A tensilon test, also called an edrophonium test, is a pharmacological test used for the diagnosis of certain neural diseases, especially

myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...

. It is also used to distinguish a

myasthenic crisis Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of skeletal muscle weakness. The most commonly affected muscles are those of the eyes, face, and swallowing. It can result in double vision, dro ...

from a

cholinergic crisis A cholinergic crisis is an over-stimulation at a neuromuscular junction due to an excess of acetylcholine (ACh), as a result of the inactivity of the AChE enzyme, which normally breaks down acetylcholine. Symptoms and diagnosis As a result of ch ...

in individuals undergoing treatment for myasthenia gravis.

Procedure

A 10 mg

edrophonium Edrophonium is a readily reversible acetylcholinesterase inhibitor. It prevents breakdown of the neurotransmitter acetylcholine and acts by competitively inhibiting the enzyme acetylcholinesterase, mainly at the neuromuscular junction. It is so ...

chloride syringe and a 2 mg

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given i ...

syringe are prepared. Atropine is prepared for immediate use in case cholinergic crisis occurs. After a neurologic examination and recording of vital signs, 2 mg edrophonium is injected intravenously. After waiting 30 seconds and ensuring that no adverse reactions have occurred, the remaining 8 mg of edrophonium is also injected. The patient is then asked to perform repetitive tasks, (i.e. lifting an object or repeatedly opening and closing their eyelids). Under the influence of edrophonium, patients with myasthenia gravis are able to complete these tasks more easily and with more strength than before the injection was administered. The effects of edrophonium last around 10 minutes. The edrophonium allows accumulation of

acetylcholine Acetylcholine (ACh) is an organic chemical that functions in the brain and body of many types of animals (including humans) as a neurotransmitter. Its name is derived from its chemical structure: it is an ester of acetic acid and choline. Part ...

(ACh) in the neuromuscular junctions, and makes more ACh available to the muscle receptors, thereby increasing muscle strength in myasthenia gravis. In newborns, a 0.15 mg/kg Neostigmine administered subcutaneously produces a response within 10 minutes. In infants, the drug is administered intravenously at a dose of 0.2 mg/kg. Improvement of diplopia is often used as an evaluation item because in this case,

placebo effect A placebo ( ) is a substance or treatment which is designed to have no therapeutic value. Common placebos include inert tablets (like sugar pills), inert injections (like Saline (medicine), saline), sham surgery, and other procedures. In general ...

can be excluded.

Precautions

The tensilon test is administered by a trained clinician, usually a neurologist. A thorough history taking and physical assessment is done before the administration of test, to rule out

hypersensitivity Hypersensitivity (also called hypersensitivity reaction or intolerance) refers to undesirable reactions produced by the normal immune system, including allergies and autoimmunity. They are usually referred to as an over-reaction of the immune s ...

, pregnancy, lactation and intestinal obstruction. Care is taken while performing the test in individuals over 50, and those under

corticosteroids Corticosteroids are a class of steroid hormones that are produced in the adrenal cortex of vertebrates, as well as the synthetic analogues of these hormones. Two main classes of corticosteroids, glucocorticoids and mineralocorticoids, are involve ...

or pro-cholinergic drugs. Vital signs are monitored before, during and after the test. The test should only be performed in a medical center equipped to manage cholinergic crisis. Following the test, the patient is observed for cholinergic responses such as increased salivation, lacrimation, nausea and vomiting.

References

{{Reflist Diagnostic neurology Diagnostic ophthalmology