From the Guidelines
A prominent grasp reflex in an adult is a significant neurological finding that indicates frontal lobe pathology or damage to the brain's upper motor neurons, and its presence warrants immediate neurological evaluation. This primitive reflex, which is normal in infants but should disappear by 4-6 months of age, reappears in adults when there is disruption of the inhibitory pathways from the frontal cortex, as noted in the context of distinguishing behavioural variant frontotemporal dementia from psychiatric disorders 1. The presence of this reflex in an adult may signal serious conditions such as stroke, brain tumor, dementia (particularly frontotemporal dementia), traumatic brain injury, or neurodegenerative diseases like Alzheimer's.
When testing for this reflex, the examiner strokes the patient's palm, and a positive response occurs when the patient involuntarily grasps the examiner's hand and cannot voluntarily release it. This finding is often accompanied by other frontal release signs such as snout, rooting, or sucking reflexes. The reemergence of this primitive reflex occurs because brain damage removes the cortical inhibition that normally suppresses these reflexes after infancy, allowing subcortical reflexive patterns to reemerge.
Key considerations in the evaluation of a prominent grasp reflex in an adult include:
- Prompt neuroimaging (MRI or CT scan) to identify any structural abnormalities
- Comprehensive neurological assessment to evaluate for other signs of frontal lobe dysfunction or damage to the upper motor neurons
- Screening for cognitive and executive function deficits, which may involve the use of tools like the Frontal Assessment Battery (FAB) or the Institute of Cognitive Neurology Frontal Screening (IFS) 1
- Consideration of the patient's overall clinical presentation and medical history to guide further evaluation and management.
Given the potential implications of a prominent grasp reflex in an adult, it is essential to approach these cases with a high index of suspicion for underlying neurological pathology and to pursue thorough evaluation and diagnosis, as suggested by the recommendations for distinguishing behavioural variant frontotemporal dementia from psychiatric disorders 1.
From the Research
Significance of Prominent Grasp Reflex in Adults
The grasp reflex is a primitive reflex that is often observed in neurodegenerative diseases and can be a symptom of underlying neurological conditions. Some key points about the grasp reflex in adults include:
- The grasp reflex can be a disabling symptom that affects quality of life, as seen in patients with neurodegenerative movement disorders 2.
- The incidence of the grasp reflex is higher in patients with hemispheric lesions, particularly those with damage to the frontal lobe or deep nuclei and subcortical white matter 3.
- The grasp reflex can be associated with other symptoms such as groping and the grasp reaction, and can be modified by will, but may reappear when the patient's attention is diverted 3.
- In some cases, the grasp reflex can be released through the use of concomitant imitation behavior during rehabilitation, as seen in a stroke patient with a lesion in the right middle frontal gyrus 4.
- Primitive reflexes, including the grasp reflex, are more common in patients with dementia and can be a useful diagnostic tool, with the grasp reflex exhibiting the highest risk for dementia 5.
Neurological Conditions Associated with Grasp Reflex
The grasp reflex has been observed in various neurological conditions, including:
- Neurodegenerative diseases such as Parkinson's disease and frontotemporal dementia 2.
- Hemispheric lesions, particularly those affecting the frontal lobe or deep nuclei and subcortical white matter 3.
- Stroke, particularly those with lesions in the middle frontal gyrus 4.
- Dementia, with the grasp reflex being a significant risk factor for the condition 5.
- Lesions in the left medial frontal lobe, which can also cause hyperlexia and transcortical motor aphasia 6.