The Vibration Quantitation Scale (VQS): A simple, reproducible bedside measure of sensory function in multiple sclerosis

Abstract

Objectives: To assess the utility of a bedside measure of sensation (the Vibration Quantitation Scale (VQS)) in patients with multiple sclerosis (MS) and in normal controls. To correlate the VQS with the Kurtzke Expanded Disability Severity Score (EDSS) and sensory abnormalities in these patients. Methods: We developed the VQS and tested its performance in patients with MS of various ages, MS types, and EDSS scores. We compared this with controls (normal volunteers or patients with other neurological diseases) who did not have sensory symptoms. In a subgroup, two examiners measured VQS independently at the same patient visit. A standard C-128 tuning fork was used for the VQS measurement. Results: The VQS had a good inter-observer reproducibility (r=0.920, p<0.001). The VQS fell with increasing age in normals consistent with declining sensory function. The VQS was significantly lower in the multiple sclerosis patients compared with age - matched controls (p<0.001). Abnormalities in VQS were present in patients with brief duration of MS (<5 years) and low EDSS scores, correlating with the presence of sensory abnormalities early in the disease course in some patients. There was a strong correlation between the VQS and EDSS (r=-0.509). The VQS correlated with abnormal sensation in the hands (r=0.310), but did not meet statistical significance for abnormal sensation in the feet or face. A second cohort of MS patients was studied using a modified VQS measure (single stimulation, omitting forehead measurement). This reconfirmed the correlation between the modified VQS and EDSS as well as with age. The modified VQS may be useful in clinical practice since it takes little time and is strongly correlated with the EDSS (r=0.578). Conclusions: The VQS provides a continuous sensory scale applicable in most patients with MS, which is measurable with standard bedside equipment, and which may avoid some of the pitfalls of sensory scoring in MS.