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Third nerve paralysis, also known as third or oculomotor nerve palsy, is a type of paralysis that affects the functions of the eye. It is named this because it affects the third of the 12 cranial nerves. This particular nerve paralysis can be partial or complete.
The third cranial nerve is responsible for the eye and its four muscles and controls the eyelid, focusing abilities, and pupil constriction. Third nerve paralysis can affect any of the functions of the eye, but is not always chronic or permanent. A partial paralysis can cause drooping eyelids or a wandering eye, known as lazy eye. Complete paralysis can cause more severe symptoms, and the eyelid can be completely closed or the eye could be unable to move at all.
Third nerve paralysis is generally caused by damage to the oculomotor nerve. Brain tumors, severe head trauma, brain infection, encephalitis, and an aneurysm can all be possible causes of these types of nerve paralysis. These conditions are referred to as acquired oculomotor palsy. In some cases, the paralysis is present at birth and does not always have a clear understanding of the causes of nerve paralysis.
Symptoms of nerve paralysis for this condition will vary depending on the severity of the paralysis, the cause, and the age of the person. Most common symptoms include double vision because the eyes are not aligned, an enlarged pupil that does not react to light, and a drooping eyelid.
Some scientists believe that children born with these types of paralysis have inherited a familial tendency in a recessive gene from a parent. Studies have also suggested that aplasia or an instance of incomplete development of the oculomotor nerve can be two possible explanations. The majority of newborn oculomotor paralysis cases, however, are usually caused by trauma suffered during birth.
Acquired cases of third nerve paralysis can have many different causes. Vascular conditions, such as heart disease and diabetes, can lead to nerve damage. Additionally, diseases that cause lesions or tumors in the brain, such as multiple sclerosis and sinus thrombosis, can be causes. In some cases, neurosurgery performed near the nerve can lead to damage if scar tissue replaces healthy tissue in the area. Autoimmune disorders, such as Sjogren’s syndrome and Myasthenia gravis, can also cause gradual paralysis of the oculomotor nerve.
There are several aspects involved when treating third nerve paralysis. A team of several doctors in different specialties will need to work together to treat symptoms and underlying causes. The nerve itself must be repaired naturally by the body. Double vision can be treated by covering one eye, and special glasses can be used to retrain the eye muscles to treat lazy eye. Surgery can be used to raise the eyelid in severe cases.