Pupil-sparing oculomotor palsy caused by fusiform arteriosclerotic aneurysm of the basilar artery--a case report

Pupil-sparing oculomotor nerve palsy caused by upward compression of a large posterior communicating artery aneurysm. Case report

A 69-year-old woman without diabetes or hypertension presented with a large posterior communicating artery aneurysm projecting beneath the oculomotor nerve manifesting as a 2-week history of progressive diplopia. Neurological examination revealed external ophthalmoplegia and blepharoptosis without pupil involvement. Neuroimaging showed a large aneurysm in the left internal carotid artery projecting postero-inferiorly. Craniotomy and neck clipping of the aneurysm revealed the origin at the junction of the internal carotid artery and posterior communicating artery, and elevation of the oculomotor nerve. Pupil-sparing oculomotor nerve palsy is often assumed to be caused by ischemic injury such as hypertension and diabetes mellitus. Sometimes compressive lesion can cause pupil-sparing oculomotor nerve palsy with a short interval from the onset of symptoms to diagnosis. Despite the 2-week interval from the onset of symptoms, this patient presented with pupil-sparing oculomotor nerve palsy caused by compressive lesion. Involvement or sparing of the pupil is often considered to be the most important criterion in the diagnosis of isolated oculomotor nerve palsy. This unique case demonstrated that unusual compressive lesions must be taken into consideration in the diagnosis of pupil-sparing oculomotor nerve palsy.

Nonaneurysmal cranial nerve compression as cause of neuropathic strabismus: evidence from high-resolution magnetic resonance imaging

PURPOSE

To seek evidence of neurovascular compression of motor cranial nerves (CNs) in otherwise idiopathic neuropathic strabismus using high-resolution magnetic resonance imaging (MRI).

DESIGN

Prospective, observational case series.

METHODS

High-resolution, surface coil orbital MRI was performed in 10 strabismic patients with idiopathic oculomotor (CN III) or abducens (CN VI) palsy. Relationships between CNs and intracranial arteries were demonstrated by 0.8-mm thick, 162-μm resolution, heavily T2-weighted MRI in fast imaging using steady-state acquisition sequences. Images were analyzed digitally to evaluate cross-sectional areas of extraocular muscles.

RESULTS

In one patient with CN III palsy, an ectatic posterior communicating artery markedly flattened and thinned the ipsilateral subarachnoid CN III. Cross-sections of the affected medial, superior, and inferior rectus muscles 10 mm posterior to the globe-optic nerve junction were 17.2 ± 2.5 mm(2), 15.5 ± 1.3 mm(2), and 9.9 ± 0.8 mm(2), significantly smaller than the values of 23.6 ± 1.9 mm(2), 30.4 ± 4.1 mm(2), and 28.8 ± 4.6 mm(2), respectively, of the unaffected side (P < .001). In 2 patients with otherwise unexplained CN VI palsy, ectatic basilar arteries contacted CN VI. Mean cross-sections of affected lateral rectus muscles were 24.0 ± 2.3 mm(2) and 29.8 ± 3.1 mm(2), significantly smaller than the values of 33.5 ± 4.1 mm(2) and 36.9 ± 1.6 mm(2), respectively, in unaffected contralateral eyes (P < .05).

CONCLUSIONS

Nonaneurysmal motor CN compression should be considered as a cause of CN III and CN VI paresis with neurogenic muscle atrophy when MRI demonstrates vascular distortion of the involved CN. Demonstration of a benign vascular cause can terminate continuing diagnostic investigations and can expedite rational management of the strabismus.

Pupil-sparing oculomotor nerve paresis as an early symptom of unruptured internal carotid-posterior communicating artery aneurysms: three case reports

Oculomotor nerve paresis caused by internal carotid-posterior communicating artery (IC-PC) aneurysm usually manifests with pupillary dysfunction. Recently, we treated three patients with unruptured IC-PC aneurysms initially manifesting as pupil-sparing oculomotor nerve paresis, which resolved after clipping of the aneurysms. Review of the 56 patients admitted to our hospital with unruptured IC-PC aneurysms between January 2000 and December 2006 identified 6 patients with oculomotor nerve disturbances, and the 3 present cases with pupil sparing. The incidence of IC-PC aneurysms manifesting as pupil-sparing oculomotor nerve paresis may be increasing with improved accessibility to medical services and wider awareness of oculomotor nerve paresis as a symptom of cerebral aneurysms. Cerebral angiography should be performed in patients with pupil-sparing oculomotor nerve paresis.

Pupil sparing incomplete third nerve palsy secondary to a cavernous sinus meningioma: challenges in management

BACKGROUND

The diagnosis of incomplete third nerve palsy can be clinically challenging because the aetiologies, as well as presentations, can be variable and subtle. The optometric clinician should be familiar with the association of third nerve palsy with compressive lesions, including the clinical presentations and management of these patients.

CASE REPORT

We present a 68-year-old hypertensive male complaining of intermittent diplopia for the previous six months. Neurological examination revealed a mild deficit in adduction, reduced range of vertical motility and questionable ptosis, all limited to the OD. No pupillary involvement was noted. MRI revealed a cavernous sinus meningioma. The patient elected against surgery, choosing MRI every six months.

CONCLUSION

Due to the subtle clinical presentation of incomplete pupil sparing third nerve palsy, this ophthalmoplegia may be easily overlooked. The associated aetiologies of palsy of cranial nerve three (CN3) carry increased risk of morbidity and mortality. Management should include evaluation for mass lesions and/or vascular aetiologies, regardless of pupillary involvement.

Case Studies in Neuro-Ophthalmology for the Neurologist

In summary, neurologists should be aware of emergent neuro-ophthalmic conditions: (1) temporal arteritis (GCA), (2) IIH, (3) intracranial shunt malfunction, (4) pituitary apoplexy, and (5) pupil-involved TNP. Earlier recognition and treatment of these disorders makes a difference in final out-come. Appropriate evaluation and management may be vision or life saving.

Pupil-sparing third nerve palsy with preoperative improvement from a posterior communicating artery aneurysm

BACKGROUND

Despite the plenitude of reports concerning partial or complete third nerve palsies, especially as presenting symptoms with posterior communicating artery (PCoA) aneurysms, we present a patient with an unusual variation.

CASE DESCRIPTION

A 66-year-old woman presented with progressive right-sided headaches and diplopia and was found to have a partial, pupil-sparing third nerve palsy. A small right-sided PCoA aneurysm, nearly indistinguishable from an infundibulum, was identified on magnetic resonance angiography and subsequent digital subtraction angiography. The third nerve palsy improved before surgical repair of the aneurysm.

RESULTS

Microsurgical exploration revealed a small PCoA aneurysm, which was tethered to the third nerve by arachnoid adhesions. Adhesions were lysed and the aneurysm was repaired sparing the PCoA and its branches. The patient's third nerve function recovered completely postoperatively.

CONCLUSIONS

Even a very small PCoA aneurysm may present with an improving, pupil-sparing partial third nerve palsy. Selection of patients for imaging studies should take this unusual variant into consideration. We describe the anatomy and potential mechanisms of this pupil-sparing third nerve palsy.

The evaluation of isolated third nerve palsy revisited: an update on the evolving role of magnetic resonance, computed tomography, and catheter angiography

The evaluation and management of the neurologically isolated third nerve palsy continues to evolve. The major concern for the clinician confronted with a patient with a third nerve palsy has been the exclusion of an intracranial aneurysm. The evolution of new imaging techniques, such as computed tomography angiography and magnetic resonance angiography, have provided new imaging options for clinicians. This article reviews the pertinent recent literature on the use of these imaging studies in evaluating the patient with a third nerve palsy.