**Question:** Which of the following is a feature of Medial Medullary Syndrome, except:

A. Hemiparesis
B. Hemiplegia
C. Horner's syndrome
D. Diplopia

**Core Concept:** Medial Medullary Syndrome is a clinical entity caused by damage to the medial longitudinal fasciculus in the medulla oblongata. This leads to a characteristic set of symptoms due to the involvement of multiple cranial nerves and associated reflexes.

**Why the Correct Answer is Right:**

Correct Answer: Diplopia (double vision).

Diplopia is a feature of ocular palsies, which can be caused by various neurological conditions. In Medial Medullary Syndrome, the ocular motor nerves (cranial nerve III, IV, and VI) are involved. However, unlike the other options, diplopia is not a direct consequence of medial medullary syndrome due to the involvement of different pathways and structures in its pathogenesis.

**Why Each Wrong Option is Incorrect:**

Option A (Hemiparesis) refers to reduced muscle strength on one side of the body. While weakness may be present in some cases, the primary feature of Medial Medullary Syndrome is diplopia due to involvement of ocular motor nerves.

Option B (Hemiplegia) refers to complete paralysis on one side of the body. Similar to hemiparesis, hemiplegia is not a key feature of Medial Medullary Syndrome, as the primary feature is diplopia due to ocular motor nerves involvement.

Option C (Horner's syndrome) refers to a constellation of symptoms involving the sympathetic autonomic nervous system, including ptosis (lowered eyelid), miosis (constricted pupil), and anhidrosis (reduced sweating). While Horner's syndrome may be seen in some cases of Medial Medullary Syndrome, it is not a key feature of the syndrome, as the primary feature is diplopia due to ocular motor nerves involvement.

**Clinical Pearl:** Medial Medullary Syndrome is often referred to as "Wallenberg's syndrome" due to the name of the physician who first described the syndrome, Sir Henry Head.

In conclusion, the correct answer, Diplopia, is a consequence of ocular motor nerves involvement in Medial Medullary Syndrome, while the wrong options are related to symptoms involving other systems or are not specific to Medial Medullary Syndrome.