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Primary aberrant regeneration or oculomotor nerve synkinesis is a rare
condition in which cranial nerve III regeneration occurs without a preceding,
acute palsy. It has been typically associated with aneurysms or meningiomas
in the cavernous sinus that do not warrant urgent imaging.1
We describe a patient with primary aberrant regeneration caused by an aneurysm
located at the junction of the left posterior communicating (PCOM) and posterior
cerebral arteries, indicating that imaging should not be delayed.
A 65-year-old woman complained of right eyelid ptosis for 3 years. She
denied diplopia. Her medical history was unremarkable. Her visual acuity was
20/25 OD and 20/20 OS. The eyelid margin to corneal reflex distance measured
2 mm OD and 4 mm OS. Her right pupil was 4 mm and reacted briskly to light.
Her left pupil was 5 mm and did not react to light. No relative afferent pupillary
defect was observed.
The patient assumed a chin-up position in primary gaze. The left eye
had decreased elevation, adduction, and infraduction; motility was full in
the right eye (Figure 1). With the
right eye fixating at distance in primary position, she had 35–prism
diopter (PD) hypotropia and 8 PD exotropia of the left eye. The hypotropia
increased in upward gaze to 40 PD and the exotropia increased to 12 PD. The
left upper eyelid retracted in downward gaze and adduction (pseudo–von
Graefe sign). Slitlamp examination, tonometry, and ophthalmoscopic examination
results were normal.
In primary position (center),
there is a left hypotropia and left exotropia. A mild right ptosis is present.
There is limited elevation, adduction, and infraduction in the left eye. Upper
eyelid retraction is seen on adduction and infraduction in the left eye (lower
Since these findings suggested aberrant regeneration of the oculomotor
nerve in her left eye, magnetic resonance imaging and magnetic resonance angiography
of the brain were performed. The results revealed an enhancing lesion in the
interpeduncular cistern, most likely impinging the left oculomotor nerve (Figure 2). Results of cerebral catheter angiography
confirmed this to be a partially thrombosed aneurysm at the junction of the
left PCOM and posterior cerebral arteries (Figure 3). After neurosurgical consultation, it was decided that
the patient receive follow-up without surgery.
Axial T1-weighted pregadolinium
(A) and gadolinium-enhanced (B) magnetic resonance image showing a 1-cm enhancing
mass in the interpeduncular cistern region (arrows), consistent with a partially
Frontal view of the cerebral angiogram
of the posterior circulation following injection of the right vertebral artery.
A focal outpouching is seen (arrow) at the P1-P2 junction of the left posterior
cerebral and posterior communicating arteries, consistent with a partially
Aberrant regeneration occurs after damage to the oculomotor nerve and
is thought to be caused by misdirection of regenerating axons to anomalous
connections.2 Clinically, the upper eyelid
retracts on attempted downward gaze (pseudo–von Graefe sign) or adduction;
there is minimal to no ptosis in primary position and there may be limited
elevation, adduction, or infraduction. Also, the pupil, which does not react
to light, may constrict on adduction and infraduction.
Primary aberrant regeneration occurs without a history of acute third
cranial nerve palsy. This syndrome was originally thought to be pathognomonic
of cavernous sinus meningiomas.1 Immediate
imaging was not recommended since these masses are slow growing. Subsequently,
other intracavernous mass lesions (aneurysms) were found to produce the syndrome.3
However, unruptured, extracavernous, intradural aneurysms may rarely
cause primary aberrant regeneration.3,4
Our patient is the fourth in the literature, to our knowledge, in whom a PCOM
aneurysm has caused primary aberrant regeneration.3- 5
In 1952, Levin5 described a 68-year-old
woman with primary aberrant regeneration who subsequently died of a ruptured
aneurysm at the junction of the left internal carotid and PCOM arteries. Cox
et al3 described a 76-year-old woman with
primary aberrant oculomotor regeneration and chronic eye pain due to a large,
partially thrombosed aneurysm at the junction of the right PCOM and internal
carotid arteries. No surgery was performed. Varma and Miller4
described a 64-year-old woman with painless primary oculomotor nerve regeneration
caused by an aneurysm at the junction of the right PCOM and internal carotid
arteries. Their patient underwent successful aneurysm clipping.
Our patient had painless primary aberrant regeneration caused by a partially
thrombosed aneurysm at the junction of the left PCOM and posterior cerebral
arteries. This is the first reported instance of an aneurysm at this location
causing primary oculomotor nerve synkinesis. Although primary aberrant regeneration
is most likely associated with slow-growing cavernous sinus lesions, PCOM
aneurysms rarely cause this syndrome. We believe that patients with primary
aberrant oculomotor nerve regeneration should undergo immediate imaging to
detect potentially treatable extracavernous, intradural aneurysms.
Corresponding author and reprints: Peter J. Savino, MD, Wills Eye
Hospital, 900 Walnut St, Philadelphia, PA 19107.
Carrasco JR, Savino PJ, Bilyk JR. Primary Aberrant Oculomotor Nerve Regeneration From a Posterior Communicating Artery Aneurysm. Arch Ophthalmol. 2002;120(5):663-665. doi: