F-wave, h-reflex and treadmill exercise stress test in the functional evaluation of lumbar canal stenosis

Abstract EN

Aim of the work : to study the relationship between the functional parameters of walking as assessed with the treadmill exercise stress walking test and the electrophysiological variables of the H-reflex and F-wave as well as radiological factors in LCS patients.

Methodology : Forty six patients were enrolled in the study with a mean age of 55.4 ± 12.4, who complained of low back pain and painful walking restriction.

Diagnosis of LCS was established by demonstrating primary or degenerative LCS in a standard CT and / or MRI.

Diagnosis of neurogenic intermittent claudication (NIC) was assessed by an initial treadmill exercise stress walking test.

H-reflex and posterior tibia F-wave parameters were measured before and immediately after the stressful treadmill walking exercise.

The parameters included latency and current intensity required to elicit threshold H-reflex as well as minimum, maximum and average F-wave latencies out of 10 responses.

Treadmill walking parameters included time-to-onset of symptoms, distance-to-onset of symptoms and average speed of walking.

A 0-8 point score was designed to quantify the radiological findings.

Results : Thirty seven patients showed positive neurogenic intermittent claudication with the initial treadmill test.

Their mean walked-distance and average speed were significantly lower than those who were negative for neurogenic intermittent claudication during the initial treadmill test.

The post treadmill walking H-latency was significantly prolonged (t = 2.48, p = 0.019).

Also, the H-threshold intensity was significantly elevated (t = 3.60, p = 0.003) as compared with the pre-treadmill walking values.

F-wave parameters did not differ significantly before and after treadmill walking.

A significant negative correlation was shown between the H-latency and distance walked till onset of symptoms (r = -0.612, p = 0.002), and the time till onset of symptoms (r = - 0.499, p = 0.018).

F-wave variables showed significant negative correlation with the distance walked till the onset of symptoms (r = -0.380, -0.477, and -0.400 respectively), while the maximum F-wave latency showed significant negative correlation with the time walked till the onset of symptoms (r = -0.354, p = 0.040).

The total radiological score of those patients who had neurogenic claudication (mean = 3.86 ± 1.58) was significantly higher than that of patients with negative claudication's (mean = 2.22±0.97) (t = 2.96, p = 0.005).

The total radiologic score was found to be significantly negatively correlated to the distance as well as the time walked to the onset of symptoms (r = -0.792 and -0.544, p = 0.000).

Conclusion : Treadmill exercise stress walking test could differentiate patients with neurogenic claudication objectively.

The electrophysiological variables as well as the radiological score correlated negatively with functional walking parameters, thus establishing the functional significance of the neuro-physiological alterations as well as the radiological findings in symptomatic lumbar canal stenosis patients.

Recommendation : A combined evaluation of those patients using H-reflex, F-wave parameters as well as radiological scoring in conjunction with treadmill exercise stress walking test would improve management, decision making and follow up of those patients.