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M.J. Kupersmith, T.A. Cox; Does the Clinical Evaluation Distinguish Third Nerve Palsies Due to Ischemia From an Unruptured Posterior Communicating Artery Aneurysm? . Invest. Ophthalmol. Vis. Sci. 2006;47(13):781.
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Numerous studies and editorials have described the risk of harboring a life–threatening intracranial aneurysm in patients with a third nerve palsy. We prospectively assessed the utility of the clinical profile in distinguishing patients with an idiopathic/ischemic etiology third nerve palsy from patients with unruptured posterior communicating (pcomm) aneurysms.
Consecutive patients with isolated acute third nerve palsy, not due to ruptured aneurysms, and patients with unruptured pcomm aneurysms had gadolinium enhanced MRI and 3D time of flight MRA. We placed patients with third nerve palsy without a causative lesion on MRA and MRI into group 1 (presumed ischemic) and patients with pcomm aneurysms seen on MRA into group 2. We assessed demographics, systemic factors, clinical features of ocular motor (focal or diffuse, ductions graded 0 to –5), lid and pupillary dysfunction, and focal pain frequency and severity (grade 0– 3).
The mean age was 61 + 17 years for 73 patients in group 1 and 59.3 + 12 years for 45 patients in group 2 (61.2 for 15 with third nerve palsy). Diabetes occurred in 34 (46%) group 1 patients and in 5 (11.1%, p=0.0001) group 2 patients. Hypertension occurred in 32 patients (41.6%) of group 1 and in 19 patients (42%) of group 2. The pattern and severity of ocular motor and lid dysfunction, and pain frequency (p>0.2) were similar for group 1 patients and 15 symptomatic group 2 patients. The mean total score for ophthalmoparesis was similar in group 1 (–11.1) and group 2 (–10.4) third nerve palsies. The amount of ptosis was similar for group 1 (5.5 mm) and group 2 (5.6 mm). The mean pupil size ipsilateral to the third nerve paresis was 4.3 mm (mean for contralateral pupil 3.8 mm) in group 1 and 5.3 mm (p=0.005) (mean for contralateral pupil 3.7 mm) for group 2 with oculomotor palsy. The pupillary light response was abnormal in 27 (37%) patients in group 1 (6 bilateral diabetic or surgical and 3 unilateral trauma associated dysfunction) and in 12 (80%, p=0.016) patients in group 2 with third nerve palsies (1 bilateral surgical trauma). Of patients with complete external third nerve palsies, 9/22 in group 1 and 0/4 in group 2 had a normal pupil.
Only one clinical feature, complete external third nerve palsy with a normal pupil, distinguishes ischemia from an unruptured pcomm aneurysm in a patient with isolated third nerve palsy.
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