Apraxias in neurodegenerative dementias

Apraxia is a state of inability to carry out a learned motor act in the absence of motor, sensory or cerebellar defect on command processed through the Praxis circuit. Breakdown in default networking is one of the early dysfunction in cortical dementias and result in perplexity, awkwardness, omission, substitution errors, toying behavior and unrecognizable gestures in response to command with voluntary reflex dissociation where, when unobserved patient will carry out reflex movements normally. Awareness into the organicity of these phenomenas will help in early diagnosis, which will help in initiating appropriate treatment and slowing down the progression of the disease.

The aim was to look for the various kinds of apraxias in patients with dementia using appropriate simple tests.

Three hundred patients satisfying Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for dementia were evaluated in detail with mandatory investigations for dementia followed by testing for ideational, ideomotor, limb-kinetic, buccopharyngeal, dressing apraxia, constructional apraxia and gait apraxias in addition to recording of rare apraxias when present.

Alzheimer's disease showed maximum association with apraxias in all the phases of the disease ideational, ideomotor, dressing and constructional apraxias early and buccopharyngeal and gait apraxia late. Frontotemporal lobe dementia showed buccopharyngeal and gait apraxias late into the disease. Cortical basal ganglionic degeneration showed limb apraxias and diffuse Lewy body disease showed more agnosias and less apraxias common apraxias seen was Ideational and Ideomotor.

Recognition of the apraxias help in establishing organicity, categorization, caregiver education, early strategies for treatment, avoiding anti-psychotics and introducing disease modifying pharmacotherapeutic agents and also prognosticating.