Eye Movement: What's the Diagnosis?

Column Author and Editor:  Joe Julian, MD, MPHTM | Hospitalist, Internal Medicine-Pediatrics; Clinical Associate Professor, Internal Medicine & Pediatrics

A 4-year-old male is brought to the emergency department by his mother for further evaluation of ear pain and headache. Symptoms started about 10 days ago with bilateral ear pain and headache. He has been very fatigued, and his appetite has been significantly diminished. There have been no associated fevers or ear drainage. He was seen in urgent care eight days prior to current presentation and was prescribed amoxicillin for treatment of bilateral acute otitis media. He developed vomiting after each dose and was switched to cephalexin three days later.

Patient started to complain of double vision yesterday, and his teacher noticed that his right eye was “pointing in.” He has never had double vision or eye movement issues in the past. He does not have any facial pain but still has headache and new right ear/neck pain. He does not have any balance or coordination issues. Due to the new onset eye symptoms, additional medical care was sought.

Vitals signs: no fever, within age-appropriate limits

General: comfortable, no acute distress, non-toxic in appearance

Head: preferentially holds head slightly rotated to right, mild tenderness of right mastoid to palpation

Ears: tympanic membranes with mild erythema without bulging bilaterally, no anterior rotation of ears

Eyes: pupils equally round and reactive (see below for eye movements)

Neck: no lymphadenopathy, full range of motion in all directions without discomfort or limitation

Facial sensation in all three branches of cranial nerve 5 are intact and equal.

There is no facial droop or slurring of speech; tongue and palate movements are appropriate.

Strength and sensation of upper and lower extremities is intact and equal without abnormalities.

Upper and lower extremity reflexes are 2+ and equal at all points tested.

via GIPHY

Question 1:

Which best describes this patient’s eye examination?

1. Right lateral gaze palsy
2. Normal examination
3. Pseudostrabismus
4. Left lateral gaze palsy

Answer:

A. Right lateral gaze palsy

The patient’s eye examination is abnormal. The left eye movements are intact in all directions while the right eye demonstrates lateral gaze impairment when attempting to track to the right. This impairment is consistent with a right lateral gaze palsy and strongly suggests cranial nerve 6 (abducens) involvement. More information for providers on cranial nerve palsies is available here through the American Academy of Ophthalmology.

Pseudostrabismus occurs when the eyes appear to have a dysconjugate gaze but they actually do not. This condition is caused by prominent epicanthal folds and is most commonly seen in infants. True strabismus should be ruled out before diagnosing pseudostrabismus. More information for parents and providers is available here through the American Academy of Ophthalmology.

Question 2:

Which of the following is the next best diagnostic step?

1. Lumbar puncture (LP)
2. Magnetic resonance imaging (MRI) of brain
3. Delay any brain imaging for three months
4. Computed tomography (CT) of head

Answer:

B. Magnetic resonance imaging (MRI) of brain

The next best step for this patient is undergo MRI of brain (with and without contrast). The patient has findings concerning for a cranial nerve 6 palsy in addition to systemic symptoms (such as headache) for which a neoplastic etiology must be evaluated. Additionally, the patient has had a prolonged course of presumptive acute otitis media, which is concerning for possible intracranial complication.

A CT of the head would not be an unreasonable first step but is not the best study to evaluate the posterior fossae of the brain (especially if evaluating for tumor). This modality would be preferred if MRI was not available. Discussion with a radiologist prior to imaging about the clinical concern would be the best way to get the most out of any CT modality, if this route is taken.

A lumbar puncture may be needed to evaluate a cranial nerve 6 palsy if a concern for an infectious etiology (such as intracranial extension of acute otitis media) or a demyelinating process (such as Miller Fisher syndrome) ultimately develops. However, given the non-isolated palsy and possibility of neoplastic process, imaging should be completed prior to lumbar puncture to evaluate for mass effect.

Delayed imaging may be reasonable in some instances of isolated cranial nerve 6 palsy. Isolated refers to findings that are unilateral, not associated with other neurological deficits, and with no concerns for elevated intracranial pressure. However, with malignancy being the most common etiology of cranial nerve 6 deficits, shared decision-making with the family should occur prior to delaying imaging.

Differential Considerations:

The most common etiology of cranial nerve 6 palsy in several case series is neoplasm. However, this risk is much lower (~10%) for those with isolated presentation rather than non-isolated (~40%).² As noted above, given the possibility of a missed tumor, even in an isolated presentation, shared decision-making with close follow-up is paramount should imaging be delayed.

Other non-neoplastic etiologies of cranial nerve 6 palsy include idiopathic intracranial hypertension, infection, inflammation, post-viral/post-vaccination, and trauma.^2,3

Clinical Course:

Due to temporary unavailability of MRI, non-contrasted CT imaging was obtained, which showed uncomplicated right-sided mastoid fluid without bony destruction and possible right transverse sigmoid dural sinus thrombosis. Vancomycin, ceftriaxone and metronidazole were started and otolaryngology (ENT) was consulted. There was concern for petrous apicitis (bony infection of the temporal bone) or otitic hydrocephalus (increased intracranial pressure due to complication of otitis media). The patient was taken to the operating room later that evening for bilateral myringotomy tube placement.

MRI of brain (plus angiography and venography) were obtained the following morning. The MRI showed a partially occlusive thrombus of the right transverse and sigmoid sinuses with extension in the right jugular vein. Additionally, it showed effusions consistent with otomastoiditis without evidence of bony erosion to suggest coalescent mastoiditis.

ENT felt that this presentation was somewhat atypical for sigmoid sinus thrombosis. Through shared decision-making with mother, the patient was taken back to the operating room on hospital day #2 for mastoidectomy to decompress any potential areas of infection and inflammation over the sigmoid sinus.

Patient had improvement of his headache after the procedures, but his gaze deficits were unchanged. Infectious diseases was consulted and his antibiotic therapy was narrowed to ampicillin-sulbactam. Blood and intraoperative cultures did not grow any pathogens. It was presumed that he had a smoldering otomastoiditis that was partially treated by his initial oral antibiotic courses. Hematology was consulted for initiation of anticoagulation, and rivaroxaban was started once he was outside of the post-operative window.

The patient completed four weeks of antibiotics with amoxicillin-clavulanate and eight weeks of anticoagulation with rivaroxaban. Per review of documentation, patient still has residual headaches, but his thrombus has resolved, and his eye symptoms are improved.

References:

1. Hanna FA, Jabaly-Habib H, Halachmi-Eyal O, Hujierat M, Sakran W, Spiegel R. Sixth nerve palsy in children: etiology, long-term course, and a diagnostic algorithm. J Child Neurol. 2022;37(4):281-287.
2. Chang MY, Borchert MS. Etiology and outcomes of acquired pediatric sixth nerve palsies. J Neuroophthalmol. 2022;42(1):e254-e259.
3. Chandrasekhar SS. Chapter 29. Otitic hydrocephalus. In: Kohan D, Heman-Ackah SE, Chandrasekhar SS, eds. Neurotology. Oxford University Press; 2014.
4. Lee AG, Prospero Ponce CM, Vickers A. Sixth cranial nerve (abducens nerve) palsy. In: Wilterdink JL, ed. UpToDate. UpToDate; 2023. Accessed August 15, 2023. https://www.uptodate.com/contents/sixth-cranial-nerve-abducens-nerve-palsy