Misinnervation in the third nerve palsy: Vertical synergistic divergence or consummate congenital bilateral asymmetrical Brown’s syndrome with congenital ptosis?

The purpose of our paper was to bring to the reader’s attention the possible confusion that can occur when one uses OCT in tobacco-alcohol-induced toxic optic neuropathy. While the first two cases showed the expected pattern of axonal loss in the temporal side of the disc, Case 3 surprisingly did not demonstrate it. It is possible that the finding in Case 3 indicates a lack of sensitivity of OCT. We believe that it indicates that the development of retinal nerve fiber layer loss in this condition may take longer than we previously expected based on our experience with other conditions demonstrating retinal nerve fiber layer loss in the temporal side of the optic disc.[3] We believe it could also indicate that possible axonal loss may have been counterbalanced by nerve fiber edema (possible due to axoplasmic flow stasis). It is therefore important to emphasize that such a pattern can occur in order to avoid diagnostic confusion.

The purpose of our paper was to bring to the reader's attention the possible confusion that can occur when one uses OCT in tobacco-alcohol-induced toxic optic neuropathy. While the first two cases showed the expected pattern of axonal loss in the temporal side of the disc, Case 3 surprisingly did not demonstrate it. It is possible that the finding in Case 3 indicates a lack of sensitivity of OCT. We believe that it indicates that the development of retinal nerve fiber layer loss in this condition may take longer than we previously expected based on our experience with other conditions demonstrating retinal nerve fiber layer loss in the temporal side of the optic disc. [3] We believe it could also indicate that possible axonal loss may have been counterbalanced by nerve fiber edema (possible due to axoplasmic flow stasis). It is therefore important to emphasize that such a pattern can occur in order to avoid diagnostic confusion.
Although we understand that VEP may be helpful in many conditions, we agree that it is not specific and do not believe it is necessary for the diagnosis. We did not use it in any of these cases. We do not believe that the presence of edema should have any correspondence with arcuate scotomas since it is hard to know exactly what the enlargement of the retinal nerve fiber layer signifies.
In conclusion, our study had the purpose of investigating the possible use of OCT in tobacco-alcohol-induced toxic optic neuropathy to quantify axonal loss and to emphasize that if may fail in that regard as documented by one of our cases. We thank for the important observations and for the opportunity to further discuss the subject. Ocular motility conforms to the pattern of alternating abducting hypertropia, broadly sported by bilateral primary superior oblique overactions [PSOOA], bilateral inferior oblique / inferior rectus palsies [IOPs / IRPs], bilateral BS, and laterally alternating skew. A negative head tilt test rules out bilateral IOPs and IRPs. Bilateral PSOOA will not produce primary position deviation or ptosis and ductions will be full, congenital laterally alternating skews are non-isolated. The jigsaw for bilateral BS is complete.

Frederico Castelo Moura, Mário L R Monteiro
Widening of a palpebral fissure and downshoot of the eye in adduction may be seen in BS, but they have been interpreted as lid retraction and synergistic divergence by the author. [1,2] Bilateral cases usually sport a V pattern, provided elevation is possible, and an A pattern noted as superior obliques [SOs] are overacting. [1] BS may not have intorsion in the primary position, but as the eyes elevate intorsion sets in.
Underaction of the IOs in the ductions was noted [1] and was strongly suggestive of BS. A forced duction test holds the key, but was overlooked. SOs could be underacting / normally acting or overacting in BS and could influence the surgical strategy, as SO tenotomies with overacting SOs might not end up in SO palsies postoperatively.
Brown's Syndrome is rare, being bilateral in 5 to 10% of the cases. [2] Associations include congenital ptosis and Marcus Gunn Jaw winking phenomena, [2] all clubbed under congenital cranial dysinnervation disorders [CCDDs], [3] congenital third nerve palsy is not one of them, as surmised. [1] Right-sided preponderance in unilateral cases may explain more severe involvement with ptosis and hypotropia in the right eye, here.

Letters to Editor
Dear Editor, I read the comments given by Pandey et al. [1] It is difficult to understand how they could convert this case [2] into a bilateral Brown's syndrome (BS) case. The only finding that bilateral superior oblique overaction is present does not point to a bilateral BS. The child on elevation of the left eye showed a direct depression of the right eye [ Fig. 1]. There is a limitation of the right eye in depression. Why should that happen in a bilateral BS? The lid retraction was present in downgaze [2] and not in adduction, very similar to one seen in pseudo-Von Graefe's sign. The adduction, depression in abduction, and elevation in adduction were restricted in the right eye but not in the left. [2] A right eye BS would not have the limitation of depression in abduction as was seen in our case. [2] The ductions were completely normal in the left eye and so a question of BS in the left eye does not arise. No Marcus Gunn jaw wink was seen which was supposedly completing the jigsaw puzzle for the authors. A forced duction test was not overlooked but the child was not cooperative and his parents did not consent for general anesthesia. [2] Not everything can be written about the case (which was discussed with the reviewers) because of the word limit.