This report details an iatrogenic paresis of the abducent nerve and partial palsy of the oculomotor nerve leading to diplopia, strabismus and ptosis following a PSA nerve block and extraction of maxillary right second molar. The patient was treated symptomatically, and the recovery was uneventful. Relevant anatomical pathways with review of literature are discussed.
Now we'll move on to look at the third, fourth and sixth cranial nerves: the oculomotor, trochlear, and abducent. They're motor nerves. Between them they supply the six muscles that move the eye, and also the levator of the upper lid. As we've seen, the oculomotor nerve arises between the cerebral peduncles, the trochlear nerve arises from the back of the midbrain, and the abducent nerve arises below the pons.
The bony opening that these three nerves pass through is the superior orbital fissure, but their openings in the dura are quite a bit further back. The oculomotor nerve passes through the dura just alongside the posterior clinoid process, which is here. The trochlear nerve passes through the dura here, the abducent nerve down here.
The third, fourth and sixth nerves pass forward in the lateral wall of the cavernous sinus. Here's the oculomotor, here's the trochlear, here's the abducent. All three nerves pass forward into the orbit through the superior orbital fissure, which is here.
OBJECT: Hearing preservation remains a challenging problem in vestibular schwannoma (VS) surgery. The ability to preserve hearing in patients with large tumors is subject to particular difficulty. In this study, the authors focus on hearing preservation in patients harboring large VSs. METHODS: A total of 344 consecutive patients underwent surgical removal of VSs over the past 9 years. Of these 344 cases, 195 VSs were > 20 mm in maximum cisternal diameter. Of the 195 cases, hearing preservation surgery was attempted for 54 patients who had a Class A, B, C, or D preoperative hearing level; that is, a pure tone average or= 50% according to the Sanna/Fukushima classification. The tumors were classified as moderately large (21-30 mm based on the largest extrameatal diameter), large (31-40 mm), and giant (>or= 41 mm) according to the international criteria. The authors categorized patients with Class A, B, C, D, or E hearing (pure tone average or= 40%) as having preserved hearing postoperatively. RESULTS: Forty-one tumors (75.9%) were totally removed and 13 (24.1%) had near-total removal. Of the 54 patients, 29 maintained their hearing postoperatively; the overall hearing preservation rate was 53.7%. Analysis based on the preoperative hearing level showed that hearing was preserved in 14 (77.8%) of 18 cases for Class A; in 8 (47.1%) of 17 cases for Class B; in 4 (57.1%) of 7 cases for Class C; and in 3 (25.0%) of 12 cases for Class D. In addition, according to the analysis based on the tumor size, 20 (52.6%) of 38 patients with moderately large tumors retained their hearing, as did 5 (50.0%) of 10 patients with large tumors and 4 (66.7%) of 6 patients with giant tumors. Complications included 2 cases of bacterial meningitis that were cured by intravenous injection of antibiotics, 3 cases of subcutaneous CSF leakage that resolved without any surgical repair, and 1 case of temporary abducent nerve palsy. There were no deaths in this series. CONCLUSIONS: The results indicate that successful hearing preservation surgery in large VSs is possible with meticulous technique and attention to adhesions between the tumor and the cochlear nerves.
The article attempts a semiotic analysis of the "humble argument," the most inward one of a nest of three arguments presented by Peirce in his 1908 essay "A Neglected Argument for the Reality of God." The analysis is based on the system of ten trichotomies Peirce developed in 1905 but never explained. The article (1) tries to establish which element of an argument acts as the sign, which element acts as the object, and which element acts as the interpretant, (2) sets out to identify structural differences between seme-abducents, pheme-abducents, and delome-abducents, and (3) draws conclusions concerning the humble argument. 041b061a72