Physical characteristics and applicability of standard assessment methods in a total population of spinal muscular atrophy type II patients

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

“…However, the method has a floor effect, since patients with very weak muscles (53) do not have the strength to overcome the threshold of the dynamometer [5,21,26]. This corresponds to our findings where an arm function corresponding to Brooke 3 was needed if all patients were to attain a score on the dynamometer.…”

“…This was based on our findings from a previous study in SMA II [5], where we found that the MRC% score of muscles with more physical capability better reflected variation among patients than a total muscle test and in accordance with our criteria patients should be assessed in their wheelchair. We chose to include thumb adduction and thumb opposition, as we had found that these movements were easier for some patients with SMA II to perform.…”

“…If we want to detect small changes in motor function, we need to focus on the upper limb region since upper-limb functions and their changes over time can be measured in even very weak patients [5,7]. Such changes may be difficult to spot in a score representing overall physical abilities.…”

“…The ability to sit independently may be lost within the first year of life or may persist into adulthood, resulting in broad variation in motor ability among these patients [2]. In general, the disease is characterized by a profound impairment of physical functions; upper limbs are stronger than lower limbs [3], with best preserved muscle strength in flexion of the elbow and in hands and fingers [4,5]. A gradual loss of muscle strength and physical functions in the upper limbs has been demonstrated [6,7].…”

“…The scale is reliable [7,12] and is often used to validate other functional scales [13][14][15][16][17]. Although it is easily administered and gives a quick impression of the patient's upper-limb capabilities, it does not cover capabilities of all SMA II patients because it has a ceiling effect among very weak patients and is too crude to register changes over time in strong patients [5,7]. While this makes the Brooke scale useful in classifying and illustrating range of upper-limb function, it is inappropriate as an evaluation tool in SMA II.…”