Patients showed heterogeneity in muscle affectation and
disability measured by different scales
Five clinically heterogeneous patients with DM1 were included in this
study, whose age of onset ranged between 15 and 48 years. Their muscle
dysfunction was studied using several different scales (Table
1 ). By using the mRS, we determined the degree of disability and/or
dependence in the daily activities of these DM1 patients. In our cohort,
P3 (with a mRS score of 1) had no significant disability and had no
limitation in daily life activities despite the presented symptoms.
Three patients, P1, P2 and P5 (mRS score of 2) presented with a slight
disability, meaning they were unable to do activities they were able to
in the past, but they remained independent. Moderate disease disability,
(mRS score of 4) was found in P4, who was unable to walk and to attend
to self-care. With regard to the MIRs scale, P3 showed minimal signs, P2
and P5 had distal weakness, and P1 and P4 mild-to-moderate proximal
weakness. We also evaluated the same patients using the MRC scale, to
measure strength in the biceps muscle (the muscle from which we obtained
muscle cells). P2, P3 and P5 had preserved muscle strength (i.e. ,
MRC score = 5). Yet, P1 and P4 had an MRC of 4, indicating decreased
muscle strength, a result consistent with the more proximal weakness
that these two patients had when assessed with the MIRS scale. The same
patients were submitted to a 6MWD test and P5 showed values within the
normal range (Casanova et al., 2011). Values below the normal range were
found for 6MWD in P1, P2 and P3. Although having better scores for mRS,
MIRS and biceps MRC than P1, P2 walked 100 meters less. P4 was not able
to perform the 6MWD test, since she was unable to walk. All scales
showed heterogeneity among the patients in muscle function and degree of
disability.