What is the recommended clinical examination for patients with left or right side agnosia?

Clinical Examination for Left vs Right Side Agnosia

The recommended clinical examination for patients with left or right side agnosia should include a comprehensive neurological assessment focusing on extinction/inattention testing, visual field testing, and specialized neurobehavioral assessments to properly diagnose and characterize the specific type of agnosia. 1

Core Assessment Components

Extinction/Inattention Testing

• Perform simultaneous double stimulation in multiple sensory modalities (visual, auditory, tactile) to assess for neglect or extinction 1
• Score 0 for normal detection in all fields, 1 for neglect/extinction to double simultaneous stimulation in one modality, and 2 for profound neglect in more than one modality 1
• Test whether the patient recognizes their own left hand or body parts (test for anosognosia) 2

Visual Field Assessment

• Test using confrontation or visual threat if necessary 1
• Document any partial hemianopia, quadrantanopia, or complete hemianopia 1
• Assess for cortical blindness which may coexist with agnosia 1

Specialized Neurobehavioral Assessment

• Evaluate line orientation ability, which is particularly impaired in mirror agnosia 3
• Test mental rotation capabilities, which are affected in both mirror agnosia and mirror ataxia 3
• Assess for ability to recognize objects in mirrors versus real space to differentiate mirror agnosia from mirror ataxia 3

Specific Tests for Different Types of Agnosia

For Visual Agnosia

• Present familiar objects for identification through vision alone, then compare with tactile recognition 4
• Test object recognition, face recognition (prosopagnosia), and color naming abilities 4
• Assess reading ability to identify pure alexia 5

For Spatial Agnosia

• Use drawing tests with guiding landmarks to quantitatively assess:
  • Omissions of lines (more common in right brain damage with left-sided agnosia) 6
  • Errors in line tracing (more common in left brain damage with right-sided agnosia) 6
• Test visuospatial construction ability using three-dimensional tasks 4

For Anosognosia (Unawareness of Deficit)

• Establish dialogue with patient and care partner about their understanding and appreciation of cognitive-behavioral symptoms 1
• Compare patient's self-assessment of abilities with actual performance on tasks 2
• Document verbal versus non-verbal awareness of deficits 2

Neuroimaging Considerations

• MRI should be obtained to identify lesion location, particularly in the parietal lobe 1, 3
• For right-sided agnosia, examine for lesions around the posterior angular gyrus/superior temporal gyrus 3
• For left-sided agnosia, examine for lesions around the postcentral sulcus 3
• When MRI is contraindicated, CT should be obtained 1

Follow-up and Referral Considerations

• Patients with atypical findings or rapidly progressive symptoms should be expeditiously referred to a specialist 1
• Neuropsychological evaluation is recommended when office-based cognitive assessment is not sufficiently informative 1
• Serial assessments may be needed to monitor changes and response to interventions 1

Clinical Pitfalls to Avoid

• Do not confuse agnosia (recognition deficit affecting a single modality) with aphasia (language deficit) 5
• Be aware that neglect and agnosia frequently co-occur but are distinct phenomena 2
• Recognize that anosognosia has significant predictive value for poor functional outcomes and requires specific management 2
• Understand that agnosia can occur without neglect and vice versa, requiring different treatment approaches 2, 3