dismetria

Dismetria, also called dysmetria, is a neurological sign indicating an impaired ability to judge distance or range when performing goal-directed movements. It arises from dysfunction of the cerebellum or its connections and leads to errors in the amplitude of voluntary movements. Movements may be too short (hypometria) or too long (hypermetria).

Clinically, dismetria is assessed with coordination tests such as the finger-to-nose or heel-to-shin tasks, where the patient overshoots or undershoots the target. It is commonly accompanied by other cerebellar signs, including intention tremor, dysdiadochokinesia (difficulty with rapid alternating movements), gait ataxia, and broad-based unsteady walking.

Causes include focal or diffuse cerebellar disease or disruption of cerebellar pathways. These can result from stroke, tumors, demyelinating diseases, degenerative ataxias, traumatic injury, chronic alcohol exposure, or metabolic or toxic conditions. Dismetria may appear in isolation or as part of a broader cerebellar syndrome.

Diagnosis is primarily clinical, based on observation of movement errors and coordination deficits. Neuroimaging, especially MRI, helps identify structural cerebellar pathology and guide management. The differential diagnosis includes sensory ataxia and vestibular disorders, which can produce similar imbalance but through different mechanisms.

Management focuses on treating the underlying condition and on rehabilitation. Physical and occupational therapy aims to improve coordination, balance, and motor planning, often with compensatory strategies to reduce functional impairment. The prognosis varies with the etiology and extent of cerebellar involvement.