Progressive supranuclear palsy (PSP) is a rare brain disorder that
causes serious and permanent problems with control of gait and balance.
The most obvious sign of the disease is an inability to aim the eyes
properly, which occurs because of lesions in the area of the brain that
coordinates eye movements. Some patients describe this effect as a
blurring. PSP patients often show alterations of mood and behavior,
including depression and apathy as well as progressive mild dementia.
The disorder's long name indicates that the disease begins slowly and
continues to get worse (progressive), and causes weakness
(palsy) by damaging certain parts of the brain above pea-sized
structures called nuclei that control eye movements
(supranuclear).
PSP was first described as a distinct disorder in 1964, when three
scientists published a paper that distinguished the condition from
Parkinson's disease. It is sometimes referred to as dementia-nuchal
dystonia, or as Steele-Richardson-Olszewksi syndrome, reflecting the
combined names of the scientists who defined the disorder. Although PSP
gets progressively worse, no one dies from PSP itself.
Approximately 20,000 Americans - or one in every 100,000 people over
the age of 60 - have PSP, making it much less common than Parkinson's
disease, which affects more than 500,000 Americans. Patients are usually
middle-aged or elderly, and men are affected more often than women. PSP is
often difficult to diagnose because its symptoms can be very much like
those of other, more common movement disorders, and because some of the
most characteristic symptoms may develop late or not at all.
The most frequent first symptom of PSP is a loss of balance while
walking. Patients may have unexplained falls or a stiffness and
awkwardness in gait. Sometimes the falls are described by the person
experiencing them as attacks of dizziness. This often prompts suspicion of
an inner ear problem.
Other common early symptoms are changes in personality such as a loss
of interest in ordinary pleasurable activities or increased irritability,
cantankerousness, and forgetfulness. Patients may suddenly laugh or cry
for no apparent reason, they may be apathetic, or they may have occasional
angry outbursts, also for no apparent reason. It must be emphasized that
the pattern of signs and symptoms can be quite different from person to
person.
As the disease progresses, most patients will begin to develop a
blurring of vision and problems controlling eye movement. In fact, eye
problems usually offer the first definitive clue that PSP is the proper
diagnosis. PSP patients have trouble voluntarily shifting their gaze
downward, and also can have trouble controlling their eyelids. This can
lead to involuntary closing of the eyes, prolonged or infrequent blinking,
or difficulty in opening the eyes.
Another common visual problem is an inability to maintain eye contact
during a conversation. This can give the mistaken impression that the
patient is hostile or uninterested.
Speech usually becomes slurred and swallowing solid foods or liquids
can be difficult. In rare cases, some patients will notice shaking of the
hands.
We know that the symptoms of PSP are caused by a gradual deterioration
of brain cells in a few tiny but important places at the base of the
brain, in the region called the brainstem. One of these areas, the
substantia nigra, is also affected in Parkinson's disease, and damage to
this region of the brain accounts for the motor symptoms that PSP and
Parkinson's have in common.
Scientists do not know what causes these brain cells to degenerate.
There is no evidence that PSP is contagious, and genetic factors have not
been implicated in most patients. No ethnic or racial groups have been
affected more often than any others, and PSP is no more likely to occur in
some geographic areas than in others.
There are, however, several theories about PSP's cause. One possibility
is that an unconventional virus-like agent infects the body and takes
years or decades to start producing visible effects. Creutzfeldt-Jakob
disease is one disease known to be caused by such an agent. Another
possibility is that random genetic mutations, of the kind that occur in
all of us all the time, happen to occur in particular cells or certain
genes, in just the right combination to injure these cells. A third
possibility is that there is exposure to some unknown chemical in the
food, air, or water which slowly damages certain vulnerable areas of the
brain. This theory stems from a clue found on the Pacific island of Guam,
where a common neurological disease occurring only there and on a few
neighboring islands shares some of the characteristics of PSP, Alzheimer's
disease, Parkinson's disease, and amyotrophic lateral sclerosis (Lou
Gehrig's disease). Its cause is thought to be a dietary factor or toxic
substance found only in that area.
Another possible cause of PSP is cellular damage caused by free
radicals, unstable molecules produced continuously by all cells during
normal metabolism. Although the body has built-in mechanisms for clearing
free radicals from the system, scientists suspect that, under certain
circumstances, free radicals can react with and damage other molecules. A
great deal of research is directed at understanding the role of free
radical damage in human diseases.
Initial complaints in PSP are typically vague and an early diagnosis is
always difficult. The primary complaints fall into these categories: 1)
symptoms of dysequilibrium, such as unsteady walking or abrupt and
unexplained falls without loss of consciousness; 2) visual complaints,
including blurred vision, difficulties in looking up or down, double
vision, light sensitivity, burning eyes, or other eye trouble; 3) slurred
speech; and 4) various mental complaints such as slowness of thought,
impaired memory, personality changes, and changes in mood.
PSP is often misdiagnosed because some of its symptoms are very much
like those of Parkinson's disease, Alzheimer's disease, and more rare
neurodegenerative disorders, such as Creutzfeldt-Jakob disease. In fact,
PSP is most often misdiagnosed as Parkinson's disease early in the course
of the illness. Memory problems and personality changes may also lead a
physician to mistake PSP for depression, or even attribute symptoms to
some form of dementia. The key to establishing the diagnosis of PSP is the
identification of early gait instability and difficulty moving the eyes,
the hallmark of the disease, as well as ruling out other similar
disorders, some of which are treatable.
Both PSP and Parkinson's disease cause stiffness, movement
difficulties, and clumsiness. However, patients with PSP usually stand
straight or occasionally even tilt their heads backward (and tend to fall
backward), while those with Parkinson's disease usually bend forward.
Problems with speech and swallowing are much more common and severe in PSP
than in Parkinson's disease, and tend to show up earlier in the course of
the disease. Both diseases share other features: onset in late middle age,
bradykinesia (slow movement), and rigidity of muscles. Tremor, almost
universal in Parkinson's patients, is rare in PSP. Although Parkinson's
patients markedly benefit from the drug levodopa, patients with PSP
respond poorly and only transiently to this drug.
PSP gets progressively worse but is not itself directly
life-threatening. It does, however, predispose patients to serious
complications such as pneumonia secondary to difficulty in swallowing
(dysphagia). The most common complications are choking and pneumonia, head
injury, and fractures caused by falls. The most common cause of death is
pneumonia. With good attention to medical and nutritional needs, however,
most PSP patients live well into their 70s and beyond.
There is currently no effective treatment for PSP, although scientists
are searching for better ways to manage the disease. In some patients the
slowness, stiffness, and balance problems of PSP may respond to
antiparkinsonian agents such as levodopa, or levodopa combined with
anticholinergic agents or amantadine, but the effect is usually temporary.
The speech, vision, and swallowing difficulties usually do not respond to
any drug treatment.
Another group of drugs that has been of some modest success in PSP are
antidepressant medications. The most commonly used of these drugs are
fluoxetine (Prozac), amitriptyline (Elavil), and imipramine (Tofranil).
The anti-PSP benefit of these drugs seems not to be related to their
ability to relieve depression.
Non-drug treatment for PSP can take many forms. Patients frequently use
weighted walking aids because of their tendency to fall backward. Bifocals
or special glasses called prisms are sometimes prescribed for PSP patients
to remedy the difficulty of looking down. Formal physical therapy is of no
proven benefit in PSP, but certain exercises can be done to keep the
joints limber.
A surgical procedure that may be necessary when there are swallowing
disturbances is a gastrostomy. A gastrostomy (or a jejunostomy) is a
minimally invasive procedure which is performed when the patient has
difficulty swallowing or when severe choking is a definite risk. This
surgery involves the placement of a tube through the skin of the abdomen
into the stomach (intestine) for feeding purposes. Surgical procedures
such as fetal brain cell implantation and pallidotomy, which are being
tested as treatments for Parkinson's disease, are not effective in PSP.
Studies to improve the diagnosis of PSP have recently been conducted at
the National Institute of Neurological Disorders and Stroke (NINDS).
Experiments to find the cause or causes of PSP are currently under way.
Therapeutic trials with free radical scavengers (agents that can get rid
of potentially harmful free radicals) are being planned for the future.
In addition, there is a great deal of ongoing research on Parkinson's
and Alzheimer's diseases at the National Institutes of Health and at
university medical centers throughout the country. Better understanding of
those common related disorders will go a long way toward solving the
problem of PSP, just as studying PSP may help shed light on Parkinson's
and Alzheimer's diseases.
Keeping on Top of Your Condition
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The following voluntary agency promotes research, provides information,
and helps affected families:
Society for Progressive Supranuclear Palsy, Inc.
Woodholme Medical
Building
1838 Greene Tree Road
Suite 515
Baltimore, Maryland
21208
(410) 486-3330
(800) 457-4777
http://www.psp.org/
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