Literature review regarding the methodology of assessing third nerve paresis associated with non-ruptured posterior communicating artery aneurysms

The association of third cranial nerve palsy subsequent to an enlarging posterior communicating artery (P-Com A) aneurysm has been well described. In our current communication, we review the relevant literature and propose a classification system for the severity of the third cranial nerve palsy, correlating it to the postoperative recovery. Our four grade scale (I-IV) included the degree of the levator palpebrae muscle paresis, the presence of pupillary reaction and the impairment of the third nerve mediated extraocular muscle movement. We evaluated five patients with third nerve palsy secondary to non-ruptured, P-Com A aneurysm. Patients were re-evaluated at 2, 4, 8, 24 weeks postoperatively. Four of the five patients had complete recovery within 4-8 weeks after surgery. One patient had grade II third nerve paresis and complete resolution of the third nerve symptoms within 4 weeks, whereas three patients with grade III and IV had complete resolution 4-8 weeks after surgery. The fifth patient, with grade IV paresis, had minimal (grade III) improvement 6 weeks after surgery, and incomplete recovery (grade I) 6 months postoperatively. Our simple grading system of third nerve palsy associated with P-Com A aneurysms, can be a helpful tool for the initial evaluation and for the monitoring of recovery in these patients.