Myasthenia Gravis: Diagnosis

The clinical history and neurological examination provide the most important data on which the diagnosis of autoimmune myasthenia gravis (MG) is based. MG produces symptomatic weakness that predominates in certain muscle groups and typically fluctuates in response to effort and rest. The diagnosis of MG therefore depends on the recognition of this distinctive pattern of fatigable weakness. Laboratory confirmation of the clinical diagnosis may be obtained using pharmacological, electrophysiological, and serological (immunological) tests. This article reviews the tests used to confirm the diagnosis of MG.

KEYWORDS

Acetylcholine receptor antibody - repetitive nerve stimulation - single-fiber electromyography - edrophonium chloride

REFERENCES

• 1 Osserman K E, Kaplan L I. Rapid diagnostic test for myasthenia gravis: increased muscle strength, without fasciculations after intravenous administration of edrophonium (Tensilon) chloride.  J Am Med Assoc. 1952;  150 265-268
• 2 Katz B, Miledi R. The binding of acetylcholine to receptors and its removal from the synaptic cleft.  J Physiol. 1973;  231 549-574
• 3 Daroff R B. The office Tensilon test for ocular myasthenia gravis.  Arch Neurol. 1986;  43 843-844
• 4 Dirr L Y, Donofrio P D, Patton J F, Troost B T. A false-positive edrophonium test in a patient with a brainstem glioma.  Neurology. 1989;  39 865-867
• 5 Fierro B, Croce G, Filosto L, Carbone N, Lupo I. Ocular pseudomyasthenia: report of a case with a pineal region tumor.  Ital J Neurol Sci. 1991;  12 593-596
• 6 Branley M G, Wright K W, Borchert M S. Third nerve palsy due to cerebral artery aneurysm in a child.  Aust N Z J Ophthalmol. 1992;  20 137-140
• 7 Rowland L P. Prostigmine-responsiveness and the diagnosis of myasthenia gravis.  Neurology. 1955;  5 612-624
• 8 Viets H R, Schwab R S. Prostigmine in the diagnosis of myasthenia gravis.  N Engl J Med. 1935;  213 1280-1283
• 9 Howard J F, Sanders D B, Massey J M. The electrodiagnosis of myasthenia gravis and the Lambert-Eaton myasthenic syndrome.  Neurol Clin. 1994;  12 305-329
• 10 McComas A J, Galea V, Einhorn R W. Pseudofacilitation: a misleading term.  Muscle Nerve. 1994;  17 599-607
• 11 Borenstein S, Desmedt J E. Local cooling in myasthenia. Improvement in neuro- muscular failure.  Arch Neurol. 1975;  32 152-157
• 12 Niks E H, Badrising U A, Verschuuren J J, van Dijk J G. Decremental response of the nasalis and hypothenar muscles in myasthenia gravis.  Muscle Nerve. 2003;  28 236-238
• 13 Killian J M, Wilfong A A, Burnett L, Appel S H, Boland D. Decremental motor responses to repetitive nerve stimulation in ALS.  Muscle Nerve. 1994;  17 747-754
• 14 Sanders D B, Stålberg E. AAEM minimonograph # 25: single-fiber electromyography.  Muscle Nerve. 1996;  19 1069-1083
• 15 Trontelj J V, Stålberg E V. Jitter measurement by axonal micro-stimulation. Guidelines and technical notes.  Electroencephalogr Clin Neurophysiol. 1992;  85 30-37
• 16 Stålberg E, Trontelj J V, Mihelin M. Electrical microstimulation with single-fiber electromyography: a useful method to study the physiology of the motor unit.  J Clin Neurophysiol. 1992;  9 105-119
• 17 Gilchrist J M. ad hoc Committee. Single fiber EMG reference values: a collaborative effort.  Muscle Nerve. 1992;  15 151-161
• 18 Trontelj J V, Khuraibet A, Milhelin M. The jitter in stimulated orbicularis oculi muscle: technique and normal values.  J Neurol Neurosurg Psychiatry. 1988;  51 814-819
• 19 Mercelis R. Abnormal single fiber electromyography in patients not having myasthenia.  Ann N Y Acad Sci. 2003;  998 509-511
• 20 Sanders D B. Clinical impact of single-fiber electromyography.  Muscle Nerve. 2002;  11(suppl) S15-S20
• 21 Vincent A, McConville J, Farrugia E et al.. Antibodies in myasthenia gravis and related disorders.  Ann N Y Acad Sci. 2003;  998 324-335
• 22 Vincent A, Newsom-Davis J. Acetylcholine receptor antibody as a diagnostic test for myasthenia gravis: results in 153 validated cases and 2967 diagnostic assays.  J Neurol Neurosurg Psychiatry. 1985;  48 1246-1252
• 23 Lennon V A. Serological diagnosis of myasthenia gravis and Lambert-Eaton myasthenic syndrome. In: Lisak RP Handbook of Myasthenia Gravis and Myasthenic Syndromes. New York; Marcel Dekker 1994: 149-164
• 24 Howard F M, Lennon V, Finley J, Matsumoto J, Elveback L R. Clinical correlations of antibodies that bind, block or modulate human acetylcholine receptors in myasthenia gravis. Myasthenia gravis: biology and treatment.  Ann N Y Acad Sci. 1987;  505 526-538
• 25 Cikes N, Momoi M Y, Williams C L et al.. Striational autoantibodies: quantitative detection by enzyme immunoassay in myasthenia gravis, thymoma, and recipients of D-penicillamine or allogeneic bone marrow.  Mayo Clin Proc. 1988;  63 474-481
• 26 Skeie G O, Romi F, Aarli J A, Bentsen P T, Gilhus N E. Pathogenesis of myositis and myasthenia associated with titin and ryanodine receptor antibodies.  Ann N Y Acad Sci. 2003;  998 343-350
• 27 Hoch W, McConville J, Helms S, Newsom-Davis J, Melms A, Vincent A. Auto-antibodies to the receptor tyrosine kinase MuSK in patients with myasthenia gravis without acetylcholine receptor antibodies.  Nat Med. 2001;  7 365-368
• 28 Scuderi F, Marino M, Colonna L et al.. Anti-P110 autoantibodies identify a subtype of “seronegative” myasthenia gravis with prominent oculobulbar involvement.  Lab Invest. 2002;  82 1139-1146
• 29 Sanders D B, El-Salem K, Massey J M, McConville J, Vincent A. Clinical aspects of MuSK antibody positive seronegative MG.  Neurology. 2003;  60 1978-1980
• 30 Sanders D B. Diseases associated with disorders of neuromuscular transmission. In: Brown WF, Bolton CF, Aminoff MJ Neuromuscular Function and Disease. Basic, Clinical, and Electrodiagnostic Aspects. Philadelphia; W.B. Saunders 2001: 1346-1347