Parkinson’s disease

Parkinson’s disease (PD) belongs to a group of conditions called motor system disorders, which are the result of the loss of dopamine-producing brain cells. The four primary symptoms of PD are tremor, or trembling in hands, arms, legs, jaw, and face; rigidity, or stiffness of the limbs and trunk; bradykinesia, or slowness of movement; and postural instability, or impaired balance and coordination. As these symptoms become more pronounced, patients may have difficulty walking, talking, or completing other simple tasks. PD usually affects people over the age of 50.  Early symptoms of PD are subtle and occur gradually.  In some people the disease progresses more quickly than in others.  As the disease progresses, the shaking, or tremor, which affects the majority of PD patients may begin to interfere with daily activities.  Other symptoms may include depression and other emotional changes; difficulty in swallowing, chewing, and speaking; urinary problems or constipation; skin problems; and sleep disruptions.  There are currently no blood or laboratory tests that have been proven to help in diagnosing sporadic PD.  Therefore the diagnosis is based on medical history and a neurological examination.  The disease can be difficult to diagnose accurately.   Doctors may sometimes request brain scans or laboratory tests in order to rule out other diseases.

Parkinson disease affects movement (motor symptoms). Other typical symptoms include disorders of mood, behavior, thinking, and sensation (non-motor symptoms). Patients’ individual symptoms may be quite dissimilar and progression of the disease is also distinctly individual.

Motor symptoms

The cardinal symptoms are (mnemonic “TRAP”):

Tremor: normally 4-6 Hz tremor, maximal when the limb is at rest, and decreased with voluntary movement. It is typically unilateral at onset. This is the most apparent and well-known symptom, though an estimated 30% of patients have little perceptible tremor; these are classified as akinetic-rigid.

Rigidity: stiffness; increased muscle tone. In combination with a resting tremor, this produces a ratchety, “cogwheel” rigidity when the limb is passively moved.

Akinesia/bradykinesia: absence of movement and slowness, respectively. Rapid, repetitive movements produce a dysrhythmic and decremental loss of amplitude.

Postural instability: failure of postural reflexes, which leads to impaired balance and falls.

Other motor symptoms include:

Gait and posture disturbances:

Shuffling: gait is characterized by short steps, with feet barely leaving the ground, producing an audible shuffling noise. Small obstacles tend to cause the patient to trip.

Decreased arm-swing.

Turning “en bloc”: rather than the usual twisting of the neck and trunk and pivoting on the toes, PD patients keep their neck and trunk rigid, requiring multiple small steps to accomplish a turn.

Stooped, forward-flexed posture. In severe forms, the head and upper shoulders may be bent at a right angle relative to the trunk (camptocormia).

Festination: a combination of stooped posture, imbalance, and short steps. It leads to a gait that gets progressively faster and faster, often ending in a fall.

Gait freezing: “freezing” is a manifestation of akinesia (an inability to move). Gait freezing is characterized by an inability to move the feet which may worsen in tight, cluttered spaces or when attempting to initiate gait.

Dystonia (in about 20% of cases): abnormal, sustained, painful twisting muscle contractions, often affecting the foot and ankle (mainly toe flexion and foot inversion) which often interferes with gait.

Speech and swallowing disturbances.

Hypophonia: soft speech. Speech quality tends to be soft, hoarse, and monotonous. Some people with Parkinson’s disease claim that their tongue is “heavy” or have cluttered speech.

Monotonic speech.

Festinating speech: excessively rapid, soft, poorly-intelligible speech.

Drooling: most likely caused by a weak, infrequent swallow and stooped posture.

Dysphagia: impaired ability to swallow. Can lead to aspiration pneumonia.

Other motor symptoms:

Fatigue (up to 50% of cases);

Masked faces (a mask-like face also known as hypomimia), with infrequent blinking;

Difficulty rolling in bed or rising from a seated position;

Micrographia (small, cramped handwriting);

Impaired fine motor dexterity and motor coordination;

Impaired gross motor coordination; Akathisia, the inability to sit still.

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