What causes apraxia of eyelid opening?
What causes apraxia of eyelid opening?
Apraxia of eyelid opening can result from involuntary inhibition of levator function, prolonged contraction of the orbicularis, or both. The classic finding of inability to open the lids after closure is postulated to be caused by persistent contraction of the activated orbicularis oculi muscle.
What nerve causes eyelid closure?
The oculomotor nerve (CNIII) innervates the main upper eyelid retractor, the levator palpebrae superiorus, via its superior branch. The inferior division of CNIII also innervates the inferior rectus muscle, which by extension via the capsulopalpebral fascia causes lower eyelid retraction in downgaze.
Is it apraxia of lid opening or blepharospasm?
This is a problem in the circuitry for opening the eyelids, much like blepharospasm is a problem in the circuitry causing squeezing of the eyelids. Pure apraxia of lid opening (which is not associated with blepharospasm) is very rare. However, apraxia of lid opening is commonly associated with blepharospasm.
How does blepharospasm cause inability to open eyes?
They usually begin as mild and infrequent twitches that progress over time to forceful and frequent spasms of the eyelids, which abate during periods of sleep. In advanced cases, these episodes can cause functional blindness from periodic inability to open the eyes.
What kind of surgery is needed for apraxia of eyelid opening?
Patients with apraxia of eyelid opening may often proceed to surgery as chemodenervation with botulinum toxin is less effective. Surgical myectomy of the orbital and palpebral orbicularis muscle in the upper (and sometimes lower) eyelids as well as surgical ablation of the facial nerve are effective in treating BEB.
What causes the inability to open the eyes?
Apraxia of eyelid opening can result from involuntary inhibition of levator function, prolonged contraction of the orbicularis, or both. The classic finding of inability to open the lids after closure is postulated to be caused by persistent contraction of the activated orbicularis oculi muscle.