Sunday, January 30, 2011

STROKE: Diagnosis And Rehabilitation

Stroke: Is an acute neurologic dysfunction of vascular origin, with a relatively rapid onset, causing focal or sometimes global signs of disturbed cerebral function that lasts for more than 24 hours.

The causes of stroke
The causes of stroke can be categorized into two major types, heamorrhagic and ischamic. Each type can be further divided into subtypes
Stroke: into hemorrhagic15% and ischaimic 85% 
Hemorrhagic: into  Subarachnoid hemorrhage 8% and Intracerebral heamorrhage 7%
Ischaimic : Thrombolic (large vessel) 40%, Lacunar (small vessel) 21% and Cerebral embolism 24%

List of possible risk factors for stroke
Medical conditions
- Hypertension
- Hypercholesterolemia
- Diabetes Mellitus
- Heart disease and atrial fibrilation
- Carotid artery disease
- Previous stroke
- Obesity
- Smoking
- Excessive alcohol use (more than 2 drinks per day)
- Drug use ( cocaine and intravenous drugs)
The combiantions of certain metabolic and physiologic risk factors, know as the metabolic syndrome X, have also been linked to cardiovascular ad stroke risk. These factors include elevated triglycerides, low HDL cholesterol, adbominal obesity, elevated blood pressure, and insulin resistance. Exercise programs that target weight loss may have positive effects on reducing the development of chronic hypertension,hypercholesterolemia,diabetes and stroke.

Pharmacologic treatments can prevent stroke in people who suffered a previous stroke?
Antiplatelet agents: The use of aspirin or the combined use of aspirin and dipyridamole can reduce risk of reccurent ischemic stroke by 21-35%. Clopidogrel is an equivalently effective antiplatelet agent for patients who cannot tolerate aspirin.
Anticoagulants: Warfarin is more effective than antiplatele therapy for the prevention of secondary stroke in selected cardiac conditions, such as atrial fibrilation and following mechanical valve replacement.Although warfarin is effective at preventing ischamic stroke in other conditions, antiplatelet agents are preferred inthe prevantion of thrombotic and lacunar strokes.
Hydroxymethylglutaryl-Coa (HMG-CoA) reductase inhibitors or statins: These agents are well tolerated and effectively reduce total and LDL cholesterol. They have also been shown to reduce recurrent ischemic stroke risk in patients with normal cholesterol.
Antihypertensive drugs: Lowering blood pressure even in patiens with normal or close to normal BP has a significant effect in reducing recurrent stroke. Angiotensin converting enzyme (ACE) inhibitors or ACE combined with diuretics have been particularly well tolerated and effective foe secodary stroke prevention.

When is carotid endarterectomy is recommended?
Patients with between 70% and 99% stenosis of the internal carotid artery benefit from surgical excision of the atherosclerotic plaque in centers that have low mortality and morbitity less than 3% associated with this surgical procedure.

List of Neurologic impairements that follow stroke and their frequencies
Impairement                       Acute%                        Chronic%
Any motor weakness              90                                  50
      Right Hemiplegia              45                                  20
      Left Hemiplegia                35                                  25
      Bilateral hemiplegia           10                                    5
Ataxia                                     20                                 10
Hemianopsia                           25                                  10
Visual perceptual deficits         30                                  30
Aphasia                                  35                                  20
Dysarthria                               50                                  20
Sensory deficits                       50                                  25
Cognitive deficits                     35                                  30
Depression                              30                                  30
Bladder incotinence                 30                                  10
Dysphagia                               30                                  10

KEY POINTS: Most Common Causes of Death during the 1st month after Stroke
1. Stroke its self (progressive cerebral edema, herniation)
2. Aspiration pneumonia
3. Cardiac events (myocardial infarction,sudden death arrhythmia,heart failure)
4.Pulmonary embolism (often occuring 2-4 weeks after stroke)

What is the pattern of typical motor recovery with stroke-related hemiplegia?
Patients with acute stroke and severe hemiplegia often initially have limb flaccidity, which is defined as less than normal tone.Later, increased tone or hyertonia appears, which is first noticeable in the lower limbs, then subsequenty in the upper limb. In some cases, this stage followed by the development of spasticity, which is a velocity-dependent resistance in stretch of the muscles and is also noticed first in the lower limb and later in the upper limb.Spasticity is seen first in distal muscles crossing the wrist, fingers and ankle and later is seen in proximal muscles such as the shoulder, elbow and hip. Patients who have voluntary movement of the limbs appearing early after stroke are less likely to have severe and disabling spasticity.
Voluntary movements usually appear first in proximal muscles, such as those crossing the hip and shoulder, and later in the distal muscles of the hand and foot. The first voluntary movementsare also seen in the hip such as hip extension and adduction. As voluntary movements gain strength, they are often first associated with synergy patterns, which are voluntary contractions of a group of limb muscles producing a stereotypical pattern of limb movement. Flexor synergy is usually seen in the upper extremities, and extsnor synergy is seen in the lower extremities. As recovery continues, movements outside of these synergy patterns are possible. Later, isolated joint movements are possible.

Flexor Synergy Pattern (arm)             Extesor Synergy Patten (leg)
 Shoulder Abduction                                  Hip Extension
 Shoulder Ext, rotation                               Hip Adduction
 Scapular retraction                                    Knee Extension
 Elbow Flexion                                           Ankle plantar flexion
 Forearm Supination                                   Ankle Inversion
Wrist and finger Flexion

Barriers to motor recovery
- Prolonged flaccidity
- Lack of voluntary movement within 2 weeks
- Severe spasticity
- Lack of movement out of synergy patterns
- Sensory deficits

Compair normal gait to typical hemiplegic gait
Time and distance characteristics: Hemiplegic gait is slower than normal adult gait, and the percent time of the gait cycle spent in stance is longer for both the hemiplegic and the unaffected sides. Double support time is also longer when compared to normal adult gait.When compared to a normal adult walking at the same slower speed as a hemiplegic patient, the percent of gait cycle in stance is the same on the unaffected side but shorter on the affected side. Because total stance time on the hemiplegic leg is shorter than normal at equivalent speeds, double support time is also shorter. This shorter stance and double support time reduce weight bearing on the more unstable hemiplegic limb and are compensated by a longer swing time than on the unaafected side.
Kinematics (joint trajectories): Compared to normal adult gait, hemiplegic patients show less hip flexion at initial contact, less hip extension at toe-oof, and more hip flexion at midstance on the affected side. Knee flexion is reduced at toe-off in the hemiplegic limb and through mid-swing. There is excessive ankle plantar - flexion at initial contact and mid-swing and reduced plantar flexion at toe-off.
Muscle activity: There are three different classes of muscle activity during gait cycle in stroke as defined by Knutsson and Richards in 1979.
- Type 1: Excessive activity of calf muscles from early to midstance phase, resulting in excessive plantar flexion, forcing the knee into excessive extension at midstance.
- Type 2: Low levels muscle activity throughout the stance phase with reduced power at toe-off.
- Type 3:  Coactivation of several muscle groups, both plantar flexors and extensors, throughout stance phase and often swing phase as well.

Venus Thromboembolism
Venus thromboembolism  will occur in 50% of patients with acute stroke if preventive measures are not applied. Although the risk of pulmonary embolism (PE) is only 1-2%the risk of death with PE is 50%. By far, the use of subcutaneous heparin ( unfractionated- or low-molecular weight) provides the most effective prophylaxis against venous thrombosis, reducing the risk to less than 5%. Patients with recent bleeding  or bleeding disorders are more safely managed with pneumatic compression devices applied to the lower limbs during bedrest. Knee-high or thigh-high elastic stockings provide a clinically significant risk reduction for venous thrombosis but should not be used in exclusion of heparin  or pneumatic compression.

 Motor Facilitation approaches frequently used in Physical rehabilitation with stroke patients.
 Proprioceptive Neuromuscular Facilitation (PNF): Kabat, Voss and Knott noted in the 1940's and 1950's that functional movements were not performed for the most part with isolated muscle contractions but involved coordinated activity  in multiple muscle groups. PNF therapy involves complex trunk and limb movements in spirals and diagonals, such as those used to throw a ball. Mastering such movements can facilitate the performance of functional activities such as walking and feeding.

Neurodevelopmental Technique (NDT) or Bobath approach: 
NDT was originally designed by Berta and Karl Bobath to facilitate motor development on children with cerebral palsy, but it was later applied to patients with stroke and brain injury. This therapy works with patients using developmental patterns of movements (rolling, sitting, crawling, and stepping) to normalize muscle tone, with the goal to enhance normal functional patterns of limb and trunk movement.

Bryan J. O'Young MD. Mark A. Young MD. Steven A. Stiens, MD, Physical Medicine and Rehabilitation Secrets Third edition 2008 Philadelphia, PA 19103-2899 MOSBY ELSEVIER. ISBN: 978-1-4160-3205-2

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