Apraxia/blehparospasm


Posted by Shanasy in IL , May 13,2002,20:45   Archive
Below is an interesting article for anyone confused about apraxia vs the blephs and why botox may not work for some.

Apraxia of lid opening may complicate blepharospasm
Date: 08-15-1997; Publication: Ophthalmology Times; Author: Anderson, Richard L.


RICHARD L. ANDERSON, MD, FACS
A praxia of lid opening is a condition in which patients who have otherwise normal eyelids have difficulty opening the eyelids. This is a problem in the circuitry for opening the eyelids, much like blepharospasm is a problem in the circuitry allowing squeezing of the eyelids.
Pure apraxia of lid opening (not associated with blepharospasm) is very rare, but apraxia of lid opening is commonly associated with blepharospasm. The specific cause or control center for both of these diseases is poorly understood, but the two must be somehow intertwined.
The patient with blepharospasm and apraxia of lid opening will typically have spasms squeezing the eyelids shut (Figure 1), and then for seconds to minutes after the spasm stops, the patient is unable to open the eyelids (Figure 2). The eyelids may then come open almost normally for a time and then, without warning, slowly droop shut again or be drawn shut by spasm. Patients with apraxia of lid opening can be seen raising their brows and trying to open their eyelids as strongly as possible, without elevation of the eyelids.
Relieve spasms
To make the diagnosis of apraxia of lid opening, all blepharospasm or squeezing in the eyelids must be relieved. In rare patients with apraxia of lid opening, it has been shown that a simultaneous firing occurs in the squeezing muscles as well as the opening muscles of the eyelids.
However, under normal conditions, antagonistic muscles in the eyelids cannot contract at the same time. Therefore, if the eyelids have even minimal squeezing, opening cannot occur. Botulinum toxin, myectomy, or a combination thereof must completely relieve muscle squeezing before a diagnosis of apraxia of lid opening can be confirmed.
We examined 100 consecutive patients with blepharospasm who presented to our clinic, and found the incidence of apraxia of lid opening to be 7% in the general population of blepharospasm sufferers. However, in patients in whom botulinum toxin therapy fails, the incidence of apraxia of lid opening is about 50%.
It is important for physicians and patients to be aware of apraxia of lid opening, as it is the most common cause of failure of botulinum toxin therapy, and increasing the dosage of botulinum toxin beyond what is necessary to relieve squeezing or spasm adequately in the eyelids frequently makes ptosis associated with apraxia of lid opening even worse.
When botulinum toxin therapy fails in blepharospasm treatment, it is important to differentiate whether the treatment has failed because of the inability of botulinum toxin to relieve squeezing in the eyelids, or whether failure to open the eyelids adequately is the problem. This can be determined by having the patient squeeze the eyelids shut vigorously. If the patient has markedly weakened eyelid squeezing, then the botulinum toxin is working and doing all it can. If the patient still cannot open the eyelids, the most common cause of this problem is apraxia of lid opening.
Ptosis easily corrected
The next most common cause of inability to open the eyelids adequately in the absence of spasms is ptosis and dermatochalasis. This is simply droopy eyelids or excess baggage or skin in the eyelids. Ptosis can easily be corrected by tightening the tendon of the muscle that raises the eyelids, and dermatochalasis can be corrected by removing the excess baggage and tissues in the eyelids. These operations are referred to as a ptosis repair and blepharoplasty.
However, in blepharospasm sufferers, we combine these surgeries with removal of the squeezing muscles in the upper eyelids and call this procedure a limited myectomy (Figure 3). Following a limited myectomy, both the function and the cosmesis of the eyelids is greatly improved (Figures 4 and 5). The amount of botulinum toxin required is decreased and the effect and duration of the botulinum toxin is increased.
Blepharospasm sufferers who have the combined advantages of success with limited myectomy and botulinum toxin are the happiest patients in our practice. They have improvement in function from both the limited myectomy and the botulinum toxin as well as cosmetic improvement.
Patients with blepharospasm and apraxia of lid opening are treated by a limited myectomy associated with tightening of the levator tendon that raises the eyelids (aponeurotic ptosis repair). By tightening the tendon of the muscle that raises the eyelids, patients can open their eyelids more effectively. By excising the squeezing muscles in the upper eyelids via a limited myectomy, residual squeezing that is not completely relieved by botulinum toxin is improved.
Most patients with apraxia of lid opening can have marked improvement with a combination of limited myectomy, ptosis repair, and botulinum toxin. Unfortunately, drugs have provided little or no improvement.
Frontalis suspension
However, despite these treatments, there remains a small group of patients in whom functioning is inadequate. In this group, a frontalis sling or frontalis suspension is performed as a second operation. The frontalis muscle is the forehead muscle that raises the eyebrows. In a frontalis sling, the frontalis is used to raise the eyelids by running a material from this muscle into the eyelids.
We have recently found that a thick Gore-Tex suture is the best material available for frontalis suspensions in patients with apraxia of lid opening. This suture material is readily obtainable and, as opposed to other synthetic materials, allows vascular ingrowth. Fascia lata, or tendons from elsewhere in the body, can also be used for frontalis suspension, but they require an additional surgical site for obtaining this material and they are not as easily adjustable if the patient' s eyes are open too much or do not close adequately after the surgery.
Anderson, Richard L., Apraxia of lid opening may complicate blepharospasm. , Ophthalmology Times, 08-15-1997, pp 42.




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