Characteristic appearances of the H-reflex and F-wave with increased stimulus intensity in patients with cerebrovascular disease.

We experienced H-reflex may be evoked with supramaximal stimulation in patients with cerebrovascular disease (CVD). In this study, we investigated the relationship between the characteristic appearances of H-reflex and F-wave with increased stimulus intensity and neurological signs. We examined the H-reflex and F-wave of the affected arm with increased stimulus intensity during muscle relaxation in 31 patients (17 males and 14 females) with hemiparesis caused by CVD. Mean patient age was 56.0 (range 30-82) years. 30 healthy subjects, mean age of 56.2 (range 28-80) were investigated using the same method as controlled group. H-reflex and F-wave with increased stimulus intensity after the median nerve stimulation at the wrist were recorded from the opponence pollicis muscle on the affected side in patients with CVD or right arm in the healthy subjects. Appearance patterns of the H-reflex and F-wave with increased stimulus intensity was separated into four types. Type 1: F-wave appeared with increased stimulus intensity, but there was no H-reflex. Type 2: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave followed disappearance of the H-reflex with increased stimulus intensity. Type 3: H-reflex and F-wave both appeared with increased stimulus intensity, but the F-wave appeared during the H-reflex with increased stimulus intensity. Type 4: Only the H-reflex appeared with increased stimulus intensity, but there was no F-wave. Neurological findings including muscle tone and tendon reflex were also evaluated. Findings on muscle tone and tendon reflex were classified into increased (markedly, moderately and slightly), normal and decreased. Results were analyzed as follows; 1) The characteristic appearances of H-reflex and F-wave in the healthy subjects and 2) The relationship between characteristic appearances of waves with increased stimulus intensity and neurological signs in patients with CVD. 1) Pattern of the H-reflex and F-wave with increased stimulus intensity in all healthy subjects were type 1. 2) Patterns of the H-reflex and F-wave with increased stimulus intensity in patients with markedly increased muscle tone and tendon reflex were almost always type 4. Those with moderately increased signs in this parameter demonstrated type 2 or 3. Those with slightly increased signs in this parameter demonstrated type 1 or 2. Those with normal or decreased signs were type 1. These findings suggest that the characteristic appearances of the H-reflex and F-wave was influenced by grade of neurological signs.