Sixth Nerve Palsy Symptoms, Treatment, Ayurveda Understanding

By Dr Raghuram Y.S. MD (Ay) and Dr Manasa, B.A.M.S
Sixth cranial nerve is a disorder which affects the eye movements. It is caused by the damage to the 6^th cranial nerve which supplies the eyes and is responsible for the eye movements. There are 12 pairs of cranial nerves in our body. Among them Abducens Nerve is the 6^th cranial nerve. It is abbreviated as VI C.N.

Among the muscles of the eyes, lateral rectus muscles are the important ones. It is located on the outer side of the eye. These muscles help in turning our eyes away from the nose. Supplying these muscles and sending signals to them is the chief function of the 6^th cranial nerve. When this muscle is weakened due to the damage of the 6^th cranial nerve, the eye looks mis-aligned because they are no longer controlled by this muscle. This condition is called 6th cranial nerve palsy wherein your eye crosses inwards towards your nose.
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Table of Contents

Symptoms

Each eye has its own lateral rectus muscle and its own 6^th cranial nerve. Therefore, one or both eyes being afflicted by 6^th nerve palsy depends on one or both nerves being afflicted. If one 6^th cranial nerve is damaged, one eye is afflicted. If both 6^th cranial nerves are damaged, both eyes are afflicted. The symptoms and severity of this condition depends on whether one eye is affected or both.

Double vision – This is the most common symptom of 6^th nerve palsy. It is an impairment of vision. This can be noticed when the patient has kept his both eyes open or when he is looking at something in the distance. Sometimes double vision occurs when one tries to look in the direction of the damaged eye. Many times 6^th nerve palsy may not be accompanied by double vision.
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Strabismus (poor eye alignment) – This is another important noticeable symptom of 6^th nerve palsy. This is also called cross eyes. In this condition both eyes don’t look in the same direction at the same time.

Both these symptoms are typical with 6^th nerve palsy. Other symptoms may also be present. The 6^th cranial nerve travels from the brainstem to the lateral rectus muscle. Therefore, sixth nerve palsy may be caused due to neurological disorders.

Isolated 6the nerve palsy – This is a condition when 6^th nerve palsy occurs without other symptoms. If other symptoms are present, it would suggest the involvement of more than just the 6^th nerve.
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Causes

Congenital 6^th nerve palsy – Congenital condition affects the person right from the birth. 6^th cranial nerve may get injured during labor / delivery of the child. Many times, the cause is unknown.
Injury – Head injury / skull fracture can damage the 6^th cranial nerve and cause this condition.
Inflammation – Inflammation of the 6^th cranial nerve is yet another important cause for this problem to occur.
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Below mentioned causes may cause either damage or inflammation of 6^th cranial nerve and cause 6^th cranial nerve palsy –

Stroke
Infection
Meningitis
Brain tumor
Diabetic neuropathy
Brain aneurysm
Multiple sclerosis
Lyme disease

In children the most common cause for this condition is trauma. This occurs mostly due to head injury following an accident and subsequent damage of the 6^th cranial nerve. In adults stroke is the most common cause for this condition.
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Risk Factors

Sixth Nerve Palsy can occur in anyone. There is no particular group of people who are at higher risk of getting this disorder. But suitable measures can be taken to protect oneself. One should take caution and protect their heads from injuries while playing sports, riding vehicles etc since trauma is a common cause for this problem.

One can also take measures to reduce the risk of stroke since it is also a common cause for 6^th cranial nerve palsy. These measures include –

Controlling stress levels
Controlling blood pressure
Increasing physical activity / regular exercising
Losing weight
Maintaining a healthy diet
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Diagnosis

If you experience double vision or if you find that your eyes are not properly aligned or facing difficulties to see you need to immediately see your doctor. The doctor would be diagnosing this condition after taking your medical history and conducting a complete physical examination on you. A series of tests and investigations may be advised to diagnose this condition. These tests are necessary because sixth nerve palsy is caused by many causes. These tests will also help in ruling out some causes. Treating the underlying problem or cause may help in correction of this disorder gradually.

Important tests which help in diagnosis of 6^th cranial nerve palsy are –

Brain Scan – to check for the presence of brain tumor, brain injury, skull fracture or increased pressure in the brain
Neurological tests to check for the presence of any abnormalities in your nervous system
Blood test / lumbar puncture is advised to diagnose or rule out meningitis as a cause of 6^th cranial nerve palsy
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Treatment

In some conditions this palsy improves all by itself with time and treatment will not be necessary. Example – 6^th nerve palsy caused by viral infection will improve by itself after the infection has gone. Apart from these conditions, most cases of 6^th cranial nerve palsy will improve only when the underlying cause have been treated.

The treatment of this condition depends on diagnosis. If the condition is caused by a bacterial infection, doctor may recommend use of antibiotics as a course.

Corticosteroids may be prescribed if the condition is caused by inflammation. Surgery, chemotherapy or any other comprehensive treatments either to remove the tumor or to kill the cancer cells are the treatment choices if the 6^th cranial nerve palsy is caused by tumors.

Sixth Cranial Nerve Palsy may never recover from the condition when it is caused by trauma. Most often doctor will keep a monitor on condition and symptoms over 6 months period. If double vision or strabismus doesn’t improve in that time or if they worsen the doctors may prefer to wear an eye patch over the affected eye for long-term so as to alleviate the double vision. Prism glasses shall also be recommended in order to provide single binocular vision and bring alignment in eyes.

Other effective medical procedures –

Botulinum toxin injections (Botoc)
Eye surgery
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Complications

Complications may be caused by the underlying conditions which are causing the sixth nerve palsy and in fact not directly by the disease itself. Therefore, a proper diagnosis is very essential in treating this condition comprehensively.

The cause of this condition is very important and the long-term outlook depends on the cause and its identification and addressing it promptly. When treated in a comprehensive way following proper diagnosis and identification of cause of sixth nerve palsy, the symptoms usually go away within the first 6 months of their onset. The symptoms will not go away after a trauma but may notice some positive changes and some improvement in vision as body heals with time.
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Ayurveda concept

Master Sushruta has explained a vision disorder named Gambhirika. This condition has been compared to the 6^th cranial nerve palsy. The disease is marked by crookedness / destruction of vision, eyes shrunk into the sockets and appears small, and eyes are drawn deep into the sockets and presence of severe pain in the eyes. Ayurveda has considered this condition as incurable.