Axon Count and Sympathetic Skin Responses in Lumbosacral Radiculopathy

Abstract

Background and PurposeElectrodiagnostic studies can be used to confirm the diagnosis of lumbosacral radiculopathies, but more sensitive diagnostic methods are often needed to measure the ensuing motor neuronal loss and sympathetic failure.MethodsTwenty-six patients with lumbar radiculopathy and 30 controls were investigated using nerve conduction studies, motor unit number estimation (MUNE), testing of the sympathetic skin response (SSR), quantitative electromyography (QEMG), and magnetic resonance myelography (MRM).ResultsUsing QEMG as the gold standard, the sensitivity and specificity of MUNE for the abductor hallucis longus muscle were 71.4% and 70%, respectively. While they were 75% and 68.8%, respectively, when used MRM as gold standard. The sensitivity and specificity of MUNE for the extensor digitorum brevis muscle were 100% and 84.1%, respectively, when the peroneal motor amplitude as the gold standard. The SSR latency was slightly longer in the patients than in the controls.ConclusionsMUNE is a simple and sensitive test for evaluating autonomic function and for diagnosing lumbosacral radiculopathy in patients. MUNE could be used routinely as a guide for the rehabilitation of patients with radiculopathies. SSR measurements may reveal subtle sympathetic abnormalities in patients with lumbosacral radiculopathy.

Motor unit number estimation of human abductor hallucis from a compound muscle action potential scan

“…The MUNE values of the present study and those of Tilki et al . are about two‐ to threefold larger than a previous report of 43 motor units .…”

“…We found that the number of the AH motor units was slightly greater than the mean of 98 units reported by Tilki and coworkers, who used incremental MUNE. Our estimate is consistent with the modestly lower estimate of approximately 100 motor units in individual hand muscles, which likely have a slightly smaller cross‐sectional area than the AH .…”

“…are about two‐ to threefold larger than a previous report of 43 motor units . The participants were of similar age in all 3 studies (Johns and Fuglevand, 25–43 years; Tilki et al ., 40 ± 11 years; and ours, 34 ± 6 years), so age cannot account for the different motor unit counts. The difference may result from different data collection and MUNE techniques.…”

“…It is often used in nerve conduction studies because the tibial nerve is readily accessible . However, studies of the estimated number of AH motor units are rather limited . In one study of 11 healthy controls, the number of AH motor units was estimated by counting the number of step increments in the CMAP over the entire stimulus intensity range .…”

Assessment of sympathetic skin response to acne vulgaris

“…Thus, sympathetic activity is assessed as rapid and painless. SSR has been evaluated in a variety of diseases such as migraine, multiple sclerosis, fibromyalgia, and lumbosacral radiculopathy [5][6][7][8]. In addition, SSR has been evaluated in skin diseases such as leprosy, palmoplantar hyperhidrosis, vitiligo and psoriasis [9][10][11][12].…”