Astasia-abasia refers to the inability to either stand

Standing (position)

Standing is a human position in which the body is held upright and supported only by the feet, referred to as an orthostatic state.Although quiet standing appears to be static, modern instrumentation shows it to be a process of rocking from the ankle in the sagittal plane...

 or walk

Walking

Walking is one of the main gaits of locomotion among legged animals, and is typically slower than running and other gaits. Walking is defined by an 'inverted pendulum' gait in which the body vaults over the stiff limb or limbs with each step...

 in a normal manner. Patients exhibit an unusual and dramatic gait disturbance, lurching wildly in various directions and falling only when a nearby physician, family member, or soft object will catch them.

Astasia refers to the inability to maintain station (stand upright) unassisted.

Abasia

Abasia

Abasia is the inability to walk due to impaired muscle coordination. The term covers a spectrum of medical disorders such as:* choreic abasia: caused by chorea of the legs...

refers to lack of motor coordination

Motor coordination

thumb|right|Motor coordination is shown in this animated sequence by [[Eadweard Muybridge]] of himself throwing a diskMotor coordination is the combination of body movements created with the kinematic and kinetic parameters that result in intended actions. Such movements usually smoothly and...

 in walking. The term literally means that the base of gait

Gait (human)

Human gait is the way locomotion is achieved using human limbs. Different gaits are characterized by differences in limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in the contact with the surface .- Foot strike :One variable in different gaits is...

 (the lateral distance between the two feet) is inconstant or unmeasurable. When seen in conversion disorder

Conversion disorder

Conversion disorder is a condition in which patients present with neurological symptoms such as numbness, blindness, paralysis, or fits without a neurological cause. It is thought that these problems arise in response to difficulties in the patient's life, and conversion is considered a psychiatric...

, the gait is bizarre and is not suggestive of a specific organic lesion

Lesion

A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...

: often the patient sways wildly and nearly falls, recovering at the last moment.

However, an acquired total inability to stand and walk can be seen in true neurological

Neurology

Neurology is a medical specialty dealing with disorders of the nervous system. Specifically, it deals with the diagnosis and treatment of all categories of disease involving the central, peripheral, and autonomic nervous systems, including their coverings, blood vessels, and all effector tissue,...

 diseases, including stroke

Stroke

A stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...

, Parkinson disease, damage to the cerebellum

Cerebellum

The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...

, Guillain-Barré, normal pressure hydrocephalus

Normal pressure hydrocephalus

Normal pressure hydrocephalus , also termed symptomatic hydrocephalus, occurs when there is an increase in intracranial pressure due to an abnormal accumulation of cerebrospinal fluid in the ventricles of the brain, which can cause ventriculomegaly...

 and many others. In normal pressure hydrocephalus for example, when the condition remains untreated, the patient's gait becomes shortened, with frequent shuffling and falls; eventually standing, sitting, and even rolling over in bed become impossible. This advanced state is referred to as "hydrocephalic astasia-abasia".

Phobias

Astasia and/or abasia are associated with the corresponding fears of walking and/or standing, variously called stasophobia, basophobia, stasiphobia, basiphobia, stasobasophobia, etc., sometimes turning into pathological forms, i.e., phobia

Phobia

A phobia is a type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational...

s.