Blepharospasm, increased blink rate may have different etiologies

This case-control study found that somatosensory temporal discrimination threshold differences in the blink reflex recovery cycle between patients with blepharospasm and those with increased blink rate alone suggest that these disorders arise from different pathological mechanisms.

It is not uncommon for ophthalmologists to be presented with patients who develop symptoms associated with excessive blinking, such as epiphora, photophobia, foreign body sensation and changes in tear break-up time, which raises questions as to whether or not these patients suffer from a neurological etiology, such as blepharospasm, or only ocular surface disease.

The authors tested the blink rate and neurophysiologic variables known to be altered in primary blepharospasm, such as blink reflex cycle and somatosensory temporal discrimination threshold (STDT) in 24 patients with excessive involuntary eyelid closure who had sustained orbicularis oculi spasms (primary blepharospasm), 16 with increased blinking alone and 18 healthy age-matched control subjects.

Patients with blepharospasm who had typical orbicularis oculi spasms had an altered blink reflex recovery cycle whereas those who had an increased blink rate alone had a normal blink reflex recovery cycle. STDT values were higher in patients than in healthy subjects, with no difference found in STDT abnormalities between the two groups of patients.

One drawback of the study is that it did not address the question of whether or not patients with increased blinking alone are predisposed to developing blepharospasm in the future.