INTRODUCTION

There are over 700,000 new strokes each year; the highest incidence in African Americans. African Americans exhibit 1.5-2.5 higher incidence of stroke. Hispanic Americans experience stroke about six years earlier than caucasians.

HOW ISCHEMIA AND INFARCT AFFECT THE BRAIN

Symptoms of stroke are dependent on the area of the brain that is involved.

The figure to the right illustrates the functions of the various area of the brain.

Ischemia or infarct in those areas results in a compromise or loss of that specific function.

The specific loss of function depends on not only which artery is affected, but the location of the atheroma.

The closer the athroma is to the base of the artery, the larger the stroke and the more function is lost.

If the atheroma is in the smaller arteries, the size of the stroke is smaller and the extent of the functional loss is limited.

General characteristics of right and left sided strokes are summarized below

Lee and colleagues reported on 23 studies between 1966-2002 observing the relationship between physical activity and stroke risk.

They found the risk of all types of strokes to be lower for the high physical activity group than for the low (=1).

Both ischemic and hemorrhagic strokes were also lower for the high physical activity groups.

The following year, Wendle-Vos and colleagues summarized 31 different studies observing physical activity and stroke.

Their findings were not different from Lee and colleagues.

The conclusion of both studies was physical activity can decrease risk of stroke 25%.

How does physical activity treat stroke?

A physical therapist will utilize specific types of exercise in the rehabilitation of a stroke patient. What we are addressing here is general physical activity.

Potempa and colleagues provided exercise training for 42 stroke patients who were randomized into control and exercise groups for 10 weeks of training 3/week @ 30-50% of VO2max.

The figure to the right illustrates the increase in VO2max found in the exercise group.

• Potempa, K., M. Lopez, L.T. Braun, J.P. Szidon, L. Fogg, and T. Tincknell. Physiological outcomes of aerobic exercise training in hemiparetic stroke patients Stroke 26:101-105, 1995.

Blood pressure control is one of the primary treatment goals for stroke patients.

The figure to the left illustrates the reduction in systolic blood pressure found in the exercise group.

Diastolic blood pressure did not change.

More importantly is the reduction in systolic and diastolic blood pressure found during work (stress).

Potempa and colleagues also measured sensory motor function. They found no improvement for the groups as a whole, but did find improvements in sensory motor function in patients who increased VO2max.

Rimmer and colleagues exercised 35 stroke survivors who were able to walk 50 feet without assistive aid for 60 min a session, 3 days per week for 12 weeks. Modes ranged from walking, strength training, and flexibility.

• Rimmer, JH., B Riley, T Creviston, and T Nicola. Exercise training in a predominantly Arian-American group of stroke survivors. Medicine and Exercise in Sports and Exercise 32:1991-1996, 2000.

Considering the Specificity of Exercise Principle, physical work capacity should not be the primary exercise focus for many stroke patients. On the other hand, Macko and colleagues conducted a study on nine older stroke patients who exhibited chronic hemiparetic gait to see if aerobic treadmill training could improve the efficiency of their abnormal gait. The patients walked on the treadmill 40 min, 3 times a week at 50-60% of heart rate reserve for six months.

• Macko, R.F., CA DeSouza, LD Tretter, KH Silver, PA Anderson, N Tomoysu, P Gorman, and DR Dengel. Treadmill aerobic exercise training reduces energy expenditure and cardiovascular demands of hemiparetic gait in chronic stroke patients: A preliminary report. Stroke 28:326-330, 1997.

Energy expenditure of a standard treadmill task (1 mph, 0% grade) was measured before and after the exercise training program.

The figure to the right illustrates lower caloric cost, oxygen uptake and heart rate at the same workrate throughout the study; indicating the work became more efficient.

Notice heart rate is multiplied by 10 to obtain the actual heart rate values.

To summarize, exercise treatment for stroke patients:

• increase physical work capacity
• increase muscle strength
• increase flexibility
• increase efficiency of movement
• lower resting systolic blood pressure
• lower sub maximal systolic & diastolic blood pressures

It is unknown whether cardiovascular exercise reduces morbidity and mortality like it does for heart disease.

MEDICAL SURGICAL TREATMENT OF STROKE

Evaluation of stroke is acomplished with a CT (computed tomography) or MRI (magnetic resonance imaging) to determine the type of stroke (hemorragic or ischemic). These images are a CT scan of a ischemic stroke as indicated by the hyodensity in the right parietal and temporal lobes.

Medical treatment is dependent on the type of stroke. Thrombolytics are the primary medication given to prevent or break clots, however, if given to a patient with hemorragic stroke, further bleeding and damage will occur. Surgery may be required for hemorragic strokes to remove excess blood or repair an aneurysm.

Unlike the myocardium, the supply vs. demand scenario is not applicable in the management of ischemia in the brain. Because most strokes are ischemic or embolytic or thrombolytic, anticoagulation or dissolving blood clots is the primary goal of pharmacology in cerebral vascular disease.

Aspirin and thrombolytics are the primary meds.

Aspirin functions include:

• anti-inflammatory
• anti-pyretic
• analgesic
• anti-platelet

Thrombolytics are often given in combination with helarin and other anticoagulant meds (Coumadin or Warfarin). Thrombolytics include:

• tissue plasminogen activator - t-PA - alteplase (Activase)
• reteplase (Retavase)
• tenecteplase (TNKase)
• anistreplase (Eminase)
• streptokinase (Kabikinase, Streptase)
• urokinase (Abbokinase)

Other medications include blood pressure medications, especially vasodilators. Anticonvulsion medications are provided for thos who exhibit seizures of spasticity. Treatment for depression is not unual.

In the coagulation cascade, illustrated to the rignt, fibrinogen is converted to fibrin which is the primary factor to form clots. Warfarin or coumadin, inhibits the systhesis of factors II, VII, and X as well as some of the regularory factors protein C, protein S and protein Z; those that depend on Vitamin K for biologically active forms.

Fibrinolysis is the breaking down of a clot. Plasmin is activated to breakdown fibrin which breaks the clot. The thrombolytic meds are forms of tissue plasminogen activator which enhances the conversion of plasminogen to plasmin. Streptokinase (and anistreplase) directly activates plasminogen conversion to plasmin.