DIAGNOSIS JUST GOT BETTER - Part 1: Research Study - Technique Can Be Important

Maximise your diagnosis with this technique!

 

 

Here's what happened in this study.

 

 

Background

 

 

NDS instructor, Dr Elena Bueno Gracia and colleagues studied the effect of neurodynamic sequencing in diagnosis of carpal tunnel syndrome.

The cornerstone in diagnosis with neurodynamic tests is reproduction of patient symptoms and that they change with structural differentiation.

Using these criteria for an abnormal test, diagnostic efficacy rates vary between studies. Good sensitivity can occur (e.g. above 80%), but it can be accompanied by poor specificity. This is a problem because the results can fall below the threshold for acceptable likelihood ratios (positive >5.0, negative <0.5) and challenges the value of neurodynamic testing for diagnosis.

Dr Bueno’s prospective study used the 3b variation (local sequence) of the upper limb neurodynamic test 1 (median nerve - MNT1) to test for abnormal responses in patients with suspected CTS.

 

Study Characteristics

 

Here are the key features of the study:

  • n=58
  • gender F= 70.7%
  • average age 54.6 years
  • duration > 3 months - 98.3%
  • main symptoms - pain (60.3%), numbness (39.7%)
  • abnormal NCS - 35/58 (60.3%)
  • abnormal test - reproduction of clinical symptoms that change with structural differentiation.
  • comparison with gold standard electrodiagnosis (motor and sensory latencies).
  • neurodynamic sequence used - 3b (focused).  The mechanisms are not clear but the idea is that the technique emphasises the nerve more locally than the standard test. 

 

 

Results

 

Reproduction of clinical pain and changing with structural differentiation were compared to electrodiagnosis for sensitivity and specificity.

  • sensitivity – 65.7%
  • specificity – 95.7%
  • positive likelihood ratio - 15.1
  • negative likelihood ratio - 0.36

Patients with electrophysiological abnormality were more likely to report responses in the wrist and hand than those without. 

 

 

Comments/Discussion

 

Even though the sensitivity of a physical test can be high, the likelihood of accurate diagnosis is often reduced by poor specificity.  If specificity helps diagnosis, it does this through a low rate of false positives.

 

High specificity suggests: “If it’s positive, it’s likely to be true.”

 

Previous studies for diagnosis of CTS have shown good sensitivity (e.g. > 80%) but often low specificity; this compromises the likelihood ratios, which balance sensitivity and specificity to give a likelihood of a test being accurate.

 

Even though the sensitivity in this study was not necessarily better than other studies, the BETTER DIAGNOSIS was achieved with the HIGH SPECIFICITY (low rate of false positives).

 

Acceptable likelihood ratios in the literature are: positive > 5.0, negative <0.5.

 

That we know of, this is the first neurodynamics study that produced 'acceptable' diagnostic efficacy.

 

 

Summary

 

USING THE 3B SEQUENCE OF THE ULNT1 FOR DIAGNOSIS WAS BETTER THAN THE STANDARD TEST.

 

IMPROVING TECHNIQUE IMPROVED DIAGNOSIS.

 

 

Come to our courses and maximise your diagnosis! 

 

Reference
Bueno-Gracia E, Fanlo-Mazas P, Malo-Urriés, Rodriguez-Mena D, Montaner-Cuello A, Ciuffreda G, Shacklock M, Estébanez-De-Miguel E 2023. Diagnostic accuracy of the upper limb neurodynamic test 1 using neurodynamic sequencing in diagnosis of carpal tunnel syndrome. Musculoskeletal Science and Practice. DOI: 10.1016/j.msksp.2023.102897.