Learning Points

* Define hemiplegia and distinguish it from hemiparesis.

* Differentiate between spastic hemiparesis and flacid hemiparesis.

Hemiplegia is total paralysis of the arm, leg, and trunk on the same side of the body, whereas hemiparesis is weakness on one side of the body.  The most common cause is stroke. The paralysis presents as weakness which may be present with abnormal tone (e.g. rigidity or spasticity).  In the stance phase, leg instability (i.e. knee buckling or hyperextension) may make walking unsafe, energy inefficient, and/or painful. During swing phase inadequate limb clearance, sensory deficits, impaired balance, and/or pain may contribute to loss of balance, falls, and increased anxiety associated with walking.  There is a loss of motor control that prevents the patient from precisely controlling the timing and intensity of muscle action. The ability to compensate for this lack of control is best in hemiplegia compared to other central neurological lesions because one side of the body is entirely intact (Perry, 181).

The phases of the gait cycle are altered dramatically in hemiplegia. Spasticity and/or weakness are the main causes of limb deformity that interfere with walking in hemiparesis, and the degree of impairment depends on the magnitude of the neurological deficit.

In spastic hemiparesis the leg is swung in a semi-circle from the hip with the pelvis tilted upward and the hip abducted.  The knee may hyperextend due to inappropriate quadriceps activity.  This stiff knee gait inhibits limb advancement and deprives the patient of shock-absorbing knee flexion during weight acceptance. The ankle excessively plantar flexes and may invert (equinovarus).  The arm may be held flexed and adducted with minimal swing.  In milder cases, some patients may only lose the arm swing and the foot may scrape the floor.

Equinovarus (inversion) is the most common pathologic lower limb posture in hemiparetic patients.  Contact with the ground occurs with the forefoot first and weight is placed mostly on the lateral border of the foot, often with toe flexion.   During the swing phase, the plantarflexion and inversion of the foot is continued resulting in problematic toe clearance (Craik, 414).

If spasticity is not present, there is excess hip and knee flexion during mid swing in order to ensure foot clearance.  The terminal swing and loading response phases are lost because the flexor activity during limb advancement changes to excess extensor activity during weight acceptance. There is premature relaxation of tibialis anterior as well as premature activation of soleus. The result is a gait that is similar to marching on tip-toes on the effected side.

The overall results of the compensatory movements generated by the hemiparetic patient include a decrease in walking velocity with a shorter duration of stance phase, decreased weight bearing, and increased swing time for the affected leg.  The unaffected leg has an increased stance time and decreased step length.

Dropfoot may be the only indication of a mildly hemiplegic stroke patient. The cause is impaired selective control of ankle dorsiflexors which results in excessive plantar flexion with an otherwise normal gait. Mid swing is the phase where the abnormality is most apparent. The excessively plantar flexed ankle causes a toe drag or the patient compensates by increasing flexion at the hip and knee (Perry, 314).

Compensatory movements used by hemiplegic patients during walking produce abnormal displacement of the center of gravity, resulting in increased energy expenditure.   The oxygen consumption of hemiplegic patients at various walking speeds was found to be 64% higher than in normal elderly at the same speed. The unassisted comfortable walking speeds of hemiplegic patients were on average 46% slower than normals. Because of the significant decrease in walking speed of hemiplegic patients, the oxygen consumption rate at comfortable walking speeds is lower than normal despite the inefficiency of the hemiplegic gait pattern. When the hemiplegic patients used metal short leg braces their oxygen consumption dropped to 54% above normal and their walking speed increased to 39% below normal (Spivek, 319).

Return to Top

Last Updated: May 15, 1999.
Copyright © 1997-2000 Molson Medical Informatics Project. All Rights Reserved.