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Show Journal of Clinical Neuro-ophthalmology 7(3):149--150, 1987. Editorial Comment Lid Position in Neufo-ophthalmology ~, 1987 Raven Press, Ltd., New York In this issue, Kansu and Subutay have reported on four patients from a series of 150 cases with myasthenia gravis who had upper lid retraction. That article touches on a point of considerable clinical significance which merits further discussion. When a patient is encountered with a manifest asymmetry of the palpebral fissures, for example, a fissure measuring 9 mm in greatest vertical diameter on the right and a fissure measuring 11 mm in greatest vertical diameter on the left, one must immediately make a quality decision-is the right fissure too narrow, the left fissure too large, or is there a combination of the two problems? Carrying this a bit further, one needs to ask the following question-am I seeing ptosis or pseudoptosis, pathologic lid retraction, or pseudo-lid reaction, or all of the above? A very important reference to this differentiation was made in a paper by Schechter (1). Beautifully illustrated in that paper was a patient with a cosmetically severe lid retraction of the right upper lid who also had a modest ptosis of the left upper lid. Just looking at the particular photograph, one probably would suspect that this was a unilateral case of primary pathologic lid retraction. However, in the very next photograph, the same patient is shown with the examiner's finger manually elevating the left upper lid; 10 and behold, the lid retraction on the fellow eye had for all practical purposes disappeared! From the surgical point of view, it would have been quite improper to have done a levator recession type procedure on the right eye of this patient, for the proper approach would have been to do a levator resection type procedure on the left eye! Years ago, I was taught that one simply had to cover one eye at a time to break up innervational pseudoptosis or pseudolid retraction, but that simply is inadequate. One must have a patient fixate a distance muscle light, and then manually elevate the upper lid on the right, while looking carefully at the left eye; next, manually elevate the left upper lid, and watch and see what happens to the right eye. This is also a very sensitive way to check for the upper lid fatigue phenomenon of oc- 149 ular myasthenia gravis. One can simply hold the patient in sustained upgaze for a minute or two; in myasthenics, the upper lids will often begin to drop-in a dramatic case, they will often cover the cornea within a minute or two. Usually, however, the fatigue phenomenon is not that overt. If the patient blinks during the test, that brief respite can often negate the previously induced fatigue. I now have patients fixate a distance muscle light; if I hold the right lid up with my finger and the left lid promptly drops every time, I interpret that as a fatigue phenomenon. I interpret this as relieving an innervational call for levator contraction on the opposite side and as a vote for ocular myasthenia gravis and an indication for a tensilon test. The Cogan lid twitch sign, in which one observes the upper lids while having the patient look down at the examiner's finger in lower field and then back at the nose, is less often helpful than the fatigue phenomenon, but in some cases it can definitely offer help and is certainly worth doing. I'd estimate the fatigue phenomenon as positive in over 80% of myasthenics, and an impressive Cogan's lid twitch sign without a fatigue phenomenon as being seen in only perhaps 10-15% of the cases. See Burde, Savino, and Trobe (2) and Neuro-ophthalmology Update (3) for discussions of pathologic lid retraction and lid position in neurology, as well as descriptions of the surgical treatment of upper lid retraction. Finally, it must be emphasized that ocular myasthenia gravis is frequently associated with thyroid eye disease. The fact that routine thyroid function tests are normal does not by any means exclude the concomitant presence of euthyroid Grave's disease in these patients. One needs to maintain a high index of suspicion for concomitant euthyroid Grave's disease in any myasthenic with lid retraction. This is an indication for a thypinone (thyrotrophin- releasing hormone suppression) test and, if available, careful measurement of the extraocular muscle sizes by orbital ultrasound looking for the muscle enlargement so frequently seen with euthyroid Grave's disease. The causes of ptosis in patients with thyroid disease include senile ptosis, 150 EDITORIAL COMMENT dermatochalasis, concomitant myasthenia, protective ptosis with incipient diplopia, and preexisting traumatic or postsurgical ptosis; if these have been excluded by old photographs and the like, a true thyroid ptosis can be suspected. The latter is definitely a diagnosis of exclusion, however, and probably should be investigated further with appropriate histologic studies of levator removed at the time of ptosis surgery. At any rate, Kansu and Subutay have touched on a very important topic; it is hoped that the references mentioned in this editorial will help the interested clinician. The bottom line is that, in a patient with myasthenia gravis and associated lid retraction, go very slowly before I Clill Nellro-ophthalmol, Vol. 7, No.3, 1987 you attribute this to myasthenia without meticulously excluding the presence of concomitant euthyroid Grave's disease. J. Lawton Smith, M.D. REFERENCES 1. Schechter RJ. Ptosis with contralateral lid retraction due to excessive innervation of the levator palpebrae superiorus. Ann OphthalmoI1978;10:1324-8. 2. Burde, Savino, Trobe, eds. Clinical decisions in neuro-ophthalmology. St. Louis, MO: Mosby, 1985:246-74. 3. Neuro-ophthalmology update. New York: Masson, 1977:9-18. |