Parkinson's disease

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Parkinson's disease

Tag: Lewy bodies, Alzheimer's disease, Tau protein, synucleinopathy, D1 receptors, D2 receptors, Braak staging of Parkinson's disease, Hoehn and yahr scale, Levodopa, Stereotactic Neurosurgery.

 

It is a slowly progressive neurodegenerative disease with insidious onset. In the beginning, the most important features are shaking rigidity, slowness of movements, and difficulty walking and writing. These motor symptoms are the characteristic feature of Parkinsonism or Parkinson's disease.

Non-motor symptoms occur early but are nonspecific. Thinking, behavioral problems, depression, and anxiety are widespread- they appear in more than one-third of Parkinson's disease. In the advanced stage of the disease, dementia is common. Other symptoms are sensory, sleep, and emotional problems.

There are two basic types of Parkinson's diseases:

(1) Idiopathic – It is common, and the cause is not known, but genetic and environmental factors are involved, and

(2) Secondary -the cause is known.

An English doctor James Parkison published the first detailed description of the disease. "An Essay of the shaking palsy in 1817. The condition is named after him - Parkinson's disease. It is widespread as the number of new cases of Parkinson's disease per year is between 08-18 per lakh people. To honor James Parkinson, 'World Parkinson's day ' is celebrated on his birthday on 11^th April. The Tulip is the symbol of the disease.

It is a neurodegenerative disease of insidious onset that mainly affects the brain's dopamine-producing neurons of Substantia nigra compacta. It is an age-related (above 60 yrs) and nonreversible disease that is more common in males (the male-female ratio is 2:1).

What are young-onset Parkinson's diseases?

When Parkinson's disease appears before the age of 50, it is young-onset Parkinson's disease.

Parkinson's Disease is the second most common neurodegenerative disorder after Alzheimer's disease. Parkinson's disease is also called synucleiopathy due to the accumulation of abnormal alpha-synuclein protein in the brain to distinguish it from other neurodegenerative disorders,e.g., Alzheimer's disease, where the Tauprotein accumulates in the brain. Clinical features also differ in synucleinopathy and tauopathies.

The main sign of Parkinson's disease are slowness of movements, tremors, stiffness, and postural instability, but there is no memory loss.

What is Parkinson's plus syndrome?

When many neurodegenerative diseases are present with parkinsonism, and then it is Parkinson's plus syndrome.

Pathophysiology:- There is a defect in the neurotransmitter dopamine secreted from the substantia nigra compact of substantia nigra. This Substantia Nigra is a part of the basal ganglion. The other group of nuclei of Basal the ganglion is:-

Caudate nucleus

Putamen Nucleus

Globus pallidus

Substantia Nigra

Subthalamic Nuclei.

A model of the motor circuit in normal conditions and Parkinson's disease has been described since 1980 with some limitations. In this model, the basal ganglion usually exerts an inhibitory influence on the motor systems, preventing them from becoming active at inappropriate times.

Neurons of Substantia nigra compacta secrete neurotransmitter dopamine and project to the Caudate nucleus and Putamen nucleus. Dopamine promotes movements by direct and indirect pathways.

Dopamine promotes a direct pathway, which is excitatory by action on D1 receptors and causes an increase in inhibition, resulting in a decrease cortical output.

Dopamine +D1 stimulates Adenyl cyclase.

Dopamine inhibits the indirect pathway by action on D2 receptors and causes a decrease in inhibition, increasing the cortical output, which increases the movements.

Dopamine +D2 inhibits Adenyl cyclase.

Neostriatum is influenced by

1.  The excitatory effect of cholinergic fibers and

2)The inhibitory effect of Dopaminergic fibers.

There is a balancing effect of these two opposite fibers for normal smooth functions of motor activity. The reduced dopamine secretion in Parkinson's disease reduces its inhibitory effect, so excitatory cholinergic fibers cause hyperkinetic features.

Aetiology:-cause of Parkinson's disease:-

1. Idiopathic or primary - the cause is not known; hereditary & environmental factors have some role.

2. Secondary:-

1.  Cerebral arteriosclerosis reduction in the rate of cerebral blood flow.

2.  Complications of diseases- encephalitis, neurosyphilis, Wilson's disease, etc.

3.  Complications of drugs- phenothiazine, reserpine.

Another way of classification:-

1.  Impaired release of dopamine- idiopathic, drugs toxins.

2.  Blockage of striatal dopamine receptors- phenothiazine

3.  Damage to striatal neurons- multisystemic disease

Due to the degeneration of substantia nigra and the Globus pallidus, dopamine concentration in the nigrostriatal system is reduced.

Risk factors:-

Family history

Exposure to certain pesticides

History of head injury.

Reduced risk in

Tobacco smokers,

And those who drink tea or coffee

Exercise in middle age reduces the risk.

Staging of Parkinson's disease:-

Braak staging of Parkinson's disease is based on pathological findings of Lewy bodies in the brain. In the early stage, Lewy bodies are detected in the olfactory bulb, medulla oblongata, and pontine tegmentum when no motor symptoms are present. Still, non-motor symptoms such as loss of sense of smell, sleep disturbance, or other automatic dysfunctions are present. As the disease progresses, Lewy bodies develop in the Substantia Nigra, midbrain areas, basal forebrain, and finally, the neocortex. These sites are the main places of neuronal degeneration in Parkinson's disease.

Hoehn and yahr scale to gauge the progression of the disease over the years. The scale was initially implemented in 1967 and included zero to five stages. These stages are:-

0) No sign of Parkinson's disease.

I)

II)

III)

IV)

V)Advanced Parkinson's disease.

Later some modification was done and known as the modified Hochn and yahr scale.

Symptoms develop when a significant number of neurons of substantial nigra are lost or not working correctly. Clinical features of Parkinson's disease is:

Hyperkinetic features:-

Resting tremor

Rigidity-lead pipe or cogwheel rigidity.

Hypokinetic features:-

Hypokinesia= bradykinesia=akinesia

Mask like face

Micrographia,

Festinate gait or shuffling gait.

Retropulsion/lateropulsion.

Pill- rolling movements.

Loss of associated movements that commonly occurs subconsciously, e.g., swinging of arms during walking.

Non –Motor functions:-

Sleep disturbance

Emotional disturbance

Dementia.

Diagnosis:- is mainly clinical:

Resting tremor, Rigidity-lead pipe or cogwheel rigidity, Hypokinesia or bradykinesia akinesia, Mask like face, Micrographia, Festinate gait. Retropulsion or lateropulsion. Pill rolling movements pinpoint the diagnosis.

Computed tomography (CT) scans are not very helpful in the diagnosis.

MRI is accurate in diagnosing the disease, specifically through iron-sensitive T2 and SWI sequences at a magnetic field strength of at least 3T. These can demonstrate the absence of the characteristic "swallowtail" imaging pattern in the dorsolateral Substantia nigra.

Treatment:-

There is no cure for this disease, and treatment is aimed to improve symptoms and slow the progress of the disease. However, there is no evidence that acupuncture, the practice of Yoga, Qigong or Tai chi, and any diet program have any effect on the course of the disease or symptoms.

Medical:- Dopaminergic medication is given. Dopamine can not enter brain tissue due to the blood-brain barrier, so it is ineffective. Levo dopa crosses the blood-brain barrier, and in the brain, many enzymes convert it into dopamine.

Surgical:- Some surgeries- Stereotactic neurosurgery is helpful to reduce the symptoms of Parkinson's disease when medical treatment fails.

Physiotherapy:- is used to overcome the deficiency. Gentle exercise will help in many cases.

Prognosis:- Parkinson's disease is not fatal, but complications are severe and often fatal. According to some reports, the complications of Parkinson's disease is the 14 th cause of death in the United States. In  India, such data is not available but certainly reduces the average life expectancy following diagnosis.

Tag: Lewy bodies, Alzheimer's disease, Tau protein, synucleinopathy, D1 receptors, D2 receptors, Braak staging of Parkinson's disease, Hoehn and yahr scale, Levodopa, Stereotactic Neurosurgery.

 

Internal link:

        https://www.blog.totalphysiology.com basal ganglion

External link:-

1. Sveinbjorns dottir,S(11 July 2016). "The clinical symptoms of Parkinson's disease."Journal of Neurochemistry.139:318-324.

2." Parkinson's disease information Page" NINDS .30 June 2016.

3. Mosley, Anthony D.(2010) The encyclopedia of Parkinson's disease 2nd edition.New York; facts on file.

4 ." Global, regional and national incidence, prevalence & years lived with disability for 310 diseases and injuries,1990-2015.Lancet .388:1545-1602.(October 2016).

5 ." Global, regional and national life expectancy,all-cause mortality, and cause-specific mortality for 249 causes of death(October 2016). 1980-2015.Lancet .388:1459-1544.