Megan McClung MD

Dell Children’s Medical Center
University of Texas at Austin

An eight year old previously healthy boy with no significant past medical history presents to the Emergency Room for evaluation of blurry vision. It started approximately 24 hours prior to presentation and has been progressively worsening.  He describes double vision and sees “two heads on one body.” His left eye has been sore for about two days.

His mother states that he has also been complaining of left-sided headaches the last couple of weeks. There is no history of head trauma or injury to the eye. Review of systems is negative for fevers, altered mental status, numbness or weakness. He reports associated photophobia, and has had one episode of vomiting.

T 37   HR65    BP100/65     RR24

GEN   He appears anxious, and is holding his head tilted to the left side.

HEENT   He has pronounced left sided proptosis, ptosis, and esotropia, with surrounding peri-orbital edema. Left pupil is 5 mm and sluggishly reactive, compared to the right which is 4mm and brisk. Visual acuity is 20/20 on the right, and 20/100 on the left

The remainder of his exam is unremarkable, including an otherwise normal neurological exam.

 

The team obtained a head CT and subsequently an MRI which revealed the diagnosis.

 

 

 

What is the diagnosis?

A.   Orbital cellulitis with abscess

B.   Arachnoid cyst

C.   Thrombosed arterial aneurysm

D.   Optic nerve glioma

E.   Neurocystercosis

 

C.   Thrombosed arterial aneurysm

More specifically, in this case the patient had a Thrombosed Giant Aneurysm of his left internal carotid artery. The proximity of cranial nerves three and six to the pathway of the internal carotid artery make them susceptible to damage from an ICA aneurysm.  In this case, the patient’s aneurysm was approximately 3 cm in diameter and impinged upon these cranial nerves producing clinically his neurologic deficits.

  • Complete palsy of CN 6 produced loss of lateral gaze on the ipsilateral side and resting left sided esotropia
  • Partial palsy of CN 3 resulted in ptosis and anisocoria

Additionally, the patient was bradycardic on presentation, which was likely due to the oculocardiac reflex.  A decreased pulse rate occurs when traction is applied to the extra-ocular muscles or when the eyeball is compressed, and is mediated by nervous fibers that connect the cranial nerves with the vagus and parasympathetic nervous system.

His CT scan revealed a well circumscribed, hyperdense mass centered on the left cavernous sinus. MRI/MRA imaging demonstrated a multi-layered thrombus with “onion skin” appearance, in keeping with the diagnosis of  giant thrombosed aneurysm.

Subsequent Cerebral Angiography revealed complete occlusion of the left ICA surrounding the aneurysm, without active flow; therefore, surgical clipping was not pursued.  His surrounding vessels were patent allowing adequate collateral flow with good neurologic prognosis.  The patient was started on steroids and aspirin, and he started to show symptomatic improvement within a couple of days. After about a week in the hospital, he was ready to go home; plan of care at time of discharge included continuing aspirin therapy, repeat CT Angiography about 3-4 weeks later, and interim eye patching to relieve his symptom of double vision.

Intracranial aneurysms are rare in children.  It is postulated that improper vascular self-repair is a contributing factor in most cases.  Sometimes there is an acute precipitant, such as preceding trauma, infection, or inflammation.

Aneurysm “types” are categorized broadly based upon different underlying pathological mechanisms; the 4 major sub-types include traumata, infection,  dissection, and saccular.

Affected patients are typically symptomatic, and exhibit signs related to ischemia, hemorrhage, and/or mass effect; common clinical presentations include seizures, headaches, neurologic deficits, and sub-arachnoid hemorrhage.

Infectious aneurysms constitute approximately 15% of all pediatric intracranial aneurysms; the most common causative pathogen is Staph aureus, followed by Strep viridans. Blood cultures will usually be positive. The infection seeds from bacteremia, such as with septic emboli related to infectious endocarditis; alternatively, the infection can seed by local extravascular extension, such as vessel wall invasion by adjacent sinus infection.

Traumatic aneurysms constitute approximately 5% of all pediatric aneurysms.  Closed head injury is the commonest precipitant, and typically the clinical presentation is delayed hemorrhage approximately 2-4 weeks following the traumatic incident.

Dissecting aneurysms are the commonest form of cerebral aneurysms in children, accounting for up to 50% of all cases.  The Giant Thrombosed Cerebral Aneurysm is of this particular subtype; in this entity, sub-acute recurrent dissections with repeated hemorrhages of varying ages produce a multi-layered thrombus with an “onion skin” appearance on neuroimaging. The onset of symptoms are typically gradual and related to mass effect, consistent with the clinical presentation of the patient in this scenario.  He did not have hemorrhagic nor ischemic changes on MRI, but rather a space occupying lesion which produced clinically cranial nerve three and six palsies related to mass effect.

Saccular, also known as “berry-type” or “classical” aneurysms, are the final subtype, and are characterized by focal luminal out-pouchings at arterial bifurcations. These tend to run in families, and are associated with underlying connective tissue disorders.

Although specific therapies vary across sub-types, common treatment goals are to prevent hemorrhage, aneurysm growth, and ischemic effects; vascular bypass, coil embolization, surgical clipping, and anti-platelet therapy are common treatment options.

References

Requejo F, Ceciliano A, Cardenas R, Villasante F, Jaimovich R, and Zuccaro G (2010). Cerebral aneurysms in children: are we talking about a single entity? Childs Nerv Sys  26: 1329-1335