The Chvostek sign ( / ˈ k v ɒ s t ɪ k / ) is a clinical sign that someone may have a low blood calcium level (a decreased serum calcium, called hypocalcemia ). The Chvostek sign is the abnormal twitching of muscles that are activated (innervated) by the facial nerve (also known as Cranial Nerve Seven, or CNVII). When the facial nerve is tapped in front of the ear, the facial muscles on the same side of the face will contract sporadically (called ipsilateral facial spasm). The muscles that control the nose, lips and eyebrows are often the ones that will spasm.
31-449: Chvostek may refer to: Chvostek sign , a clinical sign of existing nerve hyperexcitability Annabelle Chvostek (born 1973), Canadian singer-songwriter based Milan Chvostek (1932–2018), producer and director František Chvostek (1835–1884), Czech-Austrian military physician Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with
62-423: A portion of the molecule an amino-modified glycoside ( sugar ). The term can also refer more generally to any organic molecule that contains amino sugar substructures. Aminoglycoside antibiotics display bactericidal activity against Gram-negative aerobes and some anaerobic bacilli where resistance has not yet arisen but generally not against Gram-positive and anaerobic Gram-negative bacteria. Streptomycin
93-742: A primary mode of action as protein synthesis inhibitors , though additional mechanisms are implicated for some specific agents, and/or thorough mechanistic descriptions are as yet unavailable. The inhibition of protein synthesis is mediated through aminoglycosides' energy-dependent, sometimes irreversible binding, to the cytosolic , membrane-associated bacterial ribosome (image at right). (Aminoglycosides first cross bacterial cell walls— lipopolysaccharide in gram-negative bacteria—and cell membranes, where they are actively transported . ) While specific steps in protein synthesis affected may vary somewhat between specific aminoglycoside agents, as can their affinity and degree of binding, aminoglycoside presence in
124-507: A related but distinct chemical structure class often discussed with aminoglycosides, does not induce mRNA misreading and is generally not bactericidal.) It has been proposed that aminoglycoside antibiotics cause oxidation of guanine nucleotides in the bacterial nucleotide pool, and that this contributes to the cytotoxicity of these antibiotics. The incorporation of oxidized guanine nucleotides into DNA could be bactericidal since incomplete repair of closely spaced 8-oxo-2'-deoxyguanosine in
155-448: A result of hyperventilation syndrome, which can lead to a drastic reduction of the concentration in serum of calcium ions while at normal levels, for the binding of a significant proportion of ionized calcium (Ca ) with albumin and globulins. Chvostek's sign is not a very specific sign of tetany as it may be seen in 10% to 25% of healthy adults. It is therefore not a reliable clinical sign for diagnosing latent tetany . The sensitivity
186-461: Is a cofactor for adenylate cyclase , which catalyzes the conversion of ATP to 3',5'-cyclic AMP. The 3',5'-cyclic AMP (cAMP) is required for parathyroid hormone activation. It is frequently seen in alcoholics, persons with diarrhea, patients taking aminoglycosides or diuretics, because hypomagnesemia can cause hypocalcemia. It is also seen in measles, tetanus and myxedema . It can also be found in subjects with respiratory alkalosis, for example as
217-524: Is a more accurate predictor of hypocalcemia, allowing clinicians to recognise the condition earlier. The sign is named after František Chvostek , an Austrian-born surgeon who lived in Moravia, in the Czech Republic. In his professional life, Chvostek devoted himself to the study of etiopathogenesis and to the treatment of neurological disorders, including by means of electrotherapy. In 1876, he first described
248-413: Is lower than that in the corresponding Trousseau sign as it is negative in 30% of patients with hypocalcemia. Due to the combination of poor sensitivity and specificity the clinical utility of this sign is reduced. Aminoglycoside Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as
279-680: Is necessary to obtain the correct dose. These agents exhibit a post-antibiotic effect in which there is no or very little drug level detectable in blood, but there still seems to be inhibition of bacterial re-growth. This is due to strong, irreversible binding to the ribosome, and remains intracellular long after plasma levels drop, and allows a prolonged dosage interval. Depending on their concentration, they act as bacteriostatic or bactericidal agents. Aminoglycosides are useful primarily in infections involving aerobic , Gram-negative bacteria, such as Pseudomonas , Acinetobacter , and Enterobacter . In addition, some Mycobacteria , including
310-401: Is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience or studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks. Aminoglycosides can cause inner ear toxicity which can result in sensorineural hearing loss . The incidence of inner ear toxicity varies from 7 to 90%, depending on
341-478: Is the first-in-class aminoglycoside antibiotic . It is derived from Streptomyces griseus and is the earliest modern agent used against tuberculosis . Streptomycin lacks the common 2-deoxystreptamine moiety (image right, below) present in most other members of this class. Other examples of aminoglycosides include the deoxystreptamine-containing agents kanamycin , tobramycin , gentamicin , and neomycin (see below). Aminoglycosides that are derived from bacteria of
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#1732851253630372-600: The Streptomyces genus are named with the suffix -mycin , whereas those that are derived from Micromonospora are named with the suffix -micin . However, this nomenclature system is not specific for aminoglycosides, and so appearance of this set of suffixes does not imply common mechanism of action. (For instance, vancomycin , a glycopeptide antibiotic , and erythromycin , a macrolide antibiotic produced by Saccharopolyspora erythraea , along with its synthetic derivatives clarithromycin and azithromycin , all share
403-404: The translated protein product. The subset of aberrant proteins that are incorporated into the bacterial cell membrane may then lead to changes in its permeability and then to "further stimulation of aminoglycoside transport". The amino sugar portion of this class of molecules (e.g., the 2-deoxystreptamine in kanamycins, gentamicins, and tobramycin, see above) are implicated in the association of
434-531: The CFTR protein. Since they are not absorbed from the gut, they are administered intravenously and intramuscularly . Some are used in topical preparations for wounds. Oral administration can be used for gut decontamination (e.g., in hepatic encephalopathy). Tobramycin may be administered in a nebulized form. The recent emergence of infections due to Gram-negative bacterial strains with advanced patterns of antimicrobial resistance has prompted physicians to reevaluate
465-472: The DNA can result in lethal double-strand breaks. Finally, a further "cell-membrane effect" also occurs with aminoglycosides; "functional integrity of the bacterial cell membrane" can be lost, later in time courses of aminoglycoside exposure and transport. There is a significant variability in the relationship between the dose administered and the resultant plasma level in blood. Therapeutic drug monitoring (TDM)
496-602: The bacteria that cause tuberculosis , are susceptible to aminoglycosides. Streptomycin was the first effective drug in the treatment of tuberculosis, though the role of aminoglycosides such as streptomycin and amikacin has been eclipsed (because of their toxicity and inconvenient route of administration) except for multiple-drug-resistant strains. The most frequent use of aminoglycosides is empiric therapy for serious infections such as sepsis , complicated intra-abdominal infections, complicated urinary tract infections, and nosocomial respiratory tract infections. Usually, once cultures of
527-450: The balance of calcium, such as imbalanced acid and alkaline in blood causing respiratory alkalosis (an alkaline blood pH). The Trousseau sign of latent tetany is another sign of decreased calcium in blood where muscles in the hand contract when the brachial artery supplying the area is occluded. The Trousseau sign of latent tetany also generally occurs earlier than the Chvostek sign and
558-403: The causal organism are grown and their susceptibilities tested, aminoglycosides are discontinued in favor of less toxic antibiotics. As noted, aminoglycosides are mostly ineffective against anaerobic bacteria, fungi, and viruses. Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In
589-412: The cell to overcome the stop codons, insert a random amino acid, and express a full-length protein. The aminoglycoside gentamicin has been used to treat cystic fibrosis (CF) cells in the laboratory to induce them to grow full-length proteins. CF is caused by a mutation in the gene coding for the cystic fibrosis transmembrane conductance regulator ( CFTR ) protein. In approximately 10% of CF cases,
620-451: The cytosol generally disturbs peptide elongation at the 30S ribosomal subunit, giving rise to inaccurate mRNA translation and therefore biosynthesis of proteins that are truncated, or bear altered amino acid compositions at particular points. Specifically, binding impairs translational proofreading leading to misreading of the RNA message, premature termination, or both, and so to inaccuracy of
651-414: The facial nerve. The effect is the lateral deviation of the labial and nasal fold toward the stimulated side. Hitting a point between the middle third and upper third of the line joining the angle of the mouth to the zygomatic process gives rise to only a contraction of the muscles of the mouth and nose. Chvostek's sign is found in tetany . However, it may also be present in hypomagnesemia . Magnesium
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#1732851253630682-404: The mutation in this gene causes its early termination during translation , leading to the formation of a truncated and non-functional CFTR protein. It is believed that gentamicin distorts the structure of the ribosome-RNA complex, leading to a mis-reading of the termination codon , causing the ribosome to "skip" over the stop sequence and to continue with the normal elongation and production of
713-411: The nerves that control the muscle being easily excited (called hyperexcitability) due to hypocalcemia. Hypocalcemia can be caused by many things, including parathyroid conditions (such as when the parathyroid gland does not function well, called hypoparathyroidism ) and vitamin diseases (such as a vitamin D deficiency ). Sometimes, the Chvostek sign can be caused by other conditions which interfere with
744-669: The past, the aminoglycosides have been used in conjunction with beta-lactam antibiotics in streptococcal infections for their synergistic effects, in particular in endocarditis . One of the most frequent combinations is ampicillin (a beta-lactam , or penicillin-related antibiotic) and gentamicin. Often, hospital staff refer to this combination as "amp and gent" or more recently called "pen and gent" for penicillin and gentamicin. The interference with mRNA proofreading has been exploited to treat genetic diseases that result from premature stop codons (leading to early termination of protein synthesis and truncated proteins). Aminoglycosides can cause
775-488: The relatively frequent occurrence of nephrotoxicity and ototoxicity during aminoglycoside treatment makes physicians reluctant to use these compounds in everyday practice. Recent advances in the understanding of the effect of various dosage schedules of aminoglycosides on toxicity have provided a partial solution to this problem, although more research still needs to be done in order to overcome this problem entirely. Aminoglycosides are in pregnancy category D , that is, there
806-413: The sign that bears his name. Later it was independently described by another Austrian physician, Nathan Weiss (1851–1883), in 1883. It is obtained by striking with a finger or a hammer a point that is approximately 2 cm in front of the lobe of the ear and about 1 cm below the zygomatic process . Response occurs in the form of ipsilateral contraction of some or all of the muscles innervated by
837-503: The small molecule with ribosomal structures that lead to the infidelities in translation (ibid.). Inhibition of ribosomal translocation —i.e., movement of the peptidyl-tRNA from the A- to the P-site—has also been suggested . Recent single-molecule tracking experiments in live E. coli showed an ongoing but slower protein synthesis upon treatment with different aminoglycoside drugs. ( Spectinomycin ,
868-726: The suffixes but have notably different mechanisms of action.) In the following gallery, kanamycin A to netilmicin are examples of the 4,6-disubstituted deoxystreptamine sub-class of aminoglycosides, the neomycins are examples of the 4, 5 -disubstituted sub-class, and streptomycin is an example of a non-deoxystreptamine aminoglycoside. Aminoglycosides display concentration-dependent bactericidal activity against "most gram-negative aerobic and facultative anaerobic bacilli" but not against gram-negative anaerobes and most gram-positive bacteria. They require only short contact time, and are most effective against susceptible bacterial populations that are rapidly multiplying. These activities are attributed to
899-481: The title Chvostek . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Chvostek&oldid=906570526 " Category : Disambiguation pages Hidden categories: Short description is different from Wikidata All article disambiguation pages All disambiguation pages Chvostek sign These facial spasms are caused by
930-635: The types of antibiotics used, susceptibility of the patient to such antibiotics, and the duration of antibiotic administration. Another serious and disabling side effect of aminoglycoside use is vestibular ototoxicity. This leads to oscillopsia (gaze instability) and balance impairments that impact all aspects of an individual's antigravity function. This loss is permanent and can happen at any dose. Frequent use of aminoglycosides could result in kidney damage (Acute kidney injury), that could lead to chronic kidney disease . Aminoglycosides can exacerbate weakness in patients with myasthenia gravis , and use
961-412: The use of these antibacterial agents. This revived interest in the use of aminoglycosides has brought back to light the debate on the two major issues related to these compounds, namely the spectrum of antimicrobial susceptibility and toxicity. Current evidence shows that aminoglycosides do retain activity against the majority of Gram-negative clinical bacterial isolates in many parts of the world. Still,