The Role of Mirror Therapy in the Rehabilitation of the Upper Limb's Motor Deficits After Stroke: Narrative Review

The review addresses whether mirror therapy (MT) improves motor recovery and functional performance of the paretic upper limb after stroke, and how its effects vary across stroke phases (hyperacute, acute, subacute, chronic). It situates the question in the context of stroke’s high global burden, the profound impact of upper limb impairment on daily life and independence, and the need for effective, accessible rehabilitation approaches. MT leverages a visual illusion via a mirror to retrain movement by providing real-time visual feedback of the non-paretic limb, potentially restoring motor function and reducing disability. The authors aim to synthesize evidence and clarify MT’s role by stroke phase.

The review collates clinical trials of MT applied at different post-stroke phases. No trials were found for hyperacute/acute phases. Subacute phase evidence is mixed: some randomized trials report significant gains (often in Fugl-Meyer Assessment of Upper Extremity [FMA-UE], and particularly distal hand/finger function) and improvements in activities of daily living (ADL), while others show neutral results compared with sham or standard therapy. Across early and late subacute periods (<6 months), several studies show positive effects on FMA-UE, Brunnstrom stages (BSSR), and ADL measures (FIM/MBI), with some evidence for improved dexterity (BBT) and cortical motor area activation. In chronic stroke (>6 months), numerous trials demonstrate benefits in FMA-UE, ARAT, BBT, JTHFT, and ADL (FIM), though some studies are neutral (no advantage over sham or conventional therapy). Benefits often concentrate on distal wrist/hand function, with less consistent effects proximally or on spasticity. Follow-up durability is variable; some gains attenuate by 6 months. The review also compares MT with other modalities (task-based training, motor relearning programmes), noting that combined MT plus task-specific training can outperform either alone.

Narrative review methodology. The authors searched PubMed (MEDLINE) using combinations of keywords: “mirror therapy”, “stroke”, “upper limb/extremity/arm”, “motor function”, “motor deficits/impairment”, and “rehabilitation”. Reference lists of retrieved articles were also screened. Studies were organized and presented by stroke phase: hyperacute (0–24 h), acute (1–7 days), early subacute (7 days–3 months), late subacute (3–6 months), and chronic (>6 months). Outcome measures reported include motor impairment/function scales (FMA-UE, ARAT, BSSR, WMFT, MFT, FAT, MSS), spasticity (MAS/Tardieu), dexterity (BBT, JTHFT), independence in ADL (FIM, BI/MBI, LIADL), functional performance (CAHAI, TEMPA), and quality of life (EQ-5D, Stroke Impact Scale). Neurophysiological correlates were summarized where available (EEG, fMRI, kinematic analyses). No formal systematic review protocols (e.g., PRISMA) or predefined inclusion/exclusion criteria were reported beyond relevancy to MT for upper limb post-stroke.

- No MT trials in hyperacute or acute phases. - Early subacute (<3 months): Mixed findings. Some RCTs show significant improvements with MT vs control in ARAT, MI-UE, FIM, and FMA-UE (especially distal hand/finger components), while multiple trials report no added benefit over sham or standard therapy. Distal motor recovery often exceeds proximal shoulder/elbow improvements. - Across subacute (<6 months): Several RCTs demonstrate MT superiority for motor outcomes (FMA-UE) and ADL (FIM/MBI/LIADL), with occasional improvements in dexterity (BBT) and cortical activation. Some studies report neutral effects or gains limited to specific measures (e.g., FMA-UE but not BSSR/ARAT). Spasticity generally unchanged; select movements showed MAS improvements in one study. - Chronic (>6 months): Many trials find MT improves distal motor function (FMA-UE hand/wrist subscores), manual dexterity (BBT/JTHFT), and ADL performance (FIM), with supportive neurophysiological/kinematic evidence (mu rhythm suppression, improved reaction time/trajectory, fMRI shifts toward affected hemisphere). However, several RCTs report no superiority to sham or conventional therapy. Some benefits diminish at 6-month follow-up. - Distal vs proximal: MT benefits are more consistent for distal wrist/hand than proximal shoulder/elbow, potentially due to mirror setup constraints and task focus. - Comparator modalities: Task-oriented training can match or exceed MT; combination therapy (MT + task-based training) may yield the greatest improvements. - Safety/access: MT is simple, low-cost, and feasible in clinical and home settings; adverse events not prominent. - Guidance: AHA/ASA 2016 did not recommend MT; NICE 2023 advises considering MT within first 6 months (ideally within 1 month), 30-min sessions at least 5 times/week for 4 weeks.

The review suggests MT can enhance upper limb motor recovery post-stroke, particularly distal function, but effectiveness varies by patient characteristics, stroke phase, and protocol. Neurophysiological theories involve activation of the mirror neuron system and visual-proprioceptive feedback inducing cortical reorganization, increased corticospinal excitability, and rebalancing interhemispheric activity toward the lesioned hemisphere. Heterogeneity across trials (sample size, severity, spasticity, cognitive/attentional capacity, movement types, unilateral vs bilateral tasks, mirror size, control treatments) likely underlies conflicting results. Improvements in clinical motor scales do not uniformly translate to ADLs due to whole-body demands and learned non-use. Evidence indicates MT may yield stronger effects for distal hand/wrist function, with less consistent proximal gains. Compared with action observation therapy, MT uses mirror-induced visual illusions and may more selectively lateralize activation to the affected hemisphere. Durability of gains is inconsistent, with some attenuation by 6 months. Overall, MT appears valuable as an adjunct to conventional rehabilitation, and may be most beneficial in early subacute windows when neuroplasticity is heightened, provided adequate attention and engagement are ensured.

MT is a promising, safe, low-cost adjunct rehabilitation technique for upper limb motor deficits after stroke, with evidence of benefit particularly for distal motor recovery and dexterity across subacute and chronic phases. Given heterogeneity and moderate-quality evidence, large, multicenter, rigorously designed trials are needed to clarify efficacy, optimal timing, and patient selection. Standardization of MT protocols (duration, intensity, frequency, movement types, mirror parameters), integration with task-specific training, and identification of predictors of response (age, baseline severity, spasticity, cognitive/attentional status) are priorities. MT may be most effective when initiated early (within the first months post-stroke) and delivered intensively, aligning with recent NICE guidance.

- Narrative review without formal systematic methodology or predefined inclusion/exclusion criteria. - Underlying studies are heterogeneous in design, populations, stroke phases, severity, and interventions; many are small-scale single-center RCTs or pilot studies. - Limited blinding (participants/therapists) inherent to MT; variable control conditions (covered vs uncovered mirror, direct view) affect comparability. - Inconsistent follow-up durations; some benefits not maintained at 6 months. - Sparse comprehensive cognitive/attention assessments; attention during MT sessions often uncontrolled and may confound outcomes. - Limited neuroimaging/neurophysiological data across studies; few cerebellar stroke-specific investigations. - Potential publication and small-study effects favoring positive results. - Clinical scales carry subjective components; differences in setup and severity limit generalizability.