Oculomotor nerve palsies
Oculomotor nerve palsies
Description, Causes and Risk Factors:
Alternative Name: Third nerve palsy.
The third cranial nerve controls movement of four eye muscles that move the eye in, up, down and torsion. The third cranial nerve also controls constriction of the pupil, the eyelid and the ability of the eye to “focus” or accommodate and upper eyelid position.
The oculomotor nerve (cranial nerve III) innervates all internal and external ocular muscles except the superior oblique and the lateral rectus and is considered the most important nerve involved in ocular motility. Although oculomotor nerve palsy is less common than sixth and fourth cranial nerve palsies, it is associated with significant morbidity.
Patients typically present with blepharoptosis, limitation in eye movement accompanied by exotropia and a dilated pupil which poorly reacts to light.
Types May include:
Ischemia is the most common cause of pupil sparing oculomotor nerve palsy.
Intracranial aneurysms are the most common cause of isolated oculomotor nerve palsy involving the pupil.
Congenital oculomotor nerve palsy is rare compared to acquired oculomotor nerve palsy.
Most reports have stated ischemia as the most common cause of oculomotor nerve paralysis. Although the majority of patients with ischemic oculomotor nerve palsy suffer from diabetes mellitus, other disorders such as hypertension, atherosclerosis and migraine may manifest similarly.
The majority of peripheral oculomotor nerve palsies are caused by minor injury to vessels in subarachnoid space or in the cavernous sinus. Less common causes are compression (due to aneurysm or tumor) and inflammation (sarcoidosis and vasculitis). In cases of trauma-related third cranial nerve palsy, underlying lesions such as aneurysms and tumors should be considered and ruled out.
Childhood Causes of third nerve (oculomotor) palsy may include:
Viral or post-upper respiratory tract infection.
Cyclic oculomotor nerve palsy.
Symptoms May Include:
Children may develop amblyopia in the involved eye.
Symptomatic glare from failure of constriction of pupil.
Blurring of vision on attempt to focus of near objects due to loss of accommodation.
Diplopia.People over 10 years of age with third nerve palsy usually have diplopia (double vision) due to misalignment of the eyes. If a ptosis (droopy eyelid) covers the pupil, diplopia may not be noticeable.
The diagnosis is based on results of a neurologic examination and computed tomography (CT) or magnetic resonance imaging (MRI). If the pupil is affected or if symptoms suggest a serious underlying disorder, CT is done immediately. If a ruptured aneurysm is suspected and CT does not detect blood, a spinal tap (lumbar puncture), magnetic resonance angiography, CT angiography, or cerebral angiography is done.
When the paralysis is partial, especially when some adduction is preserved, the patient may benefit from maximal recession of the lateral and resection of the medial rectus muscles. This may be combined with upward transposition of the muscle insertions to counteract the hypotropia. Transfer of the superior oblique muscle to the insertion of the medial rectus muscles with or without fracture of the trochlea has also been recommended.
Ptosis surgery is postponed until alignment of the eyes has been achieved by surgery. Caution with regard to ptosis surgery is advised if elevation is impaired because of exposure problems.
Treatment if often surgical. The surgical treatment of third nerve palsies presents a formidable challenge to the ophthalmic surgeon. A complete third nerve paralysis with complete ptosis is best left untreated.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
Reference and Source are from:
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
A new research from the University of Edinburgh, UK, suggests that cheap cilostazol tablets may reduce damage to arteries, which lead to blood clots, resulting in strokes and cognitive decline. The researchers plan to assess the medications’ ability to cut the risk of...
A new study from the US discovers that flavonoids, natural compounds found in fruits and vegetables, may help preserve the lung function, which tends to decline with age. For the study, a team of researchers looked at data from 463 adults from Norway and England whose...
Quiz about this article
0 of 2 questions completed
Please answer on few questions to make our service more useful
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
0 of 2 questions answered correctly
Time has elapsed
You have reached 0 of 0 points, (0)
Question 1 of 2
Was this article useful for you?Correct
Thanks for your feedback!Incorrect
Thanks for your feedback!
Question 2 of 2
What else information about this disease you want to know ?Correct
Thanks for feedback!Incorrect
Thanks for feedback!
Good weather is the best reason to do outdoor sports, which will help not only lose weight, but also will strengthen health. Bicycle The sun dries out the local paths, so you can safely sit on your favorite bike and confidently twist the pedals, where the eyes look....read more
First aid for injuries consists of simple rules that need to be clearly implemented. If this is a closed injury, you need to immobilize the injured limb, otherwise the person may lose consciousness from a painful shock. If you need to get to the emergency room...read more
Many people spontaneously decide starting to do sport, while others weigh all the pros and cons for a log time. But almost all of them make the same mistakes, listening to the advice of non experts. There are 10 anti-tips for those who want to do plan to do some sport...read more