Blair Ford, M.D.
Center for Parkinson's Disease
& Other Movement Disorders
Columbia University Medical Center
For most people with Parkinson's
disease (PD), the most serious concern is with the motor system: stiffness,
slowness of movement, impaired handwriting and coordination, poor mobility and
balance. Descriptions of PD do not generally include the mention of pain. And
yet, when carefully questioned, more than half of all people with Parkinson's
disease say that they have experienced painful symptoms and various forms of
physical discomfort. Most people experience aching, stiffness, numbness and
tingling at some point in the course of the illness. For a few of them, pain
and discomfort are so severe that they overshadow the other problems caused by
the disease. This article will address these overlooked painful symptoms of PD,
and describe an approach to diagnosing and treating the various pain syndromes
that may occur.
Pain is described in textbooks as
an unpleasant experience associated with physical injury or tissue damage. Pain
can arise from anywhere in the body, of course. It goes without saying that
people with Parkinson's are subject to all of the painful conditions - cardiac,
gastroenterological, rheumatological, among others - that can affect people
without PD. This discussion will focus on pain that is directly related to PD
itself.
Pain syndromes and discomfort in
Parkinson's usually arise from one of five causes: (1) a musculoskeletal
problem related to poor posture, awkward mechanical function or physical wear
and tear; (2) nerve or root pain, often related to neck or back arthritis; (3)
pain from dystonia, the sustained twisting or posturing of a muscle group or
body part; (4) discomfort due to extreme restlessness and (5) a rare pain
syndrome known as "primary" or "central" pain, arising from
the brain.
It takes diagnostic skill and
clinical experience to determine the cause of pain in someone with PD. The most
important diagnostic tool is the patient's history. Where is the pain? What
does it feel like? Does it radiate? When does it occur during the day? Does it
occur in relation to any particular activity or medication? Perhaps the most
important task for people with Parkinson's who experience pain is to describe
as accurately as they can whether their medications induce, aggravate or
relieve their pain. To help your physician in diagnosing pain, refer to the
questions listed on page 5.
Musculoskeletal pain
Aching muscles and joints are
especially common in PD. Rigidity, lack of spontaneous movement, abnormalities
of posture and awkward mechanical stresses all contribute to musculoskeletal
pain in PD. One of the most common musculoskeletal complaints is shoulder
stiffness, sometimes called a frozen shoulder (this may in fact be the first
sign of PD). Hip pain, back pain and neck pain are all common painful
complaints in PD. With prolonged immobility of a limb, band-like tendons,
termed contractures, may occasionally develop, usually in the hands or feet; one
example is the clenched fist contracture that may occur with prolonged flexion
of a hand.
An accurate diagnosis of
musculoskeletal pain is based on a careful history and a physical examination
that takes into account posture, limb and trunk rigidity and gait. It can
occasionally be challenging to distinguish between back pain due to PD and that
caused by arthritis or scoliosis. Occasionally, further testing - including
x-rays, bone scans, ultrasound and rheumatologic or orthopedic consultation -
will be needed. The proper treatment of musculoskeletal pain in PD depends upon
the cause of the pain. If the pain is the result of excessive immobility or
rigidity, a physician may prescribe dopaminergic therapy, physical therapy and
an exercise program. If the treatment is successful, patients should continue
with an exercise program that strongly emphasizes range of motion, to prevent
the development of further musculoskeletal problems.
Radicular and neuritic pain
Pain that occurs close to a nerve
or nerve root is described as neuritic or radicular pain. The classic root-pain
syndrome is sciatica, caused by compression or inflammation of the L5 lumbar
root. Patients usually describe root pain as a sharp, lightning-like sensation
that radiates towards the end of a limb. Of course, any nerve or root may be
subject to injury or compression, and a careful neurological assessment is
needed for the diagnosis. Electrodiagnostic studies and neuroimaging are
occasionally required to confirm the location of the involved nerve or root,
and to determine the cause of the problem. Radicular pain can usually be
successfully treated with a mobility program and pain medication and rarely
requires surgery.
Pain associated with dystonia
Dystonic spasms are among the
most painful symptoms that a person with PD may experience. The pain arises
from the severe, forceful, sustained twisting movements and postures that are
called dystonia. This type of muscle spasm is quite different from the flowing,
writhing movements described as dyskinesias, which are not painful. Dystonia in
PD may affect the limbs, trunk, neck, face, tongue, jaw, swallowing muscles and
vocal cords. A common form of dystonia in PD involves the feet and toes, which
may curl painfully. Dystonia may also cause an arm to pull behind the back, or
force the head forward towards the chest.
The most important step in
evaluating painful dystonia is to establish its relationship to dopaminergic
medication. Does the dystonia occur when the medication is at peak effect? Or
does it occur as a "wearing-off" phenomenon, when the benefits of
medication are waning? The answers to these questions will usually clarify the
nature and timing of the dystonia, and determine its treatment. Most painful
dystonia represents an "off" parkinsonian phenomenon, and occurs
early in the morning or during wearing-off spells. In uncertain cases, the
neurologist should observe the patient in the office over a period of several
hours in order to appreciate the relationship of the dystonia to the
medication-dose cycle.
In terms of treatment,
early-morning dystonia is typically relieved by physical activity, or by the
first dose of dopaminergic medication, whether it be levodopa (Sinemet®) or a
dopamine agonist. When dystonia occurs as the medications wear off, the problem
can be corrected by shortening the "off" period. In some patients,
the dystonia is so severe that subcutaneous injections of apomorphine, with its
onset of action in minutes, may be necessary. Individuals with intractable
dystonia may benefit from deep brain stimulation, a neurosurgical procedure
that involves implanting and activating electrodes in the brain.
A few patients experience
dystonic spasms as a complication of their medications. When they take their
levodopa, these patients experience dystonic facial grimacing or uncomfortable
limb posturing. The standard treatment approach for these individuals is to
reduce the amount of dopamine medication, sometimes by substituting a less
potent agent, or adding a medication for dystonia, such as amantadine.
Akathisia
No discussion of physical
discomfort in PD is complete without a mention of akathisia, or restlessness, a
frequent and potentially disabling complaint. Some patients with parkinsonian
akathisia are unable to sit still, lie in bed, drive a car, eat at a table or
attend social gatherings. As a result of akathisia, patients may lose sleep or
become socially isolated. In about half of the cases of parkinsonian akathisia,
the symptom fluctuates with medications and may often be relieved by additional
dopaminergic treatment.
Central pain syndromes
The most alarming pain syndrome
in patients with PD is also one of the rarest: "central pain." This
affliction - which is presumed to be a direct consequence of the disease
itself, not the result of dystonia or a musculoskeletal problem - is described
by patients as bizarre unexplained sensations of stabbing, burning and
scalding, often in unusual body distributions: the abdomen, chest, mouth,
rectum or genitalia. The treatment of central pain in PD is challenging, and
usually begins with dopaminergic agents. Conventional painkillers, opiates,
antidepressants and powerful drugs for psychosis, such as clozapine, may also
be helpful treatments for central pain.
Depression and pain
It has long been known that
chronic pain can induce depression, and depressed patients often experience
pain. People who have PD are themselves at a higher-than-average risk for
developing depression, which occurs in some 40 percent of patients at some
point during the illness. It is therefore important that any assessment of pain
in an individual with PD take into account the potential contributing role of
depression, which may also require treatment.
Many patients with PD experience
pain at some point during the illness. The complaint is often overlooked
because PD is primarily a motor disorder. Yet, for a minority of patients, pain
and discomfort can be so debilitating that they dominate the clinical picture.
It is therefore important that individuals who experience pain discuss the
problem with their neurologist. A careful history and examination - including,
in some cases, additional diagnostic testing - can usually determine the cause
of the pain. Depending on the category of painful complaint - musculoskeletal,
root or nerve pain, dystonic muscle spasm, akathisia or central pain - it is
usually possible for the physician to design an effective treatment plan.
10 Questions your doctor will ask
you about pain:
Where is
your pain located?
What does
your pain feel like?
Does the
pain radiate anywhere?
When does
the pain occur?
Do you have
pain continuously, or only at certain times?
Does the
pain occur in relation to any particular activity?
What
relieves the pain?
What makes
the pain worse?
Do your
anti-Parkinson's medications relieve your pain?
Do
you have arthritis?
http://www.pdf.org/en/winter04_05_pain_in_parkinsons_disease
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