Myasthenia gravis natural history, complications and prognosis
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Natural History
The age of onset in Myasthenia gravis follows a bimodal distribution. The early type (before age of 50) is female predominant and the late type (after age of 60) is male predominant. Between the age of 50-60 there is no significant different between male and female.[1] About 50 percent of patiens have ptosis and diplopia as their presenting sign. Ptosis is usually asymmetrical. The direction and degree of diplopia may change in a MG patients because of fatigable ocular motor paresis.[2] The hallmark of myasthenia gravis is Fluctuating weakness of specific muscles in limbs, bulbar, ocular and respiratory system which get worse with activity or using the muscle.[3][4][5]
Gaze paralysis
The ocular muscle weakness in MG can cause gaze paralysis and even mimic internuclear ophthalmoplegia or midline brain lesions.[6]
Photophobia
A lot of patients with myasthenia gravis complain that bright light bothers them and can even worsen the weakness of their eye muscles. Since this symptom is seen even in untreated patients, it’s not a complication of anticholinesterases treatment.[7]
Facial weakness
The facial weakness in MG occurs without sensation impairment of face. The sensation problems along with facial weakness suggest a different diagnosis like nasopharyngeal carcinomas.[8]
Orbicularis oculi weakness
If we try to keep the upper eyelid of a MG patient open, they cannot close it against our force because of the weakness of orbicularis oculi muscle.[9]
tongue weakness, chewing problems and dysphagia
The muscles of the tongue will become weak in MG patients especially after long speech. This can lead to unintelligible speech and dysphasia. Difficulty in swallowing can cause choking and nasal regurgitation. Furthermore the weakness of mastication muscles will cause chewing problem and can lead to weight loss.[10][11]
Respiratory problems
Inability to maintain a patent airway or respiratory insufficiency can occur in MG patients especially those who are in the MG crises.[12] Respiratory problems can cause inadequate sleep and day time somnolence.[13]
Limbs muscles weakness
Because the distal part of the limbs is warmer, they have less reserve of Ach and they will show more weakness.[14] The proximal muscles of upper extremities show weakness during hair brushing or dressing.[15] The proximal muscles of lower extremities show weakness during walking up stair[16] The distal muscle of limbs are more affected especially the finger extensors.[17]
Fatigue
MG patients experience fatigue after a period of mental or physical activity.[18]
Less common symptoms
Pelvic floor weakness
The weakness of pelvic floor muscles leads to urinary incontinency especially during cough or strain.[19][20]
Complications
Prognosis
The prognosis of myasthenia gravis depends on:
- Disease duration at diagnosis: If the symptoms last less than 1 year, the patient has a 25 percent chance of going into remission by 10 years.[21]
- Disease severity[21]
- The age of onset: Younger patients seems to have better chance for remission than older ones.[21] Patients more than 50 years old are more prone to myasthenia crises like respiratory failure.[22]
References
- ↑ Alkhawajah NM, Oger J (November 2013). "Late-onset myasthenia gravis: a review when incidence in older adults keeps increasing". Muscle Nerve. 48 (5): 705–10. doi:10.1002/mus.23964. PMID 23893883.
- ↑ Osher RH, Glaser JS (March 1980). "Myasthenic sustained gaze fatigue". Am. J. Ophthalmol. 89 (3): 443–5. PMID 7369304.
- ↑ Silvestri NJ, Wolfe GI (July 2012). "Myasthenia gravis". Semin Neurol. 32 (3): 215–26. doi:10.1055/s-0032-1329200. PMID 23117946.
- ↑ Keesey JC (April 2004). "Clinical evaluation and management of myasthenia gravis". Muscle Nerve. 29 (4): 484–505. doi:10.1002/mus.20030. PMID 15052614.
- ↑ Keesey J, Buffkin D, Kebo D, Ho W, Herrmann C (1981). "Plasma exchange alone as therapy for myasthenia gravis". Ann. N. Y. Acad. Sci. 377: 729–43. PMID 6951497.
- ↑ Spooner JW, Baloh RW (January 1979). "Eye movement fatigue in myasthenia gravis". Neurology. 29 (1): 29–33. PMID 570673.
- ↑ Lepore FE, Sanborn GE, Slevin JT (July 1979). "Pupillary dysfunction in myasthenia gravis". Ann. Neurol. 6 (1): 29–33. doi:10.1002/ana.410060107. PMID 228589.
- ↑ Patten BM (1978). "Myasthenia gravis: review of diagnosis and management". Muscle Nerve. 1 (3): 190–205. doi:10.1002/mus.880010304. PMID 86952.
- ↑ Roberts ME, Steiger MJ, Hart IK (January 2002). "Presentation of myasthenia gravis mimicking blepharospasm". Neurology. 58 (1): 150–1. PMID 11781428.
- ↑ De Assis JL, Marchiori PE, Scaff M (1994). "Atrophy of the tongue with persistent articulation disorder in myasthenia gravis: report of 10 patients". Auris Nasus Larynx. 21 (4): 215–8. PMID 7779022.
- ↑ Oosterhuis H, Bethlem J (April 1973). "Neurogenic muscle involvement in myasthenia gravis. A clinical and histopathological study". J. Neurol. Neurosurg. Psychiatry. 36 (2): 244–54. PMC 1083560. PMID 4708458.
- ↑ Keesey JC (July 2002). ""Crisis" in myasthenia gravis: an historical perspective". Muscle Nerve. 26 (1): 1–3. doi:10.1002/mus.10095. PMID 12115943.
- ↑ Keesey JC (November 1999). "Does myasthenia gravis affect the brain?". J. Neurol. Sci. 170 (2): 77–89. PMID 10561522.
- ↑ Jablecki C, Benton A (1982). "The frequency of muscle involvement in myasthenia gravis correlates with mean muscle temperature". Muscle Nerve. 5 (6): 491–2. PMID 6290881.
- ↑ Engel AG, Lambert EH, Mulder DM, Torres CF, Sahashi K, Bertorini TE, Whitaker JN (June 1982). "A newly recognized congenital myasthenic syndrome attributed to a prolonged open time of the acetylcholine-induced ion channel". Ann. Neurol. 11 (6): 553–69. doi:10.1002/ana.410110603. PMID 6287911.
- ↑ Oh SJ, Kuruoglu R (June 1992). "Chronic limb-girdle myasthenia gravis". Neurology. 42 (6): 1153–6. PMID 1603341.
- ↑ Nations SP, Wolfe GI, Amato AA, Jackson CE, Bryan WW, Barohn RJ (February 1999). "Distal myasthenia gravis". Neurology. 52 (3): 632–4. PMID 10025802.
- ↑ Ochs CW, Bradley RJ, Katholi CR, Byl NN, Brown VM, Jones LL, Shohet JS (1998). "Symptoms of patients with myasthenia gravis receiving treatment". J Med. 29 (1–2): 1–12. PMID 9704288.
- ↑ Greene LF, Ghosh MK, Howard FM (August 1974). "Transurethral prostatic resection in patients with myasthenia gravis". J. Urol. 112 (2): 226–7. PMID 4843338.
- ↑ Wise GJ, Gerstenfeld JN, Brunner N, Grob D (August 1982). "Urinary incontinence following prostatectomy in patients with myasthenia gravis". Br J Urol. 54 (4): 369–71. PMID 6180793.
- ↑ 21.0 21.1 21.2 Beghi E, Antozzi C, Batocchi AP, Cornelio F, Cosi V, Evoli A, Lombardi M, Mantegazza R, Monticelli ML, Piccolo G (December 1991). "Prognosis of myasthenia gravis: a multicenter follow-up study of 844 patients". J. Neurol. Sci. 106 (2): 213–20. PMID 1802969.
- ↑ Bever CT, Aquino AV, Penn AS, Lovelace RE, Rowland LP (November 1983). "Prognosis of ocular myasthenia". Ann. Neurol. 14 (5): 516–9. doi:10.1002/ana.410140504. PMID 6651238.