High-Frequency Repetitive Sensory Stimulation as Intervention to Improve Sensory Loss in Patients with Complex Regional Pain Syndrome I

Abstract

Achieving perceptual gains in healthy individuals or facilitating rehabilitation in patients is generally considered to require intense training to engage neuronal plasticity mechanisms. Recent work, however, suggested that beneficial outcome similar to training can be effectively acquired by a complementary approach in which the learning occurs in response to mere exposure to repetitive sensory stimulation (rSS). For example, high-frequency repetitive sensory stimulation (HF-rSS) enhances tactile performance and induces cortical reorganization in healthy subjects and patients after stroke. Patients with complex regional pain syndrome (CRPS) show impaired tactile performance associated with shrinkage of cortical maps. We here investigated the feasibility and efficacy of HF-rSS, and low-frequency rSS (LF-rSS) to enhance tactile performance and reduce pain intensity in 20 patients with CRPS type I. Intermittent high- or low-frequency electrical stimuli were applied for 45 min/day to all fingertips of the affected hand for 5 days. Main outcome measures were spatial two-point-discrimination thresholds and mechanical detection thresholds measured on the tip of the index finger bilaterally. Secondary endpoint was current pain intensity. All measures were assessed before and on day 5 after the last stimulation session. HF-rSS applied in 16 patients improved tactile discrimination on the affected hand significantly without changes contralaterally. Current pain intensity remained unchanged on average, but decreased in four patients by ≥30%. This limited pain relief might be due to the short stimulation period of 5 days only. In contrast, after LF-rSS, tactile discrimination was impaired in all four patients, while detection thresholds and pain were not affected. Our data suggest that HF-rSS could be used as a novel approach in CRPS treatment to improve sensory loss. Longer treatment periods might be required to induce consistent pain relief.

CRPS Is Not Associated with Altered Sensorimotor Cortex GABA or Glutamate

“…As hypothesized and consistent with previous literature, the CRPS-affected hand displayed poor tactile acuity relative to the CRPS-unaffected hand and pain-free control subjects (Pleger et al, 2006;Maihöfner and DeCol, 2007;Peltz et al, 2011;Lewis and Schweinhardt, 2012;Reiswich et al, 2012;Catley et al, 2014;David et al, 2015). While in healthy control subjects, one might hypothesize that increased use of the dominant hand would result in better tactile acuity than the nondominant hand, we found no difference in dominant and nondominant tactile acuity in control subjects, a result consistent with findings of previous investigations (Gelber et al, 1995;Ozcan et al, 2004;Pleger et al, 2006;Tustumi et al, 2015).…”

“…Nevertheless, future studies should evaluate the difference in tactile acuity assessment via discrimination and temporal order judgment tasks to understand whether different tactile assessments can lead to different tactile acuity outcomes and relationships with GABA. This is important in a clinical setting, given that tactile acuity training reportedly helps to improve tactile acuity as well as reduce pain intensity in CRPS (David et al, 2015;Schmid et al, 2017).…”

“…This is thought to underlie the perceptual abnormalities seen in these patients; the most commonly reported is tactile acuity via two-point discrimination testing (TPD), which is simply the smallest distance between two points that is correctly perceived as two points, rather than one, touching the skin. CRPS patients have poor tactile acuity on their affected limbs (i.e., a high TPD threshold), and this has been associated with the degree of cortical reorganization (Pleger et al, 2006;Maihöfner and DeCol, 2007;Peltz et al, 2011;Reiswich et al, 2012;Catley et al, 2014;David et al, 2015). The primary motor cortex (M1) is also altered in CRPS, with reported changes in M1 function and excitability in CRPS patients (Di Pietro et al, 2013b).…”

Algodystrophy (CRPS) in minor orthopedic surgery

“…HF-rSS significantly improved tactile discrimination on the treated hand in 16 patients and pain relief by more than 30% was reported in only 4 patients. However, Authors suggested that longer treatment periods might be required to induce consistent pain relief (27). In this way the electro-analgesic therapy is a novel neuro-modulatory approach using electro-cutaneous nerve stimulation of no pain information that interferes with pain signals.…”

Transcutaneous electrical nerve stimulation using an LTP-like repetitive stimulation protocol for patients with upper limb complex regional pain syndrome: A feasibility study

“…[9][10][11][12] Additionally, a recent nonrandomised study using high-frequency repetitive sensory long-term potentiation (LTP)-like stimulation suggested it could reduce sensory impairment in patients with CRPS. 13 To date, no RCTs have investigated the effect of TENS on sensorimotor performance in patients with CRPS. However, it has been shown that TENS relieves phantom pain and facilitates perceptual embodiment of prosthetic limbs, 14 when TENS sensation is projected into the phantom limb itself.…”