I ran across an interesting medical journal article today that provides a guide for neurologists on how to diagnose three atypical parkinsonism disorders — PSP (progressive supranuclear palsy), CBD (corticobasal degeneration), and MSA (multiple system atrophy.
The full article is available online for a fee. See:
“Atypical Parkinsonism: Diagnosis and Treatment”
Maria Stamelou, MD, PhD and Kailash P. Bhatia, FRCP
Neurologic Clinics 33 (2015) 39-56
Here’s a short overview of CBD from the article:
“CBD is a rare neurodegenerative disorder typically characterized by progressive asymmetric levodopa-resistant parkinsonism, dystonia, myoclonus, and further cortical signs (eg, apraxia, alien limb phenomena, cortical sensory loss). The exact prevalence of CBD is unknown, but it is thought to be considerably lower than that of PSP or MSA, and men and women are equally affected. Average time from symptom onset to death is 8 years.”
The authors ask the question – why is it so hard to diagnose these atypical parkinsonian disorders accurately during life? Their answers:
“[The] early differential diagnosis is complicated by patients with pathologically proven PSP, CBD, or MSA that may present clinically with phenotypes other than the classic ones. Conversely, patients with the classic AP [atypical parkinsonism] phenotypes may turn out to have other pathologic abnormalities.”
So, basically, it’s really hard to tell all of these disorders apart.
The authors ask: “if it’s not PSP, CBD, or MSA, what could it be?” One disorder it could be is Parkinson’s Disease (PD). What else could it be if it’s not PD? Very commonly, it’s one of the other atypical parkinsonian disorders — PSP, CBD, MSA, and DLB (Dementia with Lewy Bodies).
What else could it be if it’s not one of the other atypical parkinsonism disorders? For PSP and CBD, very commonly it’s FTD (frontotemporal dementia). For CBD, it’s commonly AD (Alzheimer’s Disease).
I recommend shelling out some money on this article.