Parkinson's or Progressive Supranuclear Palsy? 5 Clues Doctors Look For
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Parkinson's or Progressive Supranuclear Palsy? 5 Clues Doctors Look For
A caregiver told us about her husband, who was diagnosed with Parkinson's disease at 68. The medication was supposed to help, and for a few months she thought it did a little. Then he started falling, mostly backward, and usually when he turned or stepped off a curb. He told her the stairs looked wrong, and that he could not seem to look down at his own feet.
Two years after the first diagnosis, a movement disorders specialist watched him follow a pen with his eyes and revised the diagnosis to progressive supranuclear palsy, or PSP. It is one of the conditions most often mistaken for Parkinson's disease in the early years. This story is a composite of conversations we have had with families.
Why PSP and Parkinson's Disease Can Look Alike
PSP belongs to a group called atypical parkinsonism. Parkinsonism describes a set of movement changes, slowness, stiffness, and balance trouble, that Parkinson's disease causes and that several other conditions can cause as well. PSP is much rarer than Parkinson's disease, with an estimated prevalence of three to six people per 100,000.
In the early years the two can look almost the same. One form, called PSP-parkinsonism, can closely resemble Parkinson's disease. The more common form, called Richardson syndrome, tends to show its differences sooner. Published studies put the time from first symptoms to a PSP diagnosis at roughly three to four years, and in one small study of 32 patients, most had been given a Parkinson's diagnosis first.
The 2017 diagnostic criteria from the International Parkinson and Movement Disorder Society include eye movement, postural stability, slowness of movement, and cognitive features. The five clues below come from those areas and from the National Institute of Neurological Disorders and Stroke (NINDS) fact sheet on PSP. None of them is a test on its own, and each can occur in other conditions, so the pattern across all five matters more than any single item.
Clue 1: Falls That Happen Early
In Parkinson's disease, balance problems usually develop after other symptoms have been present for a while. In PSP, unexplained falls are among the earliest signs, and the PSP Association in the United Kingdom describes early backward falls as one of the features that help separate it from Parkinson's disease.
Two details are worth writing down for a specialist: which direction the person falls, and how soon after the first symptoms the falls began. A dated note that includes what the person was doing at the time is more useful than a general statement that he falls a lot.
Clue 2: The Eyes
PSP damages the part of the brainstem that controls eye movement. NINDS states that eye problems, in particular slowness of eye movements, usually offer the first definitive clue that PSP is the correct diagnosis. The classic change is difficulty moving the eyes up and down. Other eye problems can include double vision, light sensitivity, burning eyes, and trouble maintaining eye contact during a conversation.
A clinician can check eye movements in the office in a minute or two by asking the person to follow a target. If someone has a Parkinson's diagnosis and nobody has tested how well their eyes move, that is a reasonable thing to ask for by name.
Clue 3: The Response to Levodopa
Levodopa is the main medication used for Parkinson's disease, and many people with the disease benefit markedly from it. For PSP, the NINDS fact sheet says the effect is usually minimal and short-lasting.
A weak response does not prove PSP, and some people with PSP get modest benefit for a time. A poor response is still one of the reasons a neurologist may reconsider a Parkinson's diagnosis. Anyone taking levodopa should keep taking it as prescribed and bring questions to the prescriber. A simple log of when each dose was taken and what changed afterward gives a specialist better information than memory does.
Clue 4: Speech, Swallowing, and Thinking
NINDS lists monotone speech and a mask-like facial expression among the symptoms of PSP. Trouble swallowing and slurred speech are commonly described as well, and changes in behavior and thinking can appear.
Any of these can happen in other conditions. They carry more weight alongside early falls and eye movement problems, because the diagnostic criteria look for that combined pattern.
Clue 5: The Pace
The NINDS fact sheet describes PSP as more rapidly progressive than Parkinson's disease. A family may notice that within a year or two, the changes have moved well past what the original diagnosis predicted.
NIH states that no treatment currently stops or slows PSP, and medications for symptoms tend to help only modestly. Therapy can still make a difference. A case report in the journal NeuroRehabilitation described how a person's physical and occupational therapy plans changed substantially once the correct neurodegenerative diagnosis was made.
How Doctors Diagnose PSP, and What Remains Uncertain
There is no single test that confirms PSP while someone is alive. Diagnosis rests on a specialist's examination and the pattern over time. In a study of 204 people with autopsy-confirmed PSP, using the newer category called "suggestive of PSP" reduced the average time to diagnosis from 3.8 years to 2.2 years.
Most people with Parkinson's symptoms have Parkinson's disease. A fall or a weak medication response does not mean PSP. These clues exist to help a family ask better questions at an evaluation.
What to Bring and What to Ask
If several of these clues sound familiar, the most useful step is a referral to a movement disorders specialist, a neurologist with extra training in conditions like this.
- Dated notes on falls, including the direction of each fall
- Any eye or vision complaints
- The levodopa log, with dose times and what changed afterward
- A short phone video of the person walking and turning
Then ask two questions. How confident are you in the current diagnosis, and what findings would make you reconsider it? Those are fair questions at any appointment, and a good specialist will welcome them.
This article is educational and does not replace medical advice. The opening story is a composite of conversations with families.
Sources: National Institute of Neurological Disorders and Stroke, Progressive Supranuclear Palsy fact sheet. PSP Association (UK). Höglinger, G.U., et al. (2017). Clinical diagnosis of progressive supranuclear palsy: the Movement Disorder Society criteria. Movement Disorders, 32(6), 853-864. Frontiers in Aging Neuroscience (2023), doi 10.3389/fnagi.2023.1229491. "Clinical Conditions Suggestive of PSP: Diagnostic Performance," Movement Disorders, doi 10.1002/mds.28263. NeuroRehabilitation (2023) case report, doi 10.3233/NRE-220235.