How does a Parkinson's Disease specialist make the diagnosis? The 4 Cardinal Signs
The 4 Cardinal Signs of PD
Tremor - the most common referral I get. Hands, heads, feet, and even individual fingers can shake, causing much frustration and even embarrassment. Though of course many patients just want to know how to stop shaking, the unspoken question from the referring physician is often “Could this be Parkinson’s Disease (PD)?” Though PD is not the most common cause of tremors, it is often the one patients and their family most fear.
A neurologist with specialized training in Movement Disorders can often tell within minutes whether a patients tremor is from PD or another diagnosis, like the less well known essential tremor, based purely on the story told by the patient and family and the neurologic exam. Though biomarker based testing may become more common place in the near future, most PD experts rely most heavily on looking for the 4 Cardinal Signs of PD. In fact, the International Parkinson and Movement Disorders Society used these cardinal features in their 2015 Movement Disorder Society Clinical Diagnostic Criteria for Parkinson’s Disease.
The 4 Cardinal Signs of Parkinson’s Disease are:
Rest Tremor (as opposed to an action tremor, which is most present when using the hands)
Bradykinesia (slowness of quick movements with decrement/decrease in
amplitude)
Cogwheel Rigidity (a specific type of increased tone/stiffness felt around the joints)
Postural instability (impaired balance and postural reflexes)
Of course, each patient will not have all 4 criteria; the 2015 MDS Criteria requires patients have bradykinesia and either rest tremor or rigidity to be considered for PD.
Key Points: -- Not all who have tremor have PD, and not all who have PD have tremor. -- Bradykinesia, and not tremor, is the most important finding when evaluating for parkinsonism or Parkinson's Disease.