Coordination

Coordination

Basal Ganglia Pathology

              Typical characteristics-

1.       Slowness of movement

2.       Involuntary, extraneous movement

3.       Alterations in posture and muscle tone

Coordination impairments Associated w/ Basal Ganglia pathology:

·       Akinesia – inability to initiate movement

·       Athetosis – slow, involuntary, writhing, twisting, “worm-like” movements; greater involvement of distal UE

·       Bradykinesia -decreased amplitude and velocity of voluntary movement

·       Chorea-involuntary, rapid, irregular, jerky movements involving multiple joints, most apparent in UE

·       Choreoathetosis – movement disorder with feature of both chorea and athetosis

·       Dystonia – sustained involuntary contractions of opposing muscles, can be repetitive

·       Hemiballismus – large-amplitude sudden, violent, flailing motions of the arm and leg of one side of the body

·       Hyperkinesis – abnormally increased muscle activity or movement

·       Hypokinesis – decreased motor response especially to a specific stimulus

·       Rigidity – increased muscle tone causing greater resistance to passive movement; greater in flexor muscles; not velocity dependent

o   Lead-pipe – uniform, constant resistance as limb is moved

o   Cogwheel – series of brief relaxations or “catches” as limb is passively moved

·       Tremor (resting) – involuntary, rhythmic, oscillatory movement observed at rest

Balance - all forces acting on the body are balanced so that the center of mass (COM) is within the stability limits or boundaries of the base of support (BOS)

Postural control – maintained positions of body parts with respect to each other and gravity

Sensory strategies for balance

a.       Visual system

                                                               i.      Focal vision – attending to specific object/task with central visual field/retina

                                                             ii.      Ambient vision – utilizes entire visual field (central and peripheral) for environmental cues and guide movements subconsciously

b.       Somatosensory system - includes cutaneous and pressure sensations between body and environment, and muscle and joint proprioception throughout body

c.       Vestibular system – stabilizes gaze during head movements and helps regulate postural tone and postural muscle activation.

                                                               i.      Semicircular canals detect angular/rotational acceleration and deceleration forces acting on the head; sensitive to fast movements

                                                             ii.      Otolith organs detect linear acceleration and orientation of the head with reference to gravity; responds to slow movements and positional change