The diagnostic value of the median-ulnar 2LIO comparison study.

• Research type

  Research Study

• Full title

  The diagnostic value of the median-ulnar 2nd lumbrical-interosseous comparison (2LIO): A comparison with current carpal tunnel syndrome screening procedures used in electrodiagnostic clinics at Nottingham University Hospitals.

• IRAS ID

  182920

• Contact name

  Lealah Nouri

• Contact email

  lealah.nouri@nuh.nhs.uk

• Sponsor organisation

  Aston University

• Duration of Study in the UK

  0 years, 6 months, 31 days

• Research summary

  This project will compare the “median-ulnar 2nd lumbrical-interosseous comparison study” (2LIO) with standard nerve conduction studies (NCS) employed in electrodiagnosis of carpal tunnel syndrome (CTS).

  Comparison studies are commonly used to diagnose CTS, as they compare conduction along a nerve that runs through the carpal tunnel (median nerve) with a nerve that does not (ulnar nerve); both have a similar anatomical distribution but supply different muscles in the hand. The 2LIO involves recording motor potentials at two muscles in the hand: the 2nd lumbrical and underlying dorsal interosseous muscles, which are supplied by the median nerve and ulnar nerve respectively. The inter-latency difference is measured and compared against normative values.

  Guidelines set out by the American Association of Electrodiagnostic Medicine (2002) suggest the 2LIO as a practice option rather than a practice standard based upon conflicting evidence for the diagnostic value of the 2LIO. Since publication of these guidelines, recent evidence suggests the 2LIO offers diagnostic value, in particular for patients with severe CTS and wasting of median-supplied muscles in the hand. For these patients, motor potentials often cannot be recorded using standard NCS, due to atrophy of the muscles that are being recorded from. Consequently, patients often require electromyography (EMG) in consultant-led clinics. This has led to our departmental guidelines excluding certain populations from physiologist-led clinics on account of their increased susceptibility to requiring EMG.

  The 2LIO may be beneficial in these patients because it records from the median-supplied 2nd lumbrical muscle rather than the abductor pollicis brevis, as is used for standard NCS; anatomical studies suggest the 2nd lumbrical is better preserved in severe CTS. If the 2LIO were shown to be as accurate as standard NCS and EMG, potential benefits include:
  • Reduced risk of needle-associated infection.
  • Alternative to EMG for patients taking warfarin. Warfarin is a contraindication to EMG for patients with INR ≥ 2.5.
  • Alternative for patients with needle phobia.
  • Less inconvenience and intra-subject variation for patients currently seen in physiologist-led clinics and then re-booked into consultant-led clinics
  • Fewer consultant-led appointments (economic benefit to department)
  • Fast and easy technique with only one recording site

  Statistical analysis will measure the accuracy of the 2LIO in terms of sensitivity and specificity via comparison with the results of standard NCS and EMG.

• REC name

  East Midlands - Derby Research Ethics Committee

• REC reference

  15/EM/0354

• Date of REC Opinion

  27 Aug 2015

• REC opinion

  Further Information Favourable Opinion