Sixty-two patients were randomly assigned to the Neuro explanation group or Biomechanical group, and they performed one survey that measured their perception of low back pain and leg pain (Numeric Pain Rating Scale) and two physical tests—standing lumbar flexion and single leg raise (SLR). These were taken prior to and immediately after the manual therapy intervention (central posterior–anterior mobilization). During the treatment, the physiotherapists gave each patient a neuro or bio explanation, which are summarized in the following:
“The SLR is a test of the ability of the lumbosacral plexus (sciatic nerve) to move and ultimately its sensitivity to movement. It has very high sensitivity,” Dr. Louw explained in an email interview. “The reliability depends on the intent of the test. Older theories of using the SLR to ‘diagnose’ a certain type of ‘disc herniation’ are shown to be limited, but its usefulness in ruling out (sensitivity) for radiculopathy is really high. Therefore, the test is good for leg pain, not necessarily low back pain.”
“As for pain perception, pain is complex and as a stand-alone treatment, education is not that effective in reducing pain. Furthermore, to be clinically relevant a pain reduction has to be more than two points.
“Lumbar flexion: various other PNE studies as well as sensory discrimination studies have shown immediate changes in flexion, but not this study. We’re not sure why – we can speculate – may be tied to levels of fear of movement.
The minimal clinical important difference (MCID) for SLR is 5.7 degrees and yes, in this study it did not reach that. However, when analyzing the individual data, a much larger group of patients in the PNE explanation met/exceeded the MCID than the traditional education. The statistical analysis showed that the PNE resulted in a seven times more likely chance of someone meeting/exceeding the SLR MCID compared to traditional explanations.”
“Prior to the study in question, our research team did a few pilot versions of similar style studies that brought us to this point,” Dr. Louw said.
“A case study: A lady who underwent spine surgery for back and leg pain was seen 3x/week for 2 weeks immediately after surgery and we used sensory discrimination (where am I touching you) in therapy and had her do a similar home program. The patient had a meaningful shift in spinal movement, straight leg raise and nerve sensitivity in the back and leg.
“A case series: We had 16 patients with chronic low back pain identify where we were touching them on their back via tactile discrimination and their pain decreased on average two points in five minutes
“Following the study in question, we replicated the chronic LBP study, but for knee and shoulder pain (where am I touching you) and had immediate increases in range of motion.”
Also, the researchers do not know whether if the pain explanation were to be given before or after the treatment have any influence on the outcome. Because of the patients’ different experiences and expectations of the treatment, it was difficult to give a cookie-cutter treatment approach by the therapists, who were also not blinded to the testing.
So what can therapists take away from all this?
“It’s important to realize this is one of several exploratory studies,” Dr. Louw explained. “We have similar ones going on right now. In line with sensory discrimination research, we believe manual therapy is, and can be used as, a form of sensory discrimination, thus sharpening the maps in the primary somatosensory cortex. But – the brain HAS to be involved. Manual therapy is very passive. Patients are placed with their ‘face in a hole’ and something done to them.
“By having a therapist use their skin to ‘assess’ where they are being touched or treated, the brain HAS TO be involved and this then sharpens the mapping of the brain, which has been shown to correlate to pain.”