Acute, Isolated Cranial Nerve III Palsy

Sung Hak (Steve) Choi
Doctor of Osteopathic Medicine
University of New England College of Osteopathic Medicine

CC: “I have pain and swelling on the left eye for the past two days”
HPI: A 39YO AAF without significant PMH c/o sharp pain and swelling on her left eye for two days. She was in her usual, healthy state until two days prior to the admission. The patient noticed 6/10 sharp pain on her left eyeball and the skin around and swelling of her upper eyelid upon waking up in the morning. She states that she couldn’t open her left eye because of the swelling. She took Tylenol 500mg every four to six hours, which moderately relieved her pain from 6/10 to 4/10, but the pain and swelling never went away completely. She doesn’t know if there was anything in particular that triggered or worsened her symptoms. When she forces her left eye to open with her fingers, she gets a blurry vision and 10/10 shooting pain on her eyeball and the skin around. Her current symptoms have not changed since the onset. The pain does not radiate  anywhere else and stays in her left eye region.  She reports that it hurts when she touches it and there is a tingling feeling around her left eye. She went to see her PMD  on the day of admission who sent her to the ED right away. Her PMD did not explain anything to her about what may be going on with her condition. She admits to smoking two to three cigarettes a day for about 20 years. She denies a similar episode in the past, hypertension, diabetes, recent trauma, accident, injury, loss of consciousness, HA, nausea, vomiting, fever, chills, night sweats, weight loss, tearing, redness, itching, discharge from her eyes, hearing changes, discharge, pain from her ears, sinus pain, discharge, bleeding from her nose, sore throat, family history of strokes, cardiovascular diseases, recent antibiotic uses, or vitamin overdose.
PMH: the patient denies any significant PMH
PSH: the patient admits to tubal ligation in 2008 and C-section in 2006 because of macrosomia. No complications.
MEDS: the patient denies taking any medications including vitamins and herbals
ALL: the patient denies any allergy including drugs and foods
FamHx: the patient admits to HTN in her grandmother
SocHx: the patient admits to two to three cigarettes a day for about 20 years (3 pack-year history), occasional 2-3 drinks on the weekends, denies illicit drug use. She works at a local hospital as a custodian.

PE
VS:
T: 98.7 / RR: 18 / HR: 84 / BP: 122/81
Gen: AAOx3. Pt is very concerned about her current illness. She is a reliable historian, and exhibits no marfanoid habitus
HEENT:
•    Left eye – complete ptosis with minimal edema on the upper eyelid. The eyeball and upper eyelid were tender to palpation. Mydriasis and anisocoria were noted. Complete lateral and slight inferior displacement of the eye was noted. Pupil constriction to light was sluggish and the patient was unable to move her left eye past the midline toward right; when attempted, diplopia was reported. No funduscopic exam was done due to 10/10 shooting pain in her eyeball when the eyelid was forced open with fingers. No nystagmus, tearing, discharge, erythema, foreign bodies
•    Right eye – normal pupil and fully intact EOM were noted. No edema, pain, paresthesia, tearing, discharge, erythema, foreign bodies were noted.
•    Normocephalic / No sinus tenderness, ear discharge, abnormal ear drum, abnormal nasal mucosa/discharge, dry mucosa, exudative throat
Neck: no carotid bruit was heard. The neck was supple with intact ROM. Trachea and thyroid gland was midline without any swollen lymph nodes
Hrt: rate and rhythm were regular with clear S1 & S2
Lungs: the lungs were clear to auscultation bilaterally
Ab: bowel sound was present without tender or distended abdomen
Ext: No edema and full ROM were noted.
Neuro: bilaterally 2/4 deep tendon reflex was noted in biceps, triceps, knees, ankles. Bilaterally 5/5 in the upper extremities and lower extremities were noted. Cranial nerve 4, 6-12 were grossly intact. When palpated, paresthesia was reported by the patient in the left periorbital area. (refer to HEENT for cranial nerve III – oculomotor nerve – exam)
Labs: Na=136 K=4 Cl=99 HCO3=25 BUN=12 Cr=0.8 glc=138 WBC=5.5 HGB=11.8 HCT=32 PLT=238 RDW=13 MCV=89

The Patient’s Hospital Course
I. In the emergency department, the patient received CT of the head, which showed old lacunar infarcts without currently active signs of pathology.
II. She was admitted.
III. MRI and ophthalmology and neurology consults were ordered
IV. The day after the admission, MRI of the head showed no abnormal findings. Ophthalmology consult confirmed isolated oculomotor nerve palsy and ordered neurology consult again. Neurology consult confirmed CN III and ordered MRA.
V. On day 2 of the admission, MRA showed a posterior communicating artery (PCA) aneurysm on the left side
VI. On day 3 of the admission, the patient was transferred to a different hospital with a neurosurgery department.
VII. The aneurysm was clipped during neurosurgery.
VIII. The patient was discharged

Discussion
The oculomotor nerve (cranial nerve III) innervates multiple muscles. It innervates superior rectus, inferior rectus, medial rectus, inferior oblique, levator palpebrae, sphincter pupillae, and ciliary muscles. If this nerve is damaged, malfunctioning of those muscles arises. Inferolateral displacement of the eyeball results from extraocular muscles denervation (superior rectus, inferior rectus, medial rectus, inferior oblique). Complete ptosis results from levator palpebrae denervation. Mydriasis results from sphincter pupillae and ciliary muscles denervation, which are parasympathetically regulated. The signs and symptoms always occur ipsilaterally.

Acute oculomotor nerve palsy with concurrent ipsilateral mydriasis is a PCA aneurysm on the ipsilateral side until proven otherwise. As an aneurysm from the ipsilateral PCA enlarges, it presses on the ipsilateral pupillomotor fibers, which ensheathes the oculomotor nerve. As a result, the PCA aneurysm presents with mydriasis as well as oculomotor palsy. If the patient is hypertensive, such physical findings warrant emergent blood pressure reduction because of potentially devastating rupture and hemorrhage of aneurysm. Also, vascular imaging study such as MRA must be ordered as well as neurosurgical consultation.

In the meantime, diabetes mellitus can also present as oculomotor nerve palsy. However, the presentation differs. Since it impairs vaso nervorum, which runs in the middle of the oculomotor nerve, pupil is spared (no mydriasis). The damage occurs from inside to outside, whereas the damage from PCA aneurysm from outside to inside.

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