astasia

Astasia is a medical term describing an inability to maintain an upright standing posture due to a disturbance of postural control, in which there is no primary muscular weakness accounting for the instability. The term derives from Greek, meaning "not standing." In clinical use, astasia is distinguished from abasia, the inability to walk; astasia may present with unsteady stance while leg strength is relatively preserved, and walking may be possible with support.

Astasia can occur in various neurological and systemic contexts. It may follow acute brain injury, stroke, cerebellar or vestibular dysfunction, intoxication, or metabolic disturbance. It can also appear in functional neurological disorders, where postural instability is not explained by recognized organic disease; historically, the combined term astasia-abasia has been used in this context to describe dramatic, nonorganic gait disturbances.

Clinical features typically include unsteadiness, swaying, and inability to sustain an upright posture, sometimes with exaggerated postural adjustments or movements that disappear with assistance or distraction. The diagnostic workup focuses on distinguishing true postural control impairment from muscular weakness or sensory loss, and often includes neurological examination, imaging as indicated, and assessment for intoxication or metabolic abnormalities.

Management targets the underlying cause and may include physical therapy for balance training, vestibular rehabilitation if indicated, and treatment of any systemic condition. In cases related to functional disorders, approaches such as psychotherapy and graded motor retraining can be beneficial.