How comparable are tests of apraxia?

Objective: To compare commonly used tests for the diagnosis of apraxia. Measures: People with unilateral left hemisphere lesions, diagnosed with apraxia, were compared in their scoring on commonly used tests for apraxia (n = 17). Setting: Rivermead Rehabilitation Centre, Oxford, England, a specialist inpatient neurological unit. Results: Production moment correlations were low, or did not reach significance level between three tests for ideomotor apraxia (r = 0.46 p < 0.05 one-tailed test, r = 0.005 NS, r = -0.23 NS, df = 15). Six of the seventeen apraxic patients scored above cut-off point on one test, but below cut-off point on others, indicating that commonly used tests for apraxia may not be reliable for diagnosis if used singly, Internal consistency within tests was also variable (Cronbach's alpha 0.72, 0.85, 0.85). Conclusion: The commonly used tests for apraxia may identify different people as 'apraxic', possibly by eliciting different aspects of apraxia and identifying potential subtypes of the condition, The use of multiple tests is, therefore, recommended in order to identify people with apraxia. The need for repeat reliability studies for apraxia assessments, together with a search for a 'gold standard' test is apparent.