OBJECTIVE -Sympathetic denervation and hyperemia are implicated in the pathogenesis of Charcot neuroarthropathy (CN) but are also features of diabetic peripheral neuropathy (DPN). Differences in these physiological parameters were sought by determining C-fiber function (laser Doppler imager [LDI]flare technique) and maximum microvascular hyperemia (MMH) in 13 subjects with diabetic CN (DCN), 10 subjects with DPN, and 10 healthy control subjects. Additionally, unaffected limbs of the nine DCN subjects with unilateral CN (UCN) were studied to determine whether any observed differences precede CN.RESULTS -LDIflare area was reduced in DPN (mean Ϯ SD 1.41 Ϯ 0.51 cm 2 ) and DCN (1.42 Ϯ 0.37) groups compared with the healthy control group (5.24 Ϯ 1.33; P Ͻ 0.0001). MMH was higher in DCN (432 Ϯ 88 PU [perfusion units]) than in DPN (262 Ϯ 71; P ϭ 0.001) subjects but lower than in the control group (564 Ϯ 112; P Ͻ 0.01). LDIflare area and MMH were similar in the UCN and DCN groups.CONCLUSIONS -C-fiber function is equally impaired in neuropathic patients with and without CN; however, a higher MMH distinguishes those with CN. Unaffected and affected limbs of those with unilateral CN have the same neurovascular abnormalities, suggesting that these abnormalities precede CN and are not a result of CN.
Diabetes Care 30:3077-3079, 2007P eripheral sensory neuropathy and autonomic dysfunction are accepted prerequisites for the development of Charcot neuroarthropathy (CN) but are also features of diabetic peripheral neuropathy (DPN) (1,2). CN is rare in comparison with DPN, suggesting that additional factors are involved in its pathogenesis. Small-fiber neuropathy, measured with quantitative sensory testing, has been implicated in its development (3,4). Moreover, a relatively higher maximum microvascular hyperemia (MMH) has been reported (3,4); however, whether this is a result of CN or preexisting is unknown. This study examines these features in greater detail. Small-fiber neuropathy was assessed using the laser Doppler imager (LDI)flare technique (5), a more sensitive test of small-fiber function than quantitative sensory testing. MMH was assessed using the LDImax technique (5). The unaffected foot in those with CN was also studied to determine whether any defects in these measures were preexisting, and therefore etiological, or consequential of CN.
RESEARCH DESIGN AND METHODS -Four matched groupswere studied: the DPN group, 10 subjects with type 2 diabetes and neuropathy (aged 67.2 Ϯ 7.1 years, diabetes duration 19 Ϯ 8.1 years, vibration perception threshold [VPT] 30.3 Ϯ 6.0 V); the DCN group, 13 subjects with type 2 diabetes and quiescent CN (aged 65.5 Ϯ 8.7 years, diabetes duration 20 Ϯ 11.3 years, VPT 36.1 Ϯ 9.7 V) (4 with bilateral and 9 with unilateral CN); the unilateral CN (UCN) group, 9 subjects with UCN from the DCN group in whom the unaffected limb was studied (aged 64.7 Ϯ 10.2 years, diabetes duration 21 Ϯ 10.2 years, and VPT 33.5 Ϯ 8.1 V); and the control group, 10 healthy subjects (aged 61.4 Ϯ 9.7 years, VPT 8.0 Ϯ...