ABSTRACT
Cutaneomuscular reflex responses (CMRs) have been studied in nine stroke patients (55-84 years) starting from the first 1-7 weeks after stroke and continuing at intervals of 6-8 weeks for up to 2 years. Multi-unit surface EMG signals were recorded from the stroke and non-stroke first dorsal interosseous (1DI) hand muscle while subjects gripped a dowel, and concomitant stimulation of the digital nerves of the index finger was delivered at 2.5 x threshold for perception. Motor function was measured using the Motor Assessment Scale (MAS) and patients were classified as having a good or a poor recovery according to their final functional outcome. None of the patients showed a change in the sizes of the E1, I1 and E2 reflex components over time. At initial testing, the size of the E1 component for all patients who showed good recovery fell within the 95% reference range (0-16.5% modulation of background EMG) found for normal age matched controls. In contrast, when first tested, 5/5 patients who showed no significant recovery over the 2-year period, had exaggerated spinal E1 components greater than 16.5%. We conclude that exaggerated E1 components could be predictive of a poor functional outcome at 2 years.
Subject(s)
Afferent Pathways/physiopathology , Muscle, Skeletal/physiopathology , Reflex, Abnormal/physiology , Stroke/physiopathology , Aged , Aged, 80 and over , Electric Stimulation , Electromyography , Female , Humans , Longitudinal Studies , Male , Middle Aged , Muscle Contraction/physiology , Muscle, Skeletal/innervation , Physical Stimulation , Predictive Value of Tests , Prognosis , Recovery of Function/physiology , Skin/innervationABSTRACT
Changes in cutaneomuscular reflex responses (CMRs) have been studied in relation to normal ageing in man. Multiunit surface EMG signals were recorded from right and left first dorsal interosseous (1DI) hand muscles from 23 elderly adults (mean age 71.1, range 58-88 years) and 11 young adults (mean age 25.9, range 19-31 years). Subjects (1) performed index finger abduction and (2) gripped a dowel while concomitant stimulation of the digital nerves of the index finger was delivered at x2.5 threshold for perception. The E1 spinally mediated components of the CMRs recorded from 1DI were significantly smaller in the elderly subjects compared with young subjects for both tasks. The I1 and E2 transcortical components did not show a significant change in size with age although the incidence of I1 components was significantly reduced in the elderly subjects.