Short summary

Learning more about diagnostic and predictive variables is crucial for giving patients the most effective treatment. Findings in this study could contribute significally to improve management of patients with lumbar disc herniation, including contribution to the research on optimal indications for surgery in individual patients. The study will investigate whether three clinical tests can be used to diagnose and predict clinical outcome in patients with lumbar disc herniation. 150 patients will be included for the prospective cohort study. The three quantitative clinical tests include: muscle sound recordings using Acoustic Myography, electromyographic measurements using Paraspinal Mapping and pain responses using Quantitative Sensory Pain Testing.

Rationale

Background

Lumbar disc herniation 

In Denmark it is estimated that 880.000 people live with low back pain. A frequent cause is lumbar disc herniation. To confirm the diagnosis or in cases of disagreement Magnetic Resonance Imaging (MRI) is used. However, intervertebral disc protrusions are also frequently found on MRI in asymptomatic patients. In Denmark, patients offered surgical treatment for lumbar disc herniation, often have persistent and severe symptoms or have significant neurologic deficits. From 2009-2015 a total of 8.528 operations for lumbar disc herniation pathology were performed in Denmark. This represents 1/3 of all lumbar spine surgery.

Quantitative clinical tests 

The study will combine three special quantitative test procedures, in addition to standard clinical tests and MRI. The three quantitative clinical tests include: muscle sound recordings using Acoustic Myography (AMG), electromyographic measurements using Paraspinal Mapping (PM) and pain responses using Quantitative Sensory Pain Testing (QST). 

Acoustic Myography (AMG) is a method used to record muscle sound from skeletal muscle. As a muscle fiber contracts longitudinally, it expands radially initiating a pressure wave that is transmitted through the tissues to the skin surface. This produces low frequency soundwaves that can be recorded and analysed. Harrison et al. has shown that AMG has high accuracy as a diagnostic tool for muscle function and that it is very repetable. There is a lack of studies on acoustic myography in the spine and specifically in disk herniation. 

Paraspinal Mapping (PM) is a method of quantitative needle electromyography (EMG) that detects denervation in the paraspinal muscles. The presence of fibrillating muscle cells is graded for each location and a total PM sensitivity score is determined by combining all scores. Although invasive, the examination lasts only 10 minutes and is easy for the expert electromyographer to perform, making it a clinically useful tool. The procedure is considered to be safe in the general population. The test can be used to localize the level of radiculopathy in the lumbar spine and is usually negative in patients with mechanical low back pain without radiculopathy. 

Quantitative Sensory Pain Testing (QST) is a well-defined psychophysical method that standardizes a potentially painful stimulus and quantifies the pain response from the test subject, making it possible to investigate pain processing. The current study will contribute to the research on optimal indications for surgery in individual patients. To our knowledge, no studies have been made to test the prognostic value of these three quantitative clinical tests in relation to surgery outcome in patients with LDH.

Purpose

This study will investigate whether Acoustic Myography (AMG), Paraspinal Mapping (PM) or Quantitative Sensory Pain Testing (QST) can be used to diagnose and predict clinical outcome in patients with lumbar disc herniation (LDH). 

Description of the cohort

Patients included in the project are men and women, +18 years diagnosed with Lumbar Disc Herniation. 

Data and biological material

Patient registred outcomes are collected at baseline and follow-up. Data from the quantitative clinical tests are collected at baseline.

Collaborating researchers and departments

The Parker Institute, Frederiksberg Hospital

• Kirstine Amris, Head of Clinical Research Unit, MD

Department of Rheumatology, Frederiksberg Hospital

• Gilles Fournier, MD

University of Michigan

• Professor Emeritus, Andrew J. Haig, MD