PARKINSON’S DISEASE

Parkinson’s disease is a chronic, progressive disease of the nervous system characterized by the cardinal features of Rigidity, Bradykinesia, Tremor and Postural instability.

James Parkinson first described Parkinson disease (PD) in 1817. PD is one of a number of chronic, progressive, neurodegenerative central nervous system (CNS) diseases that typically occur in adults older than 65 years.

The basic pathophysiology is a lack of dopamine-producing cells in the basal ganglia.

Epidemiology

Overall incidence of PD, based on several worldwide studies, is about 100-200 cases per 100,000 population.

The male-to-female ratio for PD is 3:2 or sometimes equally.

The prevalence of PD increases with age. In patients younger than 40 years, the prevalence is 5 cases per 100,000 population, increasing to 300-700 cases per 100,000 population in the seventh decade and rising to more than 700 cases per 100,000 population in persons older than 70 years.

Pathophysiology

PD is a disorder of the extrapyramidal system (ie, motor structures in the basal ganglia which include caudate,putamen, globus pallidus, subthalamic nucleus and the substantia nigra).

Basal ganglia plays an important role in the planning and programming of movement by selecting and inhibiting specific motor synergies. Motor programs are consolidated into efficient goal-directed motor plans, translating thought into willed movements and regulating levels of kinetic activity, muscle tone and muscle force.

PD may be caused by degeneration of dopamine-producing cells in the substantia nigra, resulting in decreased levels of dopamine in the striatum.

Symptoms of PD usually begin to appear when dopamine levels drop by at least 50%. Associated hyperactivity of cholinergic neurons in the caudate nuclei results in an imbalance in the normal dopamine-to-acetylcholine ratio, which contributes to the symptoms.

Causes

The exact cause of PD remains unclear. A combination of factors probably is responsible for the condition's development. Various theories include the following:

• Accelerated aging
• Normal aging is associated with clinical features that may resemble PD.
• Aging is associated with a decline of pigmented neurons in the substantia nigra and with decreased levels of striatal dopamine and dopa decarboxylase.
• Some authorities believe that PD may result from the effects of aging superimposed on an insult to the nigrostriatal system earlier in life.

• Oxidative stress
• PD patients may suffer the combined effects of multiple factors, culminating in damage from free radicals.
• Dopamine oxidation can result in the formation of hydrogen peroxide, as well as the superoxide anion radical.
• Hydrogen peroxide can undergo reactions with ferrous ions, resulting in formation of the highly toxic hydroxyl radical.
• These hydroxyl radicals can cause cell membrane damage.
• Genetic susceptibility
• Genetic factors seem to play a greater role in PD that has an earlier onset.
• An increased incidence of a family history of PD is observed in affected individuals (16% vs 4% of control population).
• Environmental toxins include the following:
• Cyanide
• Manganese
• Carbon disulfide
• Pesticides
• Well water
• Lead
• Methanol
• Organic solvents

• Medications that can cause parkinsonian symptoms but not PD itself include the following:
• Metoclopramide
• Domperidone
• Reserpine-containing antihypertensives
• Neuroleptics
• Increased BMI was shown in one study to be associated with an increased risk of PD development. This effect was found to be graded (the greater the BMI, the higher the risk) and independent of other risk factors.

Clinical Presentation

Symptoms and signs of PD typically begin in one extremity or side but eventually involve the other limbs and trunk.

• Muscle Rigidity - it is often the initial presentation that is seen. Patients frequently complain of heaviness and stiffness of their limbs. Two types of rigidity are identified: Cogwheel and Lead Pipe type of rigidity.

Rigidity is often asymmetrical. It typically affects proximal muscles first, especially the shoulders and neck, and it progresses to involve muscles of the face and extremities. Prolonged rigidity results in decreased range of motion (ROM) and serious secondary complications of contracture and postural deformity.

• Bradykinesia - General slowing of movements and difficulty in maintaining movements. Moments of freezing may occur and are characterized by a sudden break or block in movement. Movements are typically reduced in speed, range and amplitude.
• Resting Tremor – it is an involuntary oscillation of a body part occurring at a slow frequency of 4 to 6 Hz. It is typically seen at rest and disappears with voluntary movement. This is usually manifest as a pill-rolling tremor of the hand, although it can progress to forearm, jaw and head and trunk (postural tremor).
• Postural Instability - Assumption by patient of a stooped-forward posture is seen. Narrowing of the base of support increases postural instability. Frequent falls and fall injuries are the results of progressive loss of balance.
• Festinating gait pattern (stumbling forward) with decreased arm swing during ambulatory activity.
• Painful dystonia, usually occurring in the early morning
• Dementia, often a late feature, ultimately occurring in about one third of patients
• Autonomic symptoms
• Slowed enteric motility and constipation
• Urinary retention and incontinence
• Orthostatic hypotension
• Masklike face
• Micrographia
• Hypokinetic dysarthria
• Olfactory dysfunction (hyposmia), which may be present prior to motor symptoms and often is not recognized by the patient
• Dysphagia
• Depression
• Akathisia, a sense of an inner restlessness and need to move (inability to sit still).
• Seborrheic dermatitis, usually of the face and scalp

Clinical Course:

An estimate of the stage and severity of disease can be made using a staging scale.

The most widely used is the Hoehn-Yahr Classification of Disability Scale.

Stage	Character of Disability
I	Minimal or absent; unilateral if present
II	Minimal bilateral or midline involvement. Balance not impaired.
III	Impaired righting reflexes, unsteadiness when turning or rising from chair, some activities are restricted but patient can live independently and continue some forms of employment.
IV	All symptoms present and severe. Standing and walking possible only with assistance.
V	Confined to bed or Wheel chair.

Medical Management:

Pharmacological management –

a) Neuroprotective Therapy: Monoamine Oxidase Inhibitors (MAOs) to improve metabolism of intracerebral dopamine.

b) Symptomatic Therapy:

- Levodopa (L-dopa) is the mainstay drug. It is a metabolic precursor of dopamine that is able to cross the blood-brain barrier and raise the level of striatal dopamine in the basal ganglia.

- Dopamine Agonists – are administered along with L-dopa. They act on the postsynaptic dopamine receptors. The greatest benefit being reduction of rigidity and bradykinesia.

- Anticholinergic agents – (Trihexyphenidyl, Bentropin)

Surgical Management –

a) Abative surgery: Pallidotomy and thalamotomy.

b) Deep Brain Stimulation: involves implantation of electrodes into the brain where they block nerve signals that cause symptoms.

c) Neural Transplantation: transplantation of cells capable of surviving and delivering into striatum of patients with advanced PD is an experimental treatment.

PHYSICAL THERAPY MANAGEMENT:

Examination and Evaluation:

A comprehensive examination is required to determine the level of impairments and degree of function.

Elements of the examination for a patient with Parkinson’s disease-

Patient History –

- Age, sex, education

- Social History: behaviors, family and caregiver resources, social support systems.

- Occupational History

- Living environment : home/work barriers

- Hand dominance

- General health status

- Family history

- Medical/surgical history

- Chief complaints

- Functional status and activity level

Systems Review:

- Neuromuscular

- Musculoskeletal

- Cardiovascular/ Pulmonary

- Integumentary

Tests and Measures/Impairments:

- Cognition: mental status, memory

- Oromotor function: communication, swallowing

- Psychosocial function: motivation, anxiety, depression

- Anthropometric characteristics: BMI, girth, length, edema

- Aerobic capacity and endurance

- Sensory integrity

- Pain: intensity and location

- Joint integrity: ROM (Active and passive), muscle length and soft tissue extensibility

- Posture: alignment and position, symmetry

- Muscle performance: strength, power, endurance

- Motor function: tone, voluntary movements, slowness, arrest of movements

- Gait: pattern and speed

- Functional status: Hoehn- Yahr classification of disability, basic and instrumental ADL, FIM levels.

Aims of Treatment:

1) Patient counseling and Education

2) Early intervention

3) Reduce Tone/Rigidity

4) Improve Movement and activity

5) Improve muscle strength and exercise capacity

6) Reduce tremors

7) Improve Posture and Balance

8) Improve Gait pattern

9) Increase functional activities and independence

Physiotherapy Intervention:

ð Patient, Family, and Caregiver Education :

Education of patients, family members and caregivers is critical to attaining optimal outcomes. Education should be given about the clinical presentation, medications, and preventive measures to minimize secondary complications & impairments.

They should be taught about effective solutions to regular exercise participation and its benefits. Strategies for energy conservation and activity pacing are explained.

ð Early Intervention:

Early intervention is critical in preventing the devastating musculoskeletal impairments Parkinson’s patients are so prone to develop.

ð Motor Learning Strategies:

In the early stages of disease, practice can be expected to improve learning and performance while in the more advanced stages and in the presence of pronounced cognitive deficits, training will likely be less successful. The therapist needs to structure treatment sessions to optimize motor learning. Repetitions are included to develop skills. Long and complex movements should be avoided or broken down into parts.

External cues are effective in triggering sequential movements and improving movement characteristics in individuals with mild to moderate PD. These cues appear to facilitate movements by utilizing different brain areas. Visual and auditory cues are used more frequently.

ð Relaxation Exercises:

Gentle rocking exercises can be used to produce generalized relaxation of excessive muscle tension due to rigidity.

During therapy, slow, rhythmic, rotational movements of the extremities and trunk (lower trunk rotation, sidelying rolling) can be considered and should precede interventions such as ROM, stretching and functional training.

Diaphragmatic breathing exercises can be given to promote relaxation. Gentle yoga and Tai Chi can be effective for patients with PD because of emphasis on combining slow, steady stretching with maintenance of postures and movement forms.

ð Flexibility Exercises:

Both active and passive ROM exercises are used to improve flexibility.

Exercises should focus on strengthening the weak muscles while lengthening the tight muscles.

Traditional stretching techniques can be used to elongate muscles. Special consideration should be given to the gentle stretching of elbow flexors, hip and knee flexors and ankle plantar flexors. Stretching can be combined with joint mobilization techniques to reduce tightness of the joint capsule or of ligaments around a joint.

Passive positioning can also be used to stretch tight muscle and soft tissues. Patients in late-stage PD are likely to demonstrate severe flexion contractures of the trunk and limbs (Phantom-Pillow posture). So patients may benefit from prone lying. Mechanical low load stretching can also be used with passive positioning to stretch the tight muscles.

Because these patients have a minimum of energy to expend, they may benefit from ROM exercises in physiological patterns of motion. PNF patterns can be used as they combine several motions at once while emphasizing rotation.

ð Strength Training:

Strengthening exercises are indicated for patients with primary muscle weakness and insufficient central activation of the motor unit as well as for disuse weakness associated with prolonged inactivity. Strength training has been shown to improve motor function, functional mobility, balance, gait and in reducing fall risks.

ð Functional Training:

The overall emphasis is on improving mobility function with specific emphasis on improving mobility of axial structures, the head, trunk, hips, and shoulders.

Patients may benefit from assisted movements progressing to active movements to improve initial motor performance.

Mat activities emphasizing on rolling and transitions from one position to another (like sitting to standing, prone kneeling to sitting) helps in reducing truncal rigidity and bradykinesia.

Anterior and posterior pelvic tilts, side-to-side tilts, pelvic clock exercises can be practiced while sitting on a therapy ball. These activities help in improving pelvic mobility thus facilitating good posture while sitting and standing.

Weight shifts and rotational movements in standing should be practiced. Standing with upper extremities extended and hands weightbearing on a wall can be used to promote upper trunk extension.

Mobilizing facial muscles is important because the patient will have social interaction. The patient can be instructed to practice lip pursuing, movements of the tongue, swallowing, and facial movements such as smiling, frowning etc.,

ð Balance Training:

Balance training should emphasize practice of dynamic stability tasks e.g., weight shifts, reaching, axial rotation of head and trunk, axial rotation combined with reaching, etc.,

Seated activities include sitting on a therapy ball. Challenges to balance can be introduced by varying arm position (i.e., arms out to side, arms folded across chest), varying foot/leg position (i.e., feet apart, feet together) or adding voluntary movements (e.g., arm clapping, arms overhead, single leg raises, head and trunk rotations).

Training should focus on achieving faster initiation and execution movement times supported by the use of appropriate cueing strategies.

Strategies for varying environmental demands include altering the support surface (e.g., standing on foam), visual inputs (e.g., reduced lighting, eyes closed), or challenging the patient with a variable open environment (e.g., busy clinic setting).

Kitchen sink exercises – standing and performing heel rises and toe offs, partial wall squats or back-kicks, and marching in place.

ð Gait Training:

Gait training focuses on primary gait impairments which typically include slow speed, shuffling gait pattern, diminished arm swing and trunk movements, and an overall attitude of flexion while walking.

Training programs are designed to

- lengthen stride,

- broaden base of support,

- improve stepping,

- improve heel-toe gait pattern,

- increase contralateral trunk movement,

- increase arm swing, and

- increase speed.

Training should also be given in varying environmental demands by altering the support surface, impairing visual inputs etc.

ð Cardiopulmonary training:

Respiratory dysfunction is common due to postural changes, inactivity and rigidity of muscles.

Training program should include diaphragmatic breathing exercises and exercises that recruit neck, shoulder and trunk muscles. Deep breathing exercises helps in improving chest mobility and vital capacity.

ð Group and Home exercises:

Group exercise classes can be valuable for patients with PD. Patients benefit from the positive support, camaraderie, and communication the group situation offers. Selecting the patients with similar levels of disability is often advisable.

The patients can begin in the seated position and progress to standing. Stretching exercises can be given as a warm up exercises.

Use of a wand or cane can be effective in promoting overhead activities.