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Show Journal of Neuro- Ophthalmology 17( 3): 202- 203, 1997. © 1997 Lippincott- Raven Publishers, Philadelphia Enhanced Ptosis in Lambert- Eaton Myasthenic Syndrome Paul W. Brazis, M. D. A patient with Lambert- Eaton myasthenic syndrome ( LEMS) presented with a bilateral ptosis that improved transiently after sustained upgaze. The contralateral ptosis became aggravated on manually lifting either eyelid with and without fixation ( enhanced ptosis). Enhanced ptosis is a common finding in many patients with ptosis resulting from myasthenia gravis; however, to our knowledge, this is the first description of this sign in a patient with LEMS. The phenomenon of enhanced ptosis should be sought in all patients with ptosis. Improvement of the ptosis after sustained upward gaze suggests the diagnosis of LEMS. Key Words: Ptosis- Enhanced ptosis- Lambert- Eaton myasthenic syndrome. CASE REPORT A 66- year- old woman was seen in neuro- ophthal-mologic consultation at the Mayo Clinic- Jacksonville in July 1995 for bilateral ptosis. The patient stated that she was in good health until August 1994, when she developed generalized fatigue, malaise, nausea, and gait instability. Over a period of 1 year, she developed diffuse weakness and fatigue, and experienced a 23- pound weight loss. Other complaints included dry mouth, bilateral blurred vision, dry eyes, and droopiness of the eyelids. The patient had smoked one pack of cigarettes per day for > 50 years and drank alcohol only rarely. She denied any family history of neurologic or eye diseases, or any previous significant medical illnesses. Neuro- ophthalmologic examination showed visual acuity with correction to be 20/ 25 OD and 20/ 30 OS. Near vision with correction was 14/ 23 OD and 14/ 28 OS. Color vision was 10 of 10 Ishihara plates bilaterally, visual fields were normal, and the pupils were 4 mm and 2+ reactive to light and near with no relative afferent pupillary defect. The patient was orthophoric with full ductions, versions, and saccades and pursuit eye movements; however, she had bilateral ptosis with impaired Manuscript received September 20, 1996; accepted April 24, 1997. From the Departments of Neurology and Ophthalmology, Mayo Clinic- Jacksonville, Jacksonville, Florida, U. S. A. Address correspondences and reprint requests to: Paul W. Brazis MD, c/ o Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL, 32224, U. S. A. levator function ( Fig. 1A). The contralateral ptosis became aggravated on manually lifting either eyelid with and without fixation ( enhanced ptosis) ( Fig. IB and C). Sustained upgaze caused transient improvement in her ptosis. Tensilon did not affect her eyelid position. Cranial nerves V and VII were intact. Slit- lamp examination showed mild cataracts; fundoscopic examination was normal. Neurologic examination revealed the patient to be cachectic. Motor strength showed diffuse - 2 paresis of the proximal musculature in both upper and both lower extremities and - 1 paresis of neck flexion. The patient was areflexic with toe signs flexor. Sensation was intact. The patient's gait was markedly weak and unsteady, and she had difficulty standing, even with the assistance of the examiner. Blood studies included an anti- HU antibodies antineur antineuronal nuclear antibodies type I ( ANNA- 1), which were positive at a titer 1: 960. P/ Q and N- type calcium channel binding antibodies were positive and acetylcholine receptor antibodies were negative. Repetitive nerve stimulation studies showed decremental responses of 17- 19% in the ulnar and spinal accessory nerve at slow rates of stimulation. However, after 10 seconds of isometric exercise, these decrements resolved and there was a facilitation of 140- 200% in the amplitude of the compound motor action potentials. Needle study of extremity muscles showed motor unit potential variability. Chest x- ray was normal but a computed tomography ( CT) scan of the chest showed an indeterminate nodule in the right middle lobe of the lung and a soft tissue nodule anterior to the left upper lobe bronchus and superior left pulmonary vein. Bronchoscopy was entirely normal and transbronchial needle aspiration of the anterior portion of the left upper lobe showed negative cytology. In August 1995, the patient underwent a mediastinoscopy, results of which were was negative. Left thoracotomy was performed and a left hilar lymph node was excised. The pathology report revealed metastatic, poorly differentiated, non- small cell carcinoma. DISCUSSION The patient's proximal paresis, dry mouth and eyes, and areflexia are all characteristic of Lambert- Eaton my- 202 ENHANCED PTOSIS IN LAMBERT- EATON MYASTHENIC SYNDROME 203 FIG. 1. A: Bilateral ptosis in a patient with LEMS. The contralateral ptosis became aggravated on manually lifting either eyelid. B and C: Enhanced ptosis. asthenic syndrome ( LEMS). The decremental responses to slow rates of stimulation and the facilitation of compound motor action potential amplitudes after isometric exercise electrophysiologically confirm the diagnosis of LEMS. Our patient had P/ Q and N- type calcium channel antibodies. Almost all patients with LEMS, whether or not they have evidence of cancer, have serum P/ Q- type calcium channel antibodies; = 50% of patients also have antibodies to N- type calcium channels. Antibodies against calcium channels are also found at lower frequencies and titers in patients with paraneoplastic en-cephalomyeloneuropathies associated with lung, ovarian, and breast cancers; in a minority of patients with cancer without evident neurologic dysfunction; in patients with sporadic amyotrophic lateral sclerosis ( ALS); and, occasionally, in patients with myasthenia gravis, scleroderma, or no neurologic deficit ( 1). These antibodies may have a pathogenic role in paraneoplastic and nonparaneoplas-tic neurologic disorders. The presence of ANNA- 1 ( anti- Hu) antibodies is strongly associated with occult primary tumors, especially small- cell carcinoma of the lung ( 2). Even though our patient's node biopsy revealed metastatic, non- small cell cancer, we suspect that an underlying small- cell malignancy may be present. Although eye findings are said to be uncommon with LEMS, mild- to- moderate ptosis occurs in 54% of patients ( 3). Transient improvement of this ptosis after sustained upward gaze, as in our patient, has been previously described ( 4) and corresponds to the clinical finding of improved extremity motor strength after sustained exercise in LEMS patients. This improved strength after exercise is thought to be due to an increased release of acetylcholine quanta from the nerve endings to the muscle. Our patient demonstrated enhanced ptosis, i. e., aggravation of contralateral ptosis on manually lifting either eyelid ( 5). We and others have found this sign to be common in many patients with ptosis resulting from myasthenia gravis ( 6), but it has also been described in senile ptosis ( 7), ocular myopathy ( 8), and Fisher's syndrome ( 9). Although typically seen in diseases of the neuromuscular junction or muscle, enhanced ptosis has also been described in oculomotor nerve palsies and nuclear oculomotor infarction ( 10). To our knowledge, this is the first description of this sign in a patient with LEMS. The mechanism for enhanced ptosis can, perhaps, be explained by Hering's law of equal innervation ( 8). The phenomenon of enhanced ptosis should, thus, be sought in patients with ptosis. Its presence usually suggests a peripheral mechanism ( disease of the nerve, myoneural junction, or muscle) for the ptosis. Improvement of the ptosis after sustained upward gaze suggests the diagnosis of LEMS. REFERENCES 1. Lennon VA, Kryzer TJ, Griesmann GE, et al. Calcium- channel antibodies in the Lambert- Eaton myasthenic syndrome and other paraneoplastic syndromes. New Engl J Med 1995; 332: 1467- 74. 2. Lennon VA. Paraneoplastic autoantibodies. The case for a descriptive generic nomenclature. Neurology 1994; 44: 2236- 40. 3. O'Neill JH, Murray NMF, Newsom- Davis J. The Lambert- Eaton myasthenic syndrome. A review of 50 cases. Brain 1988; I 11: 577- 96. 4. Breen LA, Gutmann L, Brick JF, Riggs JR. Paradoxical lid elevation with sustained upgaze: A sign of Eaton- Lambert syndrome. Muscle Nerve 1991; 14: 863- 6. 5. Gorelick PB, Rosenberg M, Pagano RJ. Enhanced ptosis in myasthenia gravis. Arch Neurol 1981; 38: 53l. 6. Hirose K, Miyamoto K, Ogura M, Uono M, and Tsubaki T. Two types of so- called enhance ptosis in myasthenia gravis. Rin-shoushinkeigaku ( Clin Neurol) 1984; 24: 240- 7. 7. Iwasaki S. Enhanced ptosis in senile ptosis. Shinkeinaika ( Neurol Med) 1987; 26: 312^ f. 8. Suzuki T, Kashima Y, Nakano S, Nishida S, Ishikawa H. Three cases of ocular myopathy with enhanced ptosis phenomenon. Shinkeiganka ( Neuro- Ophthalmol Jpn) 1989; 6: 434- 8. 9. Ishikawa H, Wakakura M, Ishikawa S. Enhanced ptosis in Fisher's syndrome after Epstein- Bar infection. J Clin Neuro- Ophthalmol 1990; 10: 197- 200. 10. Averbuch- Heller L, Poonyathalang A, von Maydell RD, Rcmler BF. Hering's law for eyelids: still valid. Neurology I995; 45: 1781- 3. J Neuro- Ophthalmol, Vol. 17, No. J, 1997 |
