Functional and motor evaluation in a Brazilian Huntington’s disease cohort

Sugerimos

The global prevalence of HD is 2.7 per 100,000 inhabitants 2 . In the first semester of 2022, 3.671 families with HD were registered in the Brazil Huntington Association.
In Brazil, there are some HD clusters, such as: one in Feira Grande town -AL, with a prevalence of 10.4/10,000 inhabitants 3 ; one in Senador Sá -CE with a prevalence of 23.3/10,000 inhabitants 4 and one in Ervália town -MG with a prevalence of 7.2/10.000 inhabitants 5 . The minimal prevalence in Rio Grande do Sul state was estimated at 1.85:100,000 inhabitants 6 .
The incidence and prevalence of HD are the same for both sexes. HD alleles when inherited from the father are more likely to be more expanded and can cause the HD juvenile form 7,8 . Expanded alleles transmitted by the mother to her offspring rarely show an increase of more than 20 CAG repeats 9,10 .
The motor symptoms in HD are chorea, dystonia, dyskinesia, akinesia, hypokinesia and bradykinesia, as well as motor impersistence and rigidity. Other symptoms of HD including inquietude and the presence of movements that simulate throwing (ballism), become more evident throughout the disease progression [11][12][13][14] .
Motor impairments negatively affect the upper limbs and limit the ability to perform reaching, grasping and fine motor activities in individuals with HD. On the other hand, cognitive symptoms (psychiatric and behavioral) contribute to decreased performance on the Activities of Daily Living (ADLs) and reduced quality of life in patients with HD 13,15 .
Motor impairments contribute to the functional decline as measured by the Instrumental Activities of Daily Living (IADLs), such as feeding and hygienic practices; especially those ADLs and social activities that require a higher level of discernment and mental skills, such as finance management and cooking 16 .
Some functional activities assessment tools including the UHDRS, six-minute walk test, 10m walk, the Timed Up & Go (TUG test), Physical Performance Test (PTT) and Barthel Index have been used clinically to determine the effect of interventions and to measure disease progression in individuals with HD. Efficient, low-cost, easy-to-use tools to assess patients with HD are important to identify the current impact of motor impairment on daily activities and the quality of life in HD different stages [17][18][19][20] .

Study Design
This was a cross-sectional, observational quantitative study with a reference group.

Participants
Brazilian individuals with HD were recruited in the The scores for the MBI, FIM and FAS are shown in Table   3 and in the additional Supplementary Tables (ST02, ST03 and ST04) for each patient, and respective individual and cumulative percentages according to the MBI, FIM and FAS score.   HD individuals were categorized using disease progression according to the Shoulson and Fahn (1979) 22 .
TFC scores and all scales are shown in Table 4. As well as in the additional Supplementary Tables (ST05 and ST06), for each patient and the respective individual and cumulative percentages according to the IS and TMS score.  There was a strong association between each score obtained by UHDRS functional sections (FAS, TFC and IS) and the disease stage (score measured by TFC section) in individuals with HD (R 2 = 0.97 and p<.05); which means that 97% similarity was observed between each functional section; therefore, they were able to identify the functional impairment of normal or abnormal individuals.

Descriptive statistical analysis and comparison of the functional and motor scales between the reference and the HD groups
In the reference group (n=22) and HD group (n=22), the median value, obtained after the application of each functional scale, was used as a cutoff point for the evaluation of normal or abnormal functional performances. Table 6 shows the median, minimum and maximum values.
The scores obtained with each scale applied to the reference group were: 1) for FAS, the mean was 24.7±0.4.
In 72.7% of the individuals, the FAS score was equal or lower than 18; 2) for TFC, 100% of the individuals obtained the maximum score 13; 3) for the IS section, all subjects obtained the maximum score 100; and 4) for TMS, 90.9% of the cases had a score equal or lower than three (the higher the score, the worse the motor performance). in the reference group as expected (Table 6).

Functional performance diagnostic testing with the FIM and MBI versus UHDRS (FAS, TFC AND IS)
The FIM and MBI were compared, about their testing properties, with the functional sections of the UHDRS (  Percentile Median In addition, the MBI and MIF can be good alternatives to be used by physical therapists to assess the functional performance of HD individuals and, consequently, can be effective in the strategy of rehabilitation programs, as well as to measure the progression of the disease, considering that these scales are already used in the clinical practice of physical therapists.

SUPPLEMENTARY TABLES (ST)
ST 01. Stages of the disease according to Shoulson and Fahn (1979) 22