## Core Concept
Sydenham chorea is a neurological disorder that occurs as a complication of rheumatic fever. It is characterized by involuntary, purposeless movements. The condition is associated with an autoimmune response to Group A beta-hemolytic streptococcal infection. Treatment focuses on managing symptoms and preventing further rheumatic fever episodes.

## Why the Correct Answer is Right
The correct approach for managing intractable Sydenham chorea involves the use of immunosuppressive or immunomodulatory therapies, in addition to symptomatic treatment. Plasmapheresis and intravenous immunoglobulin (IVIG) are considered for severe, refractory cases. Among the options provided, **Plasmapheresis** is a recognized treatment for severe and intractable cases, aiming to rapidly reduce antibody levels.

## Why Each Wrong Option is Incorrect
- **Option A:** While antipsychotics or anti-choreic agents like haloperidol may help manage symptoms of chorea, they do not address the underlying pathophysiology and are not considered first-line for intractable Sydenham chorea.
- **Option B:** Valproate can be used for symptomatic relief of chorea but is not the preferred treatment for intractable cases.
- **Option C:** Corticosteroids are a mainstay in the treatment of rheumatic fever and Sydenham chorea, but for intractable cases, additional or alternative therapies are required.

## Clinical Pearl / High-Yield Fact
A key point to remember is that Sydenham chorea is a manifestation of rheumatic fever, and its management includes prophylaxis against streptococcal infections to prevent recurrence. In cases of intractable chorea, considering therapies like **plasmapheresis** or **IVIG** can be lifesaving.

## Correct Answer Line
**Correct Answer: D. Plasmapheresis.**