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Parkinson's disease PDF Print
Written by Gianni Pezzoli e Margherita Canesi   
Parkinson’s disease was described for the first time by James Parkinson in a booklet entitled “An essay on shaking palsy" , published in 1817.  Shaking palsy is the name that identified the disease for nearly a century, until one realized that the term was inappropriate, because patients with Parkinson's disease are not paralyzed.  For this reason the term idiopathic parkinsonism (idiopathic means “whose cause is unknown”) started to be used, but the most correct term in Italian is “malattia di Parkinson (=”Parkinson’s disease”), which honors the physician, who described the disease for the first time and replaces the old nineteenth-century translation “morbo di Parkinson" (=”Parkinson’s plague”).  What is Parkinson’s disease ? It is a disease of the central nervous system characterized mainly by degeneration of some nervous cells (neurons) located in a deep area of the brain called substantia nigra (“black substance”).   These cells produce a neurotransmitter i.e. a chemical substance that transmits messages to neurons in other areas of the brain. The neurotransmitter involved, which is called dopamine, is responsible for the activation of a circuit that controls movement. When dopaminergic neurons have diminished by at least 50%, receptors i.e. the arrival stations, are no longer stimulated adequately. These receptors are located in an area of the brain called striatum. Under the microscope small round particles called Lewy bodies, mainly made of alpha-synuclein, can be seen inside the ailing dopaminergic neurons of the black substance.  They are considered to be a specific feature of Parkinson’s disease that makes this disease fall into the category of synuclein disorders. These disorders vary according to the areas containing Lewy bodies.  They range from an extensive involvement of the cortex (dementia) to specific involvement of the black substance and locus ceruleus (Parkinson's disease) or involvement of nervous systems that innervate viscera (multiple system atrophy with impairment of the autonomic system). Parkinson’s disease occurs throughout the world more or less with the same frequency  in the two sexes.    Symptoms may occur at any age.  However, onset before the age of 40 years is unusual and before the age of 20 years is very rare. In most cases the first symptoms appear at about 60 years of age. The reason why these neurons diminish in size and then die is not known and still is investigated. In any case Parkinson's disease is only one of the parkinsonian syndromes or parkinsonisms. Parkinsonism is a generic term that is used both for Parkinson’s disease and for all syndromes that produce similar symptoms.      

What are the first symptoms ? When should you suspect Parkinson’s disease and consult a doctor ?

 BOX  Pay attentionThe typical tremor of PD appears at rest and diminishes or disappears as soon as one moves intentionally, for instance to lift a glass to drink Patients with PD have three characteristic symptoms: Tremor, rigidity and slow movements (bradykinesia), which may be accompanied by balance disorders, stooped posture, abnormal gait and many other secondary symptoms that are less specific and not essential for the diagnosis. At first patients report a feeling of weakness and difficulty in performing usual everyday movements, which they are able to complete, but getting tired more easily; there usually is no sensation of loss in muscle strength. Subsequently, they realize that they have difficulty in starting and completing movements at the same rate as before, as if the involved arm or leg were “bound”, rigid. The sensation that one has become slower and clumsier in moving may be the most common reason for consulting a doctor, together with the other main symptom that is typically associated with this disease and is the most evident: Tremor. It often is amongst the first symptoms due to the disease.  It usually involves the hands, appears at first on only one side and may involve either hand. The typical tremor of PD occurs at rest, for instance, when the hand is in one’s lap or one’s arms are left hanging along one’s body.   However, it is not an essential symptom for the diagnosis of PD.  Indeed, not all PD patients experience tremor and all tremors do not identify PD.
Other disturbances that often induce a PD patient to consult a doctor include changes in writing, which becomes different from what it used to be and becomes smaller and smaller as the patient continues to write; changes in voice, which sounds no longer the same to a usual listener, such as a relative and is described as weak and monotonous.  The same relative may notice that facial expression has changed:   The so-called “facies figee” i.e. a more fixed and less expressive face. All these symptoms, especially tremor, may become more evident and may be worsened by stressful events.

Figure

Difficulty in writing often is an early sign of the disease.  Writing becomes slower, loses accuracy, the letters become smaller as the patient continues to write.  The figure shows some samples of handwriting of a patient: above, at diagnosis of the disease; below, after 6 months of treatment with levodopa writing has become wider and legible once more.  Furthermore, the patient has increased his speed in writing. 

  

The main symptoms

TremorSlow oscillation (five to six times a second) of the hands, which look as if they were being used to count paper money. It generally starts in one hand and then, after a variable period of time, extends to its counterpart.  Also the feet may tremble, nearly always to a greater extent on the side where the disease started to appear, as well as the lips and mandible, much more rarely the neck and head. The typical tremor of PD appears at rest and diminishes or disappears as soon as one moves intentionally, for instance to lift a glass to drink. It is highly influenced by the emotional status of the subject, so that it worsens when emotions are experienced and improves during periods of quiet. Another type of tremor often reported by PD patients is an “internal tremor”.  This sensation is experienced by the patient, but is not visible to onlookers; it is amongst the annoying, but harmless manifestations of the disease.Gait disordersAt first a reduction in the automatic swinging of the arms appears, which is more pronounced on one side; later on steps may become shorter and “festination” may appear i.e. the patient bends forward and tends to walk faster as if he were trying to catch his centre of gravity.  In the advanced stages of the disease sudden motor block (“Freezing” of the legs) may occur, during which the feet of the subject seem to be glued to the floor. The phenomenon usually occurs in narrow passageways or when the patient starts to walk or changes direction. This difficulty may be overcome by resorting to measures, such as lifting the knees as one wanted to march, or considering lines on the floor as obstacles to be overcome, or even with a verbal rhythm, such as the ones used during military marches.Slowness in moving (bradykinesia)Impediments in moving makes the performance of any gestures slow.  This can be highlighted by making the subject perform movements that require dexterity.  These movements become clumsier and less pronounced as they are repeated until they are almost imperceptible.   Also difficulty in changing position, such as getting out of a car, turning in bed and getting dressed, such as putting on a jacket or a coat, are signs of bradykinesia. A consequence of bradykinesia is the reduction in facial expressions due to a reduction in the spontaneous facial expressions that usually accompany changes in mood, and also changes in writing, which becomes small (micrography). RigidityThis is a term that indicates an increase in muscle tone at rest or during movement. It may involve the limbs, the neck and the trunk. The reduction in upper limb swings during walking is a sign of rigidity associated with slowness in movements.PostureChanges in posture produce a stooped pose: The patients are sort of "folded" , so that their trunk is bent forward, their arms are folded and kept next to their trunk and also the knees are bent.  This posture, due to the addition of bradykinesia on top of rigidity, can be corrected by pharmacological treatment. As the disease advances the patient may develop a stoop that may become fixed.Balance disordersThese disorders appear in the later stages of the disease.  They are undoubtedly the less favorable symptoms. Balance disorders are fundamentally due to a reduction in righting reflexes and the subject loses the ability to spontaneously correct any imbalance.  They can be identified by checking the ability of the patient to correct a backward push.  The inability to maintain the standing position and to correct changes in balance can cause falls that may occur in any direction, although the patient usually tends to fall forwards. The symptom does not respond well to treatment.  
Last Updated ( Tuesday, May 15 2012 )
 
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