Vasomotor dysfunction in carpal tunnel syndrome

Abstract

Little attention has been paid to small-fiber dysfunction in carpal tunnel syndrome (CTS) although its symptoms are common. This study investigates vasomotor dysfunction, which is controlled by small nerve fibers, in patients with CTS compared with control subjects. Vasomotor function was quantified by measuring, with laser Doppler velocimetry, skin vasoconstriction induced by a eutectic mixture of local anesthetic (EMLA) cream over digit tips 3, 4, and 5. Hands with CTS (n = 32) compared with controls (n = 19) demonstrated significantly reduced vasoconstriction in digits 3 and 4, but not digit 5. A blood flow ratio (digit 3/5) of less than 0.73 identified CTS in 69% with 68% specificity. Testing for vasomotor dysfunction in CTS allows for more comprehensive neurophysiological testing, which is heavily biased towards large nerve fibers.

The relationship of nerve fibre pathology to sensory function in entrapment neuropathy

“…Clinical tests consistently confirm a dysfunction of the large fibre population in entrapment neuropathies (Lundborg et al , 1992; Padua et al , 1997; Ginanneschi et al , 2006; Tucker et al , 2007). There is growing evidence from laser-evoked potentials (Arendt-Nielsen et al , 1991), sympathetic testing (Wilder-Smith et al , 2003; Kuwabara et al , 2008) and QST (Chien et al , 2008; Tamburin et al , 2010) that the function of small fibres may also be affected. The comprehensive QST findings of this study confirm a dysfunction of both small and large fibres which is characterized by hyposensitivity to sensory stimuli (i.e.…”

“…There is preliminary evidence from clinical studies that the function of small nerve fibres may be affected in entrapment neuropathies. For instance, laser-evoked brain potentials are reduced (Arendt-Nielsen et al , 1991) and sympathetic skin reflexes and vasomotor function decreased in the median nerve territory of patients with carpal tunnel syndrome (Wilder-Smith et al , 2003; Kiylioglu, 2007). Results from quantitative sensory testing are more controversial with some authors reporting loss of function mediated by small myelinated or unmyelinated fibres in cervical radiculopathy or carpal tunnel syndrome (Chien et al , 2008; Tamburin et al , 2010; Tampin et al , 2012) whereas others could not confirm thermal hypoaesthesia indicative of small fibre dysfunction (de la Llave-Rincon et al , 2009).…”

EMLA-Induced Skin Wrinkling for the Detection of Diabetic Neuropathy

“…More recently, in a smaller sample of 32 hands, carpal tunnel syndrome has been shown to result in reduced vasoconstriction (and hence skin wrinkling) over digits 3 and 4 (40). Our study, however, could not confirm this as a confounder.…”

An assessment of the sympathetic function within the hand in patients with carpal tunnel syndrome

“…A vasomotor response, the parameter related to the activity of sympathetic system, was assessed in two studies. Wilder-Smith et al (2003) analysed vasomotor function by laser Doppler fluometry in CTS patients with no clinical features related to sympathetic activity, and in healthy controls. Measurements were performed in the tips of the III-V fingers at rest, and after topical application of EMLA cream, containing an active vasoconstrictive agent, 2.5% Prilocaine.…”

“…There have been several sympathetic skin response studies in CTS patients and their results are not consistent: reduced or normal sympathetic activity was reported in the majority (Caccia et al, 1993;Kanzato et al, 2000;Mondelli et al, 2000;Reddeppa et al, 2000;Sener et al, 2000). Vasomotor dysfunction in digital arteries was found in CTS patients in two studies, which employed the Doppler technique (Galea et al, 2006;Wilder-Smith et al, 2003). To date, capillaroscopy has not been used in the examination of sympathetic function in peripheral neuropathies.…”