If you’re a physical therapist involved in clinical practice, there’s a good chance you’ll encounter a patient with PD, a disorder of the brain’s basal ganglia. More than one million people currently have this condition, and by 2020 there may be 40 million more.¹ The majority of cases are diagnosed in people between the ages of 50 and 79. One out of 1,000 people over age 65 will develop PD, and one out of 100 will develop it over age 75.² White Americans and Europeans have higher rates of PD when compared to black Africans.³

Underlying Cause

In healthy people, the basal ganglia are a finely tuned group of nuclear masses that work to initiate voluntary movements and their associated postural adjustments as well as alternating motions. The corpus striatum in the cerebral hemisphere, the subthalamic nucleus in the diencephalon, and the substantia nigra in the midbrain interconnect to form the basal ganglia. In the basal ganglia are stored motor plans, also known as a motor “sets,” used to execute planned movements. The substantia nigra produces a neurotransmitter known as dopamine that enables the basal ganglia to function properly. When the substantia nigra doesn’t produce enough dopamine, signs and symptoms of PD become apparent. However, the basal ganglia will function properly until almost 70% to 80% of the dopamine has been depleted.⁴

While most PD is considered idiopathic, a single gene mutation may be responsible for the disease in a small percentage of people. Toxic or infectious exposures may be risk factors. Pesticides and herbicides may increase risk in sensitive people by 2% to 25%.⁴ Agents such as carbon monoxide, manganese, and cyanide, for example, have been known to damage cells in the basal ganglia, and groups of people diagnosed with PD have been found to have similar titers for herpes simplex 1 and 2, measles, rubella, and cytomegalovirus.⁴

More Than Just the Movement

In addition to motor impairments (discussed in the following section), PD has many non-motor signs. These include orthostatic hypotension, dysphasia, anxiety, increased pain sensitivity, dementia, depression, sensory difficulties, and sleep disorders, to name a few. These non-motor impairments can complicate the course of PD for the patient and the therapist. An important role of the PT is to work with other members of the healthcare team to monitor these other issues so that patients can maximize their rehabilitation. The medication for PD can also complicate the course of treatment. Patients present differently at various points in their medication cycle (known as “on” times when peak dosing is highest and “off” times when dosing is at its lowest). Also, some patients build a tolerance to the medication, decreasing the effectiveness after a period of years. Finally, there may be adverse effects of the medication, both somatic and psychiatric, that need to be addressed.

Clinical Presentation

Common characteristics of Parkinson’s disease include tremor, bradykinesia, akinesia and freezing, rigidity, and postural instability. A tremor is generally the initial symptom in patients with PD, and it is often observed unilaterally as a “pill–rolling” motion between the thumb and forefinger. Tremors may be worst at the initiation of movement or when the person is stressed or fatigued. Bradykinesia causes slowed movement, freezing, and changes in facial expression commonly seen in PD. Postural instability causes changes in posture and balance impairments, as does rigidity due to decreased arm swing and trunk rotation.

Bradykinesia and akinesia cause decreased facial expressions, as well as difficulty initiating movements that are normally automatic, such as walking or changing positions while seated. Freezing occurs in the midst of an action sequence, such as if a person is walking and his or her feet suddenly become stuck in place.⁴ Freezing can affect gait, speech, arm movements, and blinking. Often freezing occurs during changes in the environment, such as walking from a smooth floor onto a carpet. Research indicates that the striatum is not able to interpret several messages at a time from the cortical brain, such as motor and sensory input from the task and environment, and thus the action ceases.¹

Bradykinesia not only slows movements that were once routine, such as performing hygiene, walking, or eating, but it can cause speech impairments due to the affect on the muscles of the lips and tongue. Micrographia, or small writing, is another functional limitation caused by bradykinesia. Decreased activity in agonist muscles during tasks and disruptions in the anticipatory processes in the basal ganglia are thought to cause these reductions in the size and speed of movements.⁴

Rigidity affects both the agonist and antagonist muscle groups and will increase resistance to passive mobility in the effected area. It is an increased response to muscle stretch that generally begins unilaterally in proximal regions, and as the PD progresses, rigidity spreads to other limbs and the trunk.⁴ Rigidity in PD decreases arm swing during gait and limits trunk and spinal movement. This causes balance dysfunction during gait and functional activities, such as transfers and reaching.

Other causes of balance impairment in the person with PD stem from postural instability, or changes in posture, such as forward head posture; increased kyphosis; and trunk, hip, and knee flexion. Changes in the limits of stability as well as a decreased ability to use ankle, hip, and knee strategies can increase the risk of falls in a person with PD.⁵

Research has demonstrated that up to 96% of patients with PD have diminished postural reactions.⁶ Another study found that 60% of people with PD fall at least one time in a six-month period and 70% in a one-year period;⁷ of them, more than 17% sustained a fracture.⁸ Additional investigation looked at the relationship between PD and fracture risk and determined that people with PD are 2.2 times as likely to sustain a fracture, and those who fall are 3.2 times more likely to sustain a hip fracture from that fall than those without the disease.⁹

Tests and Measures  

Determining how to best treat patients with PD begins with determining their level of impairment. It is important to perform manual muscle tests, active and passive range of motion (ROM) tests, sensation tests, and the Functional Independent Measurement System assessment, but there are other useful tools that provide a more complete evaluation of these patients.¹⁰ Some scales that can be helpful diagnosing impairments, functional limitations, and guiding treatment include —

Hoehn and Yahr Scale,¹¹ one of the most common PD scales, which roughly indicates the involvement of PD the patient is experiencing. The scale classifies involvement into —  

• Stage one: Symptoms on one side of the body only
• Stage two: Symptoms on both sides of the body with no impairment of balance
• Stage three: Balance impairment with mild to moderate disease, but remains physically independent 
• Stage four: Severe disability, but still able to walk or stand unassisted
• Stage five: Wheelchair-bound or bedridden unless assisted  

Unified Parkinson’s Disease Rating Scale¹¹ is a 199-point scale that measures the progression of Parkinson’s disease over time. Three constructs are measured: cognition, behavior, and mood; ADL; and motor ability.

Parkinson’s Disease Questionnaire (PDQ – 39) is a scale completed by the patient to measure quality of life. Thirty-nine questions cover eight “dimensions,” including mobility, ADL, emotions, stigma, social support, cognition, communication, and bodily pain. This measure is reliable, valid, and helpful in determining the amount of impairment the patient is experiencing. This tool has been shown to have correlation with the Hoehn and Yahr Scale.¹²

Trunk Impairment Scale (TIS), developed for use with patients who have had experienced a stroke, are also used in patients with PD.¹³ Although rehabilitation seems to focus on the upper and lower extremities, gait, ADL, and balance, there is evidence that sitting balance may predict functional and motor recovery after a stroke.¹⁴ The TIS measures static sitting balance, dynamic sitting balance, and coordination. Examples of tasks include sitting quietly, sitting with legs crossed, leaning to the side, and trunk rotation. PD generally presents with signs that are worse on one side, trunk strength and trunk mobility that decreases with progression of the disease, as well as deconditioning from decreased mobility. The TIS can be adapted for the patient with PD and “hemiplegic side” can be changed to “weaker side.” Literature states that patients with PD develop decreased spinal ROM and trunk weakness,^15,16 so the TIS can be a useful tool for determining impairments, guiding treatment, and furthering research.^13,14

Berg Balance Scale (BBS) is a 56-point scale (=45 = higher risk for falling) that looks at static and dynamic sitting and standing tasks, such as sitting and standing quietly, standing with eyes closed, rising from a chair, functional reaching, bending to pick up an object, and standing on one foot. It is a quick, simple test that requires a yardstick, a slipper, and a few chairs. People with PD commonly have lower extremity disabilities, such as decreased strength, ROM, and coordination, as well as gait and balance abnormalities. These factors are correlated with high risk for falls.¹⁷ Research has suggested, however, that the BBS be used as a screening tool for people at risk for falls, and not a “dichotomous” test to label people as “at risk” or “not at risk.”¹⁸ The results indicate that many people who scored above the cutoff of 45 (low risk) sustained falls after all.¹⁸

Timed “Up and Go” (TUG) requires that the patient stand up from a chair, walk at a comfortable speed for 3 meters, turn around, walk back to the chair, and sit down.^19,20 Although easy to administer, it may be difficult to complete and take extra time for those with PD. A healthy 60- to 69-year-old will be able to perform the task in approximately eight seconds, regardless of gender. A 70- to 79-year-old needs approximately nine seconds, regardless of gender, and 80- to 89-year-old men are normally able to perform the TUG in 10 seconds, while their female counterparts complete it in 11 seconds.²¹

The TUG correlates well with other tests and parameters, including the Berg Balance Scale (r = -0.81), the Barthel Index of ADL (r = -0.61), and gait speed predicting falls (r = -0.78).¹⁹ One study found that in patients with PD the TUG revealed two patterns of results related to the “on” and “off” cycle of the patients’ PD medications.²² Because the test scores were markedly different during on and off times, the investigators suggested that all assessments be performed at least twice in this “on”/“off” cycle.²²

Physical Therapy Treatment

Physical therapy treatment has been shown to yield functional improvements in patients with PD.²³ Some have suggested that PT is not efficacious with PD because it is a chronic, progressive neurological disease, but recent studies have shown that patients demonstrated improvements in gait, ADL, and overall quality of life. Maintaining, if not improving, independence may keep patients with PD out of assisted living and at home for a longer time. When considering cost-containment, short, inpatient stays are much less costly than admitting someone on a long-term basis or permanently into a skilled facility or nursing home.

Conditioning: People with PD need to improve strength,²⁴ cardiovascular fitness,²⁵ spinal ROM,^15,16 and balance.¹ When people are living with a chronic, progressive disease like PD, everyday tasks become more demanding due to deconditioning, lack of mobility, fear of falling, and general malaise. PD has also been shown to cause changes in cardiovascular function that result in decreased metabolic efficiency.^26,27 This reduced efficiency could lead to the debilitating states listed above. Physical therapy can help people with PD regain some of their function from benefits gained by performing general conditioning exercises.²⁷ One study demonstrated improvements in walking economy (VO2 max and O2 consumed) and increases in six-minute walk distances. It also showed improvements in motor abilities as measured by the Parkinson’s Disease Rating Scale (PDRS), the Continuous Scale — Physical Functional Performance  (CS-PFP) <http://www.coe.uga.edu/cs-pfp/index.html>, and functional reach tests.²⁷ This overall conditioning may lead to improved endurance, increased mobility, improved balance, and a decrease in falls.

Improving Postural Stability: Approximately 96% of patients with PD see decreased postural reactions and instability.^6,28 Postural instability reduces their ability to use hip, knee, ankle, and stepping strategies for postural correction and accounts for a large number of falls. PD decreases their compensatory step size and increases the time to initiate a step. One study demonstrated that perturbation training — repetitive training of compensatory steps — can reverse these effects.²⁸ In this study, perturbation training consisted of perturbing the patient backward, forward, and to the right and left, and having them practice reacting.²⁸ It also demonstrated subsequent increases in gait velocity, step length, and cadence, as well as a decrease in time of double support. Their PDQ-39 mobility subscore increased, demonstrating a greater quality of life for these patients.

Another study on postural instability and postural correction found that patients with PD should be trained using lateral perturbations and lateral or side-stepping as a correction strategy.²⁹ Investigators found that patients with PD need increased practice with lateral weight-shifting, speed, and size of steps to improve their stability.²⁹

Education: Equally important as conditioning and postural retraining is education. PTs need to teach patients ways to compensate to help them overcome the movement disorders they face, such as bradykinesia, gait hypokinesias and akinesia, and freezing.

One technique to improve mobility in patients with PD is to teach them the effects of performing secondary motor or cognitive tasks during primary tasks, such as walking. Research has shown that “dual task performance” during walking may diminish walking performance.^30-32 Studies have demonstrated that talking, carrying items, and getting items out of a pocket may adversely effect gait by reducing stride length and speed, while time of double limb support does increase to accommodate these changes. These findings suggest people with PD are at an increased risk of falling due to an inability to modulate gait mechanics in correlation with gait speed and stride length as well as ground clearance.^1,32 PTs are responsible for teaching patients with PD about these deficits and encouraging them to avoid dual tasking during walking or other tasks, such as rising from a chair or changing positions.^1,31,32

External Cueing: Another strategy for improving mobility in patients with PD is through the use of external cueing. One study investigated the efficacy of a home-based cueing program in people with PD.³³ In this single-blind, randomized clinical trial, three types of cueing types were used: auditory, visual, and somatosensory. Investigators used a prototype cueing device that was specifically developed for their study, and the subjects were trained by PTs in their own homes. They looked at gait, gait-related activity, and health-related quality of life. They found that nine sessions of cueing training demonstrated improvements in gait and gait-related mobility. The subjects demonstrated increased gait speed and step amplitude, as well as decreased step frequency. Researchers hypothesized that balance and overall confidence were improved, too, reducing the incidences of falls that the subjects experienced.³³

Another study looked directly at walking on the treadmill and external cueing in PD.³⁴ Investigators found that walking on a treadmill decreased the variability of gait in patients with PD.³⁴ The authors state several possibilities for this outcome. First could be the steady gait timing associated with walking on a treadmill, second could be the auditory (footsteps) or visual (watching one’s feet) rhythm from walking on a treadmill, and third could be the increased level of awareness to walking.³⁴

Researchers have noted that external cues and cognitive strategies are the primary means of improving gait in people with hypokinesias.¹ The use of visual external cues, such as stepping over lines, has been documented as early as the 1960s.³⁵ Placing lines perpendicular to the direction of gait about a step length apart decreased shuffling in people with PD. The use of such visual cues has since been substantiated in other studies,³⁶ although the retention of the learning using visual cues needs further investigation.

Another study did find some lasting improvement after one month of visual training, suggesting that motor learning can improve gait in these people.³⁶ Others have investigated and had success with external auditory cueing, replacing the internal signal from the basal ganglia with an external one.³³

Part vs. Whole Training: Another useful strategy is “part training,”³⁷ or breaking tasks down. Planning sequential movements involves the basal ganglia. Therefore, breaking movements down into individual steps can help avoid the basal ganglia; the cerebellum will instead modulate the activity. Instead of telling people with PD to “get out of bed,” help them initially with external cueing and their own cueing. For example, tell them to roll onto their side, bring their legs off of the bed, and push up their body. This type of training also works well because it is task-specific.¹ Researchers believe that task-specific or “task-oriented” approaches allow the patient to problem solve in the true context of a task and encourage normal movement patterns.³⁷

Overcoming Cognitive Impairments — Learning: Because PD has an adverse effect on patients’ motor learning capacity, PTs need to look for the best ways for those with PD to learn new tasks and to learn new ways to do everyday tasks.³⁸ One study found that although a random-order practice produced better learning results in individuals without disabilities, it was too much of a challenge for those with mild PD. Because of the basal ganglia deficits, people with PD have a diminished ability to perform “task switching” and display decreased performance with random practice (e.g. ABA, CBC, ABC).³⁸ The study researchers recommend using a blocked practice order (e.g. AAA, BBB, CCC) to improve learning in those with PD.³⁸

Not all patients with PD come to a hospital or clinic with textbook signs and symptoms. Some come with PD as a comorbidity only, yet it complicates a simple total knee protocol. Some have only cognitive problems with mild tremor; others have no tremor but show a flat affect and an inability to walk unassisted. Others can walk, but they cannot initiate or find the motor strategies to get out of bed. A thorough examination using valid and reliable tools can lead to an appropriate treatment plan for each individual and his or her impairments. PTs need to be knowledgeable about this disease to execute treatment protocols designed to challenge specific deficits that affect overall performance of everyday activities.