- Occupation and age may be predictive of the location and extent of pathology seen in Ulnar neuropathies.
- Ulnar neuropathies found in the dominant arm are more commonly axonal, localized to the humero-ulnar aponeurotic arcade, and associated with repetitive or forceful manual activities.
- Those in the non-dominant arm are more typically demyelinating, localized to the retro-condylar region, and associated with external compression in younger administrative workers.
- Precise localization of an Ulnar neuropathy may require the use of both EDX testing and diagnostic Ultrasound.
Two recent studies by Omejec and Podnar (1,2) evaluated Ulnar neuropathy with the intent on determining the precision with which it can be localized by either/both EDX and diagnostic Ultrasound and the degree to which such localization correlates with pathology, age, and occupation.
In the first study, 86 arms in 83 patients were assessed by either/both incremental stimulation NCV and/or diagnostic ultrasound. The results showed:
- Ultrasound results were concordant with EDX results in localizing the site of neuropathy in 45% of the cases and was the sole confirmatory test (independent from EDX) 25% of the time.
- Incremental NCV study was the sole confirmatory test (independent from US) in 23% of the patients studied.
- 76% of the Ulnar neuropathies were at the retro-condylar region, with 63% of these being demyelinating and 98% either at or within 2 cm proximal to the medial epicondyle.
- 17% of the Ulnar neuropathies were within the humero-ulnar arcade with all of these being 2-3 cm distal to the medial epicondyle and 73% involving axonal loss.
- This study concluded that, “UNE in RTC are predominantly demyelinating, and approx. 5-times more common than UNE at HUA that are more commonly axonal.”
The second study involved 117 patients, 73% with lesions at the retro-condylar groove and 27% at the humero-ulnar arcade.
- Hard manual labor (Odds Ratio = 152) and UN affecting the dominant arm (OR = 4.12) were strongly predictive of a neuropathy at the humero-ulnar arcade.
- Also noted was that, “..UNE in the RTC groove affects mainly the non-dominant arms of younger administrative workers and is caused by external compression of the ulnar nerve.”
In summary, these studies show how all that tingles is not the same, especially regarding Ulnar neuropathy. Clinicians are encouraged to use this information to help predict the potential site of involvement and degree of neural pathology and to make use of multiple diagnostic modalities when necessary.
- Omejec G, Podnar S. Precise localization of ulnar neuropathy at the elbow. Clin Neurophysiol. 2015 Feb 14. pii: S1388-2457(15)00080-2. doi: 10.1016/j.clinph.2015.01.023. [Epub ahead of print]
- Omejec G, Podnar S. What causes ulnar neuropathy at the elbow? Clin Neurophysiol. 2015 Jun 17. pii: S1388-2457(15)00624-0. doi: 10.1016/j.clinph.2015.05.027. [Epub ahead of print]