**Question:** Which of the following is not seen in superior oblique palsy?

A. Involvement of the inferior oblique muscle
B. Diplopia in primary gaze
C. Dissociated vertical deviation in adduction
D. Dissociated vertical deviation in abduction

**Core Concept:**

Superior oblique palsy is a type of ocular motoneuron disease that primarily affects the superior oblique muscle, which is responsible for downward and medial rectus eye movement. This condition results from damage to the oculomotor nerve (CN III) or its terminal branches, leading to impaired function of the superior oblique muscle.

**Why the Correct Answer is Right:**

The superior oblique palsy typically presents with the following symptoms and signs:
1. Involvement of the inferior oblique muscle is not a typical feature of superior oblique palsy.
2. Diplopia (double vision) in primary gaze is also not typically seen in this condition, as the primary gaze is the central point of vision where the eyes are aligned, and the superior oblique muscle is not involved.
3. Dissociated vertical deviation in adduction is also not typically observed in superior oblique palsy. In this situation, the affected eye deviates upward and medially when the healthy eye is pulled downwards, which is not a typical feature of superior oblique palsy.
4. Dissociated vertical deviation in abduction, on the other hand, is a key feature of superior oblique palsy. In this condition, the affected eye deviates upward when the healthy eye is pulled downward, indicating involvement of the superior oblique muscle.

**Why Each Wrong Option is Incorrect:**

A. Involvement of the inferior oblique muscle is not a typical feature of superior oblique palsy, as mentioned above.
B. Diplopia in primary gaze is not typically seen in superior oblique palsy, as this condition involves the superior oblique muscle and not the primary gaze position.
C. Dissociated vertical deviation in adduction is not a typical feature of superior oblique palsy, as mentioned above.
D. Dissociated vertical deviation in abduction is the correct answer as it indicates involvement of the superior oblique muscle, which is typically affected in superior oblique palsy.

**Clinical Pearls:**

Superior oblique palsy can be suspected in patients with dissociated vertical deviation in abduction, as this sign is specific to the superior oblique muscle. Other symptoms and signs like dissociated vertical deviation in adduction are seen in other conditions like inferior oblique muscle palsy or gaze-evoked dissociated vertical deviation.

In summary, the correct answer is D, as dissociated vertical deviation in abduction indicates involvement of the superior oblique muscle, which is typically affected in superior oblique palsy. The other options refer to dissociated vertical deviation in adduction, which are seen in other conditions like inferior oblique muscle palsy or gaze