A slowly progressive and degenerative disease affecting the nervous system is termed Parkinson’s disease (named after its pioneer, James Parkinson in 1817). Parkinson’s disease results from an insufficiency of dopamine in the brain, and is thus categorised as a movement disorder.

According to the WHO, a chronic progressive neurodegenerative disorder of insidious onset, characterised by the presence of predominantly motor symptomatology (bradykinesia, rest tremor, rigidity, and postural disturbances) is termed Parkinson’s disease.

On the Basis of Etiology :  The etiological types of PD include:

1. Primary Parkinson’s Disease : This type affects individuals above 40 years of age and is more prevalent in males.
2. Secondary Parkinson’s Disease : This type is essentially Parkinsonism, and results from causes other than the Parkinson’s disease itself.

On the Basis of Age of Onset : According to the onset, PD can be classified into:

Early Onset Parkinson’s Disease : This type affects individuals below 40 years of age, and is further classified into:

1. Young-Onset PD: This begins between 21 and 40 years of age.
2. Juvenile PD: This begins before the age of 20 years.

Late Onset Parkinson’s Disease : This type affects individuals above 40 years of age.

Signs and Symptoms

Motor Signs and Symptoms : These characteristic manifestations of PD include:

Resting Tremors : These are one of the classical features of PD. A tremor is characterised by shaking or oscillating movement, and appears at the time when muscles are relaxed or at rest. The onset of tremors is typically seen in one finger. In other patients, it may be in the form of a slight tremor in the hand or foot, on one side of the body, or less commonly in the jaw or face.

Bradykinesia : This denotes slow movement. It describes a general decrease in spontaneous movement that may look like an abnormal stillness and a reduction in facial expressivity. It makes repetitive movements like finger tapping, buttoning a shirt, cutting food, or brushing difficult.

Muscle Rigidity : In PD, the affected limb always has a stiff muscle tone that does not relax. It may be painful. It may result in tightness of neck, shoulder, and leg.

Postural Instability : Losing balance in later stages is common.

Others Signs : Some other motor symptoms include:

1. Loss of automatic movements (blinking, smiling, and swinging arms while walking),
2. Freezing (difficulty in taking the first step),
3. Micrographia (the size of handwriting gets smaller over time),
4. Hypomimia (mask-like expression),
5. Unwanted accelerations (suddenly rapid speech, or an uncontrolled acceleration in walking, known as festination),
6. Parkinsonian gait (a common way of walking stooped over, with a combination of freezing and festination),
7. Difficulties with speech (soft voice or slurring of words),
8. Difficulty in swallowing (drooling and increased risk of choking), and
9. Sexual dysfunction.

Non-Motor Signs and Symptoms :

1. Restless Leg Syndrome (RLS),
2. Loss of sense of smell (olfactory dysfunction),
3. Pain,
4. Mood and sleep disorders,
5. Memory disturbances and dementia (in later stages),
6. Respiratory dysfunction, and
7. Depression, hallucinations, and delusions.