centrálního původu trvající déle 24 hodin, zejména u mladších osob (typicky v 2.–3. dekádě) a pokud se vyskytuje opakovaně může být prvním příznakem roztroušené sklerózy. V anamnéze nutno pátrat po zhoršování zraku, parestéziích končetin, v objektivním nálezu po známkách léze pyramidové dráhy. V průběhu onemocnění se může objevit ataxie původu cerebellárního či sensorického, zpočátku relabujícího, v pokročilejších stádiích i trvalého charakteru.

Migrenosní závratě
Závratě mohou být projevem bazilární migrény a tzv. vestibulární migrény. Bazilární migréna se častěji vyskytuje u mladých dívek a projevuje se příznaky dysfunkce vertebrobasilárního povodí (verigo, ataxie, dysartrie, periorální parestézie, skotomy, amnézie či porucha vědomí). Vestibulární migréna se projevuje akutním vertigem s náhlým začátkem trvající typicky minuty až hodiny. Vertigo může být předcházeno, následováno nebo se může vyskytovat současně s cefaleou. V 1/3 případů se může vertigo objevit i bez cefaley. Pacienti mívají mimo ataky zvýšenou tendenci ke kinetóze.

Difuzní mozkové léze a ostatní příčiny
Centrální vestibulární syndrom nebo pocit nestability může být též příznakem difůzních lézí bílé hmoty: demyelinizačních, vaskulitických, pozánětlivých ale nejčastěji při vaskulárně-ischemických změnách atherosklerotické etiologie. Jedná se o jednu z nejčastějších příčin instability ve stáří. Pacienti si stěžují na chronické nerotační závratě zhoršující se pohybem hlavou a při vertikalizaci (ortostáza). Stav kolísá se stavem hydratace a kardiovaskulárního výdeje a může progredovat do obrazu typické VBI.

Rovněž mozkové tumory, nejčastěji v parieto-temporální lokalizaci, se mohou projevovat rekurentími atakami vertiga trvajícími několik minut, někdy doprovázenými amnézií a dezorientací. Vertigo může mít vzácně rovněž epileptický původ u fokusů v této lokalizaci.

Tab. 2: Diferenciální diagnóza závratí

Autoimunitní postižení
Pacienti s celiakií, autoimunitní thyroiditis a anti-GAD (glutamic acid decarboxylase) syndromem mohou vykazovat pomalu progredující cerebellární syndrom, který je s největší pravděpodobností způsoben autoprotilátkami a v některých případech dobře reaguje na léčbu intravenózními imunoglubuliny. Diagnosticky se uplatňuje průkaz příslušných protilátek (antigliadinové, anti-transglutamináza, anti-TPO, antithyreoglubulinové, anti-GAD).

Toxická cerebellární degenerace
Nejčastěji se vyskytuje u chronických alkoholiků, nejspíše na podkladě nutriční deficience. V klinickém obraze dominuje zejména ataxie stoje a chůze, dále potom přidružené nálezy polyneuropatie či známky difuzní léze nervového systému. Je třeba pátrat po známkách akutní Wernickeho encefalopatie. CT a MRI mohou ukázat cerebellární atrofii. Terapií je abstinence alkoholu, adekvátní výživa a dlouhodobá substituce B vitaminů. Cerebellární degeneraci může způsobit i dlouhodobé podávání antiepileptika phenytoinu.

Malformace zadní jámy
Vývojové abnormity zadní jámy mohou způsobit cerebellární poruchu v dospělosti. Nejčatější je Arnold-Chiariho malformace (typ I) s kaudálním posunem mozečkových tonzil do foramen magnum. Kromě cerebellární ataxie chůze se může manifestovat obstrukčním hydrocefalem (cefalea, zvracení), kompresí kmene (vertigo, dysfagie, dysatrie) a syringomyelií (porucha termického a algického čití). Diagnostikuje se zobrazovacími metodami.

Tab. 3: Diferenciální diagnóza mozečkového syndromu

Symptomatická terapie
Závrať je subjektivně velmi nepříjemný pocit, opakované zvracení může navíc vést k dehydrataci a minerálovému rozvratu. U akutního postižení je tedy indikovaná symptomatická terapie. Základním přípravkem je fenothiazinové neuroleptikum thiethylperazin (Torecan), který působí jako antivertiginózum i antiemetikum, můžeme jej aplikovat intramuskulárně či intravenózně, k dispozici jsou i čípky a tablety. Nežádoucím účinkem, zvláště u starších pacientů může být rozvoj extrapyramidového syndromu, neměl by se proto používat u pacientů s Parkinsonovou nemocí. Další možností je použití diazepamu, který je k dispozici ve stejných formách, jako thiethylperazin. U méně intenzivního vertiga lze použít antihistaminik jako embramin (Medrin), kombinovaný perparát Arlevert (dimenhydrinát + cinnarizin), které jsou k dispozici pouze v tabletové formě či prometazin (Prothazin), který je k dispozici i v injekční formě. Nežádoucími účinky jsou útlum, ospalost a anticholinergní efekt (rozmazané vidění, tachykardie, sucho v ústech, zácpa, porucha mikce).

U chronického vertiga způsobeného ischemií labyrintu nebo Menierským syndromem je lékem první volby antihistaminikum betahistin (Betaserc), který nasazujeme v dostatečné dávce (zpočátku 48&thinsp;mg denně) po dostatečně dlouhou dobu (aspoň několik týdnů). Určitý efekt může mít i cinarizin, který je účinný i v prevenci kinetóz, může však zhoršovat Parkinsonský syndrom u staších pacientů a extrakt z ginkgo-biloby, který může zvyšovat riziko hemoragie u antikoagulovaných pacientů.

Antivertiginóza by se neměla používat ve fázi rekonvalescence z akutního vestibulárního syndromu, protože zpomalují kompenzaci. Dále by se neměla používat u chronických oboustranných vestibulárních lézích, kdy je nejdůležitější terapií vestibulární rehabilitace s nácvikem kompenzačních strategií s použitím somatosensorického a zrakového aparátu.