It's All In The Wrist: A Primer On Ulnar Nerve EMG/NCV Evaluation in Guyon's Canal

Although carpal tunnel syndrome affecting the median nerve is designated as the most common entrapment mononeuropathy in the upper extremity, another player deserves honorable mention: the ulnar nerve in Guyon’s canal.  EMG/NCV plays an important role in helping identify and localize a compromise of the ulnar nerve at the wrist.  A brief anatomical review of Guyon’s canal highlights the structures surrounding the ulnar nerve through this infamous tunnel.  The Floor: transverse carpal ligament and hypothenar muscles. The Roof: volar carpal ligament. Ulnar border: pisoform bone and pisohamate ligament and abductor digiti minimi muscle belly. Radial border: hook of hamate bone. …

What do you Expect with a Radial Nerve Injury?

A patient comes to see you with wrist drop. As you are an astute clinician you infer that the patient has a radial nerve injury, but how do you know where the likely cause of injury is? A thoughtful and thorough clinical exam should shed some light on the situation. Wrist Drop. Image source: Flickr Commons Radial nerve injuries occur most frequently after fracturing the middle third of the humerus.1 However, there are many sites of possible compromise leading to wrist drop including at the axilla, at the spiral groove, or at the arcade of Frohse. Let us take a…

It Takes Two to Tango: Why EMG and NCS Always Go Together

If you have read many of my articles, you have probably noticed that I like to refer to electrophysiologic testing as “EMG/NCS.”  Although this acronym is much shorter than the tests’ other names (like “electrophysiologic testing”) it is still a bit of a mouthful, and many people prefer to shorten it even further to simply “EMG,” or “NCS.” Although there is nothing wrong with efficiency, because of these shortened names I have had some patients react with surprise when I tell them that there will be two parts to their test.  Some say, “I was told I was getting a…

The Effect of Monochromatic Infrared Energy on Sensation in Patients with Diabetic Peripheral Neuropathy

Based on 5.07 monofilament testing there was no statistical difference in lower extremity sensitivity when using monochromatic infrared energy as compared to a placebo. This study is an underpowered, negative trial due to its small sample size and inclusion of the null value. Clinical judgments prove difficult to determine due to sample size.  Level of evidence: 2b Citation/s: Clifft, J. K., Kasser, R. J. (2005). “The effect of monochromatic infrared energy on sensation in patients with diabetic peripheral neuropathy.” Diabetes Care 28(12): 2896-2900. Lead author’s name and fax: Judy Clifft, UTHSC Department of Physical Therapy, 930 Madison Ave., Room 650,…

How Well Do You Know Your Nerves?

Evaluating the neuroanatomy of any patient is an important part of the clinical exam that is vital in making an accurate diagnosis. Just because a patient cannot raise their arm above their shoulder does not inherently mean their ailment is a musculoskeletal shoulder issue. There should be a list of possible diagnosis that need to be ruled out. Let us take for example the above mentioned shoulder patient. What are the possible diagnoses given this limited amount of information? They could have a labral tear, rotator cuff tear, axillary nerve lesion, brachial plexopathy, C5/C6 cervical radiculopathy, or frozen shoulder to…