Research article

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

Riccardo Mazzocchio , Giovanni Battista Scarfò , Aldo Mariottini , Vitaliano Francesco Muzii and Lucio Palma

Istituto di Neurochirurgia, Università di Siena, Italy

author email corresponding author email

BMC Musculoskeletal Disorders 2001, 2:4doi:10.1186/1471-2474-2-4

Published:	8 October 2001

Abstract

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.