Table 1.
Summary of six retrospective studies on patients with sixth nerve paresis
| Etiologies of acquired VI nerve palsy | |||||||
|---|---|---|---|---|---|---|---|
| Schrader1 (1960) (isolated) | Rucker2 (1966) | Johnston3 (1968) | Robertson4 (1970) (children) | Rush5 (1981) | Potel6 (2004) | Bagheri7 (2010) | |
| Total number of patients | 104 | 607 | 158 | 133 | 419 | 137 | 33 |
| Etiologies (%) | |||||||
| Neoplasm | 7 | 33 | 13 | 39 | 15 | 5 | 2 |
| Trauma | 3 | 12 | 32 | 20 | 17 | 12 | 18 |
| Aneurysm | 0 | 3 | 1 | 3 | 3 | 2 | 0 |
| Ischemic | 36 | 8 | 16 | 0 | 18 | 16 | 1 |
| Miscellaneous* | 30 | 24 | 30 | 29 | 18 | 19 | 6 |
| Undetermined** | 24 | 20 | 8 | 9 | 29 | 26 | 6 |
*
6% to 30% attributed to a miscellaneous group of causes that includes leukemia, migraine, pseudotumor cerebri, multiple sclerosis; the miscellaneous group of etiologies reflects the poor localizing value of sixth nerve paresis.
**
6% to 29%, etiology undetermined, reflecting vulnerability of the nerve to conditions which are transient, benign and unrecognizable.