Myasthenia Gravis vs Multiple Sclerosis
Pathophysiology
Myasthenia Gravis- A chronic autoimmune disorder of the postsynaptic membrane at the neuromuscular junction in skeletal muscle.
Multiple Sclerosis- an inflammatory demyelinating disease characterized by the presence of episodic neurologic dysfunction in at least two areas of the central nervous system (brain, spinal cord, and optic nerves) separated in time and space
Incidence
Myasthenia Gravis- An uncommon disease with an estimated incidence in the US of 10 to 20 cases per million population per year and a worldwide prevalence of 100 to 200 per million population
Multiple Sclerosis- Most common in white women who were raised in the northern US. Estimates of prevalence range from over 400,000 in the US population as a whole, to 250,000 to 350,000 in the white population.
Signs and Symptoms
Myasthenia Gravis- Characterized by muscle weakness that increases with exercise (fatigue) and improves on rest. Commonly presents with drooping eyelids, double vision, oropharyngeal and/or appendicular weakness, and shortness of breath.
Multiple Sclerosis- Temporary visual or sensory loss. Subtle changes in vision, ambulation, and reflexes on examination that provide evidence of previous attacks.
Labs/Diagnostic Testing
Myasthenia Gravis- Elevated serum acetylcholine receptor antibody titers or muscle-specific tyrosine kinase antibodies are present. Antibodies to 4 new autoantigens, low-density lipoprotein receptor-related protein (LRP4), agrin, collagen Q, and cortactin, located at the neuromuscular junction, have been identified.
Multiple Sclerosis- Magnetic resonance imaging (MRI) of the brain is sensitive, but very susceptible to over-interpretation in the absence of clinical correlation. Spinal MRI is abnormal less often, but lends greater specificity when present with brain lesions.
Management
Myasthenia Gravis- Treatments include anticholinesterases and immunotherapy. Thymectomy may be required and is effective in people with generalized myasthenia gravis who are acetylcholine receptor (AChR) antibody-positive with no thymoma. Taking pyridostigmine 30 minutes prior to eating with a small amount of food is helpful for those patients with oral, facial, buccal, pharyngeal and/or lingual dysfunction.
Multiple Sclerosis- Treatment of the condition can be divided into three parts: treatment of the acute attack; prevention of future attacks by reducing triggers and use of disease-modifying therapies; and symptomatic treatments of neurologic difficulties such as spasticity, pain, fatigue, and bladder dysfunction. Interferon-beta preparations, glatiramer, dimethyl fumarate, and teriflunomide are generally considered first-line agents.
References
Lisak, R. (2019). Myasthenia gravis. Epocrates. Retrieved from https://online.epocrates.com/diseases/23811/Myasthenia-gravis/Key-Highlights
Willis, M. (2019). Multiple sclerosis. Epocrates. Retrieved from https://online.epocrates.com/diseases/140/Multiple-sclerosis
Myasthenia Gravis- A chronic autoimmune disorder of the postsynaptic membrane at the neuromuscular junction in skeletal muscle.
Multiple Sclerosis- an inflammatory demyelinating disease characterized by the presence of episodic neurologic dysfunction in at least two areas of the central nervous system (brain, spinal cord, and optic nerves) separated in time and space
Incidence
Myasthenia Gravis- An uncommon disease with an estimated incidence in the US of 10 to 20 cases per million population per year and a worldwide prevalence of 100 to 200 per million population
Multiple Sclerosis- Most common in white women who were raised in the northern US. Estimates of prevalence range from over 400,000 in the US population as a whole, to 250,000 to 350,000 in the white population.
Signs and Symptoms
Myasthenia Gravis- Characterized by muscle weakness that increases with exercise (fatigue) and improves on rest. Commonly presents with drooping eyelids, double vision, oropharyngeal and/or appendicular weakness, and shortness of breath.
Multiple Sclerosis- Temporary visual or sensory loss. Subtle changes in vision, ambulation, and reflexes on examination that provide evidence of previous attacks.
Labs/Diagnostic Testing
Myasthenia Gravis- Elevated serum acetylcholine receptor antibody titers or muscle-specific tyrosine kinase antibodies are present. Antibodies to 4 new autoantigens, low-density lipoprotein receptor-related protein (LRP4), agrin, collagen Q, and cortactin, located at the neuromuscular junction, have been identified.
Multiple Sclerosis- Magnetic resonance imaging (MRI) of the brain is sensitive, but very susceptible to over-interpretation in the absence of clinical correlation. Spinal MRI is abnormal less often, but lends greater specificity when present with brain lesions.
Management
Myasthenia Gravis- Treatments include anticholinesterases and immunotherapy. Thymectomy may be required and is effective in people with generalized myasthenia gravis who are acetylcholine receptor (AChR) antibody-positive with no thymoma. Taking pyridostigmine 30 minutes prior to eating with a small amount of food is helpful for those patients with oral, facial, buccal, pharyngeal and/or lingual dysfunction.
Multiple Sclerosis- Treatment of the condition can be divided into three parts: treatment of the acute attack; prevention of future attacks by reducing triggers and use of disease-modifying therapies; and symptomatic treatments of neurologic difficulties such as spasticity, pain, fatigue, and bladder dysfunction. Interferon-beta preparations, glatiramer, dimethyl fumarate, and teriflunomide are generally considered first-line agents.
References
Lisak, R. (2019). Myasthenia gravis. Epocrates. Retrieved from https://online.epocrates.com/diseases/23811/Myasthenia-gravis/Key-Highlights
Willis, M. (2019). Multiple sclerosis. Epocrates. Retrieved from https://online.epocrates.com/diseases/140/Multiple-sclerosis
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