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      Effects of age and leg length upon central loop of the Gastrocnemius-soleus H-reflex latency

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          central loop of the gastrocnemius-soleus H-reflex latency (T c) that looks promising in the diagnosis of S1 radiculopathy; has been investigated in a few studies and only two of them have focused on the constitutional factors affecting it. Although leg length has been shown to contribute to the T c, the role of age is controversial. More confusing, none of the previously performed studies have used strict criteria to rule out subclinical neuropathy, so the results could be misleading. This study has been performed to determine the influence of leg length and age on T c among a carefully selected group of healthy volunteers.


          after screening forty six volunteers by taking history, physical examination and a brief electrophysiologic study; forty of them were selected to enroll into the study. T c was obtained in all the study subjects and leg length and age were recorded for correlational analyses.


          this group was consisted of 26 males (65%) and 14 females (35%) with the age range of 19–65 years (Mean ± SD: 37 ± 10.7) and leg length range of 29.5–43 centimeters (36.4 ± 3.4).

          Mean ± SD for T c was 6.78 ± 0.3. We found a significant correlation between T c and leg length (p value= 0.003, r = 0.49 and confidence interval 95% = 0.59–0.88), no significant correlation was found between age and T c (p value= 0.48, r = 0.11), also we obtained the regression equation as: T c = 0.04L + 5.28


          in contrast to leg length, age was not correlated with T c. Future studies are required to delineate other contributing factors to T c.

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          Most cited references 11

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          Recruitment curve of the soleus H-reflex in chronic back pain and lumbosacral radiculopathy

          Background Needle EMG may be negative in mild or predominantly sensory lumbosacral radiculopathies. In such cases, an increase in the latency of the soleus H-reflex is a useful diagnostic criterion for establishing sensory fiber compromise at the S1 root level. However, if clinical signs of radicular involvement are lacking, the latency of the H-reflex is normal. We therefore studied the recruitment curve of the soleus H-reflex to investigate whether a change in the electrical threshold for eliciting the H-reflex might be a more sensitive criterion for detecting subclinical S1 root dysfunction. Methods Clinical and electrophysiological findings from 26 patients with chronic back pain and radiculopathy were compared with data obtained from 40 healthy subjects. Results An increase in the mean H-reflex threshold was the only abnormal electrophysiological finding in patients with no clinical sign of root injury (58%). A decrease in the mean H-reflex amplitude and a prolongation of H-reflex latency was observed in patients with radicular signs (42%). In both patients groups, F-wave and needle EMG studies were normal. No radiological evidence of S1 root compression was found. Conclusions The study of the recruitment curve of the soleus H-reflex may be usefully associated to F-wave and needle EMG studies to detect possible S1 root dysfunction in mild lumbosacral radiculopathies. An increase in H-threshold may be the earliest abnormality in the absence of focal neurological signs.
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            Standardization of H reflex and diagnostic use in Sl radiculopathy.

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              Soleus H-reflex to S1 nerve root stimulation.

              H-reflexes in normals were elicited by percutaneous electrical and magnetic stimulation of proximal nerve roots at the cauda equina. H-M interval to S1 nerve root stimulation at the level of the S1 foramen was 6.8 +/- 0.33 ms, with side to side difference of 0.16 +/- 0.13 ms. Compression/ischemia of the sciatic nerve in the mid-thigh abolished the H-reflex to stimulation of the tibial nerve at the popliteal fossa when the H-reflex to S1 nerve root stimulation was preserved. The length of the S1 nerve root in human cadavers was measured to be 17.5 +/- 03 cm, providing an estimated dorsal root conduction velocity of 67.3 m/s and a ventral root conduction velocity of 54 m/s. We conclude that the H-M interval to S1 root stimulation can provide reliable measures of conduction within the spinal canal including proximal afferents, anterior horn cells and ventral roots.

                Author and article information

                BMC Neurol
                BMC Neurology
                BioMed Central (London )
                3 September 2004
                : 4
                : 11
                [1 ]Pain research group, multidisciplinary pain clinic of iran jahad danesh gahi, no 31, karimkhan zand ave. shahid hosseini alley, Tehran, Iran
                [2 ]Department of physical medicine and rehabilitaton, shiraz medical school, zand avenue, Shiraz, Iran
                [3 ]Department of biostatistics, shiraz medical school, zand avenue, Shiraz, Iran
                Copyright © 2004 Sadeghi et al; licensee BioMed Central Ltd.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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