A 40 Year Old Known Diabetic Patient Presents With Double Vision

A 50 year old man who is a known case of diabetes presents to the clinic with symptoms of double vision that started a few days ago and has not improved. His wife observed that his right eye is directed outwards and does not seem normal.
On neurological examination the patient was diagnosed to have an oculomotor nerve palsy most probably secondary to diabetic neuropathy. Rest of the examination was normal.
The picture is shown below:

The right eye is directed downwards and outwards. pupil is slightly dilated compared to the normal left side. In this case there is no ptosis (which is possible in 3rd cranial nerve palsy)

Case Discussion:

Oculomotor (3rd Cranial Nerve) Palsy:

Oculomotor nerve palsy is an eye condition resulting from damage to the third cranial nerve or any of its branch.

The oculomotor nerve supplies the majority of the muscles controlling eye movements. Thus, damage to this nerve will result in the affected individual being unable to move his or her eye normally. In addition, the nerve also supplies the upper eyelid muscle (Levator palpebrae superioris) and the muscles responsible for pupil constriction. The limitations of eye movements resulting from the condition are generally so severe that the affected individual is unable to maintain normal alignment of their eyes when looking straight ahead, leading to strabismus and, as a consequence, double vision (diplopia).

The condition is also known as "Oculomotor neuropathy".

Etiology: The are a number of conditions that may lead to the paralysis of the oculomotor nerve. These may include:

• Congenital ( which may be idiopathic, familial or sometimes secondary to severe birth trauma).
• Vascular disorders like diabetes, heart disease, atherosclerosis etc
• Aneurysms particularly of posterior communicating artery. 
• Inflammation or infection
• Trauma
• Demyelinating diseases like multiple sclerosis.
• Certain autoimmune disorders e.g myasthenia gravis.
• As a complication of neurosurgery.
• Cavernous sinus thrombosis.
• Tumors

Clinical Features: Patients most commonly present with double vision. it results because the affected eye looks outwards when the unaffected eye looks straight. The eyelid on the affected side may droop and the pupil may be dilated. Sometimes symptoms of the underlying cause may be present like severe headache when secondary to a ruptured aneurysm. 

Diagnosis: After clinical diagnosis from the presentation imaging studies are done to determine the underlying cause.

1. MRI is sensitive in picking small intraparenchymal brain stem lesions such as infractions, abscess or tumors.

2. Ct scan is helpful is detecting subarachnoid hemorrhage. 

3. Lumbar puncture may be done to rule out infection and bleeding.

4. Cerebral angiography is done to detect berry aneurysms. 

Treatment: Medical management is actually watchful waiting, since there is no direct medical treatment that alters the course of the disease. Fortunately, nearly all patients undergo spontaneous remission of the palsy, usually within 6-8 weeks.

• Treatment during the symptomatic interval is directed at alleviating symptoms, mainly pain and diplopia.
• Nonsteroidal anti-inflammatory drugs (NSAIDs) are the first-line treatment of choice for the pain. Diplopia is not a problem when ptosis occludes the involved eye.