I. Neurological recovery phase

a. Early stage (0-3 months after stroke) includes:

- recovery of penumbra from metabolic toxins, edema, pressure, and hemorrhage due to initial insult

- ischemic penumbra: surviving but inactive (electrically silent) neuronal cells located at the rim of the ischemic injury are sustained by minimal blood flow

b. Late stage (> 3 months after stroke)

- Involves neuroplastic reorganization that affects structure and function. This includes repair of damaged pathways and incorporation of other neurons to perform new functional tasks

c. Mechanism of recovery of neurologic functions

1. the first mechanism is resolution of local harmful factors, which usually accounts for early spontaneous improvement after stroke (usually within the first 3-6 months). These processes include: resolution of local edema, resorption of local toxins, improved local circulation, and recovery of partially damaged ischemic neurons.

2. the second mechanism to explain recovery is neuroplasticity, which can take place early or late. Brain plasticity is the ability of the nervous system to modify its structural and functional organization. The 2 most plausible forms of plasticity are collateral sprouting of new synaptic connections and unmasking of previously latent functional pathways. Other mechanisms of plasticity include assumption of function by undamaged redundant neural pathways, denervation supersensitivity, reversibility of diaschisis, and regenerative proximal sprouting of transected neuronal axons.

(* diaschisis: the loss of function and electrical activity caused by cerebral lesion in areas which are remote from the lesion but are neuronally connected to it)

II. Motor recovery patterns

c. Large motor strokes affecting the extremities (e.g., main branch of the middle cerebral artery) recover in a proximal to distal pattern. Extremities are initially flaccid and then develop spasticity with large synergy patterns. Coordinated movements and decreased spasticity usually follow.

d. Recovery of lower extremity is generally greater than recovery of the upper limb because of need for more complex control recovery in the upper extremities.

Basic limb synergy patterns

Flexion synergy	Extensor synergy
Upper extremity	Shoulder retraction Arm abduction Arm external rotation Elbow flexion Forearm supination Wrist flexion Wrist radial deviation Digit extension	Shoulder protraction Arm adduction Arm internal rotation Elbow extension Forearm pronation Wrist extension Wrist ulnar deviation Digit flexion
Lower extremity	Hip flexion Thigh abduction Thigh external rotation Knee flexion Ankle dorsiflexion Ankle supination Digit extension	Hip extension Thigh adduction Thigh internal rotation Knee extension Ankle plantarflexion Ankle pronation Digit flexion

Synergy patterns are the stereotyped mass movement patterns that characterized limb activity after injury to the cerebral voluntary motor system. The upper and lower limbs can assume a flexion or and extension synergy pattern.

Дата добавления: 2015-10-30