Validation of an item bank in a sample of community-dwelling survivors of a stroke.

PURPOSE: The purpose of this study was to validate an item bank of questions associated with activities of daily living (ADL), using graded item response theory (G-IRT), in a sample of community-dwelling survivors of a stroke. METHODS: The study sample consisted of 364 community-dwelling individuals who reported a recent history of stroke. Sixteen line items from the 1999-2000 National Health and Nutrition Examination Surveys (NHANES) survey were analyzed using factor analysis, internal analyses of consistency, and G-IRT. RESULTS: The 16 line items demonstrated unidimensionality and were internally reliable. Thirteen line items demonstrated good discrimination and suitable thresholds. The majority of items exhibited appropriate sensitivity across the entire spectrum of functional severity indicating that these items closely reflected the relationship of decreased function with increased severity of illness. CONCLUSION: Each of the 13 items is scale independent, is valid for measurement of functional impairment, and may be applicable for use in a scale for assessment of functional change in community-dwelling stroke survivors.

Properties of medial gastrocnemius motor units and muscle fibers reinnervated by embryonic ventral spinal cord cells.

Severe muscle atrophy occurs after complete denervation. Here, Embryonic Day 14-15 ventral spinal cord cells were transplanted into the distal tibial nerve stump of adult female Fischer rats to provide a source of neurons for muscle reinnervation. Our aim was to characterize the properties of the reinnervated motor units and muscle fibers. Some reinnervated motor units contracted spontaneously. Electrical stimulation of the transplants at increasing intensity produced an average (+/- SE) of 7 +/- 1 electromyographic and force steps. Each signal increment represented the excitation of another motor unit. These reinnervated units exerted an average force of 12.0 +/- 1.5 mN, strength similar to that of control fatigue-resistant units. Repeated transplant stimulation depleted 17% of the muscle fibers of glycogen, an indication of some functional reinnervation. Reinnervated (glycogen-depleted), denervated (no cells transplanted), and control fibers were of histochemical type I, IIA, or IIB. Fibers of the same type were grouped after reinnervation. The proportion of fiber types also changed. Reinnervated fibers were primarily type IIA, whereas most fibers in denervated and control muscles were type IIB. Reinnervated fibers of each type had significantly larger cross-sectional areas than the corresponding fiber types in denervated muscles. These data suggest that neurons with different properties can reside in the unusual environment of the adult rat peripheral nerve, make functional connections with muscle, specify muscle fiber type, and reduce the amount that each type atrophies.