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New research recommends that clinicians screen for foot peripheral sensory neuropathy during initial assessments for patients with systemic sclerosis.

The presentation of peripheral sensory neuropathy (PSN) in the feet of patients with systemic sclerosis (SSc) can result in numbness, paraesthesia, allodynia, and pain characterized as burning or stabbing. Foot PSN in SSc can often be debilitating and compromise a patient’s QOL. Despite the impact of this neurological condition, there have only been a few studies focused on foot PSN in patients with SSc; of these, the populations examined were comparatively small.

To address this knowledge gap and explore the impact of foot PSN on QOL, Begonya Alcacer-Pitarch, PhD, and colleagues developed a cross-sectional observational study with a large cohort of patients. The findings were published in Rheumatology.

Of 109 patients with SSc enrolled in the study, 88.1% were female, and the median age was 59 years. The 51 healthy controls enrolled in the study had comparable gender and age demographics. Control participants were identified for the study through a bring-a-friend technique in which participants with SSc attending a routine exam at the Scleroderma Clinic of Leeds Teaching Hospital were encouraged to bring a healthy person with them for possible inclusion in the study.

Regarding skin subsets, 78% of patients with SSc had limited cutaneous SSc (lcSSc), and 22% had diffuse cutaneous SSc (dcSSc). Eight participants had a history of foot ulcers, and the median disease duration was 8 years.

Sensory Issues

There were statistically significant differences concerning sensory testing between the SSc and control cohorts. SSc cases showed a significant median reduction of areas with preserved tactile sensitivity (14 IQR 4 vs 16 IQR 2; P<0.001) and a delayed vibration perception threshold (1.7 µm IQR 3.0 vs 1.1 µm IQR 1.3; P=0.01) compared to controls.

Impaired tactile sensitivity was also observed more often in the SSc cohort compared with controls (54%, n=59 vs 31%, n=16; P=0.007). Pathological vibratory sensitivity was also higher in the SSc cohort with no statistical significance (12%, n=13 vs 6%, n=3; P=0.2).

In the SSc cohort, 82% of participants reported neuropathic symptoms. This included 55% reporting numbness, 52% reporting paraesthesia, 37% reporting stabbing pain, and 35% reporting burning pain; these were significantly higher than reported in the control cohort (P<0.001 for all). In each of these categories of pain, the SSc cohort had higher scores on the pain numerical rating scale than the control cohort (P<0.001 for all).

QOL Impact

The researchers used patient-reported outcome tools to evaluate the relationship between foot PSN, physical function, and QOL. The Scleroderma Health Assessment Questionnaire (SSc-HAQ), which assesses daily functional activity on a scale from 0 to 3, with higher scores indicating worse disability, was applied.

The final mean score of the SSc cohort was 1.25 (IQR, 0.54–1.76). The mean score in subgroup analysis with SSc-HAQ was significantly higher in patients with neuropathic symptoms such as paraesthesia (1.47 [IQR 0.95–1.89] vs 0.74 [IQR 0.46–1.38]; P=0.003), numbness (1.47 [IQR 0.88–1.90] vs 0.70 [IQR 0.45–1.38]; P<0.001), and stabbing pain (1.42 [IQR 0.75– 1.86] vs 1.07 [IQR 0.45–1.73]; P=0.02). Application of the Manchester Foot Pain and Disability Index produced similar results.

“Foot peripheral neuropathy is a common clinical entity and represents a tangible burden on physical disability and QOL,” Dr. Alcacer-Pitarch and colleagues concluded. “However, routine screening for peripheral neuropathy is often not mentioned in best clinical practice guidelines.” They recommend, therefore, that PSN should be taken into account during initial SSc workups.