Factors may include the following: Muscle weakness (eg, caused by stroke, use of certain drugs, myelopathy due to cervical spondylosis, or muscle atrophy) Hydrocephalus Parkinsonism Painful arthritis Age-related loss of neural networks mediating postural stability (vestibular system, proprioceptive pathways), coordination (cerebellum, basal ganglia), vision, and praxis (frontal lobe) Evaluation should focus on reversible factors.