Stroke diagnosis using tongue deviation
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Tongue Deviation as a Stroke Diagnosis Indicator
Tongue deviation is a well-recognized clinical sign in stroke diagnosis, particularly in cases involving the hypoglossal nerve or its supranuclear pathways. Studies consistently show that tongue deviation is more common in stroke patients compared to healthy individuals, and its presence can provide important clues for early detection and localization of brain lesions 123459.
Quantifying Tongue Deviation Angle for Stroke Detection
Recent research has focused on quantifying the tongue deviation angle to improve the objectivity and reliability of this diagnostic sign. One study introduced a method to measure the tongue deviation angle and found that stroke and transient ischemic attack (TIA) patients had significantly higher deviation angles (mean 6.9° for stroke, 4.9° for TIA) compared to normal subjects (mean 1.4°) . A threshold deviation angle of 3.2° was identified as a warning sign for stroke, with high sensitivity and specificity (AUC = 0.96) . This quantification helps reduce the subjectivity seen in visual assessments, where interobserver variability can be substantial 110.
Clinical Patterns and Localization Insights
Tongue deviation in stroke typically occurs toward the side of limb weakness and is often associated with other neurological deficits such as facial palsy, dysarthria, and dysphagia 2359. The direction of deviation can help localize the lesion: supranuclear (upper motor neuron) lesions usually cause deviation toward the side of hemiplegia, while nuclear or infranuclear (lower motor neuron) lesions result in deviation toward the side of the lesion with contralateral hemiplegia 39. Large cortical or subcortical infarcts are more likely to present with tongue deviation, and its presence is linked to more severe clinical presentations .
Tongue Features Beyond Deviation in Stroke Diagnosis
In addition to deviation, other tongue features such as color (pale or bluish), ecchymoses, and fur characteristics have been found to be significantly associated with acute ischemic stroke 4678. Automated image analysis and deep learning models have been developed to objectively identify these features, improving diagnostic accuracy and providing a non-invasive, accessible tool for stroke assessment, especially in rehabilitation settings 47.
Reliability and Standardization Challenges
While tongue diagnosis is a valuable tool, especially in traditional medicine, its reliability can be affected by observer subjectivity. Studies highlight the need for standardized criteria and enhanced training to improve interobserver agreement, particularly for features like tongue color and fur quality 110. Automated and quantitative approaches are helping to address these challenges 147.
Conclusion
Tongue deviation is a significant and quantifiable sign in stroke diagnosis, with a deviation angle above 3.2° serving as a strong warning indicator. Combining this with other tongue features and leveraging automated analysis can enhance early stroke detection and localization. However, standardization and training remain important to ensure consistent and reliable use of tongue diagnosis in clinical practice.
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