Upper limb evaluation and one-year follow up of non-ambulant patients with spinal muscular atrophy: an observational multicenter trial

Abstract

Assessment of the upper limb strength in non-ambulant neuromuscular patients remains challenging. Although potential outcome measures have been reported, longitudinal data demonstrating sensitivity to clinical evolution in spinal muscular atrophy patients are critically lacking. Our study recruited 23 non-ambulant patients, 16 patients (males/females = 6/10; median age 15.4 years with a range from 10.7 to 31.1 years) with spinal muscular atrophy type II and 7 patients (males/females = 2/5; median age 19.9 years with a range from 8.3 to 29.9 years) with type III. The Brooke functional score was on median 3 with a range from 2 to 6. The average total vital capacity was 46%, and seven patients required non-invasive ventilation at night. Patients were assessed at baseline, 6 months, and 1 year using the Motor Function Measure and innovative devices MyoGrip, MyoPinch, and MoviPlate, which assess handgrip strength, key pinch strength, and hand/finger extension-flexion function, respectively. The study demonstrated the feasibility and reliability of these measures for all patients, and sensitivity to negative changes after the age of 14 years. The younger patients showed an increase of the distal force in the follow-up period. The distal force measurements and function were correlated to different functional scales. These data represent an important step in the process of validating these devices as potential outcome measures for future clinical trials.

Trial registration: ClinicalTrials.gov NCT00993161.

Conflict of interest statement

Competing Interests: JYH is inventor of the MyoGrip. JYH and AM are co-inventors of the MyoPinch. JYH, AC, LS and TV are co-inventors of the MoviPlate. This does not alter the authors' adherence to all PLOS ONE policies on sharing data and materials.

Figures

Fig 1. Flow chart of patients included in the clinical protocol.

Fig 2. Reliability test.

Reliability of test and retest sessions for (A) grip, (B) pinch, and (C) MoviPlate for all SMA patients for the non-dominant hands (dark dots) and the dominant hands (clear dots).

Fig 3. Correlations between clinical parameters and MyoSets measurements at baseline.

Correlations at baseline between grip, pinch, or MoviPlate on the dominant side and time spent in the wheelchair, Brooke score, or MFM total score for SMA type II (orange triangles) and type III (purple dots) patients.

Fig 4. MoviPlate correlations with grip and pinch strength.

Correlations at baseline between the MoviPlate scores and grip and pinch strength for all SMA patients for the non-dominant hands (dark dots) and the dominant hands (clear dots).

Fig 5. Follow-up MyoSets data and MFM scores for all SMA patients.

Data at 6 months and at one year for all SMA patients for (A) grip, (B) pinch, and (C) MoviPlate on the dominant (D) and non-dominant (ND) sides and for (D) MFM-D3 and MFM-Total scores. SMA type II for whom data at 6 months and one year are lacking are marked with orange triangles; for type II patients for whom data were obtained at both time points, the orange interrupted line represents their evolution. The purple solid lines represent the evolution of SMA type 3 patients. The age of 14 is marked with a vertical dotted line.