Ice pack test
Simple bedside test applying cold to ptotic eyelids to temporarily improve ptosis in myasthenia gravis patients, exploiting cold's effect on neuromuscular transmission.
Full Definition
The ice pack test is a simple, non-invasive bedside diagnostic procedure used to evaluate ptosis in suspected myasthenia gravis patients. The test involves applying an ice pack or cold compress to the affected eyelid for 2-5 minutes, after which the degree of ptosis is reassessed. In myasthenia gravis, the cold temperature improves neuromuscular junction transmission efficiency, resulting in temporary improvement of ptosis by 2mm or more. This occurs because cold reduces the activity of acetylcholinesterase, prolonging the action of available acetylcholine. A positive ice pack test supports the diagnosis of myasthenia gravis, though it is not pathognomonic and should be interpreted in conjunction with other clinical and laboratory findings.
Usage
Usage note: Measure ptosis before and after cold application. Document improvement in millimeters for objectivity.
In Context
- "The ice pack test resulted in complete resolution of right-sided ptosis after 3 minutes of cold application, supporting myasthenia gravis diagnosis." — Neurological examination
- "A positive ice pack test with 3mm improvement in ptosis prompted further investigation including acetylcholine receptor antibody testing." — Ophthalmology consultation