Dysdiadochokinesia

Dysdiadochokinesia, dysdiadochokinesis, dysdiadokokinesia, dysdiadokokinesis, or DDK (from Greek dys "bad", diadocho "receive", kinesia "movement") is the medical term for an inability to perform rapid, alternating movements.

Causes

It is a feature of cerebellar ataxia, and is the result of lesions to the cerebellar hemispheres, the posterior or frontal lobes of the cerebellum, or all of the aforementioned regions.^[1] It is thought to be caused by the inability to switch on and switch off antagonising muscle groups in a coordinated fashion due to hypotonia, secondary to the central lesion.^[2]

Dysdiadochokinesia is also seen in Friedreich's Ataxia and multiple sclerosis, as a cerebellar symptom (including ataxia, intentional tremor & dysarthria).

Presentation

It is demonstrated clinically by asking the patient to tap the palm of one hand with the fingers of the other, then rapidly turn over the fingers and tap the palm with the back of them, repeatedly. This movement is known as a pronation/supination test of the upper extremity. A simpler method using this same concept is to ask the patient to demonstrate the movement of trying a door knob or screwing in a lightbulb. The deficits become visible in the rate of alternation and the completeness of the sequence, involving both motor coordination and sequencing.^[3]

When testing for this condition in legs ask the patient to tap your hand as quickly as possible with the ball of each foot in turn. Movements tend to be slow or awkward. The feet normally perform less well than the hands.^[4]

References