What does cerebellar ataxia reveal about normal functioning of the cerebellum?

Cerebellar ataxia is a form of ataxia that can either be acute or chronic. Chronic ataxia is referred to as cerebellitis and sometimes seen with patients with multiple sclerosis. Cerebellar ataxia originates from abnormalities like inflammation in the cerebellum i.e. occipital and temporal lobes. Cerebellumis is responsible for muscle movement and motor control and learning. It is also found below the cerebrum and at the back of the brain. This form of ataxia causes loss of balance and coordination. This type of ataxia can also lead to fatigue, and visual and cognitive issues. 

 More symptoms include tremors, difficulties swallowing, double vision (diplopia), difficulty estimating passing time (dyschronometria), involuntary eye movements, and more. Symptoms vary depending on how the cerebellum was affected. Cerebellar ataxia does not have one clear cause but could be a result of underlying conditions or no obvious cause at all. It can have a genetic origin, which is a result of inherited mutations in genes SCA1 to SCA37. Abusing alcohol can also directly damage the cerebellum, which results in a loss of proper functioning. Another cause for cerebellar ataxia is infection, which causes inflammation of the cerebellum. This impairs the cerebellum’s ability to properly function. The infections that are commonly the cause for ataxia include chickenpox or even Lyme disease. Another cause for inflammation of the cerebellum includes trauma to the head or bleeding. Tumors can also affect the structure of the cerebellum and cause cerebellar ataxia. Idiopathic late onset cerebellar ataxia or ILOCA is a result of cerebellar degeneration but there is no clear cause. Patients with ILOCA show variation in the physical changes of the cerebellum. 

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Student 2

1. What does cerebellar ataxia reveal about normal functioning of the cerebellum?

            To start with the definition of Ataxia according to Medical News Today is “Ataxia is a lack of muscle coordination which may affect speech, eye movements, the ability to swallow, walking, picking up objects, and other voluntary movements.” There are many different types of ataxia and there can be many different factor which can cause it example trauma, tumor, substance abuse or genetics etc.

One major type of ataxia is cerebellar ataxia and as the name suggest it is caused by improper functioning of the cerebellum in the brain. Sensory perception, motor control and coordination are associated with this region of the brain. As this affects the muscles control it doesn’t allow the normal functioning of the cerebellum it creates many problems like floppiness, inability to perform movements which are rapid and alternating, impaired ability to control distance and speed of arm, or hand and leg eye etc. It also creates a lack of coordination between organs, limbs and the joints. And also affects the estimation skills of figuring out time passing. 

However the symptoms are only appeared up to an extent and that is determined by which part of the cerebellum is damaged. And also the occurrence of the lesions is unilateral or bilateral. Like for example a persons eye movement and balance are affected if the vestibulocerebellum is affected. The standing posture of the person will highly be affected as he or she will try to gain better balance by spreading their feet etc. If the spineocerebellum part of the cerebellum is affected the person is like to have an unusual gait with unequal steps and stuttering starts and stops with sideways steps and the spinocerebellum is responsible for regulation of body and limb movements. And moving on the person is likely to have problems with planned movements and voluntary actions if cerebrocerebellum is affected. It also causes slurring in speech and variation in the rhythm and loudness. Tremble in head, eyes, limbs and toros is observed as the voluntary moves are executed.

Usually according to the trend cerebellar ataxia emerges between the ages of 4 and 26. And if there is a late onset of this the symptoms are comparatively less severe.  And symptoms in general include Small veins appearing around the corner of the eyes, cheeks, and cause sideward curvature of the spine or delayed caused in physical as sexual development and other  things like high arching feet and diabetes. However if the ataxia is cause due to some illness or injury the symptoms often improve as the time. 

There are many many different types of options available these days like medication, supplements and nutrition, counseling, physical therapy or speech or occupational therapy or orthopedic care etc. The ataxia itself is not curable but all these fight the symptoms very well and over all improve quality of life.

Student 3

3.   Due to a spinal injury, a patient lost pain and temperature sensation on the left half of his body from the waist down. Where was his injury? Where would you expect loss of tactile sensation in this patient?

The loss of pain and temperature sensation indicates that those neurons cross the midline of the spinal cord. If the sensation is lost on the left side, then the damage might have occurred on the right side. You can expect the loss of vibration, pressure, and more and these neurons do not cross the midline of spinal cord. Any presentation of injury that is incomplete lesion can be called partial Brown-Séquard, which is the loss of vibration sense and fine touch and signs of weakness on same side of injury. 

4.     Define the motor unit. What is spinal shock?

The motor unit is made up of the somatic efferent neuron and the muscle fibers that it innervates. In the figure above, the motor units are shown diagrammatically. The efferent axon branches to form synapses with muscle fibers once it enters the muscle. Each muscle fiber is connected to one efferent neuron. The synapse (between the efferent neuron and the muscle fiber) releases acetylcholine to the point of depolarization of the muscle fiber. This is different compared to the synapses in the CNS. The rule that governs the single motor unit function: one action potential (re: efferent neuron) to one action potential in muscle fibers due to the synapse being so large. This triggers an all-or-nothing contraction or a twitch. Activating a number of different motor units makes contractions of different strengths. Motor units fall into three groups and in these groups the efferent neuron and muscle fibers have distinct properties. The three types include the slow and fast oxidative and fast glycolytic. 

Spinal shock is temporary loss of reflexes following an injury to the spinal cord. The autonomic nervous system controls your reflexes. Basically, the more sever the injury, the more sever the autonomic dysfunction. Almost all who experience a spinal cord injury will have some degree of spinal shock. After this, the spinal cord enters hyporeflexia (significant reduction) or areflexia (temporary loss). In the hours after the injury or spinal shock, the survivors may not realize they are experiencing spinal shock. 

Student 4

1.  Due to a spinal injury, a patient lost pain and temperature sensation on the left half of his body from the waist down. Where was his injury? Where would you expect loss of tactile sensation in this patient?

After reviewing the information, as well as doing some studying on spinal injuries, I have reason to believe that the injury took place on the right half of the body.  This is of course because on the body's movements of one side is controlled by the opposite side of the brain and spine.  As far as which specific part of the spine was injured, I believed it was one of the thoracic vertebrae, since these are responsible for lower body movements.   I believe T6, T7, or T8 was injured, or some combination of the 3..  It is damage to this area, is what caused the lost of sensation.  These kinds of injuries usually happen to something pretty catastrophic such as a severe car wreck or sports injury.  The image below shows the all the vertebrae in the spine. 

 2. Define the motor unit. What is spinal shock? 

A motor unit is made up of a single nerve cell or neuron that innervates a group of skeletal muscles. The neurons receive signals from the brain and stimulate all the muscle fibers in that particular motor unit. Motor units are different depending on where they are and what they do. They also come in different sizes. There are small motor units that may only stimulate five or ten fibers to do things like blinking or sniffing. You also have motor units that include hundreds of muscle fibers. These are responsible for big movements like kicking or jumping.  

Spinal shock refers to a clinical syndrome characterized by the loss of reflex, motor and sensory function below the level of a spinal cord injury. In some instances, this syndrome is associated with loss of autonomic tone leading to hypotension, hypothermia and illeus. Spinal shock usually develops suddenly or within a few hours and it is not necessarily associated with hypotension resulting in shock.