Abnormalities in diadochokinesia can be seen in the upper extremity, lower extremity and in speech. The deficits become visible in the rate of alternation, the completeness of the sequence, and in the variation in amplitude involving both motor coordination and sequencing. Average rate can be used as a measure of performance when testing for dysdiadochokinesia.

Dysdiadochokinesia 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 doorknob or screwing in a light bulb. 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. When testing for dysdiadochokinesia with speech the patient is asked to repeat syllables such as /pə/, /tə/, and /kə/; variation, excess loudness, and irregular articular breakdown are signs of dysdiadochokinesia.

Dysdiadochokinesia is a feature of cerebellar ataxia and may be the result of lesions to either the cerebellar hemispheres or the frontal lobe (of the cerebrum), it can also be a combination of both. 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.

Dysdiadochokinesia is also seen in Friedreich's ataxia and multiple sclerosis, as a cerebellar symptom (including ataxia, intention tremor and dysarthria). It is also a feature of ataxic dysarthria. Dysdiadochokinesia often presents in motor speech disorders (dysarthria), therefore testing for dysdiadochokinesia can be used for a differential diagnosis.

Dysdiadochokinesia has been linked to a mutation in "SLC18A2", which encodes vesicular monoamine transporter 2 (VMAT2).

Adiadochokinesia is a dyskinesia consisting of inability to perform the rapid alternating movements of diadochokinesia. Called also "adiadochocinesia", "adiadochokinesis", and "adiadokokinesia".

Compare with dysdiadochokinesia, which is an impairment of the ability to perform rapidly alternating movements.

Cerebellar ataxia can occur as a result of many diseases and presents with symptoms of an inability to coordinate balance, gait, extremity and eye movements. Lesions to the cerebellum can cause dyssynergia, dysmetria, dysdiadochokinesia, dysarthria and ataxia of stance and gait. Deficits are observed with movements on the same side of the body as the lesion (ipsilateral). Clinicians often use visual observation of people performing motor tasks in order to look for signs of ataxia.

Damage to the cerebellum, particularly to the cerebrocerebellum area and the cerebellar vermis, is very often associated with clinical depression and often with alcoholism. Due to difficulties in mobility, self-care, everyday activities, and pain/discomfort, those with cerebellar ataxia are more likely to be diagnosed with anxiety and depression. Almost a third of patients with isolated, late onset cerebellar ataxia go on to develop multiple system atrophy.

In recent years the cerebellum's role has been observed as not purely motor. It is intimately combined with intellect, emotion and planning.

Karak syndrome is a neurological degenerative disorder involving excess cerebral iron accumulation. The family who the disease was discovered in their siblings lived in Karak, a town in southern Jordan. It is characterized by ataxia, inverted feet (talipes calcaneovarus), dysarthric scanning speech with dystonic features, dystonic movement of the tongue and facial muscles and choreiform movement was present in both upper and lower limbs, being more marked in the lower limbs, along with dystonic posture of the distal feet, bradykinesia

present in both upper and lower limbs, dysmetria, dysdiadochokinesia, and intentional tremor were bilateral and symmetrical.