What is Parkinson’s disease?

Parkinson’s disease also known as hypokinetic rigid syndrome/HRS or paralysis agitans is a degenerative disorder of the central nervous system. The motor symptoms of Parkinson’s disease result from the death of dopamine-generating cells in the substantia nigra, a region in the midbrain. The cause of the cell death is unknown.

The main motor symptoms are collectively called parkinsonism, or a “parkinsonian syndrome”. Parkinson’s disease is often defined as parkinsonian syndrome that is idiopathic (having no known cause), although some atypical cases have a genetic origin.

Symptoms of Parkinson’s disease

Parkinson’s disease affects movement, producing motor symptoms. Non-motor symptoms, which include autonomic dysfunction, neuropsychiatric problems (mood, cognition, behavior or thought alteration), and sensory and sleep difficulties, are also common.

·         Motor: Four motor symptoms are considered cardinal in PD: tremor, rigidity, slowness of movement, and postural instability. Other recognized motor signs and symptoms include gait and posture disturbances such as festination (rapid shuffling steps and a forward-flexed posture when walking), speech and swallowing disturbances including voice disorders, mask-like face expression or small handwriting, although a range of possible motor problems that can appear is large.

·         Neuropsychiatric:  These include disorders of speech, cognition, mood, behavior, and thought. The most common cognitive deficit in affected individuals is executive dysfunction, which can include problems with planning, cognitive flexibility, abstract thinking, rule acquisition, initiate appropriate actions and inhibiting appropriate actions, and selecting relevant sensory information.

A person with PD has two to six times the risk of dementia compared to the general population.

The most frequent mood difficulties are depression, apathy and anxiety.

·         Other: Sleep problems are a feature of the disease and can be worsened by medication. Alteration in autonomic nervous system can lead to orthostatic hypotension (low blood pressure upon standing), oily skin and excessive sweating, urinary incontinence and altered sexual function.

Constipation and gastric dysmotility can be severe enough to cause discomfort and even endanger health.

Several eye and vision abnormalities such as decreased blink rate, dry eyes.

Causes of parkinson's disease?

PD in most people is idiopathic (having no known cause). However, a small proportion of cases can be attributed to known genetic factors. Other factors have been associated with the risk of developing PD, but no causal relationship have been proven.

·     Environmental factors: A number of environmental factors have been associated with an increased risk of Parkinson’s including: pesticide exposure, head injuries, and farming

·        Genetics: PD traditionally has been considered a non-genetic disorder, however around 15% of individuals with PD have a first-degree relative who has the disease. At least 5% of people are now known to have forms of the disease that occur because of a mutation of one of several specific genes.

Diagnosis of Parkinson’s disease

A physician will diagnose PD from the medical history and a neurological examination.

There is no lab test that will clearly identify the disease, but brain scans are sometimes used to rule out disorders that could give rise to similar symptoms.

The finding of Lewy bodies in the midbrain on autopsy is usually considered proof that the person had Parkinson’s disease.

Computed tomography (CT) and magnetic resonance imaging (MRI) brain scans of people with PD usually appear normal. These techniques are nevertheless useful to rule out other diseases that can be secondary causes of parkinsonism, such as basal ganglia tumors, vascular pathology and hydrocephalus.

A pattern of reduced dopaminergic activity in the basal ganglia can aid in diagnosing Parkinson’s disease.

Treatment of Parkinson’s disease

·         Pharmacological treatment:

Levodopa has been the most widely used treatment for over 30 years. Since motor symptoms are produced by the absence of dopamine in substantia nigra, the administration of L-DOPA temporarily diminished the motor symptoms.

Dopamine agonists: bromocriptine, pergolide, apomorphine, etc.

MAO-B inhibitors: selegiline and rasagiline increase the level of dopamine in the basal ganglia by blocking its metabolism.

Other drugs such as amantadine and anticholinergics may be useful as treatment of motor symptoms.

·      Surgery: Surgery for PD can be divided into two main groups: lesional and deep brain stimulation (DBS). DBS is the most commonly used surgical treatment.

Physiotherapy intervention:

The review version of the European Physiotherapy Guideline divides physiotherapy intervention for Parkinson’s into exercise and movement strategy training.

Exercise: Exercise has been proven to maintain health and wee-being in Parkinson’s and now importantly it is shown to play a big role in addressing secondary prevention (focusing on strength, endurance, flexibility, functional practice and balance.

Physical activity, in particular, aerobic exercise might slow down the motor skill degeneration and depression.

Quality of life may be increased when performing strength training against an external resistance (cycle ergometer, weight machines, therapeutic putty, elastic and, weight cuffs).

Executing dual task, e.g. talking while walking, is commonly difficult in patients with Parkinson’s. Training such patients with Motor-Cognitive Dual-Task training, improves dual-task ability and might improve gait, balance and cognition.

Movement Strategy Training:

Strategies (physical or attentional cues and combined strategies) can help overcome some of the resultant problems, hence have become an increasingly utilized method of intervention for people with Parkinson's.

The European Guidelines provides a section that describes the use of motor learning, expectations if practiced and executed as a strategy to train improvements in movement. It takes the form of cued functional and dual task training. Compensatory strategy training uses external cues, self-instruction and attention.

Examples include:

·         Visual cueing: a focus point to step over and initiate gait; strips of tape on the floor to initiate or continue walking through areas that cause slowing or freezing.

·         Auditory cueing: continue 1-2-3 to initiate walking; stepping to the beat of metronome or specific music at a specified cadence to continue the rhythm of walk.

·         Attention: Thinking about taking a big step; making a wider arc turn. This is applicable in case of correcting a bad habit- such as walking with stuff hip or hip hiking.

·         Proprioceptive cueing: rocking from side to side ready to initiate a step; taking one step backwards as a cue ready to then walk forwards.

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