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Show Journal of Neuro- Ophthahnology 19( 4): 257- 259, 1999. © 1999 Lippincott Williams & Wilkins, Inc., Philadelphia Intracranial Fatigable Ptosis Yi- Feng Kao, M. D., Min- Yu Lan, M. D., Min- Shon Chou, M. D., and Wei- Hsi Chen, M. D. Two patients sought treatment for bilateral fatigable ptosis; one patient had a hematoma, and the other patient had an intracranial metastasis. Compression of the central caudal nucleus in the dorsal midbrain is proposed as the cause of this ptosis, and an alteration of central acetylcholine neurotransmission may contribute to ocular fatigability. Because symptoms that suggest fatigable ptosis can be similar to those that suggest ocular myasthenia gravis, a careful evaluation is necessary to avoid misinterpretation. Key Words: Fatigue- Midbrain- Ptosis. Fatigable ptosis usually is considered a symptom of myasthenia gravis ( MG) rather than an anatomic lesion ( 1- 3). We describe two patients with fatigable ptosis that mimicked myasthenia, but that was found to be an intracranial mass lesion. CASE REPORTS Case 1 A 31- year- old man had acute onset of bilateral ptosis, which was associated with transient double vision on right gaze and a left temporal throbbing headache. Ptosis was less pronounced in the morning, worse at night, deteriorated after effort, and improved after rest. The width of the palpebral fissures was 8 mm on awakening, 5 mm after rest at noon, and 3 mm after 2 minutes of sustained upward gaze. A transient over- elevation of the left eyelid ( Cogan lid twitch) was seen when both eyes returned to the primary position after a sustained down-gaze. There was no proptosis, conjunctival congestion, or retrobulbar pain. Visual fields were full. Pupils were equal and reactive. Eye movements were normal and conjugate. Higher cortical functions, cranial nerves, brainstem reflexes, motor function, and sensory systems were intact. A neostigmine test produced widening of the palpebral fissures to 9 mm. However, results of the repetitive stimulation test, single fiber electromyogram, acetylcholine receptor antibody, and chest computed to- Manuscript received October 7, 1997; accepted July 30, 1998. From the Departments of Neurology ( Y. K., M. L., W. C.) and Neuroradiology ( M. C.), Kaohsiung Medical College Hospital, Kaohsiung 807, Tawain. Address correspondence to Wei- Hsi Chen, M. D., Department of Neurology, Kaohsiung Medical College Hospital, No. 100, Shin Chuan 1st Road, Kaohsiung 807, Taiwan. mography ( CT) were negative. Brain CT and magnetic resonance imaging ( MRI) ( Figs. 1A and IB) showed a hematoma in the left cerebellar hemisphere and a peduncle compressing the ipsilateral pons and dorsal midbrain. The hematoma appeared to exert upward pressure on the midbrain. Cerebral angiography revealed no vascular anomaly. Complete blood count, blood chemistry assessment, coagulation factors, lipid profile, and test results for lupus and immunology were normal. Osmotherapy was initiated. The ptosis resolved within 3 months. Case 2 A 75- year- old man had progressive development of bilateral ptosis over 3 months. His medical history included diabetes mellitus. Ptosis was less pronounced in the morning, worse at night, deteriorated after effort, and improved with rest. The palpebral fissure width was 4 mm on awakening in the morning and less than 2 mm at noon. Complete ptosis occurred after 2 minutes of a sustained upgaze. Cogan lid twitch was observed. There was no proptosis, conjunctival congestion, or retrobulbar pain. Visual fields were full. Pupils were equal and reactive. The patient showed right dysmetria, truncal ataxia, and generalized hyporeflexia. Higher cortical functions, cranial nerves, brainstem reflexes, and sensation were intact. Neostigmine produced widening of the palpebral fissures to 4 mm. However, findings of the repetitive stimulation test, acetylcholine receptor antibody, and chest CT were negative. Brain MRI showed several hyperintense lesions scattered throughout the brain, including a 2 cm x 2 cm Gadolinium- enhancing mass that compressed the left dorsal midbrain ( Figs. 2A and 2B). Ptosis was presumed to be caused by compression of the dorsal midbrain by an intracranial metastasis. Complete blood count, blood chemistry assessment, and lipid profile were normal, but carcinoembryonic antigen ( 24,0 ng/ ml) and cancer antigen- 130 ( 120 U/ ml) levels were elevated. The patient refused further diagnostic workup. Two months later, he had an acute episode of bloody emesis and gastric adenocarcinoma, which was diagnosed by stomach biopsy. He died 3 weeks later from septic shock and pneumonia. DISCUSSION Only 8 cases previously have been reported of fatigable ptosis caused by intracranial lesions ( 4- 7) ( Table 1); 257 258 Y. KAO ETAL. FIG. 1. T1- weighted image in Case 1 shows a high- intensity mass compatible with hematoma in the right cerebellar hemisphere and peduncle on sagittal ( A) and axial ( B) cut. our cases raise this total to 10. These 10 cases include 6 men and 4 women, ranging in age from 16 to 77 years ( average, 48.4 years). In contrast to the acute onset with hemorrhage in our Case 1, intracranial tumors produce progressive fatigability, reflecting gradual expansion of the lesion. All 5 patients with unilateral fatigable ptosis had parasellar lesions, whereas the 5 patients with bilateral fatigable ptosis had dorsal brainstem lesions. This suggests a neuroanatomic distinction between lesions affecting the oculomotor nerve underlying ipsilateral ptosis and lesions affecting the central caudal nucleus in the midbrain underlying bilateral ptosis. Although ptosis can result from central lesions involving the parieto- occipital or frontal cortex, fatigable ptosis has been seen with central lesions only when the lesions affect the midbrain ( 1,9), implicating the central caudal nucleus, which gives rise to bilateral efferents to levator palpebrae ( 8). FIG. 2. The sagittal section of brain magnetic resonance image in Case 2 shows an isointense mass at left dorsal midbrain ( arrow) and a hyperintense mass at cingulate gyrus ( arrowhead) at T1- weighted image ( A). The mass at dorsal midbrain shows a high uptake of Gadolinium contrast ( B). The mechanisms for fatigability remain controversial. A decrease of acetylcholinesterase at the motor end plate can explain the fatigable ptosis caused by the parasellar lesions damaging the oculomotor nerve. Acetylcholinesterase inhibitor reverses ptosis, and results of the repetitive stimulation test show a significant decrement in the series of Moorthy et al. ( 7). Administration of acetylcholinesterase inhibitor can enhance acetylcholine neurotransmission and ameliorate weakness, producing false- positive results in other neurologic diseases such as amyotrophic lateral sclerosis ( 11). False- positive edrophonium or physostigmine test results with brainstem lesions have been obtained from the patients of Dirr et al. ( 4) and in our patients, implicating a disturbance of acetylcholine. Ragge and Hoyt ( 5) hypothesized a disor- ./ Neuro- Ophthatmol, Vol. 19, No. 4, 1999 INTRACRANIAL FATIGABLE PTOSIS 259 TABLE 1. The summary of intracranial fatigable ptosis in the English literature Author I. Bilateral ptosis Dirr et al., 1989 Straube & Witt, 1990 Ragge et al., 1992 Kao et al., present study II. Unilateral ptosis Moorthy et al., 1989 Age/ sex 19/ Female 67/ Male 16/ Female 31/ Male 72/ Male 51 / Female 16/ Male 70/ Male 77/ Male 65/ Female Etiology Glioma Tumor Glioma Hematoma Metastasis Meningioma Chondrosarcoma Meningioma Meningioma Meningioma Onset Progressive Progressive Progressive Acute Progressive Progressive Progressive Progressive Progressive Progressive Location MB Pineal region MB Pons- CBM MB R sph. ridge R CavS L CavS R sph. ridge R CavS Prognosis Unknown Improve Improve Recovery Expire Recurrence Recurrence Persist Persist Improve MB, midbrain; CBM, cerebellar brachium; R, right; sph, sphenoid; CavS, cavernous sinus; L, left. dered central control of motor units. Further investigation is needed to determine whether a central defect of acetylcholine metabolism accounts for fatigue. Brain tumors may produce variable ptosis also because of changes in size from reflexive vasodilation during sleep, when carbon dioxide is retained ( 10). Clinical discrimination of fatigable ptosis from brain lesions rather than from MG may be difficult. For example, the lid twitch sign ( 12) of MG is seen with brain lesions ( 5). Although edrophonium or physostigmine tests can have positive results with intracranial fatigable ptosis, the test results for serum acetylcholine receptor antibody and the repetitive stimulation test are negative. However, these tests also may show negative results in cases of ocular MG. On the other hand, when neurologic deficits such as oculosympathetic dysfunction, focal weakness, or sensory abnormalities are found in a patient who has fatigable ptosis, an intracranial lesion should be suspected. REFERENCES 1. Oosterhuis HJGH. Acquired blepharoptosis. Clin Neurol Neuro-surg 1996; 98: 1- 7. 2. Caplan LR. Ptosis. J Neurol Neurosurg Psychiatry 1994; 37: 1- 7. 3. Osserman KE. Ocular myasthenia gravis. Invest Ophthalmol 1967; 6: 277. 4. Dirr LY, Donofrio PD, Patton JF, Troost BT. A false- positive edrophonium test in a patient with brainstem glioma. Neurology 1989; 39: 865- 7. 5. Ragge NK, Hoyt WF. Midbrain myasthenia: Fatigable ptosis, lid twitch sign, and ophthalmoparesis from a dorsal midbrain glioma. Neurology 1993; 42: 917- 9. 6. Straube A, Witt TN. Oculo- bulbar myasthenic symptoms as the sole sign of tumor involving or compressing the brainstem. J Neurol 1990; 237: 369- 71. 7. Moorthy G, Behrens MM, Drachman DB, Kirkham TH, Knox DL, Miller NR, et al. Ocular pseudomyasthenia or ocular myasthenia ' plus': a warning to clinicians. Neurology 1989; 39: 1150- 4. 8. Warwick R. Representation of the extra- ocular muscles in the oculomotor nuclei of the monkey. J Comp Neurol 1953; 98: 449- 95. 9. Barton JJS, Kardon RH, Slagel D, Thompson HS. Bilateral central ptosis in acquired immunodeficiency syndrome. Can J Neurol Sci 1995; 22: 52- 5. 10. Chen WH, Yin HL, Chang YY, Liu JS. Metastatic brain tumor manifesting as lacunar syndrome in adults. Kao- hsiung I Chili 1993; 9: 317- 21. 11. Mulder DW, Lambert EH, Eaton LM. Myasthenic syndrome in patients with amyotrophic lateral sclerosis. Neurology 1959,9: 627- 31. 12. Cogan DG. Myasthenia Gravis. Arch Ophthalmol 1965; 74: 217- 21. ./ Neuro- Ophthalmol, Vol 19, No. 4, 1999 |
