Patients may be treated for dysphagia
after suffering a stroke or after traumatic
brain injury. Other causes of dysphagia include
brain tumor, spinal
cord injuries, progressive diseases like Parkinson's Disease and multiple
sclerosis as well as metabolic encephalopathy.
The exact
incidence of dysphagia in the population of adults with
neurogenic disorders is unknown. However, when the
Rehabilitation Institute of Chicago surveyed their records,
they found that about one third of such patients in their
facility had some type of dysphagia (Cherney, 1994).
According to
Cherney (1994), stroke was the most common cause of
dysphagia, accounting for about half of the cases. Bilateral
cortical stroke was the type of CVA most likely to cause
dysphagia. Unilateral right hemisphere lesions cause more
dysphagia than do unilateral left hemisphere lesions. This
probably occurs because right hemisphere lesions often cause
impulsivity, poor judgment, and reduced ability to follow
compensatory strategies. Approximately one
third
of stroke patients have some type of dysphagia.
Traumatic Brain
Injury (TBI) was the second most common cause of dysphagia,
being the cause of about 20% of swallowing problems seen at
that facility. Overall, about 25% of patients suffering from
Traumatic Brain Injury have some type of dysphagia. As with
CVA it seems reasonable to assume that those with right
hemisphere lesions would have more problems.
Stroke tends to
cause mild or moderate dysphagia. However I have worked with
many CVAs who were quite severe. TBI more often causes
severe dysphagia.
A
stroke or cerebral vascular accident is the
temporary or permanent loss of functioning brain tissue due
to an interruption in the blood supply. There are two types
of stroke; those that result from a full or partial blockage
of an artery and those caused by hemorrhages, or ruptures of
intracranial blood vessels.
Approximately
300,000 people have strokes in the U.S. each year. The
following factors predispose an individual to stroke:
Primary
Hypertension greatly increases a person's risk of
suffering a CVA. Primary hypertension refers to elevated
diastolic or systolic blood
pressure. Systolic blood pressure (upper
number) is measured when the heart is contracting, while
diastolic pressure (lower
number) is measured when the heart muscle is between beats.
Normal blood pressure is 120/80 (mm. of mercury Hg.), while
upper limits of normal are 140/90 (Tabor's Cyclopedic
Medical Dictionary). During strenuous exercise, a normal
person's blood pressure will go up into the high range
temporarily. In cases of primary hypertension, blood
pressure remains in the high range regardless of activity
level. Untreated hypertension increases the likelihood of
stroke by pushing plaque up against arterial walls, causing
stenosis which sometimes leads to thrombosis. The cause of
primary hypertension is unknown, but is seems to be
inherited.
Smoking and
obesity further increase the risk of vascular problems in
those who have hypertension. Mild hypertension seems to
respond to exercise.
High
Cholesterol Levels (hypercholesterolemia) also increase
the risk of stroke. HDL or High Density
Lipoprotein is the "good" cholesterol.
LDL or Low Density
Lipoprotein is the "bad" cholesterol. It is all
right to have elevated levels of HDL, but having a high
concentration of LDL in the blood is a health risk. Overall
cholesterol levels should be under 200.
Hypercholesterolemia can cause stroke even in
very young people
There is research
that supports the position that arterial inflammation may be
more predective of stroke and heart attack than cholesterol
level. A simple blood test that measures C-reactive factor
can indicate the amount of inflammation.
Eating Red Meat
A study in the journal Nature Medicine (2013), points out that carnitine is a compound in red meat that is also in some energy drinks. Certain bacteria in the digestive tract convert carnitine into TMAO which promotes athersclerosis, or a thickening of the artieries. Researchers led by Stanley Hazen, chief of cellular and molecular medicine at the Cleveland Clinic, tested the carnitine and TMAO levels of omnivores, vegans and vegetarians. Robert A. Koeth etal. 2013 examined records of 2,595 patients undergoing cardiac evaluations. Patients with high levels of TMAO, the more carnitine in the blood, were more likely to develop cardiovascular disease, heart attacks, stroke and death. A number of other studies have linked consumption of red and processed meat with cardiovascular disease and some cancers.
There are two
principle types of stroke, ischemic and hemorrhagic.
The
term "ischemia" refers to a lack of blood-borne oxygen.
Ischemic strokes are more common than hemorrhagic strokes
and may be caused by stenosis, thrombosis, or thrombo-emboli.
Stenosis is a general term that
means "narrowing." In this case, it refers to the narrowing
of an artery due to the build-up of plaque. As the artery is
not completely blocked, some blood does pass through it.
However, if at least 50% of normal blood pressure is not
maintained, brain damage will occur.
Thrombosis refers to a complete
blockage of an artery due to a build-up of plaque.
Thrombo-emboli are pieces of plaque which
break lose from thrombi and travel through the arterial
system of the brain until they reach a narrowed area and
lodge there, cutting off blood supply to brain tissue beyond
that point. This sometimes occurs when a normally sedentary
person engages in strenuous activity. A blockage in the middle cerebral artery could result in aphasia.
Two different type
of ischemic events are warning signs that a stroke is likely
to occur in the near future.
TIA or Transient
Ischemic Attack
This is a
transient disturbance of the blood supply to a localized
part of the brain which produces a temporary focal lesion. Unlike
strokes, TIAs resolve in spontaneous and complete recovery within one day.
TIAs typically last between two and fifteen minutes,
although such an event could conceivably last as long as
twenty-four hours. It is also possible to have a series of
many brief TIAs during one day. For example, a patient might
have 20 transient ischemic attacks within a twenty-four hour
period. The communicating arteries in the circle of Willis may prevent an actual stroke by shunting blood around a thrombosis.
Symptoms of TIAs mimic those of stroke. These attacks may
cause temporary aphasia, numbness, and impairments of
speaking, reading, and writing abilities. Dizziness and
visual problems, such as blindness in part of the visual
field, also occur. Sometimes TIA's are very mild and involve
only numbness in a limb, or loss of sight in one eye. Severe
TIAs can not be differentiated from a stroke until recovery
occurs. I had one patient whose first TIA occurred while he
was eating lunch with his wife. She noticed that he had
stopped eating and was just sitting there with food falling
out of his mouth. He recovered completely within twelve
hours. A change of lifestyle after a TIA may prevent a
cerebral vascular accident (CVA). Patients should see their
doctors about an appropriate exercise and diet
program. The doctor may advise a vegan or vegetarian diet which might help prevent an actual stroke.
RIND or Reversible
Ischemic Neurological Defect
Some professionals feel that the term RIND is no
longer applicable. That it is really a stroke. A RIND is a
lengthy TIA. The term RIND is usually applied to attacks
that continue for more than twelve hours without
interruption, although some RINDs endure for several days.
As is the case with TIAs, patients make a complete recovery
from RINDs. (There is some evidence that RINDs do cause some
extremely subtle neurological damage, but these minor
changes are nothing like the disabilities seen after an
actual stroke.)
Sometimes, events
that last for twenty-four hours are called TIAs rather than
RINDs, so there is some inconsistency in the application of
this terminology.
Strokes, TIAs and
RINDs are most likely to occur in the morning, when blood
pressure is at its lowest. When a person gets out of bed
the change in activity level causes a change in blood
pressure.
Hemorrhagic
Strokes
Hemorrhagic stroke
occurs when a cerebral artery ruptures, causing bleeding
within the cranium. Such ruptures may be caused by aneurysms
or weak spots on the arterial walls. Aneurysms can balloon
rather than bursting. The excess pressure resulting from
this swelling can also damage brain tissue. The striata artery, a branch of the middle cerebral is quite thin and in some people can rupture easily. Because it takes blood to the internal capsule and basal ganglia a hemorrhage there can damage the axons of descending upper motor neurons (pyramidal tract) or the basal ganglia (nucleus), resulting in weakness or paralysis.
Bleeding due to
stroke or TBI can result in hemotoma or pools of congealed
blood in the epidural or subdural spaces. The former is
usually arterial while the latter is usually venous.
Bleeding can also occur within brain tissue. According to
Coch and Metter, 1994, this parenchymal bleeding occurs most
frequently in the putamen, thalamus, pons and cerebellum.
Before the advent of sophisticated scanning technology that
allows identification of the affects of light as well as
heavy bleeding it was believed that prognosis following
hemorrhage was extremely poor. It is now recognized that
patients sometimes make a better recovery after a
hemorrhagic stroke than an ischemic one. Bleeding, if it is
light may irritate brain tissue rather that damaging it. As
the brain absorbs the blood the irritated areas may recover
completely and normal function is restored.
Strokes can be
divided into the categories of completed or progressive.
Completed strokes
are the type most commonly seen. In this case the
infarction or death of brain tissue has already occurred.
Progressive
strokes are those still evolving; meaning that the patient's
condition is continuing to deteriorate. Progressive strokes
can last for a week or more. This condition is usually due
to a severe hemorrhage.
If called in to
evaluate a patient with this diagnosis, the speech/language
pathologist should test the patient, but explain in the
report that major changes could occur shortly. Particular
caution should be used when evaluating the swallowing status
of such a patient. He/she may be able to swallow safely
initially, but develop dysphagia later as his/her condition
worsens. Also, progressive strokes tend to happen to people
who have very poor cerebral vascular health and are
therefore at risk for having other strokes soon.
