Grasp reflex

Mô tả: The patient involuntary grasps the examiner’s fingers, when the examiner strokes the patients’ thenar eminence.4 The grasp reflex is a primitive reflex that is normally present in infancy, which normally disappears in later in life.4,97

Nguyên nhân: Common • MCA territory cerebral infarction • Cerebral haemorrhage • Alzheimer’s dementia • Vascular dementia Less common • Frontotemporal dementia • Parkinson’s disease • Advanced HIVAIDS

Cơ chế: The grasp reflex is present in normal infants from approximately 25 weeks to 6 months of age.90 The response may be a rudimentary response that was potentially important in arboreal life.90 The reflex is likely controlled by nonprimary motor cortical areas, which exert an inhibitory control of the spinal reflex following normal central nervous system development.90 Frontal lobe disease may result in disinhibition of the reflex, and thus ‘release’ the reflex.

Ý nghĩa lâm sàng: In a study of patients admitted to a neurology service, a positive grasp reflex predicted lesions in the frontal lobe, deep nuclei or subcortical white matter with a sensitivity of 13%, specificity of 99% and a positive likelihood ratio of 20.2.98