Ataxia - A neurological sign and symptom that consists of gross lack of coordination
of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction
of the parts of the nervous system that coordinate movement. Several possible causes
exist for these patterns of neurological dysfunction.
Cerebellar ataxia - is due to dysfunction of the cerebellum which causes a variety
of elementary neurological deficits, such as:
Antagonist hypotonia.
Asynergy.
Dysmetria.
Dyschronometria.
Dysdiadochokinesia.
Dysfunction of the vestibulocerebellum - this part of the cerebellum impairs the
balance and the control of eye movements. This presents itself with:
Postural instability, the person tends to separate their feet upon standing, in order
to gain a wider base and to avoid bodily oscillations. Instability is worsened when
standing with the feet together, regardless of whether the eyes are open or closed.
This is a negative Romberg's test. It denotes the individual's inability to carry
out the test, because the individual feels unstable even with open eyes.
Dysfunction of the spinocerebellum - this part of the cerebellum regulates body and
limb movements and presents itself with:
A wide-based gait, characterised by uncertain start and stop, lateral deviations,
and unequal steps.
Dysfunction of the cerebrocerebellum - this part of the cerebellum regulates voluntary,
planned movements and presents itself with problems such as:
Intention tremor - coarse trembling, accentuated over the execution of voluntary
movements, possibly involving the head and eyes as well as the limbs and torso.
A peculiar pattern of dysarthria - slurred speech, sometimes characterised by explosive
variations in voice intensity despite a regular rhythm.
Sensory ataxia - loss of proprioception - the loss of sensitivity to the positions
of joint and body parts. This is generally caused by dysfunction of the dorsal columns
of the spinal cord, because they carry proprioceptive, (the sense of the relative
position of neighbouring parts of the body), information up to the brain.
Another cause of sensory ataxia may also be dysfunction of the various parts of the
brain which receive positional information, such as:
The cerebellum.
The thalamus.
The parietal lobes.
Sensory ataxia presents itself as an unsteady stomping gait and heavy heel strikes,
as well as a postural instability that may worsen when the lack of proprioceptive
input cannot be compensated for by visual input.
Evidence of sensory ataxia may be demonstrated by having the patient stand with their
feet together and eyes shut. In those affected, it will cause the instability to
worsen markedly, producing wide oscillations and possibly a fall. This is called
a positive Romberg's Ref test.
Other indications.
Finger-pointing test with the eyes closed. Standing with arms and hands extended,
if the eyes are closed, the finger will tend to fall down and then be restored to
the horizontal extended position by sudden muscular contractions (the "ataxic hand").
Vestibular ataxia - dysfunction of the vestibular system, which in acute and unilateral
cases is associated with:
Vertigo.
Nausea.
Vomiting.
In slow-onset, chronic bilateral vestibular dysfunction, the manifestations may be
absent, and dysequilibrium (disturbance of a state of equilibrium), may be the sole
presentation.
There are many different types of ataxia. The symptoms vary depending on the type
of ataxia a person has, and how severe it is. If ataxia is caused by another health
condition or injury, symptoms can appear at any age, and may get better or disappear
over time.
Early symptoms may include:
Poor co-ordination in the arms and legs.
Dysarthria - slurred speech.
Difficulty swallowing.
Lack of facial expression
Nystagmus - rapid eye movement.
Es Cavus - overarched foot or feet.
Cold feet
Tremor - involuntary shaking of body parts.
As ataxia progresses, these symptoms may become more severe.
Some those may be severely affected yet others only get mild symptoms, and for some
those, the symptoms of ataxia will gradually get worse. They may lose the ability
to walk and hearing and vision can also be affected.
Cerebellar ataxia’s can either be early onset or late onset.
Early onset ataxia usually appear between the age of four and 16 years' of age.
Late onset ataxia usually appear after the age of 20. (symptoms of late-onset ataxia
are usually less severe).
Many ataxia's are hereditary and are classified by chromosomal location and pattern
of inheritance: autosomal dominant, in which the affected person inherits a normal
gene from one parent and a faulty gene from the other parent; and autosomal recessive,
in which both parents pass on a copy of the faulty gene.
Among the more common inherited ataxia's are Friedreich’s ataxia and Machado-Joseph
disease. Sporadic ataxia’s can also occur in families with no prior history.
A rare, childhood neurological disorder that causes degeneration in the part of the
brain that controls motor movements and speech. Its most unusual symptom is an acute
sensitivity to ionising radiation, such as X-rays or gamma-rays.
The first signs of the disease, which include delayed development of motor skills,
poor balance, and slurred speech, usually occur during the first decade of life.
Telangiectasias (tiny, red "spider" veins), which appear in the corners of the eyes
or on the surface of the ears and cheeks, are characteristic of the disease, but
are not always present and generally do not appear in the first years of life.
About 20% of those with A-T develop cancer, most frequently acute lymphocytic leukemia
or lymphoma. Many individuals with A-T have a weakened immune system, making them
susceptible to recurrent respiratory infections.
Other features of the disease may include mild diabetes mellitus, premature graying
of the hair, difficulty swallowing, and delayed physical and sexual development.
Children with A-T usually have normal or above normal intelligence.
Symptoms may also include:
Small red veins around the corners of the eyes, and on the cheeks and ears.
Delayed physical and sexual development.
Weakening of the immune system.
Friedreich's ataxia
An inherited disease that causes progressive damage to the nervous system resulting
in symptoms ranging from gait disturbance and speech problems to heart disease. It
is named after the physician Nicholaus Friedreich, who first described the condition
in the 1860s. "Ataxia," which refers to coordination problems such as clumsy or awkward
movements and unsteadiness, occurs in many different diseases and conditions. The
ataxia of Friedreich's ataxia results from the degeneration of nerve tissue in the
spinal cord and of nerves that control muscle movement in the arms and legs. The
spinal cord becomes thinner and nerve cells lose some of their myelin sheath — the
insular covering on all nerve cells that helps conduct nerve impulses.
Friedreich's ataxia, although rare, is the most prevalent inherited ataxia, affecting
about 1 in every 50,000 those in the United States. men and women are affected equally.
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Symptoms may also include:
Scoliosis - sideways curvature of the spine.
Cardiomyopathy - weakening of the heart.
Diabetes.
Machado-Joseph disease (MJD), which is also called spinocerebellar ataxia type 3
A rare hereditary ataxia. (Ataxia is a medical term meaning lack of muscle control.)
The disease is characterised by clumsiness and weakness in the arms and legs, spasticity,
a staggering lurching gait easily mistaken for drunkenness, difficulty with speech
and swallowing, involuntary eye movements, double vision, and frequent urination.
Some individuals also have dystonia (sustained muscle contractions that cause twisting
of the body and limbs, repetitive movements, abnormal postures, and rigidity) or
symptoms similar to those of Parkinson's disease. Others have twitching of the face
or tongue, or peculiar bulging eyes.
Almost all MJD people experience vision problems, including double vision or blurred
vision, loss of the ability to distinguish colour and/or contrast, and inability
to control eye movements. 4
Conditions that can cause acquired ataxia include:
Stroke.
Multiple sclerosis.
Tumors.
Alcoholism.
Peripheral neuropathy.
Metabolic disorders.
Vitamin deficiencies.
The cerebellum is responsible for coordinating movement, planning, motor activities,
learning and remembering of physical skills and for some cognitive abilities. The
cerebellum controls movement by collecting sensory nerve inputs, such as limb position,
balance information and vision, and synthesising them together to control movement
by sending nerve transmissions down motor nerve outputs. The learning of physical
tasks is done by trial and error and then stored into cerebellar memory.
There is some evidence that mental activities are also coordinated in the cerebellum
which could explain why cognitive dysfunction is sometimes associated with damage
to the cerebellum. The cerebellum is divided into two hemispheres by the central
"vermis" (the cerebellar vermis is a narrow, wormlike structure between the hemispheres
of the cerebellum). The surface of each hemisphere is made up of grey matter surrounding
a large mass of white matter - nerve cells with myelinated axons. The whole structure
is connected to the rest of the central nervous system by three very broad tracts
of white matter called the cerebellar peduncles.
Some of symptoms associated with damage to the cerebellum or the nervous tracts leading
to it are:
Ataxia - difficulty in coordinating movements.
Dysarthria - loss of coordination of the muscles controlling speech.
Dysdiadokokinesia - difficulty in performing rapid alternating movements.
Loss of balance.
Loss of postural tone.
Muscle weakness.
Tremors.
Vertigo.
Romberg's test - the exam is based on the premise that a person requires at least
two of the three following senses to maintain balance while standing:
Proprioception (the ability to know one's body in space).
Sensation (the ability to feel touch, pressure, or vibration.
Vision (which can be used to monitor changes in balance).
Those who have a problem with proprioception can still maintain balance by using
sensation and vision. In the Romberg test, the patient is stood up and asked to close
their eyes. A loss of balance is interpreted as a positive Romberg sign.
