Review guide to diseases similar to Parkinson’s

Some movement disorders have PD symptoms

Parkinson’s disease (PD) is not related to other well-known neurological conditions such as multiple sclerosis, muscular dystrophy, or Lou Gehrig’s disease (amyotrophic lateral sclerosis). However, there is a variety of syndromes and diseases that look like PD but have other clinical features and pathology. The American Parkinson Disease Asso ciation in Staten Island, NY, describes 14 such diseases, as follows:

• Benign (familial) essential tremor: Essen tial tremor is commonly mistaken for PD, but the tremor quality is different. It is primarily at its worst during action, less severe during posture-holding, and rare at rest. The hands are affected, and there may be a tremor of the head and neck, usually a head nod. Also, the voice has a tremulous quality, which is not seen in PD. The legs are rarely affected, and there is no slowness, stiffness, or other features of PD. Some patients with presumed essential tremor eventually may develop PD.

• Progressive supranuclear palsy: The most common of the atypical parkinsonisms, this is known in England as Steele-Richardson-Olszewski syndrome for the doctors who first described it. The palsy may appear initially like typical PD; patients may complain of gait disorder, frequent falls, visual abnormalities, or speech and swallowing problems. Tremor is usually absent. The disease’s course is shorter than that of PD, and patients may have problems with falling and imbalance much earlier. The neck may be rigid, with hyperextension. Patients assume a wide-eyed astonished stare. The hallmark of the disease is the inability to look down voluntarily, and other eye movement abnormalities may occur at later stages. No medications have been found to be useful consistently for more advanced cases.

• Multiple systems atrophy: This term refers to three main disorders, called olivopontocerebellar atrophy (OPCA), Shy-Drager syndrome (SDS or primary or progressive autonomic failure), and striatonigral degeneration (SND). All of these may be characterized by parkinsonism, although rest tremor is slight or absent. Again, the course is more rapid than PD, and treatment is usually not productive. Distinguishing features are:

— OPCA: unsteadiness or imbalance, where the impairments of balance, stability, and coordinated movements are out of proportion to other signs and symptoms.
— SDS: parkinsonism with dysautonomia, where the dysautonomia precedes or dwarfs the parkinsonism.
— SND: may appear clinically identical to PD, although tremor tends to be less prominent, and gait and balance problems may occur early. Diagnosis is usually considered in patients with parkinsonism in whom there is no response at all to levodopa or other antiparkinson drugs.

• Cortical-basal ganglionic degeneration: A parkinsonian syndrome that is characterized by very asymmetric involvement of one arm, before it eventually involves the other side, with these symptoms: extreme rigidity; a foreign feeling in or an involuntary positioning of the limb; a loss of knowing what to do with the hand, such as forgetting to brush one’s teeth; and a loss of some sensations on that side. There is infrequent rest tremor, and dementia may occur early. It almost never occurs before age 50, and the course is relatively short, with no effective treatments.

• Post-encephalitic parkinsonism (PEP): A consequence of Von Economo’s or epidemic encepha litis or encephalitis lethargica (not the post-World War I influenza epidemic) that occurred worldwide in the second and third decades of the 20th century. PEP accounted for about 12% of parkinsonism seen at major centers in the first half of the century, but there are very few patients left with this disorder. The cause was apparently a virus that has never been identified. Development of this condition ranged from weeks or months to years after the encephalitis exposure. The most dramatic feature is a dystonic deviation of the eyes. Other features include young onset, bizarre personality, behavioral changes, paralysis, and extreme fatigue. When levodopa was introduced, a population of PEP patients were started on this drug, but few could tolerate the side effects. A description of this condition is found in the book and movie Awakenings by Oliver Sacks, MD.

• Normal pressure hydrocephalus: This is an uncommon but potentially reversible condition that has a parkinsonian syndrome. It is distinguished by gait disorder, urinary incontinence, and dementia and caused by enlargement of the fluid cavities of the brain, called the ventricles. There is compression of the centers that control walking, voiding, and thinking. It sometimes may be improved by removing the fluid from the brain, most effectively done by insertion of a shunt from the brain to another part of the body (often the abdomen) to drain the fluid away.

• Vascular diseases: Strokes due to hardening of the arteries or small blood vessels (arteriosclerosis) usually come on suddenly, causing paralysis of one side of the body. Rarely, multiple little strokes in deep parts of the brain, each too small to be noticed or causing only brief weakness, eventually may result in cumulative damage to the circuit that causes the symptoms of parkinsonism. Vascular parkinsonism is generally thought to be a lower-body parkinsonism, causing problems with gait and balance but rarely tremor. Sometimes, mental impairment occurs. Patients tend to be older with a history of high blood pressure, diabetes, or heart conditions.

• Drugs and toxins: A variety of drugs and toxins have been found to be responsible for the development of parkinsonian syndromes. Most cause only temporary problems, but one toxin has resulted in permanent parkinsonism.

The toxin is MPTP, a designer drug similar to heroin. In humans and animals, it causes an irreversible, very rapidly developing parkinsonism, clinically indistinguishable from PD except for the speed of development following exposure. Severity appears to relate to degree of exposure. Patients respond well to antiparkinson medications. Also, poisoning with manganese has been reported to cause parkinsonism.

Reversible cases of drug-induced parkinsonism have been associated with the following drugs: antipsychotic medications used to treat schizophrenics, such as haloperidol (Haldol), fluphenazine (Prolixin), and chlorpromazine (Thorazine); certain antinausea drugs that are chemically related to the antipsychotic drugs, such as prochlorperazine (Compazine); metoclopramide (Reglan), a highly prescribed medication for improving stomach and bowel move - ment; and alpha-methyl dopa (Aldomet), a formerly popular antihypertensive.

• Dystonia: Primary, or idiopathic, dystonia occurs in individuals of any age. In childhood, it tends to start in the foot and gradually involve the entire body. Adult-onset dystonia tends to remain in one body location (focal Dystonia). Most frequently it involves the neck (torticollis), eyelids (blepharospasm), lower face (Meige syndrome), or hand (writer’s cramp dystonia).

• Dopa-responsive dystonia: This disorder usually begins in childhood and is more common in girls than boys. It is characterized by mild parkinsonism with more pronounced dystonia, worsening as the day wears on. It has dramatic, prolonged response to low-dose levodopa and may be confused with juvenile-onset PD.

• Alzheimer’s disease: Occasionally, some patients with Alzheimer’s disease may demonstrate features of parkinsonism. In addition, occasionally the pathology of PD and AD may occur in the same person. Nevertheless, PD is not Alz heimer’s disease, nor does it lead to Alzheimer’s disease.