Recent studies demonstrated that patients with carpal tunnel syndrome (CTS) have signs of thermal and mechanical hyperalgesia in extra-median territories suggesting an involvement of central pain mechanisms. As previous studies included patients with shoulder/arm symptoms or neck pain, a potential influence of these coexisting disorders cannot be excluded. This study therefore evaluated whether widespread sensory changes (hypoesthesia or hyperalgesia) are present in patients with unilateral CTS in the absence of coexisting disorders. Twenty-six patients with unilateral CTS with symptoms localised to their hand and 26 healthy controls participated in the study. A comprehensive quantitative sensory testing (QST) protocol including thermal and mechanical detection and pain thresholds was performed over the hands (median, ulnar and radial innervation area), lateral elbows, neck and tibialis anterior muscle. Patients with CTS demonstrated thermal and mechanical hypoesthesia in the hand but not at distant sites. Thermal or mechanical hyperalgesia was not identified at any location with traditional QST threshold testing. However, patients with CTS rated the pain during thermal pain testing significantly higher than healthy participants. This was especially apparent for heat pain ratings which were elevated not only in the affected hand but also in the neck and tibialis anterior muscle. In conclusion, CTS alone in the absence of coexisting neck and arm pain does not account for sensory changes outside the affected hand as determined by traditional QST threshold testing. Elevated pain ratings may however be an early indication of central pain mechanisms.

Preliminary evidence from studies using quantitative sensory testing suggests the presence of central mechanisms in patients with carpal tunnel syndrome (CTS) as apparent by widespread hyperalgesia. Hallmarks of central mechanisms after nerve injuries include nociceptive facilitation and reduced endogenous pain inhibition. Methods to study nociceptive facilitation in CTS so far have been limited to quantitative sensory testing and the integrity of endogenous inhibition remains unexamined. The aim of this study was therefore to investigate changes in facilitatory and inhibitory processing in patients with CTS by studying hypersensitivity following experimentally induced pain (facilitatory mechanisms) and the efficacy of conditioned pain modulation (CPM, inhibitory mechanisms). Twenty-five patients with mild to moderate CTS and 25 age and sex matched control participants without CTS were recruited. Increased pain facilitation was evaluated via injection of hypertonic saline into the upper trapezius. Altered pain inhibition through CPM was investigated through cold water immersion of the foot as the conditioning stimulus and pressure pain threshold over the thenar and hypothenar eminence bilaterally as the test stimulus. The results demonstrated that patients with CTS showed a greater duration (p = 0.047), intensity (p = 0.044) and area (p = 0.012) of pain in response to experimentally induced pain in the upper trapezius and impaired CPM compared to the control participants (p = 0.006). Although typically considered to be driven by peripheral mechanisms, these findings indicate that CTS demonstrates characteristics of altered central processing with increased pain facilitation and reduced endogenous pain inhibition.

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BackgroundA near-fall is defined as a loss of balance that would result in a fall if sufficient balance recovery manoeuvres are not executed. Compared to falls, near-falls and its associated balance recovery manoeuvres have been understudied. Older adults may not recognise a near-fall or identify the use of their balance recovery manoeuvres to prevent a fall. The consensus on the methods to collect near-fall data is lacking. The primary objective of this study was to determine the feasibility of recruitment and retention. Secondary objectives were to establish evidence that Singapore community-dwelling older adults can identify near-falls and associated balance recovery manoeuvres. Texting and calling methods were explored as reporting methods.MethodsThis study took place in Singapore (September to October 2019). Participants were healthy, community-dwelling adults aged 65 or older. Recruitment was done through poster advertisement, and all participants gave informed consent. Participants attended a briefing session and reported their near-fall or fall incidence over 21 days using either daily texting or calling. The primary outcome measures were the recruitment rate, retention rate, preferred modes for data reporting and ability to report near-falls or falls. Secondary outcomes included the self-reported incidence of falls and near-falls.ResultsThirty older adults were recruited in five weeks. All participants completed the study. They understood near-fall concepts and were able to report the occurrence and relevant balance recovery manoeuvres used to prevent a fall. 87% (26/30) chose to text while 13% (4/30) selected calling as their reporting method. One actual fall (0.16%) out of 630 responses was reported. Thirty-six incidents (5.7%) of near-falls were recorded. Sixteen participants (53.3%) experienced near-falls and half of this group experienced two or more near-falls. Use of reach-to-grasp strategy (36%), compensatory stepping (52.8%), and other body regions (11.2%) were used to prevent the fall. ConclusionsThe study provided evidence that studying near-falls in Singapore community-dwelling older adults is feasible and can be applied to a large-scale study. Recruitment and retention rates were good. Older adults were able to identify near-falls and balance recovery manoeuvres. Both texting and calling were feasible reporting methods, but texting was preferred. Trial registrationClinicalTrials identifier: NCT04087551. Registered 12th September 2019