PARKINSON DISEASE

PARKINSON DISEASE

Parkinson disease is a slowly progressive degenerative disease of nervous system associated with destruction of brain cells, which produce dopamine. It is named after the discoverer James Parkinson. It is also called parkinsonism or paralysis agitans. Great boxer Mohammed Ali is affected by parkinsonism because of repeated blows he might have received on head resulting in damage of brain cells producing dopamine.

Causes of Parkinson Disease

Parkinson disease occurs due to lack of dopamine caused by damage of basal ganglia. It is mostly due to

the destruction of substantia nigra and the nigrostriatal pathway, which has dopaminergic fibers. Damage of basal ganglia usually occurs because of the following causes:

i. Viral infection of brain like encephalitis

ii. Cerebral arteriosclerosis

iii. Injury to basal ganglia

iv. Destruction or removal of dopamine in basal ganglia. It occurs mostly due to longterm

treatment with antihypertensive drugs like reserpine. Parkinsonism due to the drugs is known as

drug-induced parkinsonism.

v. Unknown causes: Parkinsonism can occur because of the destruction of basal ganglia due

to some unknown causes. This type of parkinsonism is called idiopathic parkinsonism.

Signs and Symptoms of Parkinson Disease

Parkinson disease develops very slowly and the early signs and symptoms may be unnoticed for months or even for years. Often the symptoms start with a mild noticeable tremor in just one hand. When the tremor becomes remarkable the disease causes slowing or freezing of movements followed by rigidity.

Following are the common signs and symptoms of

Parkinson disease:

i.              Tremor

ii.             Parkinson

 In this disease, the tremor occurs during rest. But it disappears while doing any work. So, it is called static tremor or resting tremor. It is also called drum-beating tremor, as the movements are similar to beating a drum. Thumb moves rhythmically over the index and middle fingers.

These movements are called pill-rolling movements.

ii. Slowness of movements

Over the time, movements start slowing down (bradykinesia) and it takes a long time even to perform a

simple task. Gradually the patient becomes unable to initiate the voluntary activity (akinesia) or the voluntary movements are reduced (hypokinesia). It is because of hypertonicity of the muscles.

iii. Poverty of movements

Poverty of movements is the loss of all automatic associated movements. Because of absence of the

automatic associate movements, the body becomes statue-like. The face becomes mask-like, due to absence of appropriate expressions like blinking and smiling.

iv. Rigidity

Stiffness of muscles occurs in limbs resulting in rigidity of limbs. The muscular stiffness occurs because of

increased muscle tone which is due to the removal of inhibitory influence on gamma motor neurons. It affects both flexor and extensor muscles equally. So, the limbs become more rigid like pillars. The condition is called lead-pipe rigidity. In later stages the rigidity extends to neck and trunk.

v. Gait

Gait refers to manner of walking. The patient looses the normal gait. Gait in Parkinson disease is called

festinant gait. The patient walks quickly in short steps by bending forward as if he is going to catch up the

center of gravity.

vi. Speech problems

Many patients develop speech problems. They may speak very softly or sometimes rapidly. The words are repeated many times. Finally, the speech becomes slurred and they hesitate to speak.

vii. Emotional changes

The persons affected by Parkinson disease are often upset emotionally.

viii. Dementia

In later stages, some patients develop dementia.

Treatment for Parkinson Disease

As Parkinson disease is due to lack of dopamine caused by damage of dopaminergic fibers, it is treated

by dopamine injection. Dopamine does not cross the bloodbrain barrier. So, another substance called levodopa (Ldopa) which crosses the bloodbrain barrier is injected. Ldopa moves into the brain and there it is converted into dopamine. Since, Ldopa can be converted into dopamine in liver, some side effects occur due to excess dopamine content in liver and blood. So, along with Ldopa, another substance called carbidopa is administered. Carbidopa prevents the conversion of Ldopa into dopamine and carbidopa cannot pass through bloodbrain barrier. Thus, Ldopa moves into the brain tissues and is converted into dopamine. Some of the symptoms of Parkinson disease such as tremor are abolished by surgical destruction of basal ganglia or thalamic nuclei.