This study evaluated the prevalence of CTS diagnosis and surgical treatment in a national cohort of patients with SCI. It is known that CTS is an extremely common sequela of long-term upper-extremity weight bearing and wheelchair use.7,13,14
In a cross-sectional multicenter study, Yang9
found that 60% of subjects with SCI had physical examination findings consistent with CTS and 78% had electrophysical evidence of median mononeuropathy. Within our cohort of veterans with SCI, the prevalence of a diagnosis of CTS in the administrative data was 3.5%, which is significantly lower than the reported rates in other patient studies.
Many factors could contribute to this low rate of diagnosis. The first has to do with the data itself. Quality of data entry limits any administrative data, with miscoding and under-coding compromising the final results.20,21
Under-coding is magnified in complex patients with multiple medical problems. For example during an SCI primary care visit a provider may review multiple medical issues and code the visit with a general code such as ‘late effects of spinal cord injury’ (ICD-9-CM 907.2). Even if the provider discusses CTS, no related diagnosis code exists in the record. Similarly, when addressed during an inpatient hospitalization, CTS often fails to generate a diagnosis code. With a specific visit for CTS such as a consult to a hand surgeon or electro-diagnostics, the encounter generates the specific code for CTS. Even accounting for under-coding, it would be reasonable to expect that since prevalence of CTS is higher in people with SCI our VA SCI cohort would have a substantially higher rate of diagnosis than the general VA population, and not the 1% difference we found. Rates of CTS surgery were similar for VA patients with and without SCI (0.24 and 0.17%, respectively). Surgical treatment is much less likely to suffer from the problem of under-coding because a code must be entered for every surgical procedure. Given the reported higher incidence of CTS in the population with SCI we would again expect a higher rate of surgery in this population. These two results suggest that CTS is being under-diagnosed and possibly under-treated in patients with SCI. What could be the reasons for these seemingly lower than expected rates of diagnosis and surgical treatment? Identifying provider, system, and patient-level factors may help to gain understanding. Providers of SCI care are key players in the diagnosis and treatment of a variety of conditions. One constant for SCI providers is the issue of competing demands. Competing demands refers to prioritizing medical needs in complex patients. This can inherently result in decreased recognition or treatment of all health care issues. Redelmeier et al.22
demonstrated this in his study of Canadian primary care, which found an inverse correlation with the presence of a chronic disease and the treatment of unrelated health problems. In the SCI population, this may mean that ‘lesser’ issues such as CTS are not addressed during a typical visit.
Another provider factor could be caution in referring patients with SCI for invasive procedures. This could stem from comfort and experience in treating CTS non-operatively, following patient desires for conservative treatment, or uncertainty towards the efficacy of surgical interventions. The Consortium of Spinal Cord Medicine has published practice guidelines for upper extremity care in patients with SCI.23
It recommends that a medical or rehabilitative approach be considered first for non-traumatic limb injuries and only when conservative measures have failed to show improvement for 3 months should surgery then be considered. The guidelines go on to note the strain and mobility limitations that the recovery period may have on wheelchair-bound individuals. Although conservative treatment is supported in patients with SCI, especially in early CTS, additional literature shows that the most effective long-term treatment for CTS is surgical and risks are quite small.2–5,24–26
A recent meta-analysis of four randomized controlled trials concluded that surgical release of the transverse carpal ligament relieves symptoms significantly better than splinting and that a significant proportion of people treated medically will ultimately require surgery.2
Such literature suggests that even if care of CTS followed the conservative course outlined by the Consortium of Spinal Cord Medicine, there would still be many people with SCI who would require surgical release.
The ‘system-level’ factors associated with SCI care refer to aspects of health care structure and delivery methods influencing patient outcome. In the VA population, insurance status is not a barrier to care. Regarding access to specialists, the majority of patients with SCI within the VA system are cared for by teams with a dedicated focus on SCIs. Close to 90% of the CTS treatment for our VA SCI cohort came from within the ‘hub-and-spoke’ system. These providers manage the patient with SCI as a whole, and understand the specific concerns facing such patients. Access to a referral network is built into the system. Within this system of dedicated SCI care, there was an evenly distributed low rate of CTS intervention among the locations. This very well may stem from experienced SCI teams being confident and successful in treating patients with conservative measures or hand surgeons' general unwillingness to participate in SCI care. The VA has an integrated system of care and we can only hypothesize that rates would be lower in a community setting with increased systemic and monetary barriers to care.
Patient factors related to care utilization are more difficult to extrapolate from this study. Overall, demographics were similar between the VA patients with SCI and the general VA population. When comparing veterans with paraplegia to those with tetraplegia, those with paraplegia were only slightly more likely to have a diagnosis of CTS. We expected that this difference would be greater and people with tetraplegia would have much lower rates of CTS given that some would not have the strength to propel a wheelchair, bear weight, or have functional median nerves. Numerous studies have evaluated CTS in individuals with SCI below T1. However, studies on CTS in people with tetraplegia and assessing interaction of CTS with mobility status are lacking. Additional studies, between individuals with paraplegia versus tetraplegia, identifying differences in wrist position with wheelchair propulsion may elucidate this lack of significant difference.
It is known that upper-extremity function is critical to people with SCI. Such individuals rank the function of the upper limb as their most important residual function, more so than bowel, bladder, or sexual function.27
Although patients with SCI may want definitive treatment for their upper-extremity pain, they may also be hesitant to lose their sole source of mobility for several weeks or risk a more permanent surgical complication. Subjective measures, however, were not a part of our study. Future research should focus on potential patient perceptions of CTR.
An inherent limitation of this study lies in the data source utilized (NPCD). As Smith et al.18
identified, only 32.6% of SCI veterans were included in all three of the VA SCI data groups evaluated (ARC, SCD Registry, NPCD flag). The data source for this study surely did not capture all veterans with SCI. Although limited, the VA data still provide insights into care of a large cohort of patients with SCI.