Tensilon test

Tensilon test is a diagnostic procedure used to evaluate the function of the neuromuscular junction, particularly in cases where Myasthenia Gravis (MG) is suspected. The test involves the administration of edrophonium chloride, a drug that temporarily increases the levels of acetylcholine at the neuromuscular junction, thereby enhancing muscle contraction.

Procedure

The Tensilon test is performed under close medical supervision. Initially, a small "test" dose of edrophonium is administered intravenously to check for any adverse reactions. If the test dose is well-tolerated, the full dose is then given. The patient is observed for improvements in muscle strength, which, if present, indicate a positive test suggestive of MG. Due to the potential for side effects, such as bradycardia, facilities for cardiopulmonary resuscitation should be available during the test.

Indications

The primary indication for the Tensilon test is the diagnostic evaluation of Myasthenia Gravis, a chronic autoimmune neuromuscular disorder characterized by varying degrees of skeletal muscle weakness. The test may also be used to differentiate myasthenic crisis from cholinergic crisis in patients with known MG.

Contraindications

Contraindications to the Tensilon test include known hypersensitivity to edrophonium or iodine (used in some formulations of the drug), as well as certain cardiac conditions due to the risk of inducing cardiac arrhythmias.

Interpretation

A positive Tensilon test is characterized by a marked improvement in muscle strength immediately following the administration of edrophonium. This improvement typically lasts for about 5 minutes. A negative test does not necessarily rule out MG, and further diagnostic testing may be required.

Risks and Complications

While generally safe, the Tensilon test can cause side effects, including but not limited to, salivation, lacrimation, urination, defecation, gastrointestinal distress, emesis (SLUDGE syndrome), and bradycardia. In rare cases, severe complications such as cardiac arrest can occur.

Alternatives

Other diagnostic tests for Myasthenia Gravis include the Ice Pack Test, Neostigmine Test, and various serological tests to detect antibodies against acetylcholine receptors or muscle-specific kinase (MuSK). Electrophysiological studies, such as repetitive nerve stimulation and single-fiber electromyography, can also provide valuable diagnostic information.

See Also

• Acetylcholine Receptor Antibody Test
• Muscle-Specific Kinase Antibody Test
• Electromyography
• Neuromuscular Junction