What is the significance of assessing extinction and inattention in patients?

The Significance of Assessing Extinction and Inattention in Patients

Assessment of extinction and inattention is critical for accurate diagnosis, prognosis determination, and treatment planning in patients with neurological conditions, particularly stroke, as these symptoms can significantly impact mortality, morbidity, and quality of life.

Clinical Importance of Extinction and Inattention

Diagnostic Value

• Extinction and inattention are cardinal features in several neurological conditions:
  • Stroke: Item 11 on the National Institutes of Health Stroke Scale (NIHSS) specifically evaluates extinction and inattention 1
  • Delirium: Inattention is considered a cardinal diagnostic feature of delirium 1
  • Altered Mental Status (AMS): Inattention is a key symptom in the spectrum of AMS presentations 1

Prognostic Significance

• The NIHSS score, which includes assessment of extinction/inattention, provides important prognostic information:
  • Patients with lower NIHSS scores (<10) have 60-70% chance of favorable outcomes at one year
  • Only 4-16% of patients with scores >20 achieve favorable outcomes 1
  • Higher NIHSS scores correlate with increased risk of intracranial hemorrhage with thrombolytic treatment 1

Impact on Treatment Decisions

• Proper assessment guides:
  • Selection of patients for thrombolytic therapy in stroke 1
  • Implementation of delirium prevention and treatment protocols 1
  • Early intervention for cognitive deficits that may otherwise go undetected 2

Standardized Assessment Methods

NIHSS Extinction and Inattention Assessment

• Graded on a scale from 0-2 3:
  • 0: No abnormality detected
  • 1: Mild (loss of one sensory modality)
  • 2: Severe (loss of two modalities)

Limitations of NIHSS Assessment

• The NIHSS extinction and inattention subtest has only moderate agreement (Cohen's kappa = 0.404) with more specialized tests like the Oxford Cognitive Screen (OCS) heart subtest 2
• Accuracy decreases to 61.1% in patients with visual field deficits, as extinction may be confused with visual field impairment 2

Clinical Implications

For Stroke Patients

• Extinction reflects impairment of spatial selective attention while leaving basic preattentive processing intact 4
• Patients with extinction can process stimuli in either hemispace when presented in isolation but fail when stimuli compete for attention 5
• The severity of attentional impairment directly relates to the degree of completion in the unattended visual field 4

For Delirium Assessment

• Inattention is a cardinal feature of delirium that may fluctuate over the course of the day 1
• Early detection of inattention is crucial as mortality may be twice as high if delirium is missed 1
• Systematic delirium screening using tools that assess attention should be performed at least once per nursing shift 1

Neurophysiological Basis

• Functional MRI studies show that in patients with tactile extinction, simultaneous bilateral stimuli activate bilateral primary sensory cortices (SI) and secondary sensory cortices (SII) 6
• This suggests that activation of primary sensory cortex is insufficient for awareness of sensory stimuli 6
• An undamaged superior parietal lobule may suppress damaged parietal lobe function, causing extinction 6

Practical Recommendations

• Use standardized assessment tools like the NIHSS but recognize their limitations 2
• Consider supplementing with more specialized tests when extinction or inattention is suspected 2
• Be aware that visual field deficits may confound assessment of extinction and inattention 2
• In patients with delirium, implement systematic screening at least once per nursing shift 1
• For stroke patients, the presence of extinction/inattention should factor into decisions about thrombolytic therapy 1

Clinical Pitfalls to Avoid

• Relying solely on the NIHSS for detecting neglect, as it may miss signs of neglect or confuse them with visual field impairment 2
• Failing to recognize that inattention in delirium may fluctuate, requiring repeated assessments 1
• Overlooking the impact of extinction and inattention on functional recovery and rehabilitation potential 2
• Neglecting to assess extinction across multiple sensory modalities (visual, tactile, auditory) 3