Objective: To report a novel sign on inspection in PD that is present throughout different dopaminergic states

Background: Inspection is arguably one of the most important steps in any thoughtful clinical examination. A keen examiner should spend some dedicated time in careful inspection. PD is the second most common neurodegenerative condition [De Lau, 2006 #15542]and is becoming more prevalent with increasing proportion of the elderly population. It is a matter of time when one might encounter a patient suspected of or having a diagnosis of PD. It is important for a provider to be able to pick up clinical clues to a diagnosis on inspection and manual examination. Observing for reduced blink rate and rest tremor is important but the most striking aspect of a parkinsonian patient who is not dyskinetic is probably the paucity of movement. Eye movement examination, feeling for resistance to passive movement, finger tapping and hand movement as well as toe tapping and gait examination consists of the rest of the examination. Some or most of these signs may be less apparent in early disease or if the patient is on dopaminergic medications.

Method: Report a newly observed clinical sign through a simple, careful and efficient examination technique to spot parkinsonism in the office. This sign persists with DBS, on medications or in the off period.

Results: Asking the patient to sit comfortably, have hands rest in lap with palms facing up. Then ask to close eyes and name months of the year backward. Look for the angle between the thumb and index finger (thumb-index angle) on one side and compare with the other hand. Normally these are symmetric but in PD patients and those with asymmetric parkinsonism, the more affected side has a narrower angle. This may be accompanied by extension of fingers,  This can be followed up by asking patient to shrug shoulders. The more affected side lags behind. This could give the examiner a heads up about the side of onset of symptoms and even the presence of PD in a yet undiagnosed patient.

Conclusion: Careful observation of the hands in a patient with PD may reveal an abnormal posture of the hand in the absence of dystonia. The angle between thumb and index finger is asymmetric.  This has been a good exercise to screen for this sign and detect any mild tremor. This would help with detecting parkinsonism and identify the more affected side through a quick and efficient examination technique.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/asymmetric-thumb-index-angle-in-pd-a-new-observation-in-an-old-disease/