Research Appraisals

Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology

Limb apraxia in Parkinson's disease and atypical parkinsonian syndromes: a systematic review

BACKGROUND: Evidence regarding the clinical manifestations, disease-specific profiles and diagnostic significance of limb apraxia in Parkinson's disease and Atypical Parkinsonian Syndromes (APS) is limited. OBJECTIVES: The present systematic review aims to consolidate current knowledge on limb apraxia across neurodegenerative disorders, including Parkinson's disease (PD), corticobasal syndrome (CBS), Progressive Supranuclear Palsy (PSP) and Multiple System Atrophy (MSA). METHODS: A systematic literature review was conducted in accordance with PRISMA guidelines. Studies were included if they enrolled ≥ 10 patients in at least one of the patient groups and ≥ 10 control subjects with quantitative data on apraxic deficits. Risk of bias assessment was assessed. RESULTS: Twenty-two studies met inclusion criteria (PD n = 11; CBS n = 10; PSP n = 7; MSA n = 3). Across PD and APS, praxis assessment primarily involved gesture imitation, pantomime, action sequencing, actual tool use and measures of fine motor coordination. CBS demonstrated the most severe/widespread apraxic impairment, affecting both meaningless and meaningful (transitive and intransitive) gestures, as well as action sequencing and fine motor control. In PD, apraxic deficits were generally milder but shared overlapping features with CBS. Direct comparative studies between PD and CBS remain scarce. PSP was characterized by less frequent and predominantly sequence-related impairments, whereas findings in MSA were heterogeneous and less pronounced. CONCLUSIONS: Limb apraxia phenotypes differ across PD, CBS, PSP and MSA and may contribute to their differential diagnosis. Future research should adopt standardized, multimodal praxis assessment protocols in larger cohorts including all major neurodegenerative parkinsonian disorders, to facilitate the direct comparison of limb apraxia across these diseases.