The key difference between Parkinson’s and myasthenia gravis is that although myasthenia is an autoimmune disorder which is due to the production of autoantibodies within the body, Parkinson’s disease does not have an autoimmune component in its pathogenesis.
Both Parkinson’s and myasthenia gravis are neurological disorders that have a very deteriorating impact on the quality of life of the patient. Parkinson’s disease is a movement disorder characterized by a decline in the dopamine level of the brain. Myasthenia gravis, on the other hand, is an autoimmune disorder characterized by the production of antibodies that block the transmission of impulses across the neuromuscular junction.
CONTENTS
1. Overview and Key Difference
2. What is Parkinson’s
3. What is Myasthenia Gravis
4. Side by Side Comparison – Parkinson’s vs Myasthenia Gravis in Tabular Form
5. Summary
What is Parkinson’s Disease?
Firstly, Parkinson’s disease is a movement disorder characterized by a decline in the dopamine level of the brain. The cause of this condition remains controversial. The risk of Parkinson’s disease significantly increases with advanced age.
Pathology
The main morphological changes in Parkinson’s disease include the appearance of Lewy bodies and loss of dopaminergic neurons in pars compacta of the substantia nigra region of the midbrain.
Clinical Features
- Slow movements ( bradykinesia/akinesia)
- Resting tremor
- Stooped posture and shuffling gait
- Speech becomes quiet, indistinct and flat
- During the clinical examination, can identify lead pipe rigidity of the limbs
- The patient can also develop cognitive impairments in the late stage of the disease
Figure 01: Parkinson’s Disease
Diagnosis
There is no laboratory test for the exact identification of Parkinson’s disease. Therefore, diagnosis is solely dependent on the signs and symptoms recognized during the clinical examination. Moreover, MRI images will appear normal most of the time.
Treatment
Educating the patient and the family is important. Drugs such as dopamine receptor agonists and levodopa, which restore the dopamine activity of the brain, can alleviate motor symptoms. It is also important to manage sleep disturbances and psychotic episodes appropriately.
Dopamine antagonists such as neuroleptics can induce Parkinson’s disease-like symptoms, in which case, they are collectively known as Parkinsonism.
What is Myasthenia Gravis?
Myasthenia gravis is an autoimmune disorder characterized by the production of antibodies that block the transmission of impulses across the neuromuscular junction. These antibodies bind to the postsynaptic Ach receptors, preventing the binding of Ach in the synaptic cleft to those receptors. Women are five times more affected by this condition than males. There is also a significant association with other autoimmune disorders such as rheumatoid arthritis, SLE, and autoimmune thyroiditis.
Clinical Features
- Weakness of proximal limb muscles, extraocular muscles, and bulbar muscles
- There are fatigability and fluctuation with regard to the muscle weakness
- No muscle pain
- Reflexes are also fatigable
- Diplopia, ptosis, and dysphagia
- It does not affect the heart, but can affect the respiratory muscles
Investigations
- Anti ACh receptor antibodies in the serum
- Tensilon test where the administeration of a dose of edrophonium gives rise to a transient improvement of the symptoms that lasts for about 5 minutes
- Imaging studies
- ESR and CRP
Management
- Administration of anticholinesterases such as pyridostigmine
- Can give immunosuppressants such as corticosteroids to the patients who do not respond to anticholinesterases
- Thymectomy
- Plasmapheresis
- Intravenous immunoglobulins
What is the Difference Between Parkinson’s and Myasthenia Gravis?
Parkinson’s disease is a movement disorder characterized by a decline in the dopamine level of the brain whereas myasthenia gravis is an autoimmune disorder characterized by the production of antibodies that block the transmission of impulses across the neuromuscular junction. Myasthenia gravis is an autoimmune disease but Parkinson’s is not considered as an autoimmune disease. This is the main difference between Parkinson’s and myasthenia gravis. The appearance of Lewy bodies and loss of dopaminergic neurons in pars compacta of the substantia nigra region of midbrain are the hallmark morphological changes in Parkinson’s disease. In contrast, the block of the transmission of nervous impulses at the neuromuscular junction due to the action of autoantibodies is the pathological basis of myasthenia gravis.
In addition, there is no laboratory test for the exact identification of Parkinson’s disease. However, investigations such as Anti ACh receptor antibodies in the serum, tensilon test, imaging studies, ESR and CRP can help to diagnose myasthenia gravis. Furthermore, anticholinesterases such as pyridostigmine, immunosuppressants such as corticosteroids, Thymectomy, Plasmapheresis and intravenous immunoglobulins can help to manage myasthenia gravis. On the other hand, drugs such as dopamine receptor agonists and levodopa, which restore the dopamine activity of the brain, can alleviate motor symptoms in Parkinson’s.
Summary – Parkinson’s vs Myasthenia Gravis
Parkinson’s and myasthenia gravis are neurological disorders that have a very deteriorating impact on the quality of life of the patient. The main difference between Parkinson’s and myasthenia gravis is their autoimmune component.
Reference:
1. Kumar, Parveen J., and Michael L. Clark. Kumar & Clark clinical medicine. Edinburgh: W.B. Saunders, 2009.
Image courtesy:
1. “Sir William Richard Gowers Parkinson Disease sketch 1886 2” By Sir_William_Richard_Gowers_Parkinson_Disease_sketch_1886.jpg:derivative work: Malyszkz (talk) – Sir_William_Richard_Gowers_Parkinson_Disease_sketch_1886.jpg (Public Domain) via Commons Wikimedia
2. “DiplopiaMG1” By James Heilman, MD – Own work (CC BY-SA 3.0) via Commons Wikimedia