Diagnostic Value of the F-wave in Loss of Cervical Lordosis
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Neurophysiology, Vol. 52, No. 3, May, 2020
Diagnostic Value of the F-wave in Loss of Cervical Lordosis G. Y. Neşe1 and E. Yasemin1 Received June 29, 2019 We investigated peculiarities of the F waves elicited by stimulation of the median and ulnar nerves in 76 subjects having pronounced loss of cervical lordosis (LCL) and 42 control subjects. The CL angles in these two groups were 0–30 and 31–40 deg, respectively. As was found, the averaged minimum, maximum, and mean latencies and chronodispersion values of both median and ulnar F waves in most cases were slightly longer than in the control, but all intergroup differences were statistically insignificant. At the same time, the averaged median F wave persistence in both upper limbs of LCL patients was significantly smaller (P = 0.000) than that in control subjects. There was no such difference in the ulnar F responses. Recording of the median F wave can be used as an additional approach in diagnosing the LCL state.
Keywords: loss of cervical lordosis (LCL), F-wave, median nerve, ulnar nerve, latency, magnetic resonance imaging (MRI), posterior tangent method
INTRODUCTION Due to the natural sequence of the cervical vertebrae, the convexity that appears in the lateral view is called cervical lordosis. This convexity is between 31 and 40 deg in healthy adults, while values below 30 deg are considered indices of cervical flattening, loss of cervical lordosis (LCL) [1]. This anatomical change can be caused by muscular spasms, traumas, congenital defects, muscular dystrophies, amyotrophic lateral sclerosis, ankylosing spondylitis, spinal tumors, infections, and surgical complications [2]. The widely observed main cause for a reduction of cervical lordosis is a chronic spasm of the deep cervical muscles. This can result in chronic compression of the spinal cord, leading to neuronal loss in the ventral horns and demyelination of the nerve fibers [3]. Being one of the low-amplitude late responses generated due to antidromic activation of alpha motoneurons, the F response is provided by antidromic transmission from the stimulated point of the peripheral nerve to motor neurons and the orthodromic transmission to the innervated
muscle and to the recording electrode on it. Various parameters of the F wave are evaluated; the most commonly used ones are the F latency (Fl), F persistence (Fp), and F chronodispersion (Fc). Abnormal Fl values are indicative of distal conduction abnormalities, whereas those of Fp and Fc show mostly more proximal conduction abnormalities [4]. Loss of cervical lordosis may be manifested as either symptomatic or asymptomatic, depending in particular on today’s sedentary life and working conditions, [5]. Morphological and electrop hys io logical evaluation of the bones, muscles, nerves of the spinal cord, and close anatomical neighborhood using magnetic resonance imaging (MRI) are important in the diagnosis of cervical pathologies [6]. In the electrophysiological evaluation, nerve conduction studies, including estimation of the F wave parameters, ar
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