Search and selection of included reviews
Database searches identified 5435 articles, and, after removing duplicates, 4433 were screened by titles and abstracts, leaving 62 articles for full-text eligibility assessment. After full-text screening, 27 articles were included for the narrative synthesis. No additional sources were identified from the reference lists of included studies. Reasons for exclusion were: conference abstract (N = 11), no full-text available (N = 2), conditions, research design and outcome measures described did not meet the inclusion criteria (N = 13), previous version of included systematic review (N = 6) and systematic reviews included the same studies present in more recent reviews (N = 3) (Fig.1). The second reviewer (GR) screened 443 studies randomly selected from the total records (without duplicates) and did not identify any further eligible articles.
Figure 1. PRISMA flow diagram
Included systematic reviews
An overview of the main characteristics of included reviews is outlined in Table 1. More detailed information is presented: i) for each review in Additional file 2 (i.e. authors, year of publication, type of condition); ii) for studies included in each review in Additional file 3 (e.g. study designs, number and participant characteristics); (iii) in a format of summary of key findings, limitations and recommendations for each review in Additional file 4.
Table 1. Review characteristics of included studies
Out of 27 articles, 16 involved a narrative synthesis (N = 16) and were published from 2013 onwards. Most systematic reviews aimed to examine the evidence for an effect of any type of intervention (N = 9), exercise training (N = 6) or a rehabilitation intervention (N = 4) in rare neurological conditions. Most studies investigated people with NMDs (N = 13), including a number of muscle diseases (e.g. myotonic dystrophy) (N = 1), myotonic dystrophy and Welander distal myopathy (N =1), muscular dystrophy (N =1), Welander distal myopathy, muscular dystrophies and Hereditary inclusion body myopathies (N =1), idiopathic inflammatory myopathies (N = 1), Charcot-Marie-Tooth disease (N =3), McArdle disease (N =1), Guillain-Barre´ Syndrome (N = 2), critical illness myopathy and polyneuropathy (N =1) and Postpolio syndrome (N =1). More than half of reviews included one to five intervention studies for each review (N = 18). Twenty systematic reviews included at least one RCT in their reports, whilst the remaining studies included at least a quasi-randomized controlled design (N = 1), observational prospective design (N = 1), case-control design (N = 3) or pre-post design (N = 2).
Some intervention studies were reported in multiple reviews. In particular, Lui and Byl (36) and Arbesman and Sheard (37) included one randomized trial (38) and a quasi-randomized trial (39) that were discussed in Dal Bello-Haas et al. (40). Therefore, the two studies were described only once in Dal Bello-Haas et al’s review (40). In Marquer, Barbieri and Pe´rennou (41), four intervention studies were relevant for the aim of the present scoping review, however, only one was reported in the result section, as the remaining three studies were already presented in Fonteyn et al. (42).
The systematic review with the smallest number of participants included 18 individuals in total (43), whilst the one with the largest sample included 779 (44), followed by 757 (45) and 435 (16), which investigated, respectively, the effect of multidisciplinary care in individuals living with MND (44), and any type of interventions in individuals with NMDs (45), and physical therapy in people with HD (16) (see Additional file 2).
In line with the stated aims of the review, findings have been grouped by types of interventions and conditions (Fig. 2). Systematic reviews identified the following types of training: muscle strength training (N = 2) and aerobic training (N = 1) in individuals with NMDs; respiratory training in individuals with MND (N = 2); combined interventions in individuals with NMDs (N = 10), Ataxias (N = 4), MND (N = 4), HD (N = 2) and PSP (N = 2). FITT characteristics varied considerably, both within and between reviews, however, they are reported in Table 2 where possible, for each intervention.
Figure 2. Summary of types of interventions per condition
Figure’s legend: NMDs = neuromuscular diseases; MND = motor neurone disease; HD = Huntington’s disease; PSP = progressive supranuclear palsy
Twenty-two reviews across all RNCs identified in this scoping review included combined interventions. Frequency, intensity and time varied considerably between studies, with interventions lasting between one to 260 weeks, ranging between one to seven sessions per week, with each session lasting 10 minutes to eight hours (Table 2). Similar interventions across conditions were: muscle strength exercises, stretching, aerobic training, multidisciplinary interventions and gait training. Gait training and balance exercises were reported in all conditions with the exception of MND. Details on intervention intensity and frequency were not routinely reported, especially in the MND and ataxia reviews.
Table 2. Number of reviews per condition and FITT characteristics for combined interventions
Ten reviews (25, 27, 43, 45-51) addressed the effect of combined interventions in individuals with NMDs (Charcot-Marie-Tooth disease, Guillain-Barre´ Syndrome, myotonic dystrophy and Welander distal myopathy, idiopathic inflammatory myopathy, post-polio syndrome, Welander distal myopathy, Becker muscular dystrophy, limb-girdle muscular dystrophies, hereditary inclusion body myopathies, polymyositis and dermatomyositis, facioscapulohumeral muscular dystrophy, mitochondrial myopathy, critical illness myopathy and polyneuropathy).
Combined interventions in NMDs included: hand exercises (i.e. isolated and mass movements with silicone-based putty combined with resistance and stretching exercises); aerobic training (e.g. walking, bicycle training, step aerobics, home training of stationary bicycle ergometer); body weight support exercises, muscle strength training, strength exercises combined with breathing exercises, stretching, education, self-care education combined with home training, psychological and social support, passive or active motion sessions, functional exercises, multidisciplinary goal-oriented rehabilitation based on functional treatment, physical therapy training based on neurodevelopment sequences, positioning, wobble board, gait training and occupational therapy.
Four reviews (36, 37, 40, 44) addressed the effect of combined interventions in individuals living with MND, including: supervised proprioceptive neuromuscular facilitation (PNF) patterns combined with strength and a home exercise programme (stretching combined with a range of motion exercises), slow reversals resistance techniques, treadmill with biphasic positive airway pressure, individualized and progressive exercise, moderate intensity, moderate load resistance exercises and daily stretching exercises, endurance type exercises for limbs and trunk. One review investigated the effect of multidisciplinary care, including a consultant in rehabilitation, occupational therapist, physical therapist, speech–language pathologist, dietician, and social worker (44).
Two reviews (16, 52) addressed the effect of combined interventions in individuals living with HD, including: exercise individualised addressing maintenance of functional ability, flexibility, strength, video based exercise designed to reduce impairment and promote balance, physiotherapist instructed stretches, coordination, balance, one leg balance and tandem walking and upper limb ball exercises, respiratory intervention, facial exercise, whole body exercises in lying standing and sitting for gait, transfer training, postural training, a multi-sensory stimulation intervention, gait therapy, cycling, resistance exercises and aerobic exercise, use of videogames, PNF intervention, functional activities, combination with occupational therapy and social activities.
Four systematic reviews (41, 42, 53, 54) addressed the effect of combined interventions in individuals living with ataxias, including: coordination, balance, and muscular conditioning exercise, physical therapy, with a focus on balance, gait, general conditioning, muscle strength and range of motion, coordinative training with the main goal of being able to activate and engage/control mechanisms of balance, multi-joint coordination, occupational therapy (daily activities such as accessing to food, clothing, personal hygiene, and leisure were some of the main disabilities focused by these patients).
Two systematic reviews (55, 56) addressed the effect of combined interventions in individuals living with PSP, including: balance training complemented with eye movement and visual awareness training (versus balance training alone and limb coordination activities), fine motor activities, tilt board balancing, ambulation training, exercises to improve strength and coordination, static and dynamic balance, resistive and isokinetic exercises, Biomechanical Ankle Platform System, physical exercises, modified body weight support treadmill, wearable audio-biofeedback device/Dynamic Antigravity Postural System; Vibration Sound system, exercise programme of stretching, treadmill with and without body weight support, physical therapy exercises and Xbox Kinect, Virtual Gaming System, robot-assisted gait training, using end-effector robotic rehabilitation locomotion training (G-EO system device), multidisciplinary intensive rehabilitation treatment.
Muscle strength training
Two systematic reviews (28, 57) included interventions lasting from 12 to 52 weeks and investigating strength training in individuals living with NMDs, including: general muscle involvement or selected muscles, dynamic and isometric strength training with weights. Frequency of interventions was not reported in both studies, while intensity ranged between 30 and 60 minutes per session.
One systematic review included three non-randomised studies lasting 8 to 32 weeks and investigating aerobic training such as walking and cycling in individuals living with NMDs. Each session lasted between 45 and 60 minutes with a frequency of three to five times per week (58).
Two systematic reviews included studies lasting from 12 weeks to 32 months and investigating respiratory training in individuals living with MND, including: respiratory training muscle and yoga breathing technique. In one study, duration per session was 10 minutes, while other studies reported 10 to 15 repetitions per sessions, two to five times a day, every day (29, 59).
A total of 189 outcome measures were identified across the included reviews. Of these, the majority were related to body function impairments (47%) and limitation in functional activities (27%), followed by participation restrictions (6%) and body structure impairments (5%). Two domains did not fall into the ICF classification and were categorised as “Other” (e.g. Goal attainment score) (8%), and “Disease-specific” questionnaires (e.g. Unified Huntington's Disease Rating Scale or Scale for the Assessment and Rating of Ataxia) (7%). The full list of the outcome measures can be found in Additional file 5.
Most reviews included studies using outcome measures related to the domain of body function impairments (N = 26), followed by limitation in functional activities (N = 17), participation restrictions (N = 13) and body structure impairments (N = 5) (Table 3). Notably, none of the outcome measures included were agreed with the involvement of service users or members of the public.
Eleven reviews included studies using disease-specific outcome measures, while in six reviews, studies used other measures that did not fall into the ICF domains (i.e. in the “Other” category), such as goal attainment or hospital readmissions and length of stay. Most reviews used a combination of three to five different domains (N = 17), while in eight reviews two domains were present. One domain was identified in two reviews (Table 3)
Table 3. ICF domains identified for each study