Background and Objective: Apraxia, defined as inability to perform skilled or learned movements, is frequently seen in neurodegenerative diseases such as Parkinson’s disease, corticobasal syndrome and Alzheimer's dementia. Apraxia is further classified into subtypes such as limb-kinetic, ideomotor or ideational apraxia. Limb-kinetic apraxia, characterized as difficulty making precise, independent and coordinated finger and hand movements, leads to impaired dexterity and has been shown to affect activities of daily living in PD patients. To date, there is no effective treatment for limb-kinetic apraxia. We aim to report the effects of repetitive transcranial magnetic stimulation (rTMS), a noninvasive brain stimulation method on limb-kinetic apraxia in patients with Parkinson's disease.
Methods: Eight patients diagnosed with Parkinson’s disease underwent rTMS. Patients performed sequential unbuttoning and buttoning of a standardized gown they wore for assessment of limb-kinetic apraxia. A 20-minute rTMS session of the left primary motor cortex (M1) was performed (10 Hz frequency, stimulation intensity of 80% resting motor threshold, 10 seconds/train and 20 trains) in the medication-ON state.
Results: Eight PD patients (M:F=1:1, mean age 71.1 years, SE 2.5 years) underwent rTMS with no adverse events. Buttoning and unbuttoning time was found to be significantly reduced at 24 hours post-rTMS (mean change: 22%, SE: 6%), compared to the medication-ON state. No significant change was noted immediately following the rTMS session.
Conclusion: Our results suggest that high-frequency rTMS of the left M1 may be effective in limb-kinetic apraxia, lending support to the need for future long-term studies to further determine if rTMS is truly efficacious in the treatment of this disorder.
