Journal of Neuro-Ophthalmology, September 1992, Volume 12, Issue 3

Myasthenia gravis-like syndrome induced by topical ophthalmic preparations. A case report.

This case study reports on a 64-year-old female who presented for cataract surgery. She relayed a history of allergic responses to local anesthetics such as xylocaine, but was otherwise in good health. Upon instilling ophthalmic preparations into her eyes during routine ocular examination, she developed general muscular weakness but not other allergic-like symptoms. Further investigation established her myasthenic-like syndrome to be precipitated by an ophthalmic mydriatic preparation. She was able to undergo uneventful cataract surgery and enjoy 20/20 vision postoperatively, with proper management.

1'" IrI/ II[ 01 CI""( I/[ Nt'/ Iro · ol'iltlllll", oloXY 12( 31: 210- 212, 1992. © 1992 Raven Press, Ltd., ' Myasthenia Gravis- like Syndrome Induced by Topical Ophthalmic Preparations A Case Report David Meyer, M. B., Ch. B., Robert C. Hamilton, M. B., Ch. B., F. R. C. P. C., and Howard V. Gimbel, M. D., F. R. C. S. C. This case study reports on a 64- year- old female who pre­sented for cataract surgery. She relayed a history of al­lergic responses to local anesthetics such as xylocaine, but was otherwise in good health. Upon instilling oph­thalmic preparations into her eyes during routine ocular examination, she developed general muscular weakness but not other allergic- like symptoms. Further investiga­tion established her myasthenic- like syndrome to be pre­cipitated by an ophthalmic mydriatic preparation. She was able to undergo uneventful cataract surgery and enjoy 20/ 20 vision postoperatively, with proper manage­ment. Key Words: Tropicamide- Cataract surgery- Ophthal­mic preparation- Myasthenia gravis, From the Gimbel Eye Center, Calgary, Alberta, Canada. Address correspondence and reprint requests to Dr. Meyer, Gimbel Eye Center, Suite 450 4935 40 Avenue NW, Calgary Alberta, Canada T3A 2Nl. 210 A 64- year- old registered nurse was referred to our clinic by her family physician for evaluation of her cataracts. Her ophthalmic history noted only her decreased vision due to the cataracts, and dry eyes. Family history was insignificant except that she remembered that her late mother never under­went any local anesthesia. The patient wore a medic alert bracelet indicat­ing an allergy to Xylocaine. She reported an epi­sode 20 years ago in a dentist's chair when, after receiving a local anesthetic, she experienced a re­action that was interpreted as allergic in nature and she was advised never to have local anesthesia again. She clearly remembers the difficulty she had talking, as well as her shoes falling off her feet. Her recovery at that time was uneventful. She also re­called receiving a general anesthetic 20 years ago for a minor procedure, from which she took a long time to recover. Her general health was now good, however, and she was on no medications. As part of her routine ophthalmic examination the following eyedrops were instilled about 5 min­utes apart: tropicamide 1%, phenylephrine HCl 2.5%, and proparacaine Hel 0.5%. Ten minutes later, she stated that she felt as if she were " float­ing." She was not dizzy or nauseous, but felt " high." The physical examination revealed the fol­lowing findings: flushed face, sweaty hands, dry mouth, clear lungs, no laryngospasm, normal heart sounds, blood pressure of 180/ 95 mm Hg, and a pulse rate of 60/ minute ( sinus rhythm). She was fully aware and conscious, but lethargic. It was decided to only observe the patient and not to take any active intervention. After 1 hour she was fe~ ling well again, and her vital signs were normal, wIth a blood pressure of 124/ 84 mm Hg. The clinical picture that we observed did not fit in with a typical allergic reaction. The absence of signs of histamine release, such as u · ' ': an. a, MYASTHENIA GRAVIS- LIKE SYNDROME 211 chemosis, laryngospasm, bronchospasm, and hy­potension, led us to doubt the previous diagnosis of an allergy to local anesthetics. The presence of dry mouth, flushed face, bradycardia, and hyper­tension was suggestive of an anticholinergic re­sponse. Her lethargy, slurred speech, and muscle weakness prompted us to convince the patient to consent to our rechallenging her with the same medications but administered separately. She con­sented, and the test was performed about 2 weeks later. Baseline observations included blood pressure; pulse; electrocardiogram; body temperature; up­per extremity motor power for grip, flexion and extension; lower extremity motor power for flexion and extension; speech; ptosis; and diplopia. A ve­nous access was established before instillation of any drops. One drop of tropicamide 1.0% was instilled first. Within 3 to 4 minutes after instillation she re­sponded, subjectively and objectively, in exactly the same manner as before. Her motor power in both upper and lower extremities was 3/ 5 com­pared with 5/ 5 before the reaction. She was slightly tachypneic, but not markedly distressed. She had developed a ptosis in both upper lids, spoke slur­rily, felt " high," experienced no diplopia, was fully aware and conscious, but utterly lethargic. An intravenous injection of 1.5 mg edrophonium chloride dramatically reversed the reaction within a matter of seconds. Her muscle power was re­stored ( 515), speech had returned to normal, the ptosis had disappeared, and she had no more sub­jective feelings of general weakness. After a half- hour she remained fine, and pro­paracaine drops 0.5% were instilled, one drop in both inferior fornices. Within 2 minutes she expe­rienced exactly the same reaction as before. Once again, it was fully reversed with 1.5 mg endropho­nium chloride. The last drug to be tested was phenylephrine 2.5%. She experienced absolutely no adverse re­sponses to this drug in drop form. Qualitative ace­tylcholine receptor antibodies were tested for, but were absent, and the clinical diagnosis of drug­induced myasthenia- like syndrome was estab­lished. Cataract surgery was subsequently successfully performed under local anesthesia. The patient once again developed the same syndrome of gen­eral muscular weakness after both the topical drops and the retrobulbar anesthetic. Her vital ca­pacity was monitored throughout with a Wright's respirometer, and it too was severely reduced from 2.8 L at baseline to 0.5 L after the retrobulbar block. Intravenous edrophonium chloride reversed both the muscular weakness and the respiratory de­pression dramatically. Edrophonium chloride, a well- known short- acting drug, was needed in a 2 mg intravenous dose at four intervals throughout the entire procedure. Surgery was uneventful, and the patient enjoys 20/ 20 vision postoperatively. DISCUSSION It has been well documented that myasthenia­like syndromes can be induced by a vast number of drugs ( 1- 14). Numerous pharmacologic agents, such as neuromuscular blockers, antibiotics, anti­cholinesterase agents, antiarrhythmics, anti­convulsants, beta blockers, corticosteroids, D- pen­icillamine, chloroquine, lithium, and magnesium, can also decrease transmission at the neuromuscu­lar junction. Even toxins released by certain spe­cies of scorpions, ticks, wasps, spiders, and bacte­ria can also act at the neuromuscular junction. The pathogenesis of drug- induced myasthenia gravis- like syndrome ( DMG) is not clear. Current theories on the mechanism of DMG focus on al­tered immunological reactivity. A population of B- celllymphocytes has apparently been induced to manufacture antibodies to the acetylcholine recep­tors ( 10). This action could be the result of several mechanisms: ( a) altered acetylcholine- receptor an­tigenic properties, which make self- recognition more difficult ( 15); ( b) a loss of suppressor T- cell control over B- cell production of antibodies- in vitro studies demonstrate that D- penicillamine de­creases T- cell division ( 16); ( c) direct stimulation of B cells, specific or nonspecific, which would lead to increased levels of antibodies ( 10); and ( d) a di­rect toxic effect of the drug on the acetylcholine receptor ( 17). It is a very rare occurrence, however, to have this syndrome precipitated by a topical ophthalmic preparation. Coppeto ( 3) reported a case of DMG after use of topical timolol 0.5% twice a day for 2 months. An increased acetylcholine­receptor antibody level of 4.0 nmole ( normal range, 0.0 to 1.0 nmole) was found. With discon­tinuation of the eyedrops the symptoms disap­peared. We were unable to find any reports in the liter­ature of proven myasthenic- like syndromes pre­cipitated by any of the ophthalmic preparations used in our patient. The rapidity of onset of the systemic reactions has once again highlighted the well- known pharmacologic principle that absorp­tion of drugs transconjunctivally occurs directly into the conjunctival capillaries or via the nasal mucosa. As a result, the metabolic conjugation JClill Niuro- ophthalmol. Vol. 12. No. 3. 1992 212 D. MEYER ET AL. pathways within the intestinal mucosa and the first- pass liver effects are eliminated ( 18). Conse­quently, a medication placed in the eye may exert a greater pharmacologic ( or immunosensitizing) effect than one administered orally. 50 often, this fact is not fully appreciated by medical staff admin­istering topical preparations to patients. Therefore, we must recognize that potential in­advertent reactions to ophthalmic preparations are a reality and that these drugs should always be used and prescribed by medical staff who are well versed in pharmacology and the side effects of drugs. An eyedrop is as much a medicinal drug as an ampoule used for parenteral injections and should be used with the same amount of caution and respect. REFERENCES I. Confavreux C, Charles N. Aimard G. Fulminant myasthe­nia gravis soon after initiation of acebutolol therapy. Ellr Neural 1990; 30: 279--< l1. 2. Leys D. Pasquier F. Vermersch P. Gosset D. Michiels H. Kassiotis P. Petit H. Possible revelation of latent mvasthe­nia gravis by labetalol chlorhydrate ( letter). 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