Parkinson’s disease (PD) is a progressive neurological disease that mainly affects people over 60 years of age. Before we get into the signs and symptoms that can hint at the diagnosis of PD, let’s review the areas of the brain that are affected by this nerve-degenerating disease.
The brain has multiple overlapping systems involved in the initiation and execution of smooth, controlled, and coordinated movement. These systems influence and modify motor commands from the primary motor cortex.
There are six major regions of the brain that are involved in modifying movement:
- Premotor cortex
- Supplementary motor cortex
- Basal ganglion (extrapyramidal system)
These regions of the brain influence the final common pathway of motor command—the pyramidal system. The pyramidal system consists of the primary motor cortex, the corticospinal tracts, and the corticobulbar tracts.
What role do the basal ganglia and dopamine play in PD?
When it comes to PD, the basal ganglia are of particular interest. Most of the output from the basal ganglia is inhibitory and acts as a braking system on movement. Their function is far more complex than this, but for simplicity’s sake, think of the basal ganglia as providing a tonic inhibitory influence on motor commands.
To initiate movement, the brake (provided by the basal ganglia) must be lifted. Dopamine acts through the nigrostriatal tract to lift the brake on motor activity and thus allows movement.
Parkinson’s disease involves a loss of the cells that provide dopamine input to the basal ganglion, and thus the brakes are essentially left engaged. This is thought to be the mechanism behind one of the principal symptoms of Parkinson’s disease—bradykinesia. Thus, patients with PD have a difficult time initiating movement (akinesia) and their movements are slowed (bradykinesia).
What is the pattern of disease in PD?
The onset of PD usually occurs in patients in their sixties, and the disease progresses slowly. Although PD eventually results in severe disability and often dementia, life expectancy is not significantly shortened. Death is often due to secondary problems associated with the disease such as falls, pneumonia, aspiration, and immobility.
When should you consider PD as a possible diagnosis?
There is no definitively objective radiographic test or laboratory study that will make the diagnosis of PD; it is a purely clinical diagnosis. Classically, patients with PD exhibit the clinical triad of bradykinesia, tremor, and muscular rigidity. However, there are many other potential components of PD, and the disease may not be obvious—particularly in the early stages.
Early indications of PD
If you suspect that your patient has Parkinson’s disease, it is important to start by asking your patient if they are experiencing early indications of PD. These symptoms may include constipation, vocal changes including a loss of vocal strength and range, difficulty with swallowing, a loss of fine motor skills, restless legs or cramping legs at night, a loss of balance, sleep disturbances, and loss of smell.
None of these symptoms are specific for PD, but they may help you strengthen the diagnosis.
Other signs and symptoms of PD
In addition to the early indications mentioned above, PD patients often experience several other signs and symptoms which may include a loss of facial animation, a resting tremor, slow movements (bradykinesia), rigidity, postural instability, depression, and an altered gait.
Loss of facial animation in PD patients
The loss of facial animation is also called a blunted affect, which refers to the tendency for PD patients to appear unemotional, unfriendly, or depressed. Patients with a blunted affect seldom smile. Often, this results in the physician feeling as though they are having real trouble establishing a connection with a patient. For example, a PD patient may tell you that you’re quite funny, yet never smile or chuckle once during your interactions.
Tremors in PD patients
Tremors should be apparent when an extremity is at rest. This usually begins unilaterally or asymmetrically and involves the hands at rest. The classic description is a pill-rolling movement between the thumb and index finger. Tremors can worsen to include much of the arm and titubation of the head.
Tremors should dampen or go away with intentional movement. If it gets worse with intentional movement, the patient may have an essential tremor. Essential tremor is another condition arising from the basal ganglion (e.g., the extrapyramidal system). It involves a tremor that worsens with increased precision of movement and fatigue.
Essential tremor often temporarily improves with alcohol or beta-blockers. It can worsen to the point of being incapacitating, but it does not have the multitude of other motor and non-motor problems seen with PD.
Essential tremor is not thought to be a precursor of PD, but a small percentage of people with essential tremor can go on to develop PD. Notably, essential tremor and resting tremors are not typically seen together.
Bradykinesia in PD patients
Bradykinesia is also common in PD patients, and it is defined as slow movements and / or difficulty with initiating movement. This is most easily observed by watching the patient’s spontaneous activity or by asking them to perform simple tasks such as getting up and walking across the room.
Rigidity in PD patients
Patients with PD often show rigidity. To check, move the patient’s arms passively and look for stiffness or involuntary resistance to the movement that may be smooth (known as lead pipe rigidity) or jerky (known as cogwheel rigidity).
Postural instability, poor balance, and altered gait in PD patients
Check for postural instability, poor balance, and altered gait. These symptoms are common as the disease progresses and makes falling a significant risk. In PD, you will often see a shuffling, short-stepped, and hunched-over gait with decreased arm swing. Often, the shuffling may accelerate as the patient’s legs try to catch up with a tipping torso.
Depression and PD
Be aware that depression can look like PD, and PD can look like depression. As well, depression is often a component of Parkinson’s disease.
Signs and symptoms indicating that the patient may not have classic PD
There are several other Parkinson’s-like diseases that, while similar to PD, are not technically classified as PD. These diseases may not respond as well to treatment as PD does:
- Progressive supranuclear palsy
- Multiple system atrophy
- Dementia with Lewy bodies
- Corticobasal degeneration
Be sure to evaluate your patient for signs and symptoms which may indicate that the patient does not have classic PD. These signs and symptoms may include urinary or fecal incontinence, disabling orthostatic hypotension, early onset (signs and symptoms in patients younger than 50 years of age), poor response to PD medications, symmetry of findings early in the disease, and a lack of tremor.
What should you do if you suspect PD?
First, order magnetic resonance imaging (MRI) of the brain to rule out alternative diagnoses such as tumors, demyelinating diseases, and basal ganglia strokes. Next, arrange for a consultation with a movement disorder specialist who can implement an initial management plan.
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