Blinking and the release reflexes: are they clinically useful?

OBJECTIVE

To review the clinical utility of blinking and the release reflexes, palmomental, glabellar, grasp, and snout, as an important part of the bedside neurological examination.

DESIGN

Articles published from 1966 to 1993 that addressed blinking or the release reflexes were identified by searching the MEDLINE database. Thirty-seven references provided clinically useful and applicable information.

RESULTS

There is controversy regarding the optimal method of clinical elicitation of these reflexes. The release reflexes are frequently seen as an incidental abnormality in the elderly. A positive grasp reflex, especially if asymmetrical, is sensitive but not specific for abnormal brain function. Lack of habituation is more important than the mere presence or absence of a reflex. The brainstem circuits involved in the regulation of blinking and the release reflexes are discussed, as are their abnormalities in a variety of clinical settings.

CONCLUSION

Blinking and the release reflexes have clinical utility in the diagnosis and bedside clinical assessment of diseases as diverse as frontal lobe lesions, hydrocephalus, multiple sclerosis, Parkinson's disease, Alzheimer's disease and other dementias, falls in the elderly, ageing, HIV-encephalopathy, schizophrenia, tumors in the region of the sylvian aqueduct and recovery from head trauma.