The applicability of four clinical methods to evaluate arm and hand function in all stages of spinal muscular atrophy type II

Abstract

Aim: To evaluate the ability of four clinical methods to reflect arm and hand function at impairment and activity level and to determine their ability to discriminate among SMA II patients of all ages and in all stages of the disease. Methods: Fifty-two patients with SMA II (age range: 8–73 years) were assessed by means of the Egen Klassifikation 2 (EK2 scale), the Motor Function Measure Scale (MFM D3), the Manual Muscle Test (MMT) and Hand-Held Dynamometry (HHD) in full fist grip and lateral pinch grip. Patients were classified into six levels of upper limb function by means of the Brooke Upper Limb Scale, and the four methods’ ability to differentiate among patients within these levels was calculated. Modified versions of the EK2 scale (EK Upper Limb) and the MFM D3 (MFM D3 Upper Limb) were assessed in the same manner. Results: The patients’ physical abilities were best described by the MMT and EK2 while the “EK Upper Limb”, MFM D3 and MMT were best at discriminating among patients across the range of upper limb function. Quantitative muscle tests as measured by Citec™ HHD were less applicable to weak patients; full fist grip could discriminate among patients at Brooke levels 3–5, and lateral pinch grip among the strongest patients. Conclusion: At the impairment level, MMT is the superior measure of muscle function in very weak patients in whom HHD cannot reflect capacity. At the activity level, the EK 2 represents daily activities whereas the MFM D3 measures motor functions. In differentiating among SMA II patients of all ages and in all stages of the disease, the ability of abbreviated versions of scales targeting upper limb function is superior to unabridged versions of these scales.Implications for RehabilitationEvaluation of upper limb function in spinal muscular atrophy IIEven very weak patients with SMA II have some residual upper limb function that is measurable if the right method is chosen.The Manual muscle test is applicable to all patients with SMA II and is useful to determine possible interventions – such as methods to drive a wheelchair or operate a computer.Abbreviated versions of the EK2 scale and the MFM are useful as methods to evaluate subtle changes in upper limb function resulting from disease progression or interventions.