Monday, February 28, 2011

What is electrical impedance myography?

By now, we imagine you have heard the news (especially if you read our last blog entry or the New York Times) that the $1M ALS Biomarker Prize has been won. It was awarded to Dr. Seward Rutkove for his development of electrical impedance myography (EIM.)

But what exactly is electrical impedance myography?

Here's a blurb from The ALS Forum that provides some insight:

"Currently, researchers rely on death or use of a ventilator as the primary endpoints in ALS trials, measures too crude and slow to quantify drug effects early. The new test tracks disease progression with a noninvasive device that measures how electrical current travels through muscle, which degenerates as ALS progresses. Scientists can also measure muscle conductivity between needle electrodes implanted into muscle, but those methods are harder to perform and less reliable than the new device, besides being painful for patients. Rutkove's handheld device measures the electrical field generated when current runs through the muscles underneath electrodes placed on the skin.

The $16,000-$20,000 unit attaches to a laptop or personal digital assistant-like device. The test takes about 20 minutes and detects abnormalities even before a person notices muscle weakness. Rutkove has also suggested that electrical impedance myography might help doctors diagnose ALS, although it may not be able to distinguish ALS from other neurological conditions that affect muscle (Rutkove, 2009). The method does differentiate between neurogenic ALS and some myopathic conditions such as inflammatory myopathy (Garmirian et al., 2009)."

(If you haven't already, check out The ALS Forum, a great collection of the latest news and most up-to-date resources in the ALS field at

And here is a description of the technology in Dr. Rutkove's own words. After a 2009 review of potential ALS biomarkers published in The Lancet did not include a mention of electrical impedance myography, Dr. Rutkove wrote a letter to the editor that details his work and the potential impact of EIM.

Now, firmly in the limelight, Dr. Rutkove's technology is attracting interest from drug developers eager to make ALS clinical trials cheaper, faster, and more efficient. Dr. Rutkove has co-founded Convergence Medical Devices to create and market a version of the technology that can easily be used in clinical settings.

And while this biomarker has no direct therapeutic value, it holds the promise of accelerating the discovery of treatments or a cure for this disease--the mission of Prize4Life and the hope of thousands of patients and families around the world.


  1. Interesting, sounds expensive, but if it could help with earlier DX this would be very helpful.

  2. Kim, Dr. Rutkove is still determining the value of EIM as a diagnostic tool, but it does seem promising. As for the cost, the 16-20k figure is a bit daunting, but there are very few ongoing costs associated with the technology.