Gait and balance impairment in early multiple sclerosis in the absence of clinical disability

Investigators: Ms Clarissa Martin, Dr Bev Phillips, Prof Trevor Kilpatrick,   Dr Helmut Butzkueven, Dr Niall Tubridy, Dr Elizabeth McDonald, Prof Mary Galea

Gait and balance impairments are common and frequently disabling consequences of multiple sclerosis (MS). Recent evidence suggests that sub-clinical impairments may precede the onset of functional limitations in MS patients, however the extent of gait and balance disturbance in the early stages of the disease have not previously been reported.

Using laboratory-based gait analysis and clinical balance measures, this study aimed to evaluate the performance of two clinically distinct groups of recently diagnosed, minimally impaired MS patients (EDSS 0-2.5), compared to age- and gender-matched control subjects. Ten MS patients with mild pyramidal signs (MS-P), 10 MS patients with no pyramidal signs (MS-NP) and 20 control subjects were included. The results indicated that both groups of MS patients walked with reduced speed and stride length (p<0.001), and prolonged double limb support (p<0.02), compared to the control group.

Both MS groups demonstrated reduced ankle motion throughout the gait cycle, particularly reduced ankle dorsiflexion at initial contact (p<0.005), although there was no difference in knee motion compared to the control group. Alterations in the timing of tibialis anterior and gastrocnemius activity, corresponding to the ankle motion profile, were identified in both MS groups (Fig. 1). A comparison of the two MS groups revealed that the MS-P group walked with reduced speed (p=0.03) and stride length (p=0.04), and prolonged double limb support (p=0.01), compared to the MS-NP group. Both the MS-P and MS-NP groups performed poorly on the clinical balance measures, compared to the control group, particularly the Functional Reach Test (p<0.05).

The results of this study suggest that simple clinical measures may be useful in detecting incipient impairments in gait and balance performance in MS patients with recent disease onset. Changes in gait and balance parameters were evident in minimally impaired MS patients within three years of diagnosis, suggesting that motor function may begin to deteriorate in the early stages of the disease, even in the absence of clinical signs of overt neurological impairment and, in particular, of pyramidal dysfunction.

Figure 1.   Average EMG profiles for the MS and control groups: ( A ) MS-Pyramidal medial gastrocnemius; ( B ) MS-Pyramidal tibialis anterior; ( C ) MS-Non Pyramidal medial gastrocnemius; ( D ) Ms-Non Pyramidal tibialis anterior. The solid and dotted lines respectively represent the MS group mean ± 1SD; the grey band represents the control group (mean ± 1SD). The two vertical lines indicate toe off (TO) for the control (c) group (mean 62.5% stride), the MS-Pyramidal (MS-P) group (mean 64.8% stride) and the MS-Non Pyramidal (MS-NP) group (mean 63.2% stride). Heel strike (HS) occurs at 0% and 100% of the stride.

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