The elbow's connected to the...Brain?

If you've been reading my blog for a while, you've probably picked up on my fascination with neuroscience as it pertains to orthopedic dysfunction. For better or worse, the neuro-theme continues as I am now immersed in topics pertaining to human motor control. As usual, I am having more fun than I should be allowed to have...

Today's journal article comes to us from the Archives of Physical Medicine and Rehabilitation on the topic of lateral elbow pain. Lateral elbow pain continues to baffel the medical community. This should come as little surprise when you examine the relative paucity of quality research devoted to this troublesome condition.

Sensorimotor deficits have previously been documented in patients with lateral elbow pain. Despite treatment measures aimed at addressing pain and function, no studies have examined whether conservative measures address sensorimotor deficits in the short or long-term. The primary objective of the present study is to examine the effect of physical therapy and corticosteroid injections compared with a wait and-see (natural history) approach on sensorimotor function.

Design

The study design was a single-blind randomised clinical trial. Outcome measurements were taken at baseline, six-weeks, and finally at a 52-week follow up. An initial population of 497 individuals were considered for the study. Exclusion criteria were bilateral lateral LE, concomitant shoulder or neck complaints, treatment within the last ten months, or other elbow problems. This left 198 subjects available for randomisation. Sixty-seven were randomised into a wait and see group. Sixty-five were randomly assigned into a corticosteroid injection group. Sixty-six subjects were placed in the physical therapy intervention group.

Methods and Intervention

Subjects in the wait-and-see group were given ergonomic advice on how to modify activity and avoid aggravation of their symptoms. Subjects receiving the corticosteroid injection were administered a local injection of 1mL lidocaine with 10mg of triamcinolone at baseline with advice to gradually return to normal activity. The physical therapy group consisted Mulligan’s Mobilization with Movement technique along with a graded exercise program over an eight week period.

A series of reaction time tasks were performed using a standardized instrument called the Sensorimotor Interface Hand Module. The tasks consisted of an standard reaction time for one choice (SRT-1) and two choices (SRT-2). Reaction times and speed were measured for both upper extremities. These outcome measures were taken at baseline and at 3, 6, 12, 26, 52 weeks. Short-term outcomes were defined at 6 weeks with long-term results at 52 weeks. Estimates of effect were measured using a three-way analysis of variance with time, treatment group, and side (affected vs nonaffected). In addition, the LE group was compared to a healthy control group (n=40) at all time points.

Results and Conclusion

All measures of reaction time in the LE group were significantly impaired in both UE compared to normative values at baseline (P>.001). These impairments persisted at all time frames including both short and long-term follow ups. The sensorimotor deficits between all treatment groups were similar at baseline, short and long-term follow ups.

Sensorimotor deficits are evident in patients presenting with LE compared to healthy controls. These deficits persist over a 12 month course of treatment regardless of the intervention. There was a tendency for reaction time to normalize within the initial six-weeks in the treatment cohort, but this effect was not significance and reached a plateau beyond this point. The authors speculate that changes in central sensorimotor processing explain the persistent impairments in reaction time. Central changes may also explain the bilateral deficits in patients with LE.

My Take Home...

The present investigation represents a powerful example of the nervous system’s role in musculoskeletal dysfunction. Sensorimotor function is significantly impaired in patients with elbow pain, and this deficit persists over a long period of time regardless of the treatment. Moreover, these deficits were reported to persist regardless of fluctuations in the patients pain or reported levels of disability. Interestingly, the authors did not utilize pain or disability measures as an outcome measure. This was a significant limitation of the study in my mind.

Despite the limitations, the findings may partially explain the high recurrence of conditions such as lateral elbow pain, and may be useful when considering any patient who has had chronic or persistent joint pain. Therapists may want to include measures of sensorimotor function when evaluating patients with painful conditions.

The implications of this investigation are pretty significant in terms of our assessment and management of not only lateral elbow pain, but other chronic conditions as well. As usual, research like this leaves me with more questions than answers. For example:

• Just how prevalent might sensorimotor deficits be in other chronic conditions commonly seen in our clinics?


• When throughout the course of the disease do these sensorimotor deficits begin to emerge?


• Do the deficits occur secondary to chronic pain or are they the primary deficit that predisposes individuals to particular conditions?


• Are specific interventions capable of addressing these primary or secondary sensorimotor deficits?

As always, I welcome your thoughts, questions, or contributions on this or any of my other blog posts. Stay tuned as we continue to delve into topics pertaining to practice patterns, low back pain and imaging studies, clinical neurodynamics, and a host of other topical issues pertaining to orthopedic physical therapy!

L BISSET, M COPPIETERS, B VICENZINO (2009). Sensorimotor Deficits Remain Despite Resolution of Symptoms Using Conservative Treatment in Patients With Tennis Elbow: A Randomized Controlled Trial Archives of Physical Medicine and Rehabilitation, 90 (1), 1-8 DOI: 10.1016/j.apmr.2008.06.031